Textbook Notes (368,795)
Canada (162,165)
Biology (600)
BIO120H1 (305)
Chapter 3

COYNE CH3

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Department
Biology
Course
BIO120H1
Professor
Jean Jiang Nash
Semester
Winter

Description
Chapter 3: Remnants: Vestiges, Embryos, and Bad Design There are features (vestigial) and genes that were once useful. Vestiges feature of species that was an adaptation in its ancestors but has lost its usefulness or has been adapted for other uses. VESTIGIAL BECAUSE NO LONGER PERFORMS FUNCTION FOR WHICH IT EVOLVED (not necessarily that it has no function). Example: ostrich wings not for flight but for balance, weaponry and mating. Flightless birds descend from flying ancestors. Bones of wings same in both flying and flightless birds. Why lose flight: Flight is metabolically expensive and wings easily injured. If lack of predators on island or food abundant on ground, then makes sense to reserve energy. Still visible because a) has other uses b) actually in the middle of transition Also, eyes in burrowers and cave dwellers: mutations over time can just accumulate if they neither harm nor help the animal. Whales: have hind limbs. Humans: appendix (for digesting cellulose). VESTIGIAL TRAITS ONLY MAKE SENSE IN THE LIGHT OF EVOLUTION. i.e. moving ears and non-functional wings dont make sen
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