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Lecture 6

BGYB51H3 Lecture 6 Notes Sep 29

Biological Sciences
Course Code
Maydianne Andrade

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BGYB51H3 Lecture 6 Notes
-in natural experiments, introduction of new host species are observed in an area to determine
-introduction of new host can cause little competition initially compared to original host that
suddenly experiences more competition (e.g. soapberry bugs)
-in Galapagos Islands, a single lineage of finches underwent an adaptive radiation which
diversified their beak characteristics and body sizes as a result of different niches and food
-before the drought in the Galapagos Islands, natural selection favoured birds with small beaks
-during the drought in the Galapagos Islands, natural selection favoured larger birds with bigger
-offspring of survivors of the drought had larger beaks and large body sizes
-in the second drought, there was increased competition between large competitors, providing
an advantage for smaller birds
-evolution is dynamic in that populations can change repeatedly (or change in one direction,
then back again)
-environment changes bring selective pressures to cause evolutionary changes
-inferred causation increases when multiple events involving selective pressures correlate with
each other
-microevolution occurs today and causes changes in genotype frequencies
-macroevolution are changes that distinguish higher taxonomic groups
-sperm competition among different primates occurs in order for fertilization of eggs of a single
female (occurs if females mate with more than 1 male)
-large testes evolved in male primate species where females mate with more than one male
-using different primate species as independent data points overinflates the sample size by not
considering them being one evolutionary event that occurred
-an evolutionary event in primates involved changes in mating system that led to evolution of
different size in testes
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