Ecological Habitats and Niche Definitions in Ecology

Ecological Habitat Dr. Keshav Singh Associate Professor Department of Zoology D.D.U Gorakhpur University, Gorakhpur

Ecological Habitat occur and the type of community that is formed as a result. More specifically, "habitats can be defined as regions in environmental space that are composed of multiple dimensions, each representing a biotic or abiotic environmental variable; that is, any component or characteristic of the environment related directly (e.g. forage biomass and quality) or indirectly (e.g. elevation) to the use of a location by the animal." For example, a habitat might be an aquatic or terrestrial environment that can be further categorized as a montane or alpine ecosystem. Habitat shifts provide important evidence of competition in nature where one population changes relative to the habitats that most other individuals of the species occupy. For example, one population of a species of tropical lizards (Tropidurus hispidus) has a flattened body relative to the main populations that live in open savanna. The population that lives in an isolated rock outcrop hides in crevasses where its flattened body offers a selective advantage. Habitat shifts also occur in the developmental life history of amphibians, and in insects that transition from aquatic to terrestrial habitats. Biotope and habitat are sometimes used interchangeably, but the former applies to a community's environment, whereas the latter applies to a species' environment. Additionally, some species are ecosystem engineers, altering the environment within a localized region. For instance, beavers manage water levels by building dams which improves their habitat in a landscape. Biodiversity of a coral reef. Corals adapt to and modify their environment by forming calcium carbonate skeletons. This provides growing conditions for future generations and forms a habitat for many other species. The habitat of a species describes the environment over which a species is known to

Niche Definitions of the niche date back to 1917, but G. Evelyn Hutchinson made conceptual advances in 1957 by introducing a widely adopted definition: "the set of biotic and abiotic conditions in which a species is able to persist and maintain stable population sizes." The ecological niche is a central concept in the ecology of organisms and is sub-divided into the fundamental and the realized niche. The fundamental niche is the set of environmental conditions under which a species is able to persist. The realized niche is the set of environmental plus ecological conditions under which a species persists. The Hutchinsonian niche is defined more technically as a "Euclidean hyperspace whose dimensions are defined as environmental variables and whose size is a function of the number of values that the environmental values may assume for which an organism has positive fitness." Biogeographically patterns and range distributions are explained or predicted through knowledge of a species' traits and niche requirements. Species have functional traits that are uniquely adapted to the ecological niche. A trait is a measurable property, phenotype, or characteristic of an organism that may influence its survival. Genes play an important role in the interplay of development and environmental expression of traits. Resident species evolve traits that are fitted to the selection pressures of their local environment. This tends to afford them a competitive advantage and discourages similarly adapted species from having an overlapping geographic range. The competitive exclusion principle states that two species cannot coexist indefinitely by living off the same limiting resource; one will always out-compete the other. When similarly adapted species overlap geographically, closer inspection reveals subtle ecological differences in their habitat or dietary requirements. Some models and empirical studies, however, suggest that disturbances can stabilize the co-evolution and shared niche occupancy of similar species inhabiting species-rich communities. The habitat plus the niche is called the ecotope, which is defined as the full range of environmental and biological variables affecting an entire species.

Niche construction Organisms are subject to environmental pressures, but they also modify their habitats. The regulatory feedback between organisms and their environment can affect conditions from local to global scales, over time and even after death, such as decaying logs or silica skeleton deposits from marine organisms. The process and concept of ecosystem engineering is related to niche construction, but the former relates only to the physical modifications of the habitat whereas the latter also considers the evolutionary implications of physical changes to the environment and the feedback this causes on the process of natural selection. Ecosystem engineers are defined as: "organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. In so doing they modify, maintain and create habitats." The ecosystem engineering concept has stimulated a new appreciation for the influence that organisms have on the ecosystem and evolutionary process. The term "niche construction" is more often used in reference to the under-appreciated feedback mechanisms of natural selection imparting forces on the abiotic niche. An example of natural selection through ecosystem engineering occurs in the nests of social insects, including ants, bees, wasps, and termites. There is an emergent homeostasis or homeorhesis in the structure of the nest that regulates, maintains and defends the physiology of the entire colony. Termite mounds, for example, maintain a constant internal temperature through the design of air-conditioning chimneys. The structure of the nests themselves are subject to the forces of natural selection. Moreover, a nest can survive over successive generations, so that progeny inherit both genetic material and a legacy niche that was constructed before their time

TYPES OF HABITAT TWO TYPES TERRESTRIAL- 1.FOREST 2.GRASSLAND 3.DESERT 4.MOUNTAINS AQUATIC- 1. FRESH WATER 2. MARINE 3. WETLANDS 4. ISLANDS

DESERT A Desert is a type of Habitat or Biome characterised mainly by extreme temperatures and extremely low amount of precipitation. Scientifically speaking a Desert is a region which receives rainfall less than 10 inches or 25cm or less in a year. Deserts are one of the Earth s major types of ecosystems, supporting a community of distinctive plants and animals specially adapted to the harsh environment. About one-third of the Earth's land surface is Desert. Deserts are not only made of sand as commonly believed, they also consist of rocks and mountains. Desert sands are often rock which has weathered down to sand over the centuries. There are many Deserts in the World. The Largest Desert is the Sahara Desert found in North Africa. The largest continuous stretch of sand is called the 'Empty Quarter' which is part of the Arabian Desert that stretches 250,000 sq. miles. Deserts are inhabited by very few Plants and Animals. They are often able to survive by avoiding the driest times and only growing after the rains.

General Characteristics of Deserts Deserts are generally known as 'Areas of Extremes'. The reason being that temperatures in Deserts are either too cold or too hot. Temperatures are high during the day because there is very little moisture in the air to block the Sun's rays from reaching Earth. The arid conditions of the major Desert areas result from their position in subtropical regions to either side of the moist equatorial belt. The high temperature is caused by the intense radiation it receives. The sky is not sheltered by clouds, causing more than 70% of sunlight to penetrate into the ground. Once the Sun goes down, the heat absorbed during the day quickly escapes back into space. Temperatures in excess of 100 degrees fahrenheit during day are not uncommon. But at night, the same Desert experiences a temperatures fall into the 40s or 50s.

Unique Plants - Most Desert Plants are drought or salt-tolerant. Some store water in their leaves, roots, and stems. Other Desert Plants have long tap roots that penetrate the water table, anchor the soil, and control erosion. The stems and leaves of some Plants lower the surface velocity of sand-carrying winds and protect the ground from erosion. Cactus is one of the most common Desert Plant which is adapted to Desert life. Most of the Cacti store water in their leaves, stems and roots. They have very few or no leaves and in most Species, the leaves are modified to needles. Apart from Cacti, Deserts also feature Plants from the Pea Family and Sunflower Family. Cold Deserts have Grasses and Shrubs as dominant vegetation. Some of the Desert Plants Date Palm. Thyme. African Peyote Cactus. Olive Trees Acacia. Needle Grass. Reeds. Black Sage. Buckwheat Bush. Rice Grass. Salt Bush. Arctic Azaleas. Arctic Lupine. Arctic Poppies. Cinquefoil. Campanulas. Buttercups. Lichens. Wild Crocus. Yarrow.

