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Dichotomous Male Reproductive Strategies in a Polygynous Human Society: Mating versus Parental Effort. Kevin Curry Yolanda Mejia Anavely Rodriguez. Introduction. Life history theory: idea that organisms face the decision regarding the trade-off between quality and quantity of offspring.
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Dichotomous Male Reproductive Strategies in a Polygynous Human Society: Mating versus Parental Effort Kevin Curry Yolanda Mejia Anavely Rodriguez
Introduction • Life history theory: idea that organisms face the decision regarding the trade-off between quality and quantity of offspring. • Males: generally emphasize offspring quantity • Females: generally emphasize offspring quality • This creates conflict of interest
Summary of Article • Goal of paper: to examine the effect of wealth on the decision of male mating versus parental effort using offspring survivorship as a measure of parental investment. • Hypothesis: 1: a. Wealthy males will attract and gain more marriage partners. b. have higher completed fertility c. have more surviving offspring d. have higher reproductive careers than poor males 2: a. Poor males will have more offspring per wife than wealthy males b. have more surviving offspring per wife than wealthy males
Methods • Sample of 90 males, their wives and offspring • Household: a married man with one or more wives and their respective offspring. • Male fertility: all offspring recorded as sired by the male head of household. • Male’s reproductive career: calculated from the time between the first recorded and the last recorded birth of his offspring • Offspring survivorship: survivorship to 15 years of age
Results • Wealthy males had significantly more offspring survive to 15 years old than poor males -When the likelihood of obtaining mates is slim because of lack of resources, males may be maximizing a mating strategy through parental effort.
Results cont. • Wealthy males have significantly more wives than poor males (consistent with Ia.) and therefore Wealthy males sired significantly more offspring per reproductive year than poor males (prediction Ib.) • Wealthy males had longer reproductive careers than poor ones (prediction Id.)
Discussion • Consistent with Darwinian Theory • Monogamy is a result of unsuccessful mating strategy • Monogamy and Parental Care are correlated
Critique of Article • Sample: 90 males and their wives in Utah territory in the 19th century. • The sample is too small and therefore is not a proper representation of the entire population. • Men were mormons who entered polygynous marriages. • Using only mormons is not representative of the entire male population. • 1850 1860 and 1870 US census. • This is not representative of the most recent census therefore it is difficult to relate this sample to present day population.
Critique cont. • The study measured male wealth as quality but failed to take into account other male qualities that can make a difference in parental investment such as: • Male health • Special skills the male may posses • Social status • Number of kin • Or any combination of the above mentioned This could have explained inter and intrapopulation male reproductive strategies.
Critique cont. • This article has shown that monogamy in paternal investment helps increase survivorship of offspring, however in class we have discussed that it is not in a male’s best interest to be monogamous.
Quiz • 1. Parental effort was measured in the study by looking at: • a. lifetime reproductive success of parents • b. genetic variability • c. survivorship of offspring • 2. The study found that monogamy is closely associated with: • a. the occurrence of genetic mutation • b. parental care • c. fitness of offspring • 3. Survivorship of offspring was measured up to: • a. age 18 • b. age 15 • c. age 21 • True/False • 4. Male fertility was defined in the article as all offspring recorded as sired by the male head of household. • 5. Males generally emphasize offspring quality rather than quantity. • 6. Wealthy males had shorter reproductive careers than poor males.
Class Discussion • Parenting investment as a mating strategy. • Male baboons that show affection to their offspring are more likely to mate more with their mother. • High quality males resort to mating and escape parenting where as low quality males resort to parenting skills and take care of the few offspring they have so that their offspring survive. • This study has shown that high quality males have more offspring pass away than do low quality males. • Shouldn’t males with more resources have more children surviving? Which theory do you agree most with?
