Essayz - 1) ALTRUISM. The evolution of altruism represented...

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1) ALTRUISM. The evolution of altruism represented a challenge to evolutionary biology because altruistic individuals act in ways that reduce their direct fitness. Hamilton’s insights regarding inclusive fitness help to explain the evolution and maintenance of altruism. What is inclusive fitness and how does it relate to the evolution of altruism? How is inclusive fitness relevant to selection acting on different levels of biological organization? - Inclusive fitness holds that an organism can improve its overall genetic success by cooperative, social behavior. The concept serves to explain the evolution of altruism. Altruistic behaviors can exist if that “altruism genes” influences an organism’s behavior to be helpful and protective of relatives and offspring at the expense of itself, because relatives are likely to share genes with them due to common ancestor. Thus inclusive fitness acted more the level of relatives than non-relatives. Evidences from prairie dogs in the wild that gives alarm when predator nearby (those calls have lower fitness-altruistic behavior) shows that individuals are more likely to give alarms calls when close relatives are nearby. 2) LIFEHISTORY. Life history traits are often subject to strong selection, yet most exhibit substantial genetic variation. Several factors can explain the maintenance of genetic variation for life history traits, including (1) high epistasis among loci contributing to variation in life-history traits, (2) fluctuating patterns of natural selection over time, (3) negative genetic correlations among life history traits, and (4) mutation-selection balance. Explain how two of these factors can maintain genetic variation for life history traits. - Fluctuating patterns of Natural selection overtime can help maintain genetic variation in a population. If selection patterns fluctuate overt time, different alleles or genotypes may gain more fitness at different times. The overall effect may be that both alleles persist in a population. For example, changes in selection pressures over time in two grasshopper species, a brown and a green color. In the dry season, when the habitat is brown, the better-camouflaged brown grasshopper has more protection from predators. In the wet season, the environment is greener and the green grasshoppers have higher fitness. - Also mutation-selection balance can maintain genetic variation. When mutations are deleterious, selection acts to eliminate such mutations from a population, resulting in decreasing genetic variability. However, new deleterious alleles are constantly being supply by mutation. Thus, this balance between mutation and selection may explain why deleterious alleles persist in a population and maintain genetic diversity in a population. 3) SEXUALSELECTION.
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This note was uploaded on 07/27/2011 for the course BIOL 3306 taught by Professor Zufall during the Spring '09 term at University of Houston.

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Essayz - 1) ALTRUISM. The evolution of altruism represented...

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