2-26-08 - Psyc-131 February 26, 2008 Ecological factors...

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Psyc-131 February 26, 2008 - Ecological factors intervene to make it difficult for a male to increase his RS by leaving his current mate and seeking another what are the factors that influence male parental care? - Factors that influence male parental care: o 1) External v. internal fertilization/gestation o 2) How effective is care by 1 or 2 parents? Internal gestation means that care by 1 parent is sufficient (although not always) o 3) Can a deserting male improve his RS? Certain ecological conditions are imposed on the animals and constrain a male from leaving his current mate and seeking a new one could be a short breeding season, or need a territory to raise young but all territories are taken, or all the females are taken o 4) Paternal certainty this could make him stay Male can lose his reproductive investment if by leaving the female will mate with other males that could displace the first male’s sperm need to ensure that after mating, the male actually becomes the parent of the offspring that the females are carrying So there is a striking asymmetry in parental care for offspring - Infanticide illustrates this case - Langer monkeys – have a social organization in which there is 1 male and several females; male controls an area and the females remain in that area throughout their lives o Other males in all male groups that cruise another area occasionally challenge a resident male territorial male and try to take over the area and his females o Sometimes when a male took over another male’s group of females, he would work through the group (systematically, a little bit each day) and try to kill the tiny infants in the group Evolutionary point of view: when a new male takes over a group, he finds the females in various stages of reproduction While female is pregnant and lactating, she is not ovulating and therefore not available for mating activity o Male has 2 choices: can acquiesce to the situation (only mate with those females who are not pregnant and lactating), or can come in and take over the group and try to kill the tiny infants in the group Infanticide reproductive strategy o When infant dies, mother stops lactating and resumes sexual cycling o Females fight the male that commit infanticide Problem: males are larger than females and females are not really 1
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Psyc-131 February 26, 2008 that effective in protecting their offspring they try to protect their offspring but they fail Male’s reproductive interest is different than that of females Nonetheless, it seems to be adaptive Laboratory people working on rats and mice have notices: female and male rat mate; if male is still there, everything is fine; if male is removed and then you put in another male when the female is born, then the male will kill the pups
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2-26-08 - Psyc-131 February 26, 2008 Ecological factors...

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