Population Structure, Growth, and Age Estimation of Spotted Turtles, &lt;em&gt;Clemmys guttata&lt;/em&gt;, Near their Northern Limit: an 18-Year Follow-up

Seburn, David

doi:10.22621/cfn.v117i3.747

Cited by 11 publications

(4 citation statements)

References 9 publications

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“…This species occurs in small, isolated populations across its range (COSEWIC 2004;van Dijk 2011) precluding a genetic rescue effect (Tallmon et al 2004). Low vagility may result in low levels of gene flow between isolated populations because this species has high site fidelity and individuals rarely travel >2 km per year (Litzgus 1996;Seburn 2003;Rasmussen and Litzgus 2010). Individuals sampled in a small wetland in Indiana had reduced genetic diversity (measured by DNA fingerprinting) compared with individuals in a nearby large wetland, suggesting that declining populations may have reduced genetic diversity (Parker and Whiteman 1993).…”

Section: Introductionmentioning

confidence: 99%

Conservation genetics of the endangered Spotted Turtle (Clemmys guttata) illustrate the risks of “bottleneck tests”

DavyChristina

MurphyRobert

2014

Can. J. Zool.

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Studies of population genetics in turtles have suggested that turtles do not experience genetic impacts of bottlenecks as strongly as expected. However, recent studies cast doubt on two commonly used tests implemented in the program BOTTLENECK, suggesting that these findings should be re-evaluated. The Spotted Turtle (Clemmys guttata (Schneider, 1792)) is endangered both globally and within Canada, but genetic data required to develop effective recovery strategies are unavailable. Here, we conducted the first study of population genetic structure in C. guttata. We then used multiple small populations of C. guttata as replicates to test whether the commonly used program BOTTLENECK could detect the genetic signature of bottlenecks in our study populations, which are all thought to have experienced significant declines in the past 2-3 generations (75 years). Turtles (n = 256) were genotyped at 11 microsatellite loci. A suite of Bayesian population genetics analyses and a principal coordinates analysis identified a minimum of 6 distinct genetic populations and a maximum of 10 differentiated subpopulations across the sampled Canadian range of C. guttata, which corresponded to demographically independent units. BOTTLENECK failed to detect population declines. A literature review found that bottleneck tests in 17 of 18 previous genetic studies of tortoises and freshwater turtles were based on suboptimal sampling, potentially confounding their results. High retention of genetic diversity (allelic richness and heterozygosity) in isolated populations of C. guttata and other turtle species is encouraging for species recovery, but conclusions about the prevalence of genetic bottlenecks in such populations should be re-examined.Résumé : Des études de la génétique des populations chez les tortues semblent indiquer que les impacts génétiques des goulots d'étranglement sur ces dernières ne sont pas aussi forts que prévu. Des études récentes jettent toutefois un doute sur deux tests répandus utilisés dans le programme BOTTLENECK, ce qui suggère que ces résultats devraient être réévalués. La tortue ponctuée (Clemmys guttata (Schneider, 1792)) est en voie de disparation à l'échelle tant planétaire que canadienne, mais les données génétiques nécessaires à l'élaboration de stratégies de rétablissement efficaces ne sont pas disponibles. Nous avons réalisé la première étude de la structure de la génétique des populations chez C. guttata. Nous avons ensuite utilisé de multiples petites populations de C. guttata comme réplicats pour vérifier si le programme d'usage courant BOTTLENECK peut déceler la signature génétique de goulots d'étranglement dans les populations à l'étude, qui auraient toutes connu des diminutions significatives au cours des deux ou trois dernières générations (75 ans). Des tortues (n = 256) ont fait l'objet d'un génotypage sur 11 microsatellites. Un ensemble d'analyses bayésiennes de la génétique des populations et une analyse en coordonnées principales a permis de cerner au moins 6 populations génétiques distinctes ...

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Section: Introductionmentioning

confidence: 99%

Conservation genetics of the endangered Spotted Turtle (Clemmys guttata) illustrate the risks of “bottleneck tests”

DavyChristina

MurphyRobert

2014

Can. J. Zool.

