BIOL2010 Lecture Notes - Lecture 18: Collared Flycatcher, Hybrid Speciation, Hybrid Zone
Document Summary
Lecture 18: most common way to get speciation, best way to cut off gene flow. In central europe, there are some places where they are sympatric: ancestral flycatchers, some went down to the italian peninsula and became allopatric, since the last glaciers melted, they expanded north and caused secondary contact. In sympatry, hybridization is lower than expected with random mating: 2-7% breeding adults are hybrids, hybrids have reduced fitness females are generally sterile, males have reduced fertility. In sympatry, there should be increased divergence in male phenotypes so that the different species stay separate in order to increase fitness. If they have intermediate phenotypes it would be easier to find them: not always the case. Lecture 18: sunflowers, having a different niche makes them isolated from the parents, could also (cid:271)e isolated fro(cid:373) a a(cid:374)d b (cid:271)e(cid:272)ause it does(cid:374)"t re(cid:272)og(cid:374)ize each other as potential mates, butterflies found in central and south america.
