Brazil takes a leading role in the genome sequencing of jaguars

Findings have been published in the journal Science Advances

27/07/2017 - 13h18
Onça pintada (Rodrigo Teixeira)

Photo: Rodrigo Teixeira

Relying on the participation of specialists from seven countries, PUCRS has played a leading role in the genome sequencing of jaguars, the largest feline of the Americas, which is endangered. Although they are restricted to less than 50% of their original habitat, they can still be found in the Amazon and in the Pantanal area, but are critically endangered in the Atlantic Forest. The findings have been compared to those of the genomes of other four large felines (tiger, lion, snow leopard and the leopard), all of which of are members of the genus Panthera. Five years were needed to analyze this large number of information was carried out for five years, under the coordination of PUCRS’ School of Biosciences professor, Eduardo Eizirik, which culminated in the publication of an article in the journal Science Advances on Wednesday, Jul 19.

Vagalume

The jaguar’s first genome was obtained from a male jaguar named Vagalume (image), at the Sorocaba Zoo (SP). Born in the Pantanal region in 1997, and weighing 94 kg as an adult, it was left there as a baby jaguar after the death of its mother. “I looked for an originally wild jaguar that had been kept in captivity to make sample collection easier”, comments Eizirik.

Feline crossbreeds

4,6 millions of years ago, the five major felines had a common ancestor, very similar to the current leopard. It gave birth to the current species and to others that are now extinct, which spread all over the world from Asia. The study has shown many crossbreeding patterns among these species throughout their evolution, which played a very important role to their survival up until now. “These animals appear in different numbers. As top predators, they are susceptible to environmental changes, such as the reduction in the number of preys, which will bring about a reduction in the number of individuals and a loss in terms of genetic variability”, explains the professor.

One of such hybrid species (crossbreeding between different species) is the hybrid resulting from the breeding between the jaguar and the lion, which was probably of great benefit to the former. Researchers have found that it inherited two genes involved in the formation of the optical nerve, which were subject to positive natural selection (that is, they were important for the species adaptation) after the crossbreeding.

The study has also shown other genes that are likely to have been subject to natural selection and which have enabled the adaptation of species to the new environmental conditions. This may explain why the jaguar has a harder bite than other large felines, as it can prey on alligators and even turtles, with their hard shells. Another evidence is the fact that the snow leopard has a different oxygen capacity. They live in the Himalayas, the highest mountain chain on the planet, as well as in Tibet and Asia.

Tigers, lions and snow leopards have had their genome sequenced. The William Murphy group, from Texas A&M University, has played an important role in sequencing the leopard’s genome, whose findings are presented in this article, and which is now including genomes of all species of this group, for the first time. Henrique Figueiró, a then-doctoral student at PUCRS, advised by Dr. Eizirik, has worked on the sequencing of the largest feline in the Americas.

Species preservation

“In view of the latest findings, our group and collaborators in Brazil and in other countries are working on more detailed genome studies on jaguars, involving multiple individuals from different regions, which will be important to improve the current strategies employed for the preservation of this species”, claims the professor.