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“…We documented similar age class structure between the two study sites, with subadults making up 45% of the sampled population at the protected stream and 52% at the human-created ponds. Although a higher proportion of subadults in a population could indicate increased recruitment and potentially a healthy population (Seburn, 2003), it may also signal reduced numbers of adults in the population due to collection, as has been demonstrated in other freshwater turtle species (e.g., Sung, Karraker & Hau, 2013). An alternative explanation may be related to differences in habitat use between adult and subadult turtles.…”

Section: Discussionmentioning

confidence: 99%

Population demography of Oldham’s leaf turtle (Cyclemys oldhamii) in protected and disturbed habitats in Thailand

Seateun

Karraker

Stuart

et al. 2019

PeerJ

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Background Freshwater turtle populations are vulnerable to a range of human activities because of particular life history attributes, and anthropogenic impacts can cause shifts in demographic traits, including survival, density and population structure. Asian freshwater turtles have undergone dramatic population declines in recent decades principally because of collection for food, pet, and traditional medicine markets. Despite this, few studies have been conducted on the population demography of these turtles, thereby limiting our understanding of population trends and the development of conservation actions. Oldham’s leaf turtle (Cyclemys oldhamii) is one of the most commonly traded turtles in Asian markets, but previous published studies have focused solely on systematics. Methods We conducted a mark-recapture study of C. oldhamii at three sites in northeastern Thailand—a protected stream, a degraded stream, and human-constructed ponds—and evaluated differences in survival, density, population structure, and sexual dimorphism among sites. Results We captured 77 turtles at the protected stream, 67 at the constructed ponds, and two in the degraded stream. Survival was 12% lower and density was 35% lower in the constructed ponds than in the protected stream. Size class structure was skewed toward smaller individuals at the constructed ponds, and both sites exhibited subadult-skewed age class structure. Sex ratios were not statistically different than 1:1 at either site and did not differ between sites. We did not document sexual dimorphism in either population. Discussion Explanations for lower survival, lower densities, and skewed size class structure at the constructed ponds include collection for consumption or Buddhist prayer release locally, collection for illegal export from Thailand, predation by domestic dogs associated with humans living nearby, or lower habitat quality. Evidence from our study suggests that collection, either for local use or export, is the most likely explanation for differences in demographic characteristics between the two sites. The information gained from this study may contribute to a status assessment for C. oldhamii and development of conservation actions should they become necessary to protect populations in Thailand.

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“…) so that other spotted turtles in our study area could have focused on non‐ditch habitat types. Given heterogeneity in habitat structure, spotted turtles typically use slow‐moving permanent or ephemeral aquatic sites (Seburn , Yagi and Litzgus ), but move upland for nesting, estivation, or when traversing to another aquatic feature (Beaudry et al. ).…”

Section: Discussionmentioning

confidence: 99%

Novel habitat use supports population maintenance in a reconfigured landscape

et al. 2016

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Abstract. Given the limited scope of unaltered, protected areas in most regions, understanding the contributions to imperiled species conservation by landscapes in which habitat elements have been reconfigured is critical. Commercial forestry has been a driver of altered structure and composition of forests and of distribution and character of aquatic systems. In eastern North America, extensive historical wetland drainage reconfigured hydrologic environments from low-gradient wet flats and isolated wetlands to connected networks of linear ditches. Landscapes where both uplands and aquatic environments differ from historic conditions may affect most ecological aspects of semi-aquatic species, including reptiles. Our objective was to determine if habitat selection and use decisions by spotted turtles (Clemmys guttata), a rare semi-aquatic species, supported population maintenance in a reconfigured forest landscape in eastern North Carolina, USA. We captured 280 individuals and radiomarked 31 adults to examine habitat selection at multiple spatial scales with paired logistic regression, movements and home ranges with location data and utilization distributions (UDs), survival with a known-fate model, and abundance with N-mixture modeling. Across local and landscape scales, turtles selected features associated with ditches despite abundant, more natural aquatic depressions across the study area. Habitat metrics describing understory closure and substrate characteristics were important at local scales, and closed canopy forest and habitat heterogeneity was positively associated with activity areas at landscape-scale spatial grains. Both movements and home ranges were centered on ditches, and turtles exploited ditches to access mates, nest sites, or uplands for estivation. In this highly reconfigured landscape, this species appeared to have sufficient behavioral plasticity to acquire key resources contributing to high survival and an abundant population. Isolation from road traffic and collection, both which negatively affect turtles elsewhere, was facilitated by limited public access. Our results suggest that conservation and management of rare species should not rely solely on habitat information gained from studies in more pristine areas because such results may not demonstrate the range in variation in behavior that might allow persistence in novel environments, absent key threats.

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Population Structure, Growth, and Age Estimation of Spotted Turtles, <em>Clemmys guttata</em>, Near their Northern Limit: an 18-Year Follow-up

Cited by 11 publications

References 9 publications

Conservation genetics of the endangered Spotted Turtle (Clemmys guttata) illustrate the risks of “bottleneck tests”

Conservation genetics of the endangered Spotted Turtle (Clemmys guttata) illustrate the risks of “bottleneck tests”

Population demography of Oldham’s leaf turtle (Cyclemys oldhamii) in protected and disturbed habitats in Thailand

Novel habitat use supports population maintenance in a reconfigured landscape

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