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Unformatted text preview: 1/26/10 1 178 178 Levels of selection Traits may beneFt entities at different levels of organization Nevertheless, traits are not expected to evolve for the good of the species blue = altruistic, pink = selFsh 179 179 Levels of selection Group selection is only plausible if groups have heritable Ftness variation. But 1) Group heritability is likely to be low- groups often not stable entities because of migration 2) More birth/death of individuals per unit time Individual selection arguments are favored 1/26/10 2 180 180 Nevertheless, we observe apparently altruistic traits Fut 14.15 "I would lay down my life for two brothers or eight cousins-JBS Haldane Beldings ground squirrel Pied kingsher 181 181 An apparently altruistic act is associated with a tness cost to the actor and a tness benet to the recipient. Under certain circumstances, such traits can spread. Hamiltons rule: apparently altruistic traits may evolve if rb > c r = degree of relatedness between actor and recipient (full sibs, r = 0.5) b = benet to recipient c = cost to actor Inclusive tness Consider a rare allele which results in an act that reduces the tness of the indiv. Consider a rare allele which results in an act that reduces the tness of the indiv....
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This note was uploaded on 03/29/2010 for the course EVE EVE 100 taught by Professor Davidbegun during the Winter '10 term at UC Davis.
- Winter '10