module 10, p1

island biogeography

Study of how species are distributed and interact on islands.

species-area curve

Pattern showing that larger islands contain more species than smaller islands.

plateauing curve

On normal scales, species richness increases with island size but levels off.

log scale curve

When plotted with log scales, species-area relationships become a straight line.

z-value slope

Species-area curve slope typically falls between 0.20 and 0.35 across taxa.

island size effect

Larger islands are easier to find, support larger populations, and contain more habitats.

extinction risk

Smaller populations on small islands are more prone to extinction.

habitat diversity

Larger islands contain more biotic and abiotic conditions that support more species.

wetlands example

Ontario wetlands showed species-area curves for plants, amphibians, birds, and mammals.

trophic limits

Small islands lack enough producers to support top predators.

herbivore release

Without predators, monkeys, iguanas, and ants overconsumed plants on small Lago Guri islands.

distance effect

Near islands accumulate more species than far islands because of higher immigration.

fumigation experiment

Researchers cleared islands of invertebrates and tracked recolonization; near islands gained most species.

colonization curve

Immigration rates high when few species present, but decline as island fills.

extinction curve

Extinction rates low with few species, but rise as competition and predation increase.

equilibrium species

Point where colonization and extinction balance, determining island's species number.

large island model

Lower extinction rates allow more species than on small islands.

far island model

Lower colonization rates result in fewer species than on near islands.

four island types

Near-large have most species, far-small have least species.

conservation insight

Protecting large, nearby habitat tracts conserves more species than small, isolated tracts.

specialists on islands

Isolated species often evolve unique traits like ground nesting or flightlessness.

invasive species risk

Specialists without defenses are vulnerable to generalist invaders.

avian malaria

Introduced to Hawaii by mosquitoes, leading to native bird declines and extinctions.

extinction stats

Nearly half of 724 animal extinctions in 400 years were island species.