Defining population structure for the Mojave desert tortoise

Hagerty, Bridgette E.; Tracy, C. Richard

doi:10.1007/s10592-010-0073-0

Cited by 35 publications

(36 citation statements)

References 60 publications

(78 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We found significantly lower genetic diversity at the periphery of the range of the gopher tortoise, a pattern that has also been reported in other Gopherus species (Fujii and Forstner 2010;Hagerty and Tracy 2010). Specifically, like Ennen et al (2010) and Clostio et al (2012), we found reduced genetic diversity in the Western region, but we also found significantly lower levels in the East Georgia region as well.…”

Section: Gene Flow Demographic History and Genetic Diversitysupporting

confidence: 87%

Range-Wide and Regional Patterns of Population Structure and Genetic Diversity in the Gopher Tortoise

Gaillard

Ennen

Kreiser

et al. 2017

Journal of Fish and Wildlife Management

View full text Add to dashboard Cite

The gopher tortoise (Gopherus polyphemus) has experienced dramatic population declines throughout its distribution in the southeastern United States and is federally listed as threatened in the area west of the Tombigbee and Mobile rivers. While there is molecular support for recognizing the listed portion of the range as genetically distinct, other research has suggested that additional population structure exists at both range-wide and regional scales. In this study, we sought to comprehensively define genetic population structure at both spatial scales by doubling the data available in terms of the number of sampling sites, individuals, and microsatellite loci compared to previously published work. We also compared patterns of genetic diversity, gene flow, and demographic history across the range. We collected 933 individuals from 47 sampling sites across the range and genotyped them for 20 microsatellite loci. Our range-wide analyses supported the recognition of five genetic groups (or regions) delineated by the Tombigbee and Mobile rivers, Apalachicola and Chattahoochee rivers, and the transitional areas between several physiographic province sections of the Coastal Plains (i.e., Eastern Gulf, Sea Island, and Floridian). We found genetic admixture at sampling sites along the boundaries of these genetically defined groups. We detected some degree of additional genetic structure within each of the five regions. Notably, within the range listed as threatened under the Endangered Species Act, we found some support for two additional genetic groups loosely delineated by the Pascagoula and Chickasawhay rivers, and we detected four more genetic groups within the Florida region that seemed to reflect the influence of the local physiography. Additionally, our range-wide analysis found the periphery of the range had lower levels of genetic diversity relative to the core. We suggest that the five main genetic groups delineated in our study warrant recognition as management units in terms of conservation planning. Intraregional population structure also points to the potential importance of other barriers to gene flow at finer spatial scales, although additional work is needed to better delineate these genetic groups.Citation: Gaillard D, Ennen JR, Kreiser BR, Qualls CP, Sweat SC, Birkhead R, Tuberville TD, Aresco M, McCoy ED, Mushinsky, HR, Hentges TW. 2017. Range-wide and regional patterns of population structure and genetic diversity in the gopher tortoise.

show abstract

Section: Gene Flow Demographic History and Genetic Diversitysupporting

confidence: 87%

Range-Wide and Regional Patterns of Population Structure and Genetic Diversity in the Gopher Tortoise

Gaillard

Ennen

Kreiser

et al. 2017

Journal of Fish and Wildlife Management

View full text Add to dashboard Cite

show abstract

“…Our PCA analysis identified three primary groupings of tortoises, corresponding to a north/south division, and within the southern group, and east-west division (inset of Figure 4). Certain aspects of these groupings were also suggested in previous analyses (Hagerty and Tracy 2010), although the concordance is not perfect. In particular, the split between the California Cluster and the Las Vegas Cluster of Hagerty and Tracy is almost exactly replicated on PC1, and the NC, WM, and EC splits among the California Cluster are recovered by PC2.…”

Section: Discussionsupporting

confidence: 62%

Desert Tortoises in the Genomic Age: Population Genetics and the Landscape

McCartney‐Melstad

et al. 2017

Preprint

Self Cite

View full text Add to dashboard Cite

The California Department of Fish and Wildlife (CDFW) provided research funds to study the conservation genomics and landscape genomics of the Mojave desert tortoise, Gopherus agassizii, in response to the Desert Renewable Energy Conservation Plan (DRECP). To do this, we consolidated tissue samples of the desert tortoise from across the species range within California and southern Nevada, generated a DNA dataset consisting of full genomes of 270 tortoises, and analyzed the way in which the environment of the desert tortoise has determined modern patterns of relatedness and genetic diversity across the landscape. Here we present the implications of these results for the conservation and landscape genomics of the desert tortoise. Our work strongly indicates that several well-defined genetic groups exist within the species, including a primary north-south genetic discontinuity at the Ivanpah Valley and another separating western from eastern Mojave samples. We also use existing desert tortoise habitat modeling data with a novel extension of genetic "resistance distance" using geographic maps of continuous space to predict the relative impacts of five proposed development alternatives within the DRECP and rank them with respect to their likely impacts on desert tortoise gene flow and connectivity in the Mojave. Finally, we analyzed the impacts of each of the 214 distinct proposed development area "chunks", derived from the proposed development polygons, and ranked each chunk in terms of its range-wide impacts on desert tortoise gene flow.

show abstract

“…The distribution of mtDNA haplogroups despite gene flow with isolation by distance (Murphy et al. ; Hagerty and Tracy ) suggests a unique population history of northern G. agassizii clades. Northern clades potentially diverged during extended periods of isolation from southern populations; however, the current genetic structure may also be maintained by local adaptation.…”

Section: Discussionmentioning

confidence: 99%

Testing Taxon Tenacity of Tortoises: evidence for a geographical selection gradient at a secondary contact zone

Edwards

Berry

Inman

et al. 2015

Ecology and Evolution

View full text Add to dashboard Cite

We examined a secondary contact zone between two species of desert tortoise, Gopherus agassizii and G. morafkai. The taxa were isolated from a common ancestor during the formation of the Colorado River (4–8 mya) and are a classic example of allopatric speciation. However, an anomalous population of G. agassizii comes into secondary contact with G. morafkai east of the Colorado River in the Black Mountains of Arizona and provides an opportunity to examine reinforcement of species' boundaries under natural conditions. We sampled 234 tortoises representing G. agassizii in California (n - 103), G. morafkai in Arizona (n - 78), and 53 individuals of undetermined assignment in the contact zone including and surrounding the Black Mountains. We genotyped individuals for 25 STR loci and determined maternal lineage using mtDNA sequence data. We performed multilocus genetic clustering analyses and used multiple statistical methods to detect levels of hybridization. We tested hypotheses about habitat use between G. agassizii and G. morafkai in the region where they co-occur using habitat suitability models. Gopherus agassizii and G. morafkai maintain independent taxonomic identities likely due to ecological niche partitioning, and the maintenance of the hybrid zone is best described by a geographical selection gradient model.

show abstract

Defining population structure for the Mojave desert tortoise

Cited by 35 publications

References 60 publications

Range-Wide and Regional Patterns of Population Structure and Genetic Diversity in the Gopher Tortoise

Range-Wide and Regional Patterns of Population Structure and Genetic Diversity in the Gopher Tortoise

Desert Tortoises in the Genomic Age: Population Genetics and the Landscape

Testing Taxon Tenacity of Tortoises: evidence for a geographical selection gradient at a secondary contact zone

Contact Info

Product

Resources

About