BIO 3400 1nd Edition Lecture 12 Outline of Last Lecture Female choice Good genes hypothesis Direct benefits Preexisting sensory biases Runaway sexual selection Outline of Current Lecture Sexual selection Runaway sexual selection Cryptic female choice Method for studying selection and adaptation Biology of Natural Predators Experimental study Tephritid flies and jumping spiders Observational study Garter snakes Current Lecture Sexual Selection Good gene hypothesis handicap hypothesis Direct benefits Preexisting sensory biases Runaway sexual selection Runaway Sexual Selection The evolution of female preference and male advertisement reinforce each other This can happen if there is a genetic correlation between the male trait and female preference for the trait ex finches offspring will have 1 genes for long tail and 2 genes preferring long tail Cryptic Female Choice 1 Females often mate multiple times 2 Many species have the ability to store sperm for long periods of time 3 Opportunity for females to choose which sperm to use to fertilize eggs Methods for Studying Selection and Adaptation These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute How do we know if something is an adaptation Adaptation a trait that increases an individual s fitness relative to those without the trait Adaptation is expected to be common Phenotypic variation is nearly always present Most traits have non zero heritability Phenotypic variation often correlates with fitness We do not accept adaptive hypotheses just because they are plausible or appealing Methods The comparative method Biology of natural populations Selection experiments Comparison of real organism with predictions of theoretical models Biology of Natural Populations Experimental Study Tephritid flies and jumping spiders Tephritid flies wave their wings to ward off predators such as the jumping spider Scientists tested the effect of wing waving groups flies left untouched control flies with wings cut off and reglued houseflies with tephritid fly wings tephritid flies with housefly wings normal housefly tested to see if the jumping spider would attach each group or not Observational Study Garter Snakes 1 In ectotherms performance is tied to temperature 2 performance measured as endurance speed digestive efficiency and hearing efficiency 3 Hypothesis 1 Garter snakes choose habitats that keep them near an optimal temperature 2 Garter snakes do not behaviorally thermoregulate 4 SO makes should choose habitats that keep their temperature in a certain range 5 For the experiment scientists tagged and tracked snakes monitored snake temperatures and monitored environmental temperatures 6 Results Garter snakes do a great job of keeping their body temperature in a optimal range by hiding under rocks and laying in the sun
View Full Document
Unlocking...