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Lecture 28

BIOLOGY 1M03 Lecture 28: Lecture 8 - Dr. Quinn

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McMaster University
Ben J Evans

Friday, March 17, 2017 Lecture 8 - Dr. Quinn Patterns of genetic variation/ skin colour Evolutionary Psychology - Last time and Today - lactose maalbsoprtion, lactase persistence wrap up - environment of evolutionary adaptedness - sexual selection refresher Lactase Persistence and Detecting Selective Sweeps - beneficial mutation favoured by natural selection - when a new favourable mutation spreads, it is surrounded by a chunk of other genes that are of the same sequence, this sequence is linked with the mutation and is called a haplotype since they are close enough together, they will travel together as a haplotype • • this particular region of the chromosome has similar things (haplotypes) - Figure with 16 chromosomes - Four different regions as haplotypes - one column is a haplotype, all the grey haplotypes are the same, all the green haplotypes are the same - each haplotype have four representative sequences - they share in common the same pattern • initially, there is a 50/50 relationship between white and black alleles - after natural seleciton has occurred for a while, there has been a beneficial mutation that has carried other sequences with it - crossing over will start to disrupt this pattern - the mutation may be taken apart from its haplotype - Selection pressure, 1 Friday, March 17, 2017 - With a small selective advantage, the frequency o the allele can sweep to prominence within 7000 years - Convergent adaptation of human lactase persistence in Africa and Europe - Dairying barriers that affect the dsitributio not lactose malabsorption - you can’t absorb the lactose very well - figure, larger dots are populations with lactose malabsorption - far away from the equator, they do better with milk, those closer do worse - areas where there is cattle disease keep less cattle, thus more likely to be lactose intolerant - greenland and siberia are so north that they cannot keep their cattle - lactose malabsorption is found high frequencies in low lattitudes, high temps and areas with ah high number of cattle diseases - barriers to dariyign seem to explain patterns of lactose malabsorption - lactose d digestion ability in mature people of dairying ancestry exemplifies culture as a seelcitv force driving organic evolution - culture is driving organic evolution - contours in skin colour - smooth gradient away from the equator, a lot of sunshine - Contours of ge
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