Ecology

Ecology

A Review

Habitat

The place in which an organism lives. Some organisms can share the same habitat but they will have different microhabitats. Organisms usually cannot survive in other habitats where conditions can be quite different. However some organisms can tolerate a range of conditions and live in a variety of habitats

Niche

Simply put, this is the organism’s role in the community – its job. Generally it is related to how the species obtains food eg as a predator, producer etc. It is a description of the opportunities provided by the habitat and the adaptations of the organism that enable it to take advantage of the opportunities

Each of the organisms in this ecosystem has a particular way of fitting into the oak tree environment - they each occupy a niche within the ecosystem. For example the blue tits and the squirrels, though they both inhabit the same tree, do not directly compete for food: the squirrels feed on acorns, while the tits feed on moth larvae. The two species occupy different niches within the oak ecosystem.

http://www.bbc.co.uk/schools/gcsebitesize/biology/livingthingsenvironment/0habitatsandpopsrev5.shtml

Gause’s Principle

No two species can occupy the same ecological niche in the same habitat for an indefinite period.

Environmental Factors

There are 2 types of environmental factors

Biotic – living factors, including other organisms such as food, predators, parasites, competitors

Abiotic – physical, non-living factors, including temperature, light intensity, salinity

Tolerance and Limiting Factors

The environmental factors that can effect an organism do not remain constant. For a species to be able to survive in its habitat it needs to be able to tolerate variation in these factors.

The range in which it thrives is called an organisms optimum range. Outside the optimum range are tolerance limits. If an organism exceeds this, it can suffer stress and, if too severe, die.

Acclimation is the adjusting of tolerance limits, eg getting a tan, growing thicker fur in winter

Adaptations

All organisms inherit characteristics that increase their chances of survival.

These are commonly divided into three categories: Behavioural – how the organism behaves

Structural – the shape and size of an organism

Physiological – the working of an organisms body

Camels are well adapted for survival in the desert. They have:• the ability to store a lot of water, and to lose very little via urination and sweating • the ability to tolerate body temperatures up to 42 degrees C • a large surface area / volume ratio - maximising heat loss • a hump which can store scarce food as fat without insulating the body • thick fur on the top of the body to provide shade, and thin fur on the rest of the body to allow easy heat loss, and • large, flat feet well-suited for walking on sand


Cacti are well adapted for survival in the desert. They have:• spines instead of leaves, which minimise surface area and therefore evaporation, and also... • protect them from animals which might eat them • stems which can store water, and • widespread root systems, which can collect water from a large area


Community Patterns

Communities are often complex and their composition and structure is ever changingThis can be caused by physical factors (eg tidal wave) or biotic factors (eg forest shading)3 Patterns of change in a community are: Succession Stratification Zonation

Relationships

Relationships exist between all organisms in an ecosystem.

Co-operative or competitive relationships

These can be: Beneficial (+) Harmful (-) Neutral (0)

Summary of Relationships

Revision Activity

Try these links to complete revision activities: http://www.bbc.co.uk/apps/ifl/schools/gcsebitesize/

biology/quizengine?quiz=habitatsandpops&templateStyle=biology

http://www.quia.com/shared/search

Ecology

Documents

Transcript of Ecology