20 evolulon specialon specialon process of forming two


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Unformatted text preview: essory or main olfactory bulbs. Previous experiments show that olfactory informaLon is criLcal for nurturing. Therefore, FosB may also aﬀect the integraLng of many olfactory inputs that regulate the nuturing response. There were also slight detecLons of FosB within other regions of the brain, suggesLng that FosB may also be aﬀected by subtle environmental changes. The expression of FosB within so many regions of the brain suggests that it may also have other funcLons in the central nervous system. New geneLc tools to study behavior index ring index / ring ﬁnger PopulaLon GeneLcs and EvoluLon 18 Some important quesLons • What is evoluLon? • How is evoluLon measured? • What are the factors that aﬀect whether a populaLon evolves? 19 What is evoluLon? EvoluLon occurs at the level of the populaLon and is deﬁned as a change in gene (allele) frequency over Lme. 20 evoluLon ≠ speciaLon SpeciaLon: Process of forming two (or more) new species (non ­hybridizable populaLons) from a common ancestor, usually involving the accumulaLon of new alleles. This oden referred to as EvoluLon 21 What populaLons are evolving? EvoluLon occurs at the level of the populaLon and is deﬁned as a change in gene frequency over Lme Lactose Tolerance is a derived state. The ancestral state is lactose intolerance. In African populaLon the frequency of the derived allele that confers lactose tolerance has increased dramaLcally in about the last 3000 years. 22 Lactose Tolerance is a Derived State Normally Lactase ProducLon Shuts oﬀ in Childhood. 90% of Individuals in Scandanavian PopulaLons Maintain Lacose Tolerance Through Adulthood. A SNP in the gene encoding lactase (LCT) (C/T ­13910) is associated with the ability to digest milk as adults (lactase persistence) in Europeans. A genotype ­phenotype associaLon study in 470 Tanzanians, Kenyans and Sudanese and idenLﬁed three SNPs (G/C ­14010, T/G ­13915 and C/G ­13907) that are associated with lactase persistence and signiﬁcantly enhanced transcripLon from the LCT promoter in vitro. Convergent adapta-on of human lactase persistence in Africa and Europe Sarah A Tishkoﬀ 23 hHp://www.nature.com/scitable/knowledge/library/evoluLon ­is ­change ­in ­the ­inherited ­traits ­15164254 How do we tell if a populaLon is likely to evolve or is evolving? hHp://anthro.palomar.edu/syntheLc/synth_2.htm 25 How do we tell if a populaLon is likely to evolve or is evolving? •Markers/Polymorphisms •Look at the populaLon over mulLple generaLon 26 Hardy Weinberg EquaLon If 1 ­p = q an...
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This note was uploaded on 01/20/2014 for the course BIOL 221 taught by Professor Gallagher,kimberly during the Spring '13 term at UPenn.

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