Tracing Eastern Wolf Origins From Whole-Genome Data in Context of Extensive Hybridization

Southeastern Canada is inhabited by an amalgam of hybridizing wolf-like canids, raising fundamental questions regarding their taxonomy, origins, and timing of hybridization events. Eastern wolves (Canis lycaon), specifically, have been the subject of significant controversy, being viewed as either a distinct taxonomic entity of conservation concern or a recent hybrid of coyotes (C. latrans) and grey wolves (C. lupus). Mitochondrial DNA analyses show some evidence of eastern wolves being North American evolved canids. In contrast, nuclear genome studies indicate eastern wolves are best described as a hybrid entity, but with unclear timing of hybridization events. To test hypotheses related to these competing findings we sequenced whole genomes of 25 individuals, representative of extant Canadian wolf-like canid types of known origin and levels of contemporary hybridization. Here we present data describing eastern wolves as a distinct taxonomic entity that evolved separately from grey wolves for the past similar to 67,000 years with an admixture event with coyotes similar to 37,000 years ago. We show that Great Lakes wolves originated as a product of admixture between grey wolves and eastern wolves after the last glaciation (similar to 8,000 years ago) while eastern coyotes originated as a product of admixture between western coyotes and eastern wolves during the last century. Eastern wolf nuclear genomes appear shaped by historical and contemporary gene flow with grey wolves and coyotes, yet evolutionary uniqueness remains among eastern wolves currently inhabiting a restricted range in southeastern Canada.

Automated summary

Eastern wolves (Canis lycaon) in southeastern Canada have been a topic of controversy. Mitochondrial DNA analysis suggests that they evolved in North America, while nuclear genome studies indicate they are a hybrid entity. By sequencing whole genomes, it was discovered that eastern wolves are a distinct taxonomic entity that evolved separately from grey wolves for about 67,000 years with a hybridization event with coyotes about 37,000 years ago. Great Lakes wolves originated from admixture between grey wolves and eastern wolves after the last glaciation, while eastern coyotes originated from admixture between western coyotes and eastern wolves in the last century. Eastern wolf nuclear genomes show signs of historical and contemporary gene flow with grey wolves and coyotes.