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Abstract The recognition and delineation of cryptic species remains a perplexing problem in systematics, evolution, and species delimitation. Once recognized as such, cryptic species complexes provide fertile ground for studying genetic divergence within the context of phenotypic and ecological divergence (or lack thereof). Herein we document the discovery of a new cryptic species of trapdoor spider,Promyrmekiaphila korematsuisp. nov. Using subgenomic data obtained via target enrichment, we document the phylogeography of the California endemic genusPromyrmekiaphilaand its constituent species, which also includesP. clathrataandP. winnemem. Based on these data we show a pattern of strong geographic structuring among populations but cannot entirely discount recent gene flow among populations that are parapatric, particularly for deeply diverged lineages withinP. clathrata. The genetic data, in addition to revealing a new undescribed species, also allude to a pattern of potential phenotypic differentiation where species likely come into close contact. Alternatively, phenotypic cohesion among genetically divergentP. clathratalineages suggests that some level of gene flow is ongoing or occurred in the recent past. Despite considerable field collection efforts over many years, additional sampling in potential zones of contact for both species and lineages is needed to completely resolve the dynamics of divergence inPromyrmekiaphilaat the population–species interface.
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The population genetics of speciation by cascade reinforcement
Abstract Species interactions drive diverse evolutionary outcomes. Speciation by cascade reinforcement represents one example of how species interactions can contribute to the proliferation of species. This process occurs when the divergence of mating traits in response to selection against interspecific hybridization incidentally leads to reproductive isolation among populations of the same species. Here, we investigated the population genetic outcomes of cascade reinforcement in North American chorus frogs (Hylidae:Pseudacris). Specifically, we estimated the frequency of hybridization among three taxa, assessed genetic structure within the focal species,P.feriarum, and ascertained the directionality of gene flow withinP.feriarumacross replicated contact zones via coalescent modeling. Through field observations and preliminary experimental crosses, we assessed whether hybridization is possible under natural and laboratory conditions. We found that hybridization occurs amongP.feriarumand two conspecifics at a low rate in multiple contact zones, and that gene flow within the former species is unidirectional from allopatry into sympatry with these other species in three of four contact zones studied. We found evidence of substantial genetic structuring withinP.feriarumincluding a divergent western allopatric cluster, a behaviorally‐distinct sympatric South Carolina cluster, and several genetically‐overlapping clusters from the remainder of the distribution. Furthermore, we found sub‐structuring between reinforced and nonreinforced populations in the two most intensely‐sampled contact zones. Our literature review indicated thatP.feriarumhybridizes with at least five heterospecifics at the periphery of its range providing a mechanism for further intraspecific diversification. This work strengthens the evidence for cascade reinforcement in this clade, revealing the geographic and genetic landscape upon which this process can contribute to the proliferation of species.
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- Award ID(s):
- 2121058
- PAR ID:
- 10499900
- Publisher / Repository:
- Ecology and Evolution
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 13
- Issue:
- 2
- ISSN:
- 2045-7758
- 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/10.1002/ece3.9773
