BIOB51H3 Lecture Notes - Lecture 2: Modern Synthesis (20Th Century), Macroevolution, Geologic Time Scale
14 Oct 2016
School
Department
Course
Professor
Document Summary
1- natural selection acts on individuals, but its consequences occur in populations. Individuals did not change their beak size; they simply lived or died some finches survived the drought while others perished. What changed was the average beak size, a characteristic of population. The effort of cracking tribulus seeds did not make the beaks of individual finches grow larger. Nor did the birds" need for more food, or their desire for bigger beaks, make their beaks grow. Instead, the average beak depth in the finch population increased due to the simple, if cruel, fact that more small-beaked finches died. Likewise, the effort of attracting pollinators had no effect on the pigments in the flowers of individual snapdragons. Instead, the proportion of white versus yellow flowers changed simply because white plants exported more pollen and made more seeds. A woman who sunbathes while pregnant does not give birth to a baby with darker skin.
