Outlines

Outline

8-1Community Structure and Species Diversity
A.Ecologists use three characteristics to describe a biological partnership.
1.Physical appearance: the relative sizes, stratification, and distribution of its populations and species
a. extended terrestrial communities are patchy.
b.Transition occurs around the edges, where two community types interact.
c.Increased edge area may be bruising due to habitat fragmentation; galore(postnominal) species become more vulnerable to predators and loss of colonization ability.
2.Species diversity: a confederacy of bits of different species ( vastness) and abundance of individuals within each species (species evenness)
3. deferral structure: the number of ecological niches, their resemblance or release from each other, and interaction of species with each other
a.High species richness much is correlated with low species evenness (few numbers per species).
b.deuce major factors affect diversity of species in a community: parallel in terrestrial communities and pollution in aquatic systems.
B.The number of species on an island is determined by how immobile new species arrive, how fast old species become extinct, the size of the island, and the distance from the mainland.
1.



The species equilibrium poser, or the theory of island biogeography, was proposed in the 1960s to explain differences in species richness with island size.
a.Balance between two factors is important in this model: rate of immigration of species and rate of extinction of existing species.
b.Two island features are important: size and distance from mainland.
2.This model has been expand to include habitat islands in protected areas such as national parks.

8-2Types of Species
Species in a community play many different roles in its ecology.
A.Types of Species
1.Native species are those whose original domicil is in this particular ecosystem.
2.Nonnative species originally evolved in a different ecosystem and migrated or were introduced to a new...If you want to get a full essay, order it on our website: Orderessay



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