why does South America have so many canines?

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 derive from a single species that arrived on the continent between 3.5 and 4 million years ago. return. This disproves the earlier theory that modern species had multiple ancestors.

The research, published in the journal Proceedings of the National Academy of Sciences, shows how new species can appear and spread rapidly in habitats where there is no competition. Additionally, the study provides advice on how best to conserve endangered South American canine species.

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

Interestingly, some naturally occurring genetic mutations responsible for the emergence of extreme size and diet variation in South American canids have also been artificially provided by us humans over thousands of years in dogs. , resulting in the multitude of races 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 moment is very short from an evolutionary point of view. This raised a question in the minds of many scientists: how could so many species of canids appear in such a short time? They hypothesized that several different ancestors crossed the isthmus at different times, leading to the emergence of species that exist today and others that are now extinct.

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

To their surprise, the genetic data pointed to a single common ancestor who arrived on the continent between 3.5 and 4 million years ago – even before the isthmus was fully ascended – and whose population consisted of approximately 11,600 individuals.

“We found that all extant canids derive from the incursion of a single ancestral species that entered the continent through a path east of the Andes,” Chavez explains.

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

1663896307741 From maned wolf to vinegar dog why America
The Dressing 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 even more meat-dependent than European wolves and North American) are the closest species of all. . Their height difference stems from changes in a gene that regulates the length of their legs.

“South American canids are the wild equivalent of the domestic dog due to their wide variety of diets and leg sizes, and all of this differentiation occurred over a period of only 1 to 2 million animals. years,” says Wayne. “All of this happened because South America didn’t originally have this type of carnivorous animal, indicating that there was a huge amount of prey and no medium or large predators with who would compete. In this unoccupied niche, canids thrived and differentiated.

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