Desert Adapted Animals - Animals that live in the hot Desert have many adaptations. Some animals never drink, but get their water from seeds (some can contain up to 50% water) and plants. Many Animals are nocturnal, sleeping during the hot day and only coming out at night to eat and hunt. Some animals rarely spend any time above ground. Spadefoot toads spend nine months of every year underground. Deserts are home to many Reptiles, Insects, Birds, and small Mammals. The kangaroo mice of North America and the Bilby and Red Kangaroo of Australia are Desert Specialists. The most universal behavioural adaptation used by small Mammals, Reptiles, and Insects to deal with high temperatures is staying in the shadow (shade) of plants or rocks, thus avoiding the direct rays of the Sun. These animals also seek shelter by burrowing into the ground. a burrow, even a few feet underground, can decrease the temperature by several degrees. Another behavioural adaptation used by Desert animals is to remain inactive during the hot daylight hours. They hunt at night when temperatures are cool and when there is less risk of losing precious body water. Animals that use this adaptation are referred to as Nocturnal. Some animals get all of the water they need from the insects, bulbs, and seeds they eat. They will not drink water even when it is available. Some animals have developed salt glands, a physical adaptation that allows the secretion of salt without the loss of water. The absence of sweat glands, and the concentration of urine are other physical adaptations made by Desert animals. Because fat intensifies heat, a unique physical adaptation of some Desert animals is the storage of fat in humps or tails, rather than throughout the entire body. Camel is the best example of such a adaptation. Animals found in Cold Deserts have adopted to the cold environment by having thick fur and fatty layered bodies which protect them from cold and save them during harsh times. Some are even coloured as snow to camouflage themselves from predators and to catch prey as well. Arctic Fox and Polar Bear are examples of such colour adaptations. Some of the Desert Animals Camel. Desert or Kangaroo Rat. Armadillo Lizard. Desert Tortoise. Bilby. Red Kangaroo . Ground Squirrel. Jack Rabbit. Arctic Fox. Rock Ptarmigan. Arctic Wolf. Polar Bear. Musk Ox.

FOREST Forest is a type of Habitat or Biome which has high density of Trees. The FAO (Food and Agriculture Organization) defines Forest as a land with Tree crown cover (or equivalent stocking level) of more than 10% and area of more than 0.5 hectare. The Forest is in fact a complex ecosystem with distinct interrelationships of non living organisms (the plants, animals, micro-organisms) and the non-living, inorganic or abiotic part (soil, climate, water, organic debris, rocks) of an environment. Forests can develop wherever there is an average temperature greater than about 10 C in the warmest month and an annual rainfall in excess of about 200 mm annually. Forests houses over two-thirds of known terrestrial Species of the World. There are various type of Forests of which the Tropical Rainforests are located at latitudes of 10 north and south of the Equator and the latitudes between 53 N and 67 N have Boreal Forests. Over 30% of the Earth's surface is covered with Forests in modern times where as once they covered 50% of total surface of the World. This has happened mainly because of Deforestation caused by Human need for wood, food, housing etc.

General Characteristics of Forests Domination of Trees - Forests are mostly dominated by large Plants like Trees. Some Trees especially in Rainforests gain a lot of height to get more sunlight. Most of other Plants face tough competition from large Plants as these tend to receive most of the nutrition from the environment. Some Plants have evolved to become Creeper and Climbers to combat this competition. They climb over Trees to reach the sunlight as well. Forest Canopy - Forest Canopy refers to the cover of Tall Forests. This top portion of a community of Trees or Plant Crowns serves as the interface between the atmosphere and the land. The Canopy is also the upper habitat for other biological organisms in a Forest ecosystem. The structure of Forest Canopy varies from Forest to Forest because because of the availability of nutrients, Tree arrangement and differences in biological Species. The Forest Canopy is an Ecosystem in itself as it supports a variety of life which is not found in the Forest itself. Availability of good amount of Water - Most of the Forests receive sufficient rains to support the organisms which depend on it. It is only in dry season that these may face shortage of water. This rain water forms ponds and streams which supports further life forms like Plant and Animals. Great Biodiversity - Forests are one of the major Habitats which support a great biodiversity of life than any other Habitat. This is attributed to the easy availability of food and shelter. Scientists estimate that more than half of all the world's plant and animal Species live in tropical Rainforests. A part of this diversity are the local tribal people who depend on the Forest for almost all their needs. Forest Floor - The Forest Floor is composed of fallen leaves, stems, twigs, branches and bark on the surface of the soil. A Forest floor also contains organic and inorganic substances. The Forest Floor is inhabited by various living organisms, such as the fungi, bacteria and other microorganisms as it is rich in nutrients and mineral contents. The Forest Floor has a significant role in the transfer of nutrients in the life cycle of the Forest ecosystem. The leaves that fall on the Forest Floor keep on piling up. These leaves decompose over a period of time and provide essential nutrients which promote the growth of Trees. Variation in Soil Fertility - The soil of Temperate Forests is fertile because Trees' leaves drop to the ground every fall. This litter contributes to the layers of organic material found in Forest soil. The old leaves become a source of food for bacteria and fungi. These organisms facilitate the breaking down of the leaves and other organic material. Decomposition enriches the Forest soil as it provides more nutrients to the living Trees and plants in the Forest ecosystem. However, the soil in tropical rain Forests has poor quality because of the torrential rains. The constant rain erodes and dissolves soil nutrients before the Trees can benefit from them. Complex Ecosystems - Forests are among the most complex ecosystems in the World. Conifer Forests have the simplest structure: a Tree layer rising to about 98 feet (30 m), a shrub layer that is spotty or even absent, and a ground layer covered with lichens, mosses, and liverworts. Deciduous Forests are more complex; the Tree canopy is divided into an upper and lower story, while Rain Forest canopies are divided into at least three strata. The Forest floor in both of these Forests consists of a layer of organic matter overlying mineral soil. The humus layer of tropical soils is affected by the high levels of heat and humidity, which quickly decompose whatever organic matter exists. Fungi on the soil surface play an important role in the availability and distribution of nutrients, particularly in the northern coniferous Forests. Some Species of fungi live in partnership with the Tree roots, while others are parasitically destructive.

