Week 8- Sexual Selection and Speciation
Week 8- Sexual Selection and Speciation Biology 152
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This 2 page Class Notes was uploaded by BettyAnn Mead on Friday March 27, 2015. The Class Notes belongs to Biology 152 at University of Massachusetts taught by Peteh in Winter2015. Since its upload, it has received 63 views.
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Date Created: 03/27/15
Satellite Behavior 0 Some male toads wait silently near another male that is calling to attract females 0 Try to intercept and mate with the females that are moving toward the calling male 0 Both behaviors persist in population even though satellites have less reproductive success FrequencyDependent Selection The phenotype that yields the greatest tness depends on how common each alternative phenotype IS 0 Many traits have evolved because they help males win the competition for access to females 0 But what about females 0 Theory predicts females should be choosy 0 Do females make bene cial adaptive choices 0 Easiest to tell when male provides female with direct material bene t Example Food or parental care Sexual Suicide The male inserts his sperm into the female and then enters her mouth In most animal species though males provide only sperm 0 When females get no direct material bene t are they still choosy o Females prefer males with particular traits even when males provide no direct bene t o Females preference can select for the evolution of extravagant ornaments and behaviors Why Sex Key Concepts Parasite load Redqueen hypothesis Inbreeding and population bottlenecks Genetic Drift By chance some individuals may leave more offspring just by chance 0 In contrast evolution via natural selection selects individuals with higher tness not just by chance Genetic drift is more common in smaller populations Costs of Sex Time and energy devoted to mating Exposure to predation during courtship Sexually transmitted disease Females Only 50 of genes passed to next generation Population growth rate have lower upper bound Bene ts of Sex Better ability to deal with harmful mutations Genetic diversity to deal with changing environment 0 Diseases 0 Food sources 0 Climate change Species Variation in life s form not continuous Life come in discrete packages These distinct entities are species Objectiver real not arti cial constructs Evolution must produce not only changes over time within a lineage but must also create new lineages What mechanism create and maintain new species What is a species Not fully addressed until 1930 s Thought of species as reproductive communities The Biological Species Concept quotSpecies are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groupsquot