Talk:Trivers–Willard hypothesis

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16:58, 3 December 2018 (UTC)Avram Primack (talk)

comment[edit]

This makes no sense. The sex of a mammal is determined by the sperm. There is no way for a female deer or monkey to 'choose' to give birth to sons rather than daughters. Though the may favor newborns of one sex leading to different survival rates.

The Trivers-Willard hypothesis makes perfect sense, and for this reason has been investigated hundreds of times. The sex of an animal is indeed determined by the sperm, but whether that animal even exists or not is determined by the parent. In fact there are many potential ways in which the secondary sex-ratio (sex-ratio at birth) may be biased by the mother. One of these is induced abortion, which is conceptually no different from infanticide (an ultimate example of the (dis)favoring of newborns you mention). Another would be identification and selection of male or female sperm. Ianrickard (talk) 18:26, 11 October 2008 (UTC)[reply]

I removed the statement that said that there is no proposed mechanism for the Trivers-Willard hypothesis. Um...Actually, there is one. See Cameron's "Facultative adjustment of mammalian sex ratios in support of the Trivers–Willard hypothesis: evidence for a mechanism" for a good overview of the work relating to T-W that had been published through 2004. AnonymousAnthropologist (talk) 00:32, 20 October 2009 (UTC)[reply]

One possible explanation is that a high level of circulating glucose in the mother's bloodstream favors the survival of male blastocysts. This conclusion is based on the observed male-skewed survival rates (to expanded blastocyst stages) when bovine blastocysts were exposed to heightened levels of glucose. As blood glucose levels are highly correlated with access to high-quality food, they may serve as a proxy for maternal condition.

This is a mechanism that goes directly from better-quality food to the survival of male blastocysts. As presented, it isn't mediated or gated by a genetic mechanism subject to evolutionary pressure. As such, it is a mechanism for the phenomenon of sex ratios depending on conditions, but not for the Trivers–Willard hypothesis, which says that this dependence is caused by evolutionary pressure.

I'm wondering if the proposed relationship of the glucose mechanism to the Trivers-Willard hypothesis is original research. Is the glucose mechanism juxtaposed to the the Trivers-Willard hypothesis in one of the articles, or is the argumentation being made here on the Wikipedia page?

In any case it is an interesting idea. 2A02:1210:2642:4A00:C9E4:9F6:5E99:526E (talk) 18:54, 23 June 2023 (UTC)[reply]

I removed the link to Dan Willard. It is the wrong Dan Willard. The one referenced in the link is still alive and not an ecologist. My advisor is the correct Dan Willard and does not have a page in Wikipedia. He passed away some ten years ago. Avram Primack (talk) 16:58, 3 December 2018 (UTC)[reply]

The paper introducing the Trivers-Willard hypothesis is listed in the C.V. linked on the Dan Willard wikipedia page, which also lists an affiliation with the Harvard mathematics department at the time of the paper's publication, like the Dan Willard who is an author of the paper. I therefore think it reasonable that the two are the same, and am re-adding the link. Selantic (talk)