BS 148H Lecture 4 - BS148HLecture4 16:34...

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BS 148H Lecture 4 16:34 Adaptation and Imperfection What is an adaptation? o A trait that works better and is maintained by current selection o Adaptations are imperfect because there are tradeoffs and selection and  adaptation are mechanisms meant to optimize the tradeoff not necessarily  the individual trait Ex) barn swallow tails have evolved to improve both aerodynamics and  attractiveness for mating  How do adaptations evolve? o Evolved in response to past selection  Article: Cats lack a sweet tooth Is loss of sugar receptors in cats an adaptations? o You can’t really tell based on lack of data due to not having cats  that  possess sugar receptors and you can’t tell if losing sugar receptors has  increased cats level of fitness It is most reasonable to infer that cats lost the sugar receptors due to  being mainly carnivorous and not needing to taste for sugar 
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BS 148H Lecture 4 - BS148HLecture4 16:34...

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