BIOL 2040 Lecture Notes - Lecture 10: Inclusive Fitness
27 Apr 2018
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Professor
Lecture 10 - Adaptation (pt. 2)
April 9, 2018
4:12 PM
Question
• AA, Aa = dark phenotype (better camouflaged against dirt)
o S = 0.20
• aa = light phenotype (better camouflaged against sand)
o S = 0.20
• 20% migration from mainland (dirt) to island (sand)
• Question:
o Allele A is fixed on mainland - what is the p value on beach?
• Answer:
o There is a 20% migration from mainland (dark) to beach (light)
o The selection value is 0.20
o Migration and selection is equal, so it's perfectly balanced - p value would be near 0.5 on
beach
o To get a value:
• P = pm (m/m+s)
• Pm = 1, the p value on the mainland
• P = 1 (0.2/0.2+0.2)
• P = 0.5
• At another more remote beach, only 5% migration occurs
o Selection pressure is 0.2
• Selection pressure tends to be bigger than mutation pressure (it's rare that mutation
pressure is larger than selection pressure)
o Mutation value is 10-6
• There is a low q of mutation
o Migration increases frequency of A allele on island
o Selection decreases frequency of A allele on island (0.2 against dark)
o Migration is 0.05 on 2nd beach - much lower than selection value (0.2), so selection
decreases the overall A allele frequency
Observational Studies
• Testing predictions against observation
Desert Lizards
• They don't internally regulate body temperature
o They stay in the shade to cool off, bask in sun to warm up, etc.
• We want to know what the optimal body temperature of lizards are that would maximize
efficiency
o If they are too cold, they slow down
o If they're too hot, they "fall apart"
• Lizards tend to keep their body temperature around the optimal
• They measured how well the lizards performed based on different body temperatures -
temperature of where all the performances intersected on the graph specified the optimum body
temperature
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