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Title: Persistence of a Geographically-Stable Hybrid Zone in Puerto Rican Dwarf Geckos
Abstract Determining the mechanisms that create and maintain biodiversity is a central question in ecology and evolution. Speciation is the process that creates biodiversity. Speciation is mediated by incompatibilities that lead to reproductive isolation between divergent populations and these incompatibilities can be observed in hybrid zones. Gecko lizards are a speciose clade possessing an impressive diversity of behavioral and morphological traits. In geckos, however, our understanding of the speciation process is negligible. To address this gap, we used genetic sequence data (both mitochondrial and nuclear markers) to revisit a putative hybrid zone between Sphaerodactylus nicholsi and Sphaerodactylus townsendi in Puerto Rico, initially described in 1984. First, we addressed discrepancies in the literature on the validity of both species. Second, we sampled a 10-km-wide transect across the putative hybrid zone and tested explicit predictions about its dynamics using cline models. Third, we investigated potential causes for the hybrid zone using species distribution modeling and simulations; namely, whether unique climatic variables within the hybrid zone might elicit selection for intermediate phenotypes. We find strong support for the species-level status of each species and no evidence of movement, or unique climatic variables near the hybrid zone. We suggest that this narrow hybrid zone more » is geographically stable and is maintained by a combination of dispersal and selection. Thus, this work has identified an extant model system within geckos that that can be used for future investigations detailing genetic mechanisms of reproductive isolation in an understudied vertebrate group. « less
Authors:
; ; ;
Award ID(s):
1657656
Publication Date:
NSF-PAR ID:
10149298
Journal Name:
Journal of Heredity
Volume:
110
Issue:
5
Page Range or eLocation-ID:
523 to 534
ISSN:
0022-1503
Sponsoring Org:
National Science Foundation
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  1. Determining the mechanisms that create and maintain biodiversity is a central question in ecology and evolution. Speciation is the process that creates biodiversity. Speciation is mediated by incompatibilities that lead to reproductive isolation between divergent populations and these incompatibilities can be observed in hybrid zones. Gecko lizards are a speciose clade possessing an impressive diversity of behavioral and morphological traits. In geckos, however, our understanding of the speciation process is negligible. To address this gap, we used genetic sequence data (both mitochondrial and nuclear markers) to revisit a putative hybrid zone between Sphaerodactylus nicholsi and Sphaerodactylus townsendi in Puerto Rico, initially described in 1984. First, we addressed discrepancies in the literature on the validity of both species. Second, we sampled a 10-km-wide transect across the putative hybrid zone and tested explicit predictions about its dynamics using cline models. Third, we investigated potential causes for the hybrid zone using species distribution modeling and simulations; namely, whether unique climatic variables within the hybrid zone might elicit selection for intermediate phenotypes. We find strong support for the species-level status of each species and no evidence of movement, or unique climatic variables near the hybrid zone. We suggest that this narrow hybrid zone ismore »geographically stable and is maintained by a combination of dispersal and selection. Thus, this work has identified an extant model system within geckos that that can be used for future investigations detailing genetic mechanisms of reproductive isolation in an understudied vertebrate group.« less
  2. Abstract

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