Thursday, July 28, 2016

The Great Wolf Taxonomy Debate

Rutledge_quote_logo_blog

A flurry of news articles about wolf taxonomy hit the press today based on new research published by Bridgett M. vonHoldt, et al in Science Advances.

Wolf taxonomy, a messy topic for sure, will continue to be the subject of a lengthy, ongoing scientific debate. This latest genomic analysis is the newest chapter.

An Overview:

On taxonomy: There is general agreement that (1) there were at least three waves of migrant wolves from Eurasia during the Pleistocene, and (2) coyotes are endemic to North America.

The Debate:

  • Those in the 2-species camp (gray wolf, coyote), Bridgett M. vonHoldt, et al, believe that all wolves evolved in Eurasia. The waves of immigrant wolves during the Pleistocene were the ancestors of Canis lupus, the gray wolf. Under this scenario, Algonquin wolves and red wolves are of hybrid (gray wolf-coyote) origin.
  • Those in the 3-species camp (Algonquin wolf/red wolf, grey wolf, coyote), Linda Rutledge, et al, believe that a lineage of large canid originally arose in North America. Some members of this canid lineage migrated to Eurasia, where they were geographically isolated from the North American wolves and evolved into another species: Canis lupus. At the same time, back in North America, Algonquin wolves, red wolves, and coyotes also evolved from this canid lineage. When gray wolves returned during the Pleistocene era, they colonized western North America. But Canis lycaon (Algonquin wolves) and Canis rufus (red wolves) remained separate, viable species in eastern North America. Linda Rutledge's genomic research published in Biology Letters in 2015 supports the 3-species model which concluded Algonquin wolves and red wolves represent a separate species.

Common Ground:

When it comes to conservation and management, the scientists from both camps agree that the role canids play in ecosystems should be the focus, not just the evolutionary history of a species. 

“Conservation focuses on a very species-specific model,” Rutledge stated in an interview in The Nature Conservancy's Cool Green Science. “Agencies often want to know first whether a species is taxonomically valid, but that may not be an efficient way to approach conservation in general. Our research shows that what species are can be very difficult to pin down."

In her paper, Bridgett M. vonHoldt concludes, "Our findings provide a critical heuristic lesson in endangered species management. The overly strict application of taxonomy to support endangered species status is antiquated. Species and taxonomic concepts are varied, complex, and difficult to apply in practice. We maintain that the Endangered Species Act could be interpreted in a modern evolutionary framework, devaluing the Victorian typological concept in exchange for a more dynamic view that allows for natural selection to occur on admixed genomes and to evolve phenotypes that are adapted to human-altered habitats and changing climates. These suggestions follow the “ecological authenticity” concept, in which admixed individuals that have an ecological function similar to that of the native endangered taxon, and that maintain a portion of the endangered genetic ancestry, warrant protection."

Conclusion:

While the debate on wolf taxonomy continues, we acknowledge there is critical need for common ground among members of the scientific community when it comes to guiding decision making. Ecosystems need top predators. Their importance to a balanced and resilient ecosystem is undeniable. In other words, as Rutledge sums it up, "Let’s quit trying to make wolves fit into our neat little taxonomic boxes. Let’s focus instead on how to protect and restore their critical role as top predators."

No comments: