BIOL 2200 Chapter Notes - Chapter 24: Macroevolution, Speciation, European Pied Flycatcher
1 Feb 2017
School
Department
Course
Professor
Document Summary
24. 3 hybrid zones reveal factors that cause reproductive isolation. Hybrid zone region where different species meet and mate, producing offspring of mixed ancestry. Patterns within hybrid zones: some hybrid zones form narrow bands. A narrow band separates species of yellow bellied toad and fire bellied toad. As you get get deeper into the line, going from one side to the other, the allele frequency for yellow bellied toad decreases until it reaches 0% on the other side. Pattern in allele frequency caused by an obstacle to gene flow. Most hybrids do not survive to reach adulthood and produce few offspring with parent population: located where interbreeding species meet. If hybrids don"t form a new species then other outcomes for hybrid zones are: Hybrids are less fit than the parent species, so natural selection should strengthen prezygotic barriers to reduce the formation of unfit hybrids. Reproduction barriers between between species should be stronger for sympatric populations than allopatric populations: ex.
