05_ontogeny '09

05_ontogeny '09 - 1 First REQUIRED Term Paper Assignment...

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Unformatted text preview: 1 First REQUIRED Term Paper Assignment: Choose 3 topics from list of topics posted on course web site. Rank topics in order of preference, with #1 your most preferred and #3 your least preferred. Turn in one-page, single-spaced typed summary and comments by September 10 th . NO E-MAIL SUBMISSIONS! First REQUIRED Writing Assignment: In Sherman & Alcock, read your choice of: Gene Robinson, From Society to Genes with the Honey Bee OR John Vandenburgh, Prenatal Hormone Exposure and Sexual Variation OR Andrew Bass, Shaping Brain Sexuality Turn in one-page, single-spaced typed summary and comments by September 17 th . Artificial selection for maze Artificial selection for maze-running running performance in rats performance in rats No. of Individuals Maze-running performance generation 0 No. of Individuals Maze-running performance No. of Individuals Maze-running performance generation 2 generation 7 bright dull Bidirectional selection Clearly, variation in maze-running has a genetic component. Is environment also important? Is environment also important? Experiment Experiment Rear “bright” and “dull” rats in 3 kinds of environments: • restricted (1/cage; no toys) restricted (1/cage; no toys) • normal (3/cage; no toys) normal (3/cage; no toys) • enriched (12/large cage; 5 enriched (12/large cage; 5-6 objects) 6 objects) Measure maze running for each combination (3x2=6). Mean No. Errors 170 bright dull We call this a genotype x environment interaction 110 Rearing Environment Restricted Normal Enriched Effect of genotype depends on environment! Effect of genotype depends on environment! Rats in enriched environment treatment had: ¡ thicker cerebral cortex ¡ more synaptogenesis (= more ¡ more synaptogenesis (= more new synapses) 2 Environment matters! Food for Thought Food for Thought How might such considerations be How might such considerations be extended to human behavior and public policy? Another Example of Role of Environment Another Example of Role of Environment Sex determination usually genetic (e.g., fru locus in Drosophila ). Not so in many reptiles, including turtles, some lizards and all… CROCODILES! All crocodilians have TSD, or All crocodilians have TSD, or temperature temperature-dependent sex determination dependent sex determination Sex depends on the temperature at which egg is incubated during a sensitive period . Nile Crocodile Data T ≤ 31.7 o C Ö females females 31.7 < T < 34.5 o C Ö males males T ≥ 34.5 o C Ö females females • Sensitive period is ~ 10 days long in middle third of embryonic development • Involves activation of steroid-producing enzymes and steroid receptors • Can lead to biased sex ratios • Can be disrupted by toxins such as PCBs Ontogeny (= Development) of Behavior Ontogeny (= Development) of Behavior Two basic processes: Two basic processes: a. a.internal processes internal processes environment consists of an animal’s Behavior and Environment Behavior and Environment environment consists of an animal s...
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This note was uploaded on 12/09/2009 for the course ECOL 487R taught by Professor Papaj during the Spring '09 term at Arizona.

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05_ontogeny '09 - 1 First REQUIRED Term Paper Assignment...

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