Dr. Tatiana's New Evidence of Female Promiscuity
The paper that I examined focuses on the possible genetic component of female promiscuity. Dr. Tatiana mentioned in her first book, "If a proclivity for promiscuity is genetic, then yes, promiscuous behavior will become more common if loose females tend to have more children than their monogamous peers... Unfortunately, though, we don't know much about the genes that influence female sexual behavior in any animal...". Fortunately, it has been 20 years since she wrote that and people have taken time to do a little more research on this matter.
Researchers distinguished two hypotheses for how the genetic constraint influences female promiscuity. The first hypothesis states that there are homologous traits for female and male promiscuity, and that alleles that increase promiscuity in the population are retained by males. Females that inherit these alleles exhibit promiscuity even though it does not benefit them (this was known as "intrasexual pleiotropy". The second hypothesis states that female promiscuity stays in the population because its alleles are casual and thus linked to other female traits that are under selection (this was known as "intersexual pleiotropy"). In order to develop an experiment to test out these two hypotheses, these researchers gathered a population of zebra finches, and examined them over eight generations in both a cage/laboratory setting and an aviary. Under these conditions, they measured behavioral traits that were related to extra-pair mating. It was established in a previous study that the intersexual pleiotropy was much more likely to be occurring.
In order to measure promiscuity, researchers measured "male courtship rate" and "female unpaired response" in unpaired males and unpaired females who had not yet met. There were 6 breeding lines that were started (two control, two high, and two low). This was done by choosing founders that had certain estimated breeding levels (high and low). Breeding and extra-pair breeding was closely monitored in both the aviaries and the cages. Multiple different constraints and conditions were placed on the experiment in order to assure that there were less confounding variables. Researchers were successful in exacerbating the genetic component of breeding values throughout subsequent generations. The high lines had high values and the low lines had low values. The control line had intermediate values. A moderately strong positive correlation was distinguished between extra-pair male courtship and female fecundity (figure 1D).
The link between female fecundity and female promiscuity is mentioned in Dr. Tatiana's book. This study adds to the book because it is giving more evidence towards Dr. Tatiana's claim that "loose" females have more and healthier children.
Source: Wang, D., Forstmeier, W., Martin, K., Wilson, A., & Kempenaers, B. (2020). The role of genetic constraints and social environment in explaining female extra‐pair mating. Evolution, 74(3), 544-558. doi:10.1111/evo.13905
Hi Mary-Clare! This was a challenging article (I was so intrigued that I went a got a copy for myself!). Are the authors arguing that promiscuity is indirectly selected for in females because female fecundity is positively correlated with responding to courtship and females response to extra-pair courtship is correlated with the proportion of their offspring who are fathered via EPP?
ReplyDeleteDr. Bray, I agree! This was an extremely difficult article to understand. Unfortunately I'm not super confident in my understanding of it, but I was in too deep when writing about it so I felt like I couldn't back out. I think that the authors are arguing that there was a positive correlation between female fecundity and the response to courtship. There was a lower positive response for females response to extra-pair courtship and the correlation with the proportion of their offspring who were fathered via EPP.
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