Temporal Speciation Patterns

Species Radiation and Extinction through Geologic Time Text Readings: pages 39-41 Box 3.3 (pg 85) 86-89 224-225

Speciation occurs with a split in a gene pool of a species such that the separate lines become reproductively incompatible

Washington Community & Tech. College

How does Speciation Occur? 1.Allopatric Speciation • microallopatric speciation

2.Sympatric Speciation 3.Parapatric Speciation

1) Allopatric Speciation - populations become reproductively isolated during periods of geographic separation (e.g. by mountains, land bridge disappearance, sea strait). - this mode is recognized as important for speciation of many plants and animals; - the best evidence comes from birds (Darwin's finches, Hawaiian honeycreepers), mammals, butterflies and Drosophila (e.g. Hawaii)

One of the best examples is the accepted history behind Darwin’s Galapagos finches. The initial colonist is believed to be a finch from Cocos Island, off the mainland of Costa Rica. The Cocos finch is the sole finch species on Cocos Island, whereas many species occupy the Galapagos islands owing to emigration followed by allopatric speciation on ‘new’ islands in the Galapagos. Habitat and food specialization and geographic isolation facilitated species Cocos Island

Cocos finch

Darwin's finches

Hawaiian Honeycreepers same process as per Darwin's finches except the scale of radiation and morphological variation in beak size was far more extensive. Process occurred in