Abstract
BackgroundPhylogenetic studies of wild Canis species have relied heavily on the mitochondrial DNA control region (mtDNA CR) to infer species relationships and evolutionary lineages. Previous analyses of the CR provided evidence for a North American evolved eastern wolf (C. lycaon), that is more closely related to red wolves (C. rufus) and coyotes (C. latrans) than grey wolves (C. lupus). Eastern wolf origins, however, continue to be questioned. Therefore, we analyzed mtDNA from 89 wolves and coyotes across North America and Eurasia at 347 base pairs (bp) of the CR and 1067 bp that included the ATPase6 and ATPase8 genes. Phylogenies and divergence estimates were used to clarify the evolutionary history of eastern wolves, and regional comparisons of nonsynonomous to synonomous substitutions (dN/dS) at the ATPase6 and ATPase8 genes were used to elucidate the potential role of selection in shaping mtDNA geographic distribution.ResultsWe found high concordance across analyses between the mtDNA regions studied. Both had a high percentage of variable sites (CR = 14.6%; ATP = 9.7%) and both phylogenies clustered eastern wolf haplotypes monophyletically within a North American evolved lineage apart from coyotes. Divergence estimates suggest the putative red wolf sequence is more closely related to coyotes (DxyCR = 0.01982 ± 0.00494 SD; DxyATP = 0.00332 ± 0.00097 SD) than the eastern wolf sequences (DxyCR = 0.03047 ± 0.00664 SD; DxyATP = 0.00931 ± 0.00205 SD). Neutrality tests on both genes were indicative of the population expansion of coyotes across eastern North America, and dN/dS ratios suggest a possible role for purifying selection in the evolution of North American lineages. dN/dS ratios were higher in European evolved lineages from northern climates compared to North American evolved lineages from temperate regions, but these differences were not statistically significant.ConclusionsThese results demonstrate high concordance between coding and non-coding regions of mtDNA, and provide further evidence that the eastern wolf possessed distinct mtDNA lineages prior to recent coyote introgression. Purifying selection may have influenced North American evolved Canis lineages, but detection of adaptive selection in response to climate is limited by the power of current statistical tests. Increased sampling and development of alternative analytical tools will be necessary to disentangle demographic history from processes of natural selection.
Highlights
Phylogenetic studies of wild Canis species have relied heavily on the mitochondrial DNA control region to infer species relationships and evolutionary lineages
Similar to other studies on the control region [18], we found a higher proportion of New World (NW) coyote clustering haplotypes per sample size at both the control and adenosine triphosphatase (ATPase) region (0.38, 0.33) compared to Old World (OW) haplotypes (0.29, 0.26). (Haplotype assignments to specific samples are shown in Additional File 1: Summary of sample locations and Mitochondrial DNA (mtDNA) control region and ATPase region haplotypes)
We found high concordance between results from the control region and those from the ATPase region despite the different selective forces acting on the two regions
Summary
Phylogenetic studies of wild Canis species have relied heavily on the mitochondrial DNA control region (mtDNA CR) to infer species relationships and evolutionary lineages. Phylogenies and divergence estimates were used to clarify the evolutionary history of eastern wolves, and regional comparisons of nonsynonomous to synonomous substitutions (dN/dS) at the ATPase and ATPase genes were used to elucidate the potential role of selection in shaping mtDNA geographic distribution. Adaptive selection may be important [12] with climatic adaptation acting as an influential factor in mtDNA geographic distribution [13,14,15], some have disputed the climate hypothesis [8,16,17] Despite this controversy, most agree that the evolution of mtDNA is likely more complex than any single factor could account for. Suggests that the mtDNA ATPase genes in particular, may be influenced by positive selection [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