Importance of Forests Forests are commonly referred to as Lungs of the Earth. It is primarily because of the presence of a variety of Plants which due to their high density produce massive amount of Oxygen which enables other organisms to breathe. According to one estimate 1 acre of Forest provides over 6 tons of oxygen per year. Forests provide home to diverse Animal and Plant Species which not only provide biodiversity on the Earth but each Species has an important role in the ecosystem. About 1/4 of all the medicines that is produced, originates from Rainforest Plants. For example Curare (toxic plant) comes from a tropical vine, and is used as an anaesthetic and to relax muscles during surgery. Similarly Quinine is derived from the 'Cinchona Tree' which is used to treat Malaria. Forests provide timber which is used for building houses, furniture etc. Forests are the most important component of Earth's Ecosystem as it prevents soil erosion, maintains water cycle, check global warming etc. Without all these roles performed by Forests, the Earth would be uninhabitable. Wildlife tourism generates lots of capital which in turn increases the revenue of the government. Forests still harbour various Species of living organisms which are still being discovered. Each Animal, Insect and Plant contains its individual genetic material that has been evolving for thousands of years. Protecting the Forests not only preserves a process of life that started billions of years ago but it also gives us missing clues to various riddled aspects of life itself.

Forest Classification Tropical Forest - These type of Forests are characterised by their location neat the equator. They have year-round high temperatures and abundant rainfall which makes them a dense and lush with vegetation. They are vital storehouses of biodiversity on the planet. Sub-tropical Forests - These are found to the south and north of the Tropical Forests. The Trees here are adapted to resist the summer drought. Mediterranean Forests - These Forests are found to the south of the temperate regions around the coasts of the Mediterranean, California, Chile and Western Australia. The growing season is short and almost all Trees are evergreen, but mixed hardwood and softwood. Temperate Forests - These Forest are found in eastern North America, north-eastern Asia, and western and eastern Europe. Temperate Forests are a mix of Deciduous and Coniferous Evergreen Trees. Usually, the Broad-Leaved Hardwood Trees shed leaves annually. There are well-defined seasons with a distinct winter and sufficient rainfall. Coniferous Forests - Coniferous Forests are found in the cold, windy regions around the poles. There are both Hard-woods and Conifers found in this region. The Conifers are evergreen and structurally adapted to withstand the long drought-like conditions of the long winters, whereas the Hard-Woods are Deciduous. Montane Forests - These Forests receive most of their precipitation from the mist or fog that comes up from the lowlands and as such are also known as cloud Forests. Some of these Montane Woodlands and Grasslands are found in high-elevation tropical, subtropical and temperate zones. Plants and animals in these Forests are adapted to withstanding the cold, wet conditions and intense sunlight. Trees are mainly Conifers.

ISLAND An Island is a type of Habitat which is surrounded by water on all it's sides and is smaller than a Continent. Islands are found in Oceans, Seas, Lakes and Rivers all over the World. Canada probably has far more Islands than either country, as it has immense areas of Island-strewn lakes and thousands of miles of rocky coastline. Several small countries have no Islands at all. Very small Islands are known as Islets or Keys. A grouping of geographically or geologically related Islands is called an Archipelago. A Desert Island is an Island which is Uninhabited or is yet to be Inhabitable by humans. It is known as a Desert Island not because it has dry climate but because it is deserted, or abandoned. De Long Islands and Blasket Islands are some of the examples of a Desert Island. An Artificial Island is an Island that has been constructed by humans rather than formed by natural means. They are created by expanding existing islets, construction on existing reefs, or amalgamating several natural islets into a bigger Island. Palm Jumeirah in Dubai and Northstar Island, an artificial Island for oil drilling in the Beaufort Sea, are some of the examples of Artificial Island. Classification / Types of Islands 1. Continental Islands - Continental Islands are bodies of land that are connected by the Continental Shelf to a Continent. That is, these Islands are part of an adjacent Continent and are located on the Continental Shelf of that Continent. The Continental Shelf is a gently sloping and relatively flat extension of a Continent that is covered by the Oceans. Its believed most Continental Islands were, at one point, connected to their respective Continents. Rising water levels created them, typically by cutting off a former Peninsula or simply rising high enough to cover most of the coastal regions, leaving only the high ground as Islands. A drop in sea level can reconnect these Islands to the mainland. Microcontinental Island - There is also a special type of Continental Island, known as the Microcontinental Island, which occurs when a Continent is rifted. Examples are Madagascar and Socotra off Africa; New Zealand; New Caledonia; the Kerguelen Islands; and some of the Seychelles. Barrier Island - It is a long narrow sandy Island (wider than a reef) running parallel to the shore. It formed by deposition of tiny rocks where a water current loses some of its carrying capacity. They usually occur in chains, consisting of anything from a few Islands to more than a dozen. Some Continental Islands Greenland and Sable Island off North America. Barbados and Trinidad off South America. Sicily off Europe. Sumatra and Java off Asia. New Guinea and Tasmania off Australia.

2. Oceanic Islands - Oceanic Islands are those that rise to the surface from the floors of the ocean basins. Most Oceanic Islands rise from the sea as a result of volcanic activity on the ocean floor. They do not have any links with the continents. Some oceanic Islands are built up around one or two volcanic vents while others, like Tahiti, are formed by a whole series of vents. As they emerge from Volcanoes, they are also known as 'Volcanic Island. At first such Islands are uninhabitable but gradually, as the lava cools, they begin to support life. Sometimes, coral Islands develop from reefs that form around the volcanic Island. The original volcano may sink following movements in the Earth s crust, or due to rise in the sea level. Volcanic Island Arc - It is a type of Oceanic Island arise from volcanoes where the subduction of one plate under another is occurring. Hotspots - A Hotspot is more or less stationary relative to the moving tectonic plate above it, so a chain of Islands results as the plate drifts. Plate movement across a hot-spot produces a line of Islands oriented in the direction of the plate movement. An example is the Hawaiian Islands. Atoll - An atoll is an Island formed from a Coral Reef that has grown on an eroded and submerged volcanic Island. The Reef rises to the surface of the water and forms a new Island. Atolls are typically ring-shaped with a central lagoon. Examples include the Maldives in the Indian Ocean and Line Islands in the Pacific. Some Oceanic Islands Mariana Islands. Aleutian Islands. most of Tonga in the Pacific Ocean. Some of the Lesser Antilles. South Sandwich Islands are the only Atlantic Ocean Islands. 3. River Islands - River Islands occur in river deltas and in large rivers. They are caused by deposition of sediment at points in the flow where the current loses some of its carrying capacity. In essence, they are River Bars, isolated in the stream. While some are temporary, and may disappear if the river's water volume or speed changes, others are stable and long-lived. Sandwip Island, Richards Island, Majuli are some of the River Islands.

