In this lecture, we wrap up our introduction to The Modern Synthesis by describing how population genetics connected particulate inheritance (genes with discrete alleles) to quantitative traits and natural selection. After reviewing the initial conflict between Mendelism and Darwinism, we use a simple additive effect example to show how discrete alleles can produce approximately continuous features (that are even more continuous when considering the effect of the environment on gene expression). We then discuss the contributions of Haldane and Wright to population genetics, summarize the key components of population genetics, and hold up population genetics as a foundational core to The Modern Synthesis which also include the primacy of natural selection in evolution. This gives us an opportunity to discuss Stephen Jay Gould's objections, punctuated equilibria, biological constraints (including the "spandrels of evolution"), and historical contingency. We conclude with a brief introduction to the central dogma of molecular biology, which helps to explain how genes lead to the expression of phenotypic traits that confer fitness on alleles. We end this discussion a little early (due to starting a little late).
Whiteboard notes for this lecture can be found at: https://www.dropbox.com/s/vc5rsqpmpymih60/SOS220-LectureG2-2023-03-23-Basic_Population_Genetics_and_Evolutionary_Biology.pdf?dl=0
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