An article published in the journal “Biology Letters” describes a genetic research on the gray whale populations that live in the western and eastern Pacific Ocean to look for clues that help understand the disparity of their populations. Pofessor Andrew DeWoody of Purdue University and his collaborator, postdoctoral researcher Anna Brüniche-Olsen, compared the DNA of 77 western gray whales and 135 eastern gray whales and discovered a genetic divergence between the two populations, however there are some interbreedings and genetic diversity that offers hopes for their future.
Gray whale (Eschrichtius robustus) is the only species that exists today in the Eschrichtiidae family of medium-sized cetaceans, being up to 15 meter long. This species also lived in the Atlantic Ocean but the last specimens were sighted in the 18th century and it’s possible that their disappearance was caused by hunting. In the Pacific Ocean there are still two populations, survivors of the hunt that brought the species to the brink of extinction.
For decades gray whales have been a protected species and the specimens off the coast of California and Mexico are now estimated at around 27,000, the problem is in the population off the coast of Russia, reduced to around 200 specimens. There may be environmental differences in the two areas of the Pacific Ocean in terms of pollution that could have affected one of the two populations more than the other and it’s possible that the western gray whales are still killed by Japanese hunters. A genetic research can help to understand if there are other factors and possibilities for recovery of the Western population.
Genetic analyzes showed that there’s a divergence between the two populations, which might now be considered even two subspecies. However, they can still interbreeding without problems and traces of hybridizations have been detected in some individuals. Some whales crossed the Pacific Ocean leading to a certain amount of interbreedings.
The genetic diversity detected is positive because it prevents the entire population of gray whales from weaknesses caused by genetic problems. The analysis of the characteristics of Western and Eastern specimens can provide useful information to understand if the two groups can mix even more to increase the western population. It can also enable to understand how vulnerable they can be to environmental changes.
In the case of environmental influences, certain dangers may exist for other species too, so much so that similar studies have been recently conducted or are in progress on orcas, others may be specific such as those related to food sources. Those are complex situations that require long-term studies and because some problems don’t concern gray whales only, they can also be important for the study of other parts of those ecosystems offering suggestions for other similar studies.
