Genetic study provides new information about endangered whales

Understanding how the booming population of gray whales in the east is connected to approximately 200 western gray whales along the Russian coast.

An eastern gray whale, pictured off the coast of Mexico, and its cousins to the west have similar levels of genetic diversity, though they have genetically diverged into two distinct subgroups, according to a Purdue University study. A genetic analysis of the whales suggests there are enough genetic resources between the populations to offer hope for the critically endangered populations to the west. (Photo credit: Anna Brüniche-Olsen)
An eastern gray whale, pictured off the coast of Mexico, and its cousins to the west have similar levels of genetic diversity, though they have genetically diverged into two distinct subgroups, according to a Purdue University study. A genetic analysis of the whales suggests there are enough genetic resources between the populations to offer hope for the critically endangered populations to the west. (Photo credit: Anna Brüniche-Olsen)

Seek after an alarmingly low number of grey whales in the western Pacific Ocean may rest with their cousins toward the east, as indicated by a Purdue University investigation of the animals’ genetic resources.

Andrew DeWoody, teacher in the Department of Forestry and Natural Resources and the Department of Biological Sciences, and Anna Brüniche-Olsen, a postdoctoral specialist in DeWoody’s lab, wanted to see how the booming populace of gray whales in the east — numbering around 27,000 along the shorelines of California and Mexico — is associated with roughly 200 western dark whales along the Russian coast.

“At any one time, there is an enormous disparity in the number of whales in every area. Some believe that extreme Russian and Japanese business whaling in the 1950s may have wiped out the whole populace in the west.

DeWoody said, “It’s possible then that a few survived and have been increasing in population. Or some might have dispersed from the east to make up today’s western population. It might also be a combination of the two.”

Scientists compared the genotypes of 77 western and 135 eastern gray whales and found that the two populations have diverged genetically. The genotypes show distinct alleles – variations in genes – in each group. The separation is similar to levels sometimes seen between distinct subspecies.

The investigation likewise appears, notwithstanding, that there is some genetic admixture. Whales have been observed navigating the Pacific Ocean, and hereditary information demonstrates that there is by all accounts, at any rate, some interbreeding among the populace.

The study reveals that both populations of whales have significant amounts of genetic diversity, which is especially important for the endangered western gray whales. The authors will monitor the subgroups to see whether they continue to diverge or if the intermingling will lead to a loss of the distinct groups.

The findings may also inform new standards for the International Union for Conservation of Nature, which maintains the Red List, a comprehensive list of endangered animals around the world. DeWoody is involved with a group in the IUCN that is developing guidelines for using genetics to determine the threat level for animals such as the gray whale.

DeWoody said, “As we’ve seen with gray whales, it’s a lot more complicated than the number of animals in the west and the east. Using genetics is going to prove to be a better method for understanding the population structures of endangered species and how those might be affected by human pressures or by natural processes such as ocean currents.”

The findings are reported in the journal Biology Letters.