A bastard seal from the past reveals the potential for human hybrids

December 3, 2018, University of Helsinki
Credit: CC0 Public Domain

Almost 90 years ago on a freezing January morning, the keepers of the Stockholm Zoo in Sweden discovered a dead seal pup in their seal pond. The pup was immediately recognized as a bastard—a hybrid between species that should not interbreed. Only two grey seal males and one ringed seal female, species belonging to different mammalian genera, were housed in the pond. The hybrid appeared to carry a mixture of features of both the parent species.

The researchers in the University of Helsinki and their international colleagues have located the preserved hybrid in the , and confirmed genetically that the skull specimen is the hybrid between the grey and ringed seal.

They also examined new genomic data from wild Baltic Sea grey and ringed seals. By comparing these genomic sequences with that of the Saimaa ringed seal, it was possible to examine whether the grey and the ringed seals could have interbred also in the wild. As is the case between many , including , the analyses revealed genetic traces of hybridization between the seal species in the Baltic.

"The shape of the skull, and especially the teeth of grey and ringed seals are so different that they could be classified as belonging to different families if discovered as fossils. Yet, the seal hybrid was found to be an almost perfect intermediate between the species with no detectable anomalies. When placed into the context of other hybridizing mammals, the grey and ringed seals provide the extreme bracket of shape difference found between hybridizing species pairs," says Academy Professor Jukka Jernvall from the Institute of Biotechnology, University of Helsinki.

Compared to Neanderthals and , grey and ringed seals are genetically and dentally at least twice as different, suggesting that there may be more fossil human hybrids to be discovered. The analyses also revealed that landlocked , such as the Saimaa ringed seals found only in Lake Saimaa, can be genetically quite distinct as they have had no mates other than their own kin.

Explore further: Decrease of genetic diversity in the endangered Saimaa ringed seal continues

More information: Yoland Savriama et al, Bracketing phenogenotypic limits of mammalian hybridization, Royal Society Open Science (2018). DOI: 10.1098/rsos.180903

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torbjorn_b_g_larsson
5 / 5 (1) Dec 04, 2018
Seems reasonable. The genetic distance between Neanderthals and Africans was ~ 2x0,5 or 1 Myrs (assuming same and constant evolutionary rate, so using years as proxy). The genetic distance between denisovans and the ghost 4th lineage they crossbred with could have been 2x1.5 or 3 Myrs if they were remnant populations of our ancestors Erectus.
jonesdave
not rated yet Dec 04, 2018
Seals.....bastards. Have been saying it for years. It is in my ToE. Honest!

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