Chapter 12 Part 1 Flashcards
Termite colonies
typically consist of one large reproductive queen, a smaller male king, and a colony of sterile individuals
hymenoptra
consists of termites, all ants, some wasps, and some bees
group of most noted eusocial insects
eusociality
describes species with overlapping generations, cooperative care of young, and reproductive division of labor where many individuals in a group are permanently sterile
altruism
a behavior that benefits other tot the detriment of the one performing the behavior
first analyzed by C. Wynne-Edwards who argued that altruistic behaviors evolved in species to the benefit of the species as a whole rather than the individual
group selection
the process that occurs when groups differ in their collective attributes and these differences affect the survival chances of the group
explanation for group-benefiting altruism
Darwin argued… to explain altruism
that preferred hereditary attributes can persist if parents go on to produce additional offspring in addition to the killed offspring that participated in self-sacrificing altruism
propagation of genes shared by relatives
William D. Hamilton argued … to explain altruism
that through an indirect route, the altruistic behaviors of some are self-sacrificing but aid in the continuation of genes/preferential alleles among a population through non-descendant relatives
coefficient of relatedness (r)
the probability that an allele present in one individual will be present in a close relative; the proportion of the total genotype of one individual present in the other as a result of shared ancestry
an estimation of the degree of relatedness between individuals
Examples of coefficient of relatedness
between a parent (Aa alleles) and a child (who would receive A or a from that parent), there is a coefficient of .5
two sisters - .5 but the amount of shared maternal/paternal genes received will differ between the two
a man and his sister’s son (nephew) - .25 coefficient (1/4 chance of sharing ancestral alleles from parent/grandparent)
two cousins - .125 r (1/8 chance of sharing ancestral alleles from grandparents)
example of coefficient of relatedness to explain altruism
parent-offspring coefficient is .5 for one offspring
parent-niece/nephew coefficient is = to relatedness x # of nieces/nephews; so, caring for three nieces/nephews is equal to .25 x 3 = .75
Thus, they can directly pass .5 to an offspring or indirectly to .75 closely related relatives
kin selection
a type of natural selection that favors the reproductive success of an organism’s relatives, even at a cost to the organism’s own fitness
direct fitness
a measure of the reproductive (genetic) success of an individual based on the number of its offspring that live to reproduce
indirect fitness
a measure of the genetic success of an altruistic individual based on the number of relatives (or genetically similar individuals) that the altruist helps reproduce that would not otherwise have survived to do so
inclusive fitness
a total measure of an individual’s contribution of genes to the next generation generated by both direct fitness (derived from reproduction) and indirect fitness (which depends on social interactions with relatives)
for an altruistic trait to be adaptive..
the inclusive fitness of altruistic individuals has to be greater than it would have been if those individuals had tried to reproduce personally
a rare allele ‘for’ altruism will become more common only if the indirect fitness gained by the altruist is greater than the direct fitness if loses as a result of self-sacrificing behavior