WETLANDS Wetland is a type of Habitat or Biome whose land mass is saturated with moisture either permanently or seasonally. Wetlands can be covered partially or completely by shallow pools of water. Although Wetlands are often wet, a Wetland might not be wet year-round. In fact, some of the most important Wetlands are only seasonally wet. Wetlands are the link between the land and the water. They are transition zones where the flow of water, the cycling of nutrients, and the energy of the sun meet to produce a unique ecosystem characterized by hydrology, soils, and vegetation. Wetlands can be natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres. Wetlands make up 6% of the Earth's surface. 14 % of the World's Wetlands are located in Canada. An acre of Wetland can store 1 1.5 million gallons of flood water. A Wetland one mile deep can reduce storm surge by 1 to 1.5 feet. 1. Classification / Types of Wetlands based on Tidal Activity Tidal Wetlands - Wetlands where the land meets the Sea are known as Tidal Wetlands. These areas are periodically flooded by sea water during high or spring tides or, are affected by the cyclic changes in water levels caused by the tidal cycle. Tidal Wetlands are not limited to Banks, Bogs, Salt Marshes, Swamps, Meadows and Flats. They are also known as Coastal or Estuarine Wetlands. Non-Tidal Wetlands - Non-Tidal Wetlands occur along streams in poorly drained depressions, and in the shallow water along the boundaries of Lakes, Ponds, and Rivers. They are inland, freshwater areas not subject to tidal influence and are usually covered or saturated with water for long periods during the growing season. They are also known as Freshwater, or Palustrine Wetlands. Non-tidal Wetlands may occur far from Rivers or Creeks as well. 2. Types of Wetlands based on Vegetation and Location Bogs - Bogs are Freshwater Wetlands often formed in old Glacial Lakes, characterized by Spongy Peat deposits, evergreen Trees and Shrubs, and a floor covered by a thick carpet of Sphagnum Moss. When large chunks of Glacial ice is left behind by retreating Glaciers, they may be surrounded by sediments flowing out of these melting Glaciers. When these chunks of ice melt, the depressions that form, turn into Bogs if the water retained there does not drain out. Bogs have acidic water and floating Mats form from partly-decayed Plant material. The Mats start at the shore and grow inward, eventually covering the entire Bog. These Mats are very interesting places with unique Plant communities, including Sphagnum Mosses which add to the acid levels in the Bog. Eventually the Mat fills in the entire Bog. Many well- preserved skeletons of ice-age Animals such as woolly Mammoths and Mastodons have been discovered in filled-in Bogs that have been mined for Peat, which is the stuff from the old Bog Mat.

Fens - Fens are freshwater peat-forming Wetlands covered mostly by Grasses, Sedges, Reeds and Wild Flowers. Fens are unusual as they form when water seeps through alkaline soils (containing limestone or its related minerals) into depressions along gentle slopes found in the sediments left behind by melting Glaciers. The water in Fens is alkaline, and Plants living there must be adapted to these alkaline conditions. Fens are less acid and more mineral-rich than are Bogs. Swamps - Swamps are Wetlands which get flooded seasonally flooded. They have more woody Plants than a Marsh and better drainage than a Bog. They are also known as Forested Wetlands due to the presence of large number of Trees. These Wooded Wetlands are dominated by 25% or greater cover of Trees or tall Shrubs. The most common Trees in a Swamp may include Pin Oaks, Swamp White Oaks, and Red Maple. Other trees such as Tupelo, Sycamore, Cottonwood, and American Elm are also often found. Shrubs include Elderberry, Swamp Rose and European Buckthorn. Marshes - Marshes are open Wetlands without Trees. They are dominated by soft- stemmed vegetation. Common Plants in marshes include Cattails, Sedges, and Rushes. A number of Grasses are found in marshes as well. Marshes are rich in wildlife, including many Birds and Mammals like Mink, Raccoon and Muskrat. Vernal Pools - Vernal Pool is a type of a Wetland that receives most of its water from precipitation.These are temporary Ponds that fill with water during the spring rains and floods, but which dry up later in the summer or fall. They are very important for a number of Wildlife Species, including Amphibians like Frogs, Toads, and Salamanders, which don't live in them year-round but need these pools to breed and lay eggs

Grassland A Grassland is a is a type of Habitat or Biome which is dominated by Grasses and other Herbaceous (non- woody) Flowering Plants and a variety of scattered Trees and Bushes. Grasslands occur in areas where there is not enough regular rainfall to support the growth of a Forest, but not so little as to form a Desert. About one quarter of the Earth's land is covered with Grasslands. Grasslands may occur naturally or as the result of human activity. Grasslands created and maintained by human activity are called 'Anthropogenic Grasslands'. Those formed naturally are called 'Natural Grasslands

MOUNTAIN Mountain is a type of Habitat or Biome which rises well above its surroundings and generally exhibits steep slopes, a relatively confined summit area and considerable inequalities of elevation. A Mountain is generally steeper and higher than a Hill. It is generally considered that for land mass to be qualified as a Mountain, it needs to be higher than 600 metres (2,000 feet). Those less than 600 metres are called Hills. Mountains are formed by the folding, faulting, or upwarping of the Earth s surface due to the movement of plates. They can also be formed by the positioning of volcanic rock onto the surface. For example, the Himalayan Mountains where India meets the Eurasian Plate were formed by a collision between plates that caused extreme compressional folding and the uplifting of large areas. Mountains cover one-fifth of the Earth s land surface, and occur in 75% of the World s Countries. The height of a Mountain is measured as distance above sea level. The tallness of a Mountain is from the centre. A Mountain Belt is an area of Mountain which can be tens to hundreds of kilometres wide and hundreds to thousands of kilometres long. It stands above the surrounding surface, which may be a coastal plain, as along the western Andes in northern Chile, or a high plateau, as within and along the Plateau of Tibet in south-west China. Mountain Ranges or Chains are long chains or groups of Mountains. They can extend tens to hundreds of kilometres in length. A group of Mountain Ranges is called a 'Mountain System'. For example, the Mountain Systems of the United States include the Rockies and the Appalachians. A Mountain's 'Summit' is the 'Highest Area on the Mountain' and the 'Highest Point of a Mountain' is called the 'Peak'. A 'Seamount' is a Mountain rising from the ocean sea floor that does not reach to the water's surface (sea level), and thus is not an Island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a sea-floor of 1,000 4,000 metres depth. A 'Monadnock' or 'Inselberg' is an isolated rock hill, knob, ridge, or small Mountain that rises abruptly from a gently sloping or virtually level surrounding plain. Volcanic or other processes may give rise to a body of rock resistant to erosion, inside a body of softer rock such as limestone which is more susceptible to erosion. When the less resistant rock is eroded away to form a plain, the more resistant rock is left behind as an isolated Mountain

Basic Types of Mountains 1. Fold Mountains (Folded Mountains) - These are the most common Mountain types. The world s largest Mountain ranges are Fold Mountains. These ranges were formed over millions of years. Fold Mountains are formed when two plates collide head on, and their edges crumbled, much the same way as a piece of paper folds when pushed together. Fold Mountains are formed when two plates collide head on, and their edges crumbled, much the same way as a piece of paper folds when pushed together. The Himalayan Mountains were formed when India crashed into Asia and pushed up the tallest Mountain range on the continents. Some of the Fold Mountains Himalayan Mountains in Asia. The Alps in Europe. The Andes in South America. The Rockies in North America. The Urals in Russia.

