Biogeography Exam 2

Small populations

founder effects, drift, inbreeding

founder effect

colonists carry subset of mainland diversity

Inbreeding

Lower fitness (inbreeding depression)

ecological release

niche expansion, high densities

generalists win over specialists

broader diets and habitat flexibility

small islands

fewer coexisting niche competitors

over generations we see…

less dispersal capacity favored

evolution works faster on…

islands rather than the mainland

plant diaspores

achene increase, pappus decrease

time scale

few generations on small islets

tendency (the island rule)

small vertebrates —> larger; large —> dwarfs

drivers (the island rule)

resource limits, enemy release, stability

examples (the island rule)

komodo (giant varanids); pygmy elephants

caveat (the island rule)

mixed empirical support across taxa