Why are there so many canines in South America?

South America has the largest variety of canines in the world, and a new study from the University of California-Los Angeles (UCLA) shows how all these animals come from a single species that arrived on the continent between between 3.5 and 4 million years old. return. This disproves the earlier theory that modern species have multiple ancestors.

The research, published in the journal Proceedings of the National Academy of Sciences, shows how new species can arise and spread rapidly in residences where there is no competition. In addition, the study provides advice on how to best conserve South America’s endangered dog species.

Currently, ten species of canids – a family that includes dogs and wolves – live in South America, seven of which are wolves. The other three are the maned wolf, the bush dog, and the short-eared dog.

Interestingly, some of the naturally occurring genetic mutations responsible for the emergence of the extreme size and dietary diversity of South American canids have also been artificially introduced to us humans over thousands of years in dogs, which resulting in many breeds that we see today.

Short-eared bush dog, a species native to South America | Credit: Igor de le Vingne, via Wikimedia Commons.

South American canids

South America had very few placental animals and no canids before the Isthmus of Panama rose above sea level about 3 million years ago, allowing the arrival of new species. . The time interval between this geological event and the present time is very short from an evolutionary point of view. This raises a question in the minds of many scientists: how can so many species of canids appear in such a short time? They hypothesize that many different ancestors crossed the isthmus at different times, leading to the emergence of species that exist today and some that are now extinct.

To test this hypothesis, Robert Wayne, a professor of evolutionary biology at UCLA, and Daniel Chavez, a researcher at Arizona State University, sequenced 31 genomes for 10 canid species found in South America. . They trace the evolutionary relationships between them by analyzing their residencesthe size of their populations and the types of genetic mutations.

To their surprise, the genetic data points to a common ancestor that arrived on the continent between 3.5 and 4 million years ago – even before the isthmus completely rose – and whose population consisted of approximately 11,600 you individuals.

“We found that all existing canids came from the entry of an ancestral species that entered the continent through a passage east of the Andes,” said Chavez.

These animals quickly spread throughout South America – including the narrow strip of land west of the Andes – adapting to different environments and becoming more genetically diverse. The researchers found that the 10 species that exist today arose between 1 and 3 million years ago.

1663896307 741 From the maned wolf to the vomit dog why America
The Vinegar Dog, Closest Species to the Maned Wolf | Credit: Vladimir Wrangel, via .

They also found that the maned wolf (the longest-legged South American canid whose diet is mostly fruit) and the bush dog (short-legged and more dependent on meat than European and North American wolves) are the closest species to everything. . The difference in their height comes from changes in a gene that regulates the length of their legs.

“The canids of South America are the wild equivalent of the domestic dog because of their different diets and leg sizes, and all of this differentiation occurred within a period of 1 to 2 million years. animal. years,” Wayne said. “All this happened because South America did not originally have this type of carnivorous animal, which shows that there is a large amount of prey and no medium or large predators to compete with. that niche, canids evolved and diversified.

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