General Characteristics of Grasslands Domination of Short Plants - Grasslands generally have very short season, the climate is too dry and the soil too poor. This condition limits the growth of woody and large Plants. However this condition favours the growth of small Plants like Grass and Shrubs which dominate this type of Habitat. Another factor which favours short Plants is the maintenance of these habitats by fire and grazing, which prevent the succession of the Grassland vegetation toward Tropical Deciduous Forest or Temperate Forest. However in the absence of heavy Mammalian grazing and especially of regular fires Woody Plants, shrubs or trees, may occur on some Grasslands forming Savannahs, Scrubby Grassland or Semi-Wooded Grassland, such as the African Savannahs or the Iberian Dehesa. Such Grasslands are sometimes referred to as Wood- Pasture or Woodland. Grassland vegetation can vary in height from very short, as in chalk downland where the vegetation may be less than 30 cm (12 in) high, to quite tall, as in the case of North American tall-grass Prairie, South American Grasslands and African Savannah. Short Growing Season - Natural Grasslands, whether Tropical or Temperate occur in environments in which growing conditions are favourable In Tropical Grasslands the growing season is usually the rainy season or, in some cases, the season when the ground is not waterlogged or submerged. In Temperate Grasslands the growing season is usually the short period between the cold, damp winter and the hot, dry summer. Perennial Grasses, relying on subterranean reserves of stored food for rapid shoot growth, are well adapted to exploiting such brief growing seasons, reaching their maximum size and completing their seeding within a few weeks. Their aboveground parts then die back, providing potential fuel for the Grass fires that typify these environments. The underground perennating (surviving from one season to the next) roots and rhizomes of the Grasses, however, are relatively for only a short season. well protected from fire. Fast Growth of Grass - Grasses are specialists when it comes to regrowth. Their growing points are situated low down near the soil enabling them to grow back in spite of grazing or overgrazing. Many Grass Species can grow back quickly after a fire has swept through the Grassland, and some have seeds that can grow after being burned in a fire Grasslands tend to produce larger amounts of new growth if subjected to some type of repeated disturbance, usually grazing or fire, that prevents the accumulation of a thick layer of dead litter. Where such a layer is allowed to develop, it retains nutrients in a form not immediately available to roots and acts as a physical barrier for new shoots growing from the soil surface toward the light; in temperate Grasslands this layer acts as thermal insulation, slowing the spring warming of the soil. This has obvious implications for grazing management of these systems. Grasslands can therefore support a high density of grazing Animals.

Mostly Hot and Dry Areas - Grassland climates are varied, but all large regions of Natural Grassland are generally hot, at least in summer, and dry. In general, Tropical Grasslands receive 500 to 1,500 millimetres (20 to 60 inches) of rain in an average year and in every season experience temperatures of about 15 to 35 C (59 to 95 F). The dry season may last as long as eight months. An excess of rainfall over evaporation, leading to ephemeral river flow, occurs only during the wet season. The tropical Grassland climate overlaps very broadly with that of Savannah. Temperate Grasslands have cold winters and warm summers with rain or some snow. Balance between different Plants - A dynamic balance commonly exists between Grasslands and related vegetation types. Droughts, fires, or episodes of heavy grazing favour Grassland at some times, and wet seasons and an absence of significant disturbances favour woody vegetation at others. Changes in the severity or frequency of these factors can cause a change from one vegetation type to another.

Changing Appearances - Grasslands change their appearance throughout the year. In winter (or in the tropical dry season), Grasslands look drab and lifeless. In the Temperate Grasslands, spring brings about a transformation as tender shoots emerge, the Grass starts growing, and the first flowers bloom. A similar change is seen in Tropical Grasslands when the onset of the rainy season changes the landscape from dull brown to bright green. Specialised Plants - The Plants of Grasslands have adapted themselves to survive the prevalent conditions. Grasses generally have pollen that is spread by the wind and are as such not much dependant on other organisms for pollination. Some Plants have bad-tasting and poisonous chemicals which prevent them from being eaten by Animals. They also have thick latex sap contained in their leaves or stem and upon breakage, they ooze the gummy sap. If this is tapped by an insect , it hardens in the air and gums up the insect's mouth parts. Milkweeds and Dogbane are such Plants. The Stinging Nettle Plant can cause a painful feeling in the Animal that touches it. Also, a kind of Grass can cut the tongue of the Animal that eats it. In addition, there is also a kind of Poison Ivy. During a fire, while above- ground portions of Grasses may perish, the root portions survive to sprout again as Grasses grow from near their base, not from tip, thus are not permanently damaged from grazing Animals or fire. Extensive root systems prevent grazing Animals from pulling roots out of the ground.

Importance of Grasslands Grassland are an important part of ecosystem as they cover nearly one third of the earth s land surface and supply three quarters of the energy that the World needs. They support an amazing variety of Animals and Plants which are important components of the Grassland Habitat and maintain a rich biodiversity. Some Species are endemic to these Habitats and as such these Habitats should be conserved. No other habitat is as agriculturally useful to humans as Grasslands. Soils tend to be deep and fertile, perfect for crop land or pastures. Much of the North American Prairie lands have been converted into one of the richest agricultural regions on Earth. According to an estimate one hectare of natural Grassland can provide four persons requirements of Wheat. If properly managed Grasslands can be mutually beneficial to Humans as well as to local Fauna and Flora. Grasslands separate Forests from Deserts. Grasslands act as barrier towards desertification of land as they have Plants which bind the soil and prevent erosion of the land. Grasslands are a source of income through Tourism as well. The increasing number of tourists add to the revenues of most countries where they are found. Grassland are important for researchers and scientists as Grasslands are needed to be fully understood so that they can benefit Humans in innumerable ways. Certain adaptations of Plants towards harsh climates are and can be utilised to develop better quality of Plants. Certain Animal Species use various strategies and techniques to survive in Grasslands and these can be applied in scientific research and development for the benefit of mankind.

2. Fault-Block Mountains - These type of Mountains are formed when faults or cracks in the Earth's crust force some materials or blocks of rock up and others down. Instead of the Earth folding over, the Earth's crust fractures (pulls apart). It breaks up into blocks or chunks. Sometimes these blocks of rock move up and down, as they move apart and blocks of rock end up being stacked on one another. Often Fault-Block Mountains have a steep front side and a sloping back side. Some of Fault-Block Mountains The Sierra Nevada Mountains in North America. The Harz Mountains in Germany. 3. Dome Mountains - Dome Mountains are formed when a large amount of magma pushes up from below the Earth's crust, but it never actually reaches the surface and erupts. Instead of bursting the magma pushes up overlaying rock layers. After some time the magma cools and forms a dome shape rock. The uplifted area created by rising magma looks like the top half of a sphere or ball, thereby giving it the name Dome Mountain. It also gets its name because the uplifted area is higher than its surroundings, erosion by wind and rain occurs from the top. This results in a circular Mountain range. 4. Volcanic Mountains -Volcanic Mountains are created when magma (molten rock) deep within the Earth, erupts, and piles upon the surface. When the ash and lava cools, it builds a cone of rock. This material builds up around the Volcanic Vent is known as Volcanic Mountain. Some of the Volcanic Mountains Mount St. Helens in North America. Mount Pinatubo in the Philippines. Mount Kea and Mount Loa in Hawaii. 5. Plateau Mountains - Plateau Mountains are created when running water carves deep channels into a region, creating Mountains. Over billions of years, the rivers can cut deep into a Plateau and make tall Mountains. Plateau Mountains are usually found near Mountain. Because they are formed by erosion they are also known as Erosion Mountains. The Mountains in New Zealand are examples of Plateau Mountains.

