|
area |
↑ potential for geographical isolation of separated populations |
↓ by ↑ survival of refuge populations |
|
environmental factors strongly correlated with area |
population size |
↑ rate of appearance of beneficial mutations, standing genetic variation, persistence of incipient species |
↓ by buffering populations from demographic stochasticity, environmental disasters, habitat loss |
↑ number of species with viable populations supported |
|
habitat diversity |
↑ population divergence through local adaptation |
|
↑ niche space available |
|
fragmentation /topographic diversity |
↑ isolation of populations; however past a certain point, will ↓ speciation by ↓ population size |
if fragmentation results in too small patches of area or habitat, will ↑ extinction rate |
↑ by allowing more ecologically equivalent species to be supported |
environmental factors not strongly correlated with area |
energy availability |
↑ rate of molecular evolution, rate of coevolutionary dynamics, size of populations supported |
|
↑ by facilitating specialization to narrow niches |
clade traits |
life-history traits |
faster life cycle ↑ speciation by increasing mutation rate |
faster life cycle ↓ extinction by ↑ resilience to disturbance |
|
|
range size |
larger range sizes ↑ speciation by ↑ potential for isolation of populations |
larger range sizes ↓ extinction by ↑ survival of refuge populations |
smaller range sizes ↑ diversity limit by allowing more species to pack into same area |
|
niche breadth |
narrower niche breadths associated with ↑ speciation |
narrower niche breadths associated with ↑ extinction |
narrower niche breadths ↑ diversity limit by allowing finer subdivision of niche space |
|
dispersal |
↓ by reducing potential isolation of populations, but can also ↑ speciation rate by ↑ rate at which species colonize new regions |
↓ by ↑ resilience to disturbance |
↓ if high dispersal ability is associated with large, non-overlapping species ranges |