Bio 3400 1nd Edition Lecture 13 Outline of Last 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 Outline of Current Lecture Selection Experiments Mice and wheel running Other selection experiments Endler s guppies Comparison of real organisms with predictions of theoretical models Current Lecture Selection Experiments Laboratory selection experiments artificial conditions experimenter decides who reproduces many examples Why conduct selection experiments the process of evolution can be directly observed how do interrelated traits evolve EXAMPLE MICE Experimental Design starting population 112 male and 112 female mice of the outbred Hsd ICR strain genetic variation similar to human populations used for several other selection experiments selected based on how many times they ran on a wheel Background and Rationale voluntary activity levels affect energy expenditure balance body composition 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 fitness psychological well being individual differences in voluntary activity levels are large in humans and mice Results wheel running had significant narrow sense heritability in the base population What else changes morphological changes lower body mass and fat larger heart kidneys and lungs behavioral decreased parental care more intermittent locomotion physiological more efficient glucose uptake higher hematocrit higher endurance Other selection experiments Lenski s E Coli experiment fitness increased over 50 000 generations measured by how much of the plate the strains took up fox tameness belyaev increased tameness shorter skulls whining barking Late reproduction in drosophilia Rose later reproduction increased lifespan decreased early reproduction increased size increased stress resistance Selection on guppies in new environments Endler s guppies Greenhouse selection experiment no predation L low predation R high predation C Field introductions transferred guppies from high predation sites to low predation sites why wanted them to survive long enough to be observed high predation low predation Results when transferred from site to site guppies evolved to be more like the control group in that site Comparison of real organisms with predictions of theoretical models Models in biology all models are unrealistic models balance complexity and realism models tell us what happens when the assumptions of the model are met Example Aerodynamic models predict high aspect ration long and narrow efficient not very maneuverable gliders low aspect ration shorter and wider less efficient more maneuverable fighter jet Question does maneuverability correlate with wing size and shape in flying animals 2 species of bats Similar to expected
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