Fresh water Freshwater refers to water from rivers, lakes, reservoirs, underground streams, and other sources. Water is continually evaporated from the oceans and then returned to the land as ice, snow, or rain. Ice and snow melt from mountains to release freshwater to our rivers, streams, lakes, and to resupply underground streams. New Zealand's freshwater habitats range from glaciers and seepages in the mountains, down to lowland rivers and streams that flow into estuaries. They include lakes, rivers, streams, some wetlands, cave systems, geothermal areas and underground aquifers. Importance of freshwater habitats Freshwater ecosystems contribute to biodiversity, the economy, recreational opportunities, cultural significance and our well-being. Freshwater is used by a wide variety of native plants and animals. Some of these are unique to New Zealand and often highly specialised to the habitats they are found in. Tangata whenua have strong links to water. Awa (river) are an important part of whakapapa (geneaology) and freshwater sustains taniwha and protects w hi tapu (sacred areas). Awa also provide valuable resources such as mahinga kai (harvesting), harakeke (flax) and habitat for species of cultural importance (e.g. tuna/eels).

There are three basic types of freshwater ecosystems: Lentic: slow moving water, including pools, ponds, and lakes. Lotic: faster moving water, for example streams and rivers. Wetlands: areas where the soil is saturated or inundated for at least part of the time

POND ECOSYSTEM An ecosystem consists of all living plants and animals, and the environment in which these organisms thrive. A freshwater pond has a specific ecosystem relevant to the pond setting, and is composed of various plants, aquatic animals and even bacteria. As with all ecosystems, each element of a freshwater pond's ecosystem is dependent on the other elements and organisms for survival. Producers The producers of a freshwater pond's ecosystem include rooted or floating plants and phytoplankton. The producers provide crucial nutrients for other organisms of the ecosystem. Water lilies are a common rooted plant in many freshwater ponds, especially man-made ponds. In addition to providing nutrients for the other organisms, these plants also provide oxygen. Curly pond weed, duck weed and marsh marigolds are all common pond producers. Phytoplankton grows in fresh and salt water, and is one of the biggest contributors to the production of oxygen in a pond's ecosystem. Primary Consumers Zooplankton is considered a primary consumer in the ecosystem of a pond. Zooplankton is a floating group of unicellular and multicellular animals. Zooplankton consumes the phytoplankton and is extremely important in connection with the fish population of a pond. Zooplankton is incredibly small, usually invisible to the human eye.

Secondary Consumers Fish are considered as a secondary consumer in a pond's ecosystem because fish consume zooplankton, the primary consumer. There are many different types of fish in a freshwater pond. Goldfish and koi are most common in small, man-made, backyard-type ponds. Larger freshwater ponds can contain catfish, bass, minnows and carp. Fish are usually at the top of the food chain for ponds, unless the pond contains turtles or ducks, also known as tertiary consumers. Tertiary Consumers There are some large fishes that feed on small fishes and thus become Tertiary(Top consumer). Some birds and Human,s are also the top consumer. Decomposers and Other Elements Producers and consumers are the primary elements of a pond's ecosystem, but other elements contribute to the pond's ecology. The sun is an important part of the ecosystem. Without sunlight, the producers would not exist. Fungi and bacteria are another important aspect of the ecosystem, and are known as decomposers. Decomposers break down materials that can be used by consumers, particularly zooplankton.

POND ECOSYSTEM

MARINE HABITATS The marine environment supplies many kinds of habitats that support life. Marine life partially depends on the saltwater that is in the sea ( marine comes from the Latin mare, meaning sea or ocean). A habitat is an ecological or environmental area inhabited by one or more living species. Marine Habitats: Coral reefs provide marine habitats for tube sponges, which in turn become marine habitats for habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in the area that extends from as far as the tide comes in on the shoreline, out to the edge of the continental shelf. Most marine life is found in coastal habitats, even though the shelf area occupies only seven percent of the total ocean area. Open ocean habitats are found in the deep ocean beyond the edge of the continental shelf. Alternatively, marine habitats can be divided into pelagic and demersal habitats. Pelagic habitats are found near the surface or in the open water column, away from the bottom of the ocean. Demersal habitats are near or on the bottom of the ocean. An organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, an organism living in a demersal habitat is said to be a demersal organism, as in demersal fish. Pelagic habitats are intrinsically shifting and ephemeral, depending on what ocean currents are doing. Marine habitats can be modified by their inhabitants. Some marine organisms, like corals, kelp, mangroves and seagrasses, are ecosystem engineers, which reshape the marine environment to the point where they create habitats for other organisms.

MARINE HABITATS INCLUDES- Marine habitats includes coastal zones, intertidal zones, sandy shores, rocky shores, mudflats, swamps and salt marshes, estuaries, kelp forests, seagrasses, and coral reefs. In addition, in the open ocean there are surface waters, deep sea and sea floor. Intertidal zones (those areas close to shore) are constantly being exposed and covered by the ocean s tides. A huge array of life lives within this zone. Sandy shores, also called beaches, are coastal shorelines where sand accumulates. Waves and currents shift the sand, continually building and eroding the shoreline. Longshore currents flow parallel to the beaches, making waves break obliquely on the sand. These currents transport large amounts of sand along coasts, forming spits, barrier islands and tombolos. Longshore currents also commonly create offshore bars, which give beaches some stability by reducing erosion. The relative solidity of rocky shores seems to give them a permanence compared to the shifting nature of sandy shores. This apparent stability is not real over even quite short geological time scales, but it is real enough over the short life of an organism. In contrast to sandy shores, plants and animals can anchor themselves to the rocks. Mudflats are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily.

Mangrove swamps and salt marshes form important coastal habitats in topical and temperate areas respectively. An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds. Kelp forests occur worldwide throughout temperate and polar coastal oceans. Seagrasses are flowering plants from one of four plant families which grow in marine environments. They are called seagrasses because the leaves are long and narrow and are very often green, and because the plants often grow in large meadows, which look like grassland. Reefs comprise some of the densest and most diverse habitats in the world. The best-known types of reefs are tropical coral reefs, which exist in most tropical waters; however, reefs can also exist in cold water. Reefs are built up by corals and other calcium-depositing animals, usually on top of a rocky outcrop on the ocean floor. Reefs can also grow on other surfaces; this has made it possible to create artificial reefs. Coral reefs also support a huge community of life, including the corals themselves, their symbiotic zooxanthellae, tropical fish, and many other organisms

Estuary Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea. Estuaries are home to unique plant and animal communities that have adapted to brackish water a mixture of fresh water draining from the land and salty seawater. However, there are also several types of entirely freshwater ecosystems that have many similar characteristics to the traditional brackish estuaries. For example, along the Great Lakes, river water with very different chemical and physical characteristics mixes with lake water in coastal wetlands that are affected by tides and storms just like estuaries along freshwater estuaries also provide many of the ecosystem services and functions that brackish estuaries do, such as serving as natural filters for runoff and providing nursery grounds for many species of birds, fish, and other animals. Estuaries are among the most productive ecosystems in the world. Many animals rely on estuaries for food, places to breed, and migration stopovers. Estuaries are delicate ecosystems. Congress created the National Estuarine Research Reserve System to protect more than one million acres of estuarine land and water. These estuarine reserves provide essential habitat for wildlife, offer educational opportunities for students, and serve as living laboratories for scientists the oceanic coasts. These

BIOTIC FACTOR Biotic Factors Definition Biotic factors are the living parts of an ecosystem. Because of the way ecosystems work as complex systems of competitionand cooperation, where the action of every life form can effect all the others any living thing within an ecosystem can be considered a biotic factor. Biotic factors such as soil bacteria, plant life, top predators, and polluters can all profoundly shape which organisms can live in an ecosystems and what survival strategies they use. Biotic factors, together with non-living abiotic factorssuch as temperature, sunlight, geography, and chemistry, determine what ecosystems look like and what ecological niches are available. Types of Biotic Factors Biotic factors are grouped by scientists into three major groups, which define their role in the flow of energy which all living things in the ecosystem need to survive. These groups are producers or autotrophs, consumers or heterotrophs, and decomposers or detritivores. Producers Producers also known as autotrophs, from the Greek words auto for self and troph for food are organisms that make their own food using inorganic materials and energy sources. Producers are extremely important: without them, no life could exist at all! The very first life forms on Earth had to learn to make fuel and building materials to make more cells out of non-living materials. That s because when the first life forms appeared, there were no other life forms to feed on! So the first life forms had to be producers. Producers remain vital today as the life forms that can harness inorganic energy to be used as fuel for life. There are two major classes of producers: 1. Photoautotrophs are by far the most common type of producer on Earth today. These producers harness energy from sunlight to power their life functions. Green plants, green algae, and some bacteria are photoautotrophs. Most photoautotrophs use a pigment, such as chlorophyll, to catch photons from the Sun and harvest their energy. They then package that energy into a form that all life forms can use, and use it to create proteins, sugars, lipids, and more essential materials for life. In most ecosystems, plants which are producers that are multicellular, highly complex, and very efficient at turning sunlight into fuel for living organisms form the bottom of the energy pyramid. All other organisms depend on the energy plants harvest from the Sun to survive. 2. Chemoautotrophs are fairly rare in most ecosystems. They obtain energy from chemicals such as hydrogen, iron, and sulfur, which are not common in most environments. Nonetheless, they can still play an important role in ecosystems because of their unusual biochemistry. Some methanogens microorganisms that make methane are chemoautotrophs. Methane, a greenhouse gas which is much more powerful than carbon dioxide, may play a major role in regulating the planet s temperature. Other chemoautotrophs can produce similarly powerful chemicals with their unique metabolisms. It is actually not known whether the first forms of life on Earth were photoautotrophs or chemoautotrophs. Photoautotrophs are more common today, but that may simply be because sunlight is more plentiful than the chemicals chemoautotrophs use as their energy source. Consumers

Consumers, also called heterotrophs, are organisms that eat other living organisms in order to obtain energy. Their name comes from the Greek hetero for other and troph for food. Herbivores who eat plants, carnivores who eat animals, and omnivores who eat both plants and animals, are all heterotrophs. Heterotrophy probably evolved when some organisms discovered that they could eat autotrophs as a source of energy, instead of creating their own energy and organic materials. Some autotrophs subsequently evolved symbiotic relationships with consumers, such as angiosperms plants which produce nectars and fruits to attract animals, who ultimately help them to reproduce. Most levels of most ecosystems energy pyramids consist of consumers herbivores, minor predators, and top predators who eat other organisms. Decomposers Decomposers, or detritovores, are organisms that use organic compounds from producers and consumers as their source of energy. They are important to ecosystems because they break down materials from other living things into simpler forms, which can then be used again by other organisms. Decomposers include soil bacteria, fungi, worms, flies, and other organisms that break down dead materials or waste products from other life forms. They are distinct from consumers, because consumers usually consume other organisms while they are still alive. Decomposers, on the other hand, metabolize waste products that might not be of interest to consumers, such as rotting fruit and dead animals. In the process they break down these dead things into simpler chemicals that can be used by heterotrophs to thrive and produce more energy for the ecosystem as a whole. This is the principle behind the practice of composting where waste scraps of plants and animal products are put into a pile, where decomposers such as bacteria, worms, and flies are allowed to thrive. These decomposers turn the waste products into rich fertilizer for the composter s garden, which then grows bigger and healthier thanks to the decomposers breaking down the waste products in the compost. Decomposers are the link between the bottom of an ecosystem s energy pyramid and the other levels. Decomposers can take energy and raw materials from dead plants, herbivores, lesser carnivores, and even top carnivores, and break it down into a form that can be used by the ecosystem s producers to make it easier for them to harness sunlight. In this way, the ecosystem s energy cycle is preserved.

POPULATION AND COMMUNITY ECOLOGY Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting populations of different species. Metapopulations span multiple populations of the same species that occupy different areas. Metapopulations interact through immigration and emigration, providing genetic diversity that lends resilience to harsh environments. Population size and density can be estimated using quadrat and mark and recapture methods.

Populations Are Dynamic and Interactive A population, or group of individuals, belonging to the same species and inhabiting the same general area, continuously changes in response to both biotic (living) and abiotic (non-living) factors. Influential abiotic factors include weather, elevation, latitude, soil and water composition, and pollution, among others. The biological study of how organisms interact with each other and their environment is called ecology. Metapopulations include multiple populations of the same species that inhabit distinct areas. Metapopulations continuously exchange members through immigration, movement into an area, and emigration, movement out of an area. This exchange ensures genetic diversity, helping populations withstand unpredictable and unfavorable environmental conditions by increasing the likelihood that adaptive (i.e., helpful) traits will be naturally selected (i.e., emerge in the population). Communities Are Combinations of Co-existing, Interacting Populations An ecological community is comprised of multiple co-existing and interacting populations in the same habitat, and a community s species richness is merely the number of species. The combination of ways a species uses environmental resources and interacts with other community members reflects the distinct niche the species occupies. In other words, a niche is like the job a species performs in its community. Competition arises when species niches overlap. Bluebirds and woodpeckers both favor insectivorous diets and open areas with sparsely distributed trees. In an example of interspecific competition, these two species vie for limited food and housing resources. Bluebirds also compete with other bluebirds for these resources (intraspecific competition). Competition can be avoided by partitioning resources, or occupying different areas of a shared environment. Predator-prey relationships, another important community interaction, resemble an evolutionary arms race. In prey animals, natural selection strongly favors features that help prevent predation. For example, Caligo (or Owl ) butterflies have large eyespots on their wings that resemble owl eyes, which deter threatening predators. Predators also co-adapt to prey adaptations; both predator (e.g., leopard) and prey (e.g., deer) species use camouflage to avoid detection.

