Molecular Systematics of the Canidae

Abstract

Despite numerous systematic studies, the relationships among many species within the dog family, Canidae, remain unresolved. Two problems of broad evolutionary significance are the origins of the taxonomically rich canidae fauna of South America and the development in three species of the trenchant heel, a unique meat-cutting blade on the lower first molar. The first problem is of interest because the fossil record provides little evidence for the origins of divergent South American species such as the maned wolf and the bush dog. The second issue is problematic because the trenchant heel, although complex in form, may have evolved independently to assist in the processing of meat. We attempted to resolve these two issues and five other specific taxonomic controversies by phylogenetic analysis of 2,001 base pairs of mitochondrial DNA (mtDNA) sequence data from 23 canidae species. The mtDNA tree topology, coupled with data from the fossil record, and estimates of rates of DNA sequence divergence suggest at least three and possibly four North American invasions of South America. This result implies that an important chapter in the evolution of modern canids remains to be discovered in the fossil record and that the South American canidae endemism is as much the result of extinction outside of South America as it is due to speciation within South America. The origin of the trenchant heel is not well resolved by our data, although the maximum parsimony tree is weakly consistent with a single origin followed by multiple losses of the character in several extant species. A combined analysis of the mtDNA data and published morphological data provides unexpected support for a monophyletic South American canidae clade. However, the homogeneity partition tests indicate significant heterogeneity between the two data sets.

Genome sequence, comparative analysis and haplotype structure of the domestic dog

“…The only outlier (,1/790 bp) is the Alaskan malamute, which is the only breed studied that belongs to the Asian breed cluster 91 . The grey wolf (,1/580 bp) and coyote (,1/420 bp) show greater variation when compared with the boxer, supporting previous evidence of a bottleneck during dog domestication, whereas that the SNP rate is lower in the grey wolf than in the coyote reflects the closer relationship of the grey wolf to the domestic dog [1][2][3]92 (see section 'Resolving canid phylogeny').…”

“…In contrast, the smaller size of the mouse genome is primarily due to a higher deletion rate. Specifically, the amount of extant 'ancestral sequence' is much lower in mouse (1,474 Mb) than in human (2,216 Mb) or dog (1,997 Mb). Assuming an ancestral genome size of 2.8 Gb (ref.…”

“…The dog family, Canidae, contains 34 closely related species that diverged within the last ,10 million years 1 . Resolving the evolutionary relationships of such closely related taxa has been difficult because a great quantity of genomic sequence is typically required to yield enough informative nucleotide sites for the unambiguous reconstruction of phylogenetic trees.…”

“…The history of the domestic dog traces back at least 15,000 years, and possibly as far back as 100,000 years, to its original domestication from the grey wolf in East Asia [1][2][3][4] . Dogs evolved through a mutually beneficial relationship with humans, sharing living space and food sources.…”

Updating the evolutionary history of Carnivora (Mammalia): a new species-level supertree complete with divergence time estimates

“…Of the three genera that have been difficult to place historically, Nyctereutes, Otocyon and Urocyon , the former two form successive sister taxa to the remaining Vulpini, whereas the latter forms the sister group to all remaining canids (in agreement with [43-47]). However, all the genera represent long-branch taxa (range = 15.9 to 16.3 Ma old) that together with Canini and Vulpini diverge at the base of the canids in an exceedingly short time span (< 0.5 Ma).…”