Phylogeographic analyses of an endemic Neotropical fox (Lycalopex vetulus) reveal evidence of hybridization with a different canid species (L. gymnocercus)Garcez, Fabricio Silva; Tchaicka, Ligia; Lemos, Frederico Gemesio; Kasper, Carlos Benhur; Dalponte, Júlio Cesar; Eizirik, Eduardo
doi: 10.1093/jhered/esae012pmid: 38412545
The hoary fox (Lycalopex vetulus) is the only species of the Canidae (Mammalia: Carnivora) endemic to Brazil, and so far has been the target of few genetic studies. Using microsatellites and mtDNA markers, we investigated its present genetic diversity and population structure. We also tested the hypothesis that this species currently hybridizes with the pampas fox (L. gymnocercus), as suggested by previous mtDNA data from two individuals. We collected tissue and blood samples from animals representing most of the two species’ distributions in Brazil (n = 87), including their recently discovered geographic contact zone in São Paulo state. We observed that the hoary fox exhibits high levels of genetic diversity and low levels of population structure. We identified six individuals from São Paulo state with clear evidence of hybridization based on introgressed pampas fox mitochondrial DNA and/or admixed microsatellite genotypes (three individuals bore both types of evidence). These results demonstrate the existence of admixed individuals between hoary and pampas foxes in southeastern Brazil, representing the first identified case of interspecies admixture between native South American canids. We discuss our findings in the context of the evolutionary history of these foxes and address potential conservation implications of this interspecies hybridization process.
Whole-genome analysis reveals the diversification of Galapagos rail (Aves: Rallidae) and confirms the success of goat eradication programsChavez, Daniel E; Hains, Taylor; Espinoza-Ulloa, Sebastian; Wayne, Robert K; Chaves, Jaime A
doi: 10.1093/jhered/esae017pmid: 38498380
Similar to other insular birds around the world, the Galapagos rail (Laterallus spilonota Gould, 1841) exhibits reduced flight capacity following its colonization of the archipelago ~1.2 mya. Despite their short evolutionary history, rails have colonized seven different islands spanning the entire width of the archipelago. Galapagos rails were once common on islands with sufficiently high altitudes to support shrubs in humid habitats. After humans introduced goats, this habitat was severely reduced due to overgrazing. Habitat loss devastated some rail populations, with less than 50 individuals surviving, rendering the genetic diversity of Galapagos rail a pressing conservation concern. Additionally, one enigma is the reappearance of rails on the island of Pinta after they were considered extirpated. Our approach was to investigate the evolutionary history and geographic distribution of Galapagos rails as well as examine the genome-wide effects of historical population bottlenecks using 39 whole genomes across different island populations. We recovered an early divergence of rail ancestors leading to the isolated populations on Pinta and a second clade comprising the rest of the islands, historically forming a single landmass. Subsequently, the separation of the landmass ~900 kya may have led to the isolation of the Isabela population with more panmictic populations found on Santa Cruz and Santiago islands. We found that rails genomes contain long runs of homozygosity (>2 Mb) that could be related to the introduction of goats. Finally, our findings show that the modern eradication of goats was critical to avoiding episodes of inbreeding in most populations.
Conservation genomics of wolves: The global impact of RK Wayne’s researchMusiani, Marco; Randi, Ettore
doi: 10.1093/jhered/esae007pmid: 38381553
RK Wayne has arguably been the most influential geneticist of canids, famously promoting the conservation of wolves in his homeland, the United States. His influence has been felt in other countries and regions outside the contiguous United States, where he inspired others, also including former graduate students and research fellows of his, to use modern molecular techniques to examine the evolutionary biology of canids to inform the conservation and management of wolves. In this review, we focus on the implications of Wayne’s work on wolves outside the United States. He envisioned a clear future for wolf conservation research, involving the study of wolves’ ecological and genetic diversity, and the description of ecotypes requiring conservation. He also documented widespread hybridization among canids and introgression of DNA from domestic dogs to wolves, a process that started dozens of thousands of years ago. His work therefore calls for innovative studies, such as examining the potential fitness benefits of introgression. Inspired by his results, for example, on the purging of deleterious alleles in small populations, wolf researchers should use novel molecular tools to challenge other conservation genetics paradigms. Overall, RK Wayne’s work constitutes a call for answers, which as scientists or citizens concerned with conservation matters, we are obliged to address, as we contribute to monitoring and maintaining biodiversity during our period of dramatic transformations of the biosphere.
The value of hybrid genomes: Building two highly contiguous reference genome assemblies to advance Canis genomic studiesBredemeyer, Kevin R; vonHoldt, Bridgett M; Foley, Nicole M; Childers, Isabella R; Brzeski, Kristin E; Murphy, William J
doi: 10.1093/jhered/esae013pmid: 38416051
Previous studies of canid population and evolutionary genetics have relied on high-quality domestic dog reference genomes that have been produced primarily for biomedical and trait mapping studies in dog breeds. However, the absence of highly contiguous genomes from other Canis species like the gray wolf and coyote, that represent additional distinct demographic histories, may bias inferences regarding interspecific genetic diversity and phylogenetic relationships. Here, we present single haplotype de novo genome assemblies for the gray wolf and coyote, generated by applying the trio-binning approach to long sequence reads generated from the genome of a female first-generation hybrid produced from a gray wolf and coyote mating. The assemblies were highly contiguous, with contig N50 sizes of 44.6 and 42.0 Mb for the wolf and coyote, respectively. Genome scaffolding and alignments between the two Canis assemblies and published dog reference genomes showed near complete collinearity, with one exception: a coyote-specific chromosome fission of chromosome 13 and fusion of the proximal portion of that chromosome with chromosome 8, retaining the Canis-typical haploid chromosome number of 2n = 78. We evaluated mapping quality for previous RADseq data from 334 canids and found nearly identical mapping quality and patterns among canid species and regional populations regardless of the genome used for alignment (dog, coyote, or gray wolf). These novel wolf and coyote genome reference assemblies will be important resources for proper and accurate inference of Canis demography, taxonomic evaluation, and conservation genetics.