![]() ![]() This may also be contributing to their reproductive isolation from other killer whales in the Southern Ocean. In killer whale populations with more diverse DNA, offspring would inherit a greater mix of genes more likely to mask such traits. Their similar DNA makes it more likely that offspring will inherit the same DNA sequences responsible for otherwise recessive traits from both parents. The authors hypothesize that the low level of diversity may underlie the unique appearance of type-D killer whales, with their bulbous heads and tiny white eye patches. “Any pair of type-D killer whales are genetically more similar than any pair of individuals from other known killer whale populations.” The research found that type-D whales from Chile and New Zealand had almost identical genetic code, “which suggests inbreeding over many generations,” said Andrew Foote of the Norwegian Institute of Science and Technology, who is the lead author of the new research published today in the Journal of Heredity. Type-D killer whales may represent a new species of killer whale, which could make it the largest undescribed species left on the planet. They were taken during a summer expedition off stormy Cape Horn, at the tip of South America. In January 2019, an international team of researchers collected samples from living type-D killer whales for the first time. In the Southern Ocean, five different types have been recognized and given letter-names as they have been identified: types A, B1, B2, C and D. Killer whale “types”, often called ecotypes, are identified based on differences in appearance, behavior, habitat, and/or prey preferences. Results published in the Journal of Heredity indicate that the “type D” killer whales have among the lowest genomic diversity and highest level of inbreeding of any mammalian species. They were taken from a skeleton from an animal stranded in Aotearoa, New Zealand in 1955, and from biopsies taken from live animals off Chile in 2019. A new study analyzed genomes from the only known samples. Credit: TAAF-MNHN-CEBC (top photo) Robert Pitman (bottom photo).Ī recently recognized and very different-looking type of killer whales native to the Southern Ocean has remained genetically isolated even though its range overlaps with other killer whale types. A type D killer whale with a tiny eyepatch and rounded head (top) a “regular” killer whale with large white eyepatch and more pointy snout (bottom). ![]()
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