BIO 3400 1nd Edition Lecture 11 Outline of Last Lecture Genetic Drift and Gene Flow Selection and Gene Flow Selection and Genetic Drift Sexual Selection Outline of Current Lecture Female choice Good genes hypothesis Direct benefits Preexisting sensory biases Runaway sexual selection Current Lecture Female Choice Red collared widow birds Group had tails artificially shortened expensive to carry around a big long tail Control and short treatments did not differ in territory establishment size of territory quality of territory DID differ in number of active nests long tailed control group had more Frogs Females prefer frogs with longer calls Why do female preferences evolve 1 good genes hypothesis handicap hypothesis 2 direct benefits 3 preexisting sensory biases 4 runaway sexual selection Good Genes Hypothesis Displays indicate genetic quality more attractive males are genetically superior ex peacocks ex frogs in high and low food conditions larval growth survival etc 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 Direct Benefits Resources avoiding parasites etc Ex hanging fly direct relationship with duration of copulation and sperm transferred Pipefish males invest more resources than females in offspring females can produce eggs faster than males can rear a brood female reproductive success is limit by access to male pouch space therefore males are the choosy sex Preexisting Sensory Biases sensory preference exists for some reason unrelated to mate discrimination the preference for certain cues causes sexual selection on males to display those cues ex finch taped white feathers to male heads females strongly preferred white crest feather why white one hypothesis nests are lined with white feathers for camouflage Discussion Forsgren et al 1996 1 What is producing intrasexual selection in sand gobies the availability of resources specifically the number of shells 2 What is producing interseuxal selection in sand gobies a large number of shells and male size 3 What predictions do the authors make regarding these two types of sexual selection they predict that an increase in the number of shells will decrease intrasexual selection and increase intersexual selection 4 How did the authors test their predictions Which aspects were carried out in the field and which were carried out in artificial conditions 5 Did their results support their prediction Did you agree with their conclusions 6 What possible limitations to their study do the authors discuss 7 Do you think it is a good strategy to use both field and lab studies What do you think the strengths and weaknesses of each are Do you think one type of study is better than the other
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