BIOB51H3 Lecture Notes - Reproductive Isolation, Sexual Selection, Parental Investment
10 Dec 2013
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Document Summary
Once gene flow stops, then the process of exchange of allele stops. Sexual selection is subset of natural selection; competition over mates. Variation in plumage colours of monarch flycatchers; different coloured birds will rarely interbreed. Divergence sometimes leads to reproductive isolation; can occur if species come back together but can"t breed or that hybrids do very poorly. If they cannot interbreed, they are separate biological species already. Divergence can only happen if there is no gene flow. Sexual dimorphism is change in behavior/form of males and females. Darwin thought there were different selection pressures because females invest more in offspring than males. Parental investment involves a tradeoff; less for future offspring. In species where care of the young is required, maternal care is usually more expensive than paternal care. Female output is limited by the resources they have to build egg; sperms are present in excess and males aren"t limited by sperm.
