Bio 113 Week 6 notes
Bio 113 Week 6 notes BIO 113
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This 2 page Class Notes was uploaded by Paige Brabant on Monday February 22, 2016. The Class Notes belongs to BIO 113 at Wake Forest University taught by Anderson, Todd Michael and Clifford W. Zeyl in Spring 2016. Since its upload, it has received 22 views. For similar materials see Evolutionary and Ecological Biology in Biology at Wake Forest University.
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Date Created: 02/22/16
Bio 113 Class Notes Speciation: the evolution of two species from one ancestral species Two categories of explanation… 1. Allopatric Speciation: Interbreeding is prevented by some physical obstacle (water, mountains, glaciers…) 2. Sympatric Speciation: Selection somehow favors both different traits (usually ecological, avoiding competition) and mating preferences (individuals avoid mates with traits different from their own) *Important to note that speciation is not necessarily associated with an adaption If a single mutation causes genetic incompatibility with the rest of the species, this individual won’t survive because it won’t be able to mate and reproduce If multiple mutations are required, there isn’t a mechanism to prevent interbreeding, which would spread the mutation throughout the species instead of creating an entirely new species Dobzhansky-Muller Model- An effect of allopatric speciation After the ancestral lineage separates into two independent lineages, different mutations spread through each new lineage These mutations are genetically incompatible and if contact is restored, there is selection against mating of these different alleles because there would be a lower fitness, which is a waste of reproductive effort Once contact is restored, “isolating mechanisms” prevent interbreeding In regions of sympatry, differences in the species are more distinct than in areas of allopatry because the greater contrast is adaptive and it reduces the risk of choosing a mate of the wrong species and wasting reproductive effort Temporal Isolation: deals with the time of the year of breeding When in areas of sympatry, the species have completely different breeding times In areas of allopatry, the breeding seasons can overlap Speciation of Different Pollinators Example: Hummingbirds are attracted to flowers with red color, a long tube and a large volume of nectar; bees are attracted to flowers with pinkish purple flowers, a convenient place to land and small volumes of concentrated vector This causes distruptive selection because this flower will either be the first time or the second, one in the middle wouldn’t attract either pollinator and wouldn’t be reproductively successful This also prevents cross-pollination because only one pollinator is attracted, which causes genetic isolation
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