EEB214H1 Lecture 23: Are Humans Still Evolving?

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Ecology & Evolutionary Biology
Jennifer Carpenter

EEB214 Lecture 23: Are Humans Still Evolving? Evolution is change in allele frequencies across generations • Selection on survival • selection for reproduction • random changes [aka genetic drift] • migration Are there environmental factors that cause some people to survive and reproduce that others cannot? • selection is happening in a way that they have alleles which don’t make individual’s sick • selections acting in ways that diseases still exist and no way to treat them • Selection is acting o variation in phenotypes o differential fitness o heritability • E.g., In a long term study of Australian women who are twins, they tracked various health related phenotypes o compare identical twins (monozygous) to non-identical (dizygous) o comparing twins we can tell there’s heritability and they also have fitness but measures how fitness correlates with other phenotypes • Based on these data what would the phenotype of a woman with maximal fitness be? [In Australia] o Period at 8 or 9, lower fitness compared to period at 11 or 12 –higher than average and later than 15—higher than average o Selection for this trait if it’s heritable o Also, age of reproduction: having kid at 15-17 then fitness is good, the later in life to have kids, the lower fitness will be o Age at menopause: starting at 20, fitness is lower than average compared to late 50s • This is selection to increase breeding length • Selection might be extending the amount of time that humans are reproductively capable
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