BIOA01H3 Lecture Notes - Lecture 11: Hybrid Zone, Paraphyly, Protist

• School: UTSC
• Department: Biological Sciences
• Course: BIOA01H3
• Professor: Shelley Brunt

Document Summary

What happens when isolated populations of related species come back into contact (depends on time of divergence if they can breed again) Hybrid zone: area where interbreeding between two population occurs and hybrid offspring are common (mix between mitochondrial dna) Hybridization often leads to extinction but sometimes lead to the origination of a new species. Reinforcement: hybrids are less fit, eventually hybridization can no longer occur. If two populations of related species have diverged extensively and are distinct genetically, their hybrid offspring will most likely have lower fitness and will not develop or reproduce normally. When post zygotic isolation occurs, there is a strong natural selection against interbreeding. Selection for traits that isolate populations reproductively is called reinforcement. Sympatric species living in the sane area rarely want to mate with one another. Allopatric species living in different areas are often willing to mate with one another. Fusion: reproductive barriers weaken and become one species.