Genetic Assessment of Taxonomic Uncertainty in Painted Turtles

Jensen, Evelyn L.; Govindarajulu, Purnima; Russello, Michael A.

doi:10.1670/14-010

Cited by 14 publications

(25 citation statements)

References 29 publications

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“…data). This range encompasses three subspecies, C. p. bellii, C. p. marginata and C. p. picta, that are not genetically distinct (Jensen, Govindarajulu, & Russello, 2015; Figure 2). Like most turtles, C. picta have TSD type Ia (Janzen & Paukstis, 1991), the system in which only male hatchlings are produced at relatively cool temperatures and females at warm temperatures.…”

Section: Study Systemmentioning

confidence: 99%

Breadth of the thermal response captures individual and geographic variation in temperature‐dependent sex determination

et al. 2019

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Population‐scale responses of key ecological traits to local environmental conditions provide insight into their adaptive potential. In species with temperature‐dependent sex determination (TSD), short‐term, individual developmental responses to the incubation environment have long‐term consequences for populations. We took a model‐based approach to study within‐ and among‐population variation in the physiological components of TSD in 12 populations of painted turtles (Chrysemys picta). We used laboratory and field incubation data to quantify variation in thermal reaction norms at both population and clutch scales, focusing on the pivotal temperature that produces a 1:1 sex ratio (P) and the transitional range of incubation temperatures (TRTs) that produce mixed sex ratios. Defying theoretical expectations, among‐population variation in P was not convincingly explained by geography or local thermal conditions. However, within some populations, P varied by >5°C at the clutch scale, indicating that the temperature sensitivity of gonadal differentiation can vary substantially among individual nesting females. In addition, the TRT was wider at lower latitudes, suggesting responsiveness to local incubation conditions. Our results provide a potential explanation for discrepancies observed between constant‐temperature experimental results and outcomes of fluctuating incubation conditions experienced in natural nests, exposing important knowledge gaps in our understanding of local adaptation in TSD and identifying shortcomings of traditional laboratory studies. Understanding individual variation and the timing of gonadal differentiation is likely to be far more useful in understanding local adaptation than previously acknowledged. A free Plain Language Summary can be found within the Supporting Information of this article.

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Section: Study Systemmentioning

confidence: 99%

Breadth of the thermal response captures individual and geographic variation in temperature‐dependent sex determination

et al. 2019

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“…Traditional taxonomy has recognized one species (Chrysemys picta) subdivided into four subspecies (Ernst and Lovich 2009). More recent phylogeographic research (Starkey et al 2003;Jensen et al 2015) has identified the southern subspecies as a monophyletic group, resulting in the elevation of this taxon to species status as C. dorsalis (TTWG (Turtle Taxonomy Working Group) et al 2017). We focus on the three northern subspecies of C. picta, and refer to these throughout as picta, marginata, and bellii ( Fig.…”

Section: Study Systemmentioning

confidence: 99%

“…These three subspecies display considerable genetic variability, including multiple mitochondrial clades exhibiting spatial structure across the range. However, past research using phylogenetic methods has been unable to come to a clear consensus regarding the historical processes that have generated this variability, as there is a lack of strict monophyly among morphologically defined subspecies (Starkey et al 2003;Jensen et al 2015; Figure S1).…”

Section: Study Systemmentioning

confidence: 99%

“…PCR products were then either directly sent for sequencing to Genewiz (South Plainfield, NJ, USA) or purified using Exosap (Affymetrix, Santa Clara, CA, USA) and then sequenced at the AMNH. Each sequence was aligned to published haplotypes (Starkey et al 2003;Jensen et al 2015) using GENEIOUS version 8.1.2 (Kearse et al 2012). Sequences that did not match any previously published sequence were first searched using NCBI BLAST to confirm that these sequences were novel.…”

Section: Mitochondrial Dna Sequencingmentioning

confidence: 99%

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Disentangling the genetic effects of refugial isolation and range expansion in a trans-continentally distributed species

et al. