Biological Niche• An organism’s Niche describes

the full biotic and abiotic conditions in which an organism lives– Biotic factors:

• Predators• Prey• competition• Vegetation

– Abiotic factors:• Climate• Soil (nutrients)• Terrain

Community Interactions• Interactions of a community:

interactions that affect an ecosystem and drive evolution– Competition - negative effect on both

species • interspecific competition - 2 species

compete for the same resource • Interspecific interactions and adaptation

– drives coevolution and adaptation of species living in close proximity to each other

– exclusion principle states that no 2 species can occupy the same niche

Community Interactions• Predation - benefits one and has

a negative effect on the other – drives evolution - mimicry and

other diverse adaptations – The number and phenotype of the

prey determines the phenotype and number of the predators

Community Interactions

• Symbiosis… “Same Life”– Mutualism - benefits

both equally – Commensalism - one is

benefited while the other is unaffected • very rare in nature

Community Interactions

• Parasitism - parasite benefits while the host is harmed – Parasite obtains most or all of

its nutrition from the host– Can exert a substantial

influence on a population – The parasite generally weakens

but does not kill the host– Disease - similar to parasite

Ecological Succession• Ecological succession refers to

the slow changes in an ecosystem over time– Primary succession• Begins with NO soil

– New islands, bare rock following glacier movement, and volcanic debris are examples

– Lichens (pioneer species) … fungus that breaks down rocks to form soil

Ecological Succession

• Secondary Succession– Process of restoring ecological

balance once soil is present• Following a fire is an example

– Reestablishment of a forest can take up to 300yrs

– The climax community is a representative of the stable ecosystem