The longer body size means more calves for females for mothers Palin whale, unlike the popular hypothesis

Long whale mothers are likely to have male calves, according to a new study led by Washington University. The results contradict a popular evolutionary hypothesis that assumes that strong mammals benefit more than males.

In 1973, Robert Trains and Dan Williad Proposal Female mammals can suit the possibilities of their grandchildren through the presence of males. The big mothers will raise the large and powerful calves that can surpass the other males of their colleagues. However, according to the hypothesis, female fitness is less dependent. Studies that support this argument focused on Earth’s mammals, such as deer and Ayes, and often included tens of animals or hundreds of animals.

UW researchers have tested the hypothesis in marine mammals by comparing the length of the mother and the gender of the fetus in more than 100,000 Palin whales. They found that the embryonic sex rate gives a female for a longer period – and therefore more convenient – a young whale, the prevailing family of the whale that includes hump and blue whales. The results indicate that female calves benefit more than genetic fitness more than males.

Carrying and caring for young people is exhausting, and whales often multiply away from food sources. They should rely on the stored fats to maintain themselves and their youth during and after pregnancy. The results are published in The facts of the Royal Society B.

“The question that we wanted to answer was if you are in good condition, and if you are big and fat and you will have a large wheel of fats you will survive and multiply – do you want the calf to be male or female?” Zoe Rand, a PhD at the University of California in quantitative and resource management, said.

To answer this question, the researchers have turned into historical whale hunting data.

Once again in the early twentieth century, when people hunting whales, a group of Norway began collecting data on their hunting. This practice was recorded in a law that requires all Norwegian fishermen to record the length of the whale, sex and pregnancy, as well as the sex and size of the fetus. In the thirties of the twentieth century, the Norwegian list became international law.

“When they hunting whales, there were often biologists around them who were in the depth of the knee in the sacrifice, residing and collecting samples,” said Rand. In 1986, the International Whale Hunting Committee banned the protection of the decreasing population from more judiciary. However, IWC data is a treasure for researchers.

“We have a massive data collection that includes hundreds of thousands of data points that are found for almost any number of wild population,” said Trevor Branch, a UW professor at the College of Water Science and Fisheries. In 2023, a branch created an interactive map depicting the distribution of the whale from data.

Rand data also gave an opportunity to investigate fetal sex rates in marine mammals. Experts argue that some animals It can affect the gender of their offspring Only after pregnancy. Nobody knows exactly how this works for mammals, but the adaptation of sex rates based on physical or environmental conditions is useful.

Rand said: “I think about the brains of mammals, it is a bit confusing, but insects, Like bees Ants have a lot of control over their atoms, so it is not quite surprising that mammals have little control. “

In this study, the researchers designed the length of the mother against sex for the fetus by three feet and longer – the size in which the sex becomes clear. It included seven types of whale in the Rorqual family, with a total of more than 100,000 whales.

If the Trivers-Willard hypothesis is correct, the researchers would have seen a slight increase in the number of male embryos with an increase in the length of the mother. Instead, they noticed a declining direction, indicating that less males were born to larger mothers. Some species of species varied: the taller females were 77 % more likely to get a feminine, and this possibility increased to 99 % SEI whales.

There are many possible explanations for the cause of the fluctuation of these results, the hypothes-willaard hypothesis, and the trends observed in the ground mammals. Some male whales compete for their colleagues, but competition may not be of great importance as female size because small female whales are likely to struggle to reproduce and raise healthy youth. On the other hand, large whales will have large calves that will grow into long mothers with strong reproductive capabilities.

For Baleen’s mothers, energy investment in female calves is the best way to ensure generations of grandchildren.

Research also indicates that many types of whales have become smaller, which may spell trouble for future generations if females are unable to support birth control. The results can have effects on memorization, but Rand said this would require more research to confirm.

“In the past, it was assumed that if you had a male male competition for her colleagues, it would be for the male major mothers,” said Rand. “Our paper shows that you cannot take this assumption because there is also an advantage of being a big as a female.”