Two males became fathers of half of the pups in a population of killer whales

Two males became fathers of half of the pups in a population of killer whales

A flock of populations of the southern resident whales. In the foreground – L41, one of the two males that became fathers of more than half of the cubs born after 1990.

Candice Emmons / NOAA Fisheries

Two males became fathers in more than half of the calves in the small sedentary population of 80 whales that live in the Pacific ocean. In this case, four of the whales were born as a result of inbreeding, researchers report in an article Animal Conservation. According to the researchers, the reason for the inbreeding was a small number of fertile adults and the isolation of populations.

Killer whales (Orcinus orca) are of different types. Sedentary or resident living near the coast more or less in one place; transit and migrate along the coast at relatively large distances (e.g. from Alaska to California); a third type of killer whale. Sedentary populations of dolphins occur in the North Pacific and Atlantic oceans and off the coast of Antarctica.

The social structure of the sedentary orcas is quite complex and consists of several levels. Lower level – mother group, consisting of females, the matriarch, her daughters and their offspring, closely related to the group of 10-50 animals, and they in turn – in clans, United by common dialect. It should be noted that males rarely mate with females from his pack, apparently to avoid inbreeding.

One of the settled populations of the South, lives in the Pacific ocean off the coast of North America. Now it has about 80 species and it gradually disappears. In the 1960-ies 47 of killer whales caught for dolphinariums. Then, despite the fact that the populations were brought in the red book of the US and the catch of dolphins was banned, its population has not recovered. Her negative effect is the chemical contamination and reduction of the number of salmon which is almost 100 per cent of the diet of dolphins. In addition, the sedentary southern killer whales are under the threat of inbreeding due to the fact that the number is able to breed in the population was less than 30.

American marine biologists led by Michael Ford (Michael Ford) from the National Oceanic and Atmospheric Administration (NOAA) was decided to evaluate the effective sedentary population of the killer whales. For DNA analysis, the researchers collected skin samples and faeces of dolphins, and also took samples from several skeletons. Individuals (not all of them belonged to the sedentary southern population).

Two males became fathers of half of the pups in a population of killer whales

The maternal line is shown in gray lines, paternal – colored. J, K, L are the name packs.

M.Ford et al. / Animal conservation, 2018

26 individuals. While males are often mate with females from the same flock, the whole population is divided into three flocks. Two males became fathers, 52 percent of the cubs born after 1990. One of them was mixed with 9 females and fathered 16 calves, the other had 20 offspring of 11 females. It also turned out that four of the whales were born as a result of inbreeding. At the time of writing, in 2017, all four babies were alive, what would happen to them, it is not yet clear.

Recently, the researchers described the infanticide among orcas. Adult male with the help of his mother drowned a newborn orca. This was probably done to ensure that the woman was able to conceive.

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