research findings Flashcards
What are the finding for Muller - “Male Chimps Prefer Mating Older Females”
Male chimpanzees demonstrate a significant preference for older females.
- Older females had higher copulation rates with high-ranking males, indicating a preference for mating with older females among the more dominant males.
- The rate of male-male aggression in contexts involving estrous females was higher with older females, suggesting that males compete more intensely for access to older females.
What are the findings for Malo - “Antlers Honestly Advertise Sperm”
The study provides evidence supporting the phenotype-linked fertility hypothesis, which suggests that secondary sexual ornaments in males, such as antlers, may honestly advertise male fertility. Specifically, it was found that a global measure of relative antler size and complexity in male red deer is associated with relative testes size and sperm velocity.
Antlers serve not only as weapons in male-male competition but also as signals of male reproductive quality.
Findings for Mitani - “Why Chimps Hunt and Share Meat”
-observations showed that hunting primarily occurred during times of food abundance.
- Male chimpanzees did not gain a mating advantage through sharing meat.
- Findings were consistent with the hypothesis that male chimpanzees use meat as a tool for social bonding.
While males shared meat more frequently with estrous females than would be expected by chance, sharing was not common and did not lead to increased mating success for males.
Finding for Michalczyk - “Inbreeding Promotes Promiscuity”
-The study found that polyandry (mating with multiple males) significantly enhances reproductive fitness in inbred populations of Tribolium castaneum (flour beetle).
-While monandrous (single-male mating) females in inbred populations experienced substantial inbreeding depression, polyandrous females showed reproductive fitness levels comparable to those in non-inbred control populations.
- Inbreeding reduces sperm competitiveness in Tribolium castaneum.
Finding for Roberts - “A Bruce Effect in Wild Geladas”
The study provides compelling evidence of a Bruce effect in wild geladas, with data showing a significant reduction in births following the replacement of a dominant male within a group. After new males took over, pregnant females terminated approximately 80% of pregnancies within the weeks following the male replacement.
Findings for Hoover - “Mafia Behavior by Parasitic Cowbird”
- The research supports the “Mafia” hypothesis that Cowbirds retaliate against hosts when hosts rejects the Cowbird eggs
- Nests that weren’t parasitized but still accessible to Cowbirds saw moderate rate of predation (20%) which corresponded to farming behavior where nests are destroyed to create more parasitism
- “Ejector” nests that didn’t allow Cowbirds eggs produced less Warbler offspring due to the nest being destroyed, and “Accepted” nests had more offspring but also had to care for Cowbird eggs
Findings for Lieberman - “Females Avoid Fathers When Fertile”
During times of high fertility, women called their father significantly less. Not generalized result about parents women did not show a reduction in calling behavior to their mothers during high fertility.
Women want freedom with their sexuality
Findings for Gettler - “Longitudinal Evidence Fatherhood Test”
All men showed a modest but significant decrease in both AM and PM T Levels. Men who were both newly partnered and new fathers showed the largest decline in AM and PM T.
Finding for Kanazawa - “Beautiful Parents Have More Daughters”
Very attractive people are less likely to have a son
Findings for Hawkins - “Transient masculinization in Malagasy fossa”
Females are not born masculinized, gain masculine features then lose them. No evidence that masculization of fossas is androgen dependent.
Findings for Pruetz - “Chimpanzees Hunt with Tools”
- Results did not support the nutritional shortfall or meat-for-sex hypotheses.
-chimpanzees hunted during times of food abundance rather than scarcity.
- males did not gain a mating advantage through sharing meat. male social bonding hypothesis.
Findings for Young - “Successful same-sex pairing in Laysan albatross”
Female–female pairs had lower overall reproductive success compared to male–female pairs, mainly due to lower hatching rates.
However, fledging rates were similar between both types of pairs, indicating that female–female pairs were as capable as male–female pairs in chick rearing once the egg had hatched.
These long-term partnerships suggest that female–female pairing is a stable and long-term strategy within this population.
Findings for Boesch - “Evidence Female Chimps Invest Sons”
Dominant female chimpanzees invested approximately two years more in their sons than in their daughters. In contrast, subdominant females invested about 11 months more in their daughters than in their sons. The difference in investment by dominant females in their sons was statistically significant.
Sons of dominant females exhibited higher survival rates compared to other offspring.
The findings support theories of parental investment that predict parents should favor the offspring gender that promises a greater number of grandchildren.
Findings for Griggio - “Females Poor Condition Prefer Average Male”
There was no significant preference for males with enlarged or average badges.
-Females in poor condition displayed a clear preference for males with average-sized badges
In contrast, females in good condition did not show a distinct preference for badge size.
Possibility that poor-quality females may prefer males that are better providers of parental care or that they may seek to avoid aggressive interactions with highly ornamented males.
Finding from Johnson - “Sexual Conflict Bluethroats”
Males whose throat ornaments were blackened displayed increased mate-guarding behavior and decreased singing, presumably to compensate for their reduced attractiveness and increased risk of paternity loss.
Despite intensified mate-guarding by blackened males, paternity analyses revealed that these males experienced significantly higher paternity loss compared to control males.