Parasitism and Pray Predator Relationship Predation In predation, one organism kills and consumes another. Predation provides energy to prolong the life and promote the reproduction of the organism that does the killing, the predator, to the detriment of the organism being consumed, the prey. Predation influences organisms at two ecological levels. At the level of the individual, the prey organism has an abrupt decline in fitness, as measured by its lifetime reproductive success, because it will never reproduce again. At the level of the community, predation reduces the number of individuals in the prey population. The best-known examples of predation involve carnivorous interactions, in which one animal consumes another. Think of wolves hunting moose, owls hunting mice, or shrews hunting worms and insects. Less obvious carnivorous interactions involve many small individuals consuming a larger one. Such group predation is common among social carnivores such as lions, hyenas, and wolves. Group predation also occurs with ants and social spiders. This is, however, only part of the picture. Seed consumption can sometimes constitute predation. Seeds are considered organisms. Under ideal circumstances, seeds grow to become plants. However, consumption of a seed kills the plant before it can grow, making seed consumption an example of predation. Not all predators are animals. Carnivorous plants, such as the Venus fly trap and the pitcher plant, consume insects. Pitcher plants catch their prey in a pool of water containing digestive enzymes, whereas the Venus fly trap captures an insect between the two lobes of a leaf and seals the insect inside with digestive enzymes. These plants absorb nutrients from the insects as they become available during digestion. On a microscopic scale, protozoa and bacteria also consume prey organisms. They play an important role in maintaining population sizes in microbial communities, which promotes the diversity of microorganisms and contributes to a stable community structure. .

Predation and Adaptation Predation influences the fitness of both predators and prey. Individuals must both feed and avoid being eaten to survive and reproduce. Genetically-determined traits that improve an organism s ability to survive and reproduce will be passed on to its offspring. Traits associated with improved predation for predators and escaping predation for prey tend to be positively selected by natural selection. Predators exhibit traits such as sharp teeth, claws, and venom that enhance their ability to catch food. They also possess extremely acute sensory organs that help them to find potential prey. Consider the ability of raptors to spot potential prey from over a kilometer away, the acute sense of smell of moles, the ability of owls to locate mice by sound, the ability of pit vipers to sense body heat when tracking prey, and the ability of bats and dolphins to echolocate. Predators catch their prey either by pursuing potential prey or by ambushing them. Organisms that give chase are capable of short bursts of speed. Those that lie in wait tend to be camouflaged to avoid detection . In a similar manner, prey species exhibit traits that help them avoid detection or capture. Many, such as leaf insects, moths, a variety of frogs and small lizards, and herbivorous mammals, are cryptically colored to make them more difficult to see. Behaviorally, they freeze after detecting the presence of a predator. This lack of movement helps them better blend in with their background and inhibits the ability of the predator to find them. But when predators venture too close, prey will take flight, running or flying to escape. When a chase ensues, prey will typically survive if they stay out of reach until the predator tires. Some species buy extra time by distracting the predator. Examples include moths that flash brightly colored hindwings, lizards that drop their tails, and insect larvae that discharge slime. Such actions surprise the predator and give the prey time a few extra moments to escape. When a predator chases after potential prey, the predator is running for its dinner. The prey is running for its life. If the predator fails to capture the prey, it goes hungry, but it will not experience a large decline in fitness as a result of the interaction. In contrast, if the predator catches the prey, the captured individual loses any future opportunities to reproduce. This life-dinner principle sets up an evolutionary arms race between the two species (Dawkins & Krebs 1979). In this race, the prey experience strong selective pressure to evolve better adaptations to avoid being eaten. At the same time, predators must capture sufficient food to survive and reproduce, and they too are subjected to selective pressure for traits that allow them to hunt successfully. Over time, this arms race leads to traits that enable prey to better avoid capture, whereas predators become better able to capture prey. Not all species that exhibit vivid coloration are truly toxic. Some have evolved patterns and colors that mimic those of toxic species. Examples of such Batesian mimicry include the extraordinarily polymorphic Papilio dardanus swallowtail butterfly in southern Africa and Madagascar (Salvato 1997). Females of this species occur in a wide variety of physical appearances, nearly all of which mimic distasteful species of the Danaeus and Amauris genera with which they co-occur

Parasitism In parasitism, an individual organism, the parasite, consumes nutrients from another organism, its host, resulting in a decrease in fitness to the host. In extreme cases, parasites can cause disease in the host organism; in these situations, we refer to them as pathogens. We divide parasites into two categories: endoparasites, which live inside the body of their hosts, and ectoparasites, which live and feed on the outside of the body of their host. Examples of endoparasites include flukes, tapeworms, fungi, bacteria, and protozoa. Ectoparasites include ticks and lice, plants, protozoa, bacteria, and fungi. Plants and animals typically act as hosts. In most situations, parasites do not kill their hosts. An exception, however, occurs with parasitoids, which blur the line between parasitism and predation. The best-known parasitoids include several species of wasp, which immobilize but do not kill a host by stinging it. The female then carries the host to a burrow, where she lays eggs within the host s body. After the larvae hatch, they consume the living tissues of the host, eventually killing it . Entomogenous fungi also act as parasitoids; they infect the bodies of insects, either through the mouth while foraging or by penetrating the outer cuticle of the insect s body (Ferron 1978, Roy et al. 2006). Spores circulate inside the host, whose body provides the nutrients needed for fungal growth. Eventually, the fungal load becomes too great for the host, and the insect dies (Figure 4b). The major distinguishing difference between parasitoids and predators is that parasitoids feed on living tissue, whereas the predator kills its prey before, or in the process of, consuming it. Parasite Transmission For all parasites, the host exists as an island of habitat. But the island lives for a finite period of time, and the parasites must find a new host before the existing one dies. Transmission to a new host can happen either directly, or through a vector. In direct transmission, the parasite moves from one host to another of the same species without an intermediate organism. In vector transmission, an intermediate organism, the vector, transfers the parasite from one host to the next. Many endoparasites have a complex life cycle that involves two hosts, and the parasite must spend time in both to complete its life cycle. Take, for example, the protozoan parasite Plasmodium, which causes malaria. Plasmodium must spend time in humans and in an Anopheles mosquito to complete its life cycle. The mosquito acts as a vector, transferring Plasmodium from infected humans to uninfected individuals. Additionally, the mosquito acts as an intermediate host. When a female mosquito ingests blood containing Plasmodium, some of the red blood cells contain gametes (eggs and sperm). In the mosquito s gut, the gametes come together to form a zygote, the development of which results in sporozoites. It is this life stage that can then go on to infect a new human when the mosquito feeds

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