ANTHRO 7 Chapter Notes - Chapter 3: Maladaptation, Random Effects Model, Genetic Drift
Document Summary
When individuals that have particular variants of one character also tend to have particular variants of a second character, the two characters are said to be correlated. Beak depth is measured as the top-to-bottom dimension while beak width is the side-to-side dimension. Correlated characters occur because some genes affect more than one character. Pleiotropic effects: phenotypic effects created by genes that influence multiple characters. When two characters are correlated, selection that changes the mean value of one character in the population also changes the mean value of the correlated character. Correlated response: an evolutionary change in one character caused by selection on a second, correlated character. Can cause other characters to change in a maladaptive (detrimental to fitness) direction. Selection favored narrower beaks (generate more force to open seeds); however, due to correlated response to selection on beak depth, mean beak width also increased less likely to suvive. Selection produces optimal adaptations only at equilibrium.
