14_Biogeography_BI319

Speciation

The process that produces new species.

Extirpation

The local extinction of a species.

Alpha diversity

Local species pool

Beta diversity

Species turnover from community to community

Gamma diversity

Regional species pool

Vicariance

Evolution of species due to geographic barriers while the species remains in the same location.

Pangaea

An ancient supercontinent that existed around 250 million years ago, before continental drift.

Equilibrium Theory of Island Biogeography

Predicts species richness based on colonization and extinction

Oceanic crust

thinner and denser

Continental crust

Thicker and less dense

Core

Interior of hot, dense metal

Mantel

Layer surrounding core

Crust

Outer layer of earth, floats on mantel

Hypotheses of tropical species richness

Diversification is higher; diversification time is greater; carrying capacity is higher

Higher diversification at tropics

Larger area and stable temperatures decrease extinction rates and increase speciation

Higher diversification time at tropics

Tropics have longer evolutionary history, and were not affected by ice ages

equilibrium of islands

Point where colonization and extinction rates intersect

Colonization

Decreases with isolation

Extinction

Decreases with population size

Equal relationship between local and regional diversity

All regional species are found locally (rare); slope = 1

Proportional relationship between local and regional richness

Slope <1; richness correlated with regional richness, with local processes limiting diversity

Saturation relationship between local and regional richness

Curve levels off; local limitations to species richness