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Hypochilus is a relictual lineage of Nearctic spiders distributed disjunctly across the United States in three montane regions (California, southern Rocky Mountains, southern Appalachia). Phylogenetic resolution of species relationships in Hypochilus has been challenging, and conserved morphology coupled with extreme genetic divergence has led to uncertain species limits in some complexes. Here, Hypochilus interspecies relationships have been reconstructed and cryptic speciation more critically evaluated using a combination of ultraconserved elements, mitochondrial CO1 by-catch, and morphology. Phylogenomic data strongly support the monophyly of regional clades and support a ((California, Appalachia), southern Rocky Mountains) topology. In Appalachia, five species are resolved as four lineages ( H. thorelli Marx, 1888 and H. coylei Platnick, 1987 are clearly sister taxa), but the interrelationships of these four lineages remain unresolved. The Appalachian species H. pococki Platnick, 1987 is recovered as monophyletic but is highly genetically structured at the nuclear level. While algorithmic analyses of nuclear data indicate many species (e.g., all H. pococki populations as species), male morphology instead reveals striking stasis. Within the California clade, nuclear and mitochondrial lineages of H. petrunkevitchi Gertsch, 1958 correspond directly to drainage basins of the southern Sierra Nevada, with H. bernardino Catley, 1994 nested within H. petrunkevitchi and sister to the southernmost basin populations. Combining nuclear, mitochondrial, geographical, and morphological evidence a new species from the Tule River and Cedar Creek drainages is described, Hypochilus xomote sp. nov. We also emphasize the conservation issues that face several microendemic, habitat-specialized species in this remarkable genus.
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Genome-wide Data Reinforces the Evolutionary Relationships of Previously Problematic Earless Lizards (Phyrnosomatidae: Holbrookia)
In the face of anthropogenic change and the potential loss of species, documenting biodiversity – including accurately delimiting species complexes – is of tantamount importance. Genome-wide data are powerful for investigating lineage divergence, though deciding if this divergence represents species-level differentiation remains challenging. Here, we use genome-wide data to investigate species limits in four currently recognized species of Earless Lizards (Phrynosomatidae: Holbrookia), with a focus on H. lacerata and H. subcaudalis, the latter having potentially imperiled populations. This group’s taxonomy has been repeatedly revised; most recently, H. lacerata and H. subcaudalis were elevated to species status using conserved morphological data and a few molecular markers. In this study, we used double-digest restriction-site associated DNA sequencing to delineate species limits for our focal taxa. We recovered five populations that corresponded to five well-supported lineages with very little gene flow among them. Our results support the recognition of H. lacerata and H. subcaudalis as two separate species, based on strong phylogenetic support for these lineages and genetic divergence measures that exceed those of currently recognized species within Holbrookia. Genomic methods for species delimitation offer a promising approach to assess biodiversity in taxonomically confounded taxa or organisms of conservation priority.
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- PAR ID:
- 10540759
- Publisher / Repository:
- Society of Systematic Biologists
- Date Published:
- Journal Name:
- Bulletin of the Society of Systematic Biologists
- Volume:
- 3
- Issue:
- 2
- ISSN:
- 2768-0819
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.18061/bssb.v3i2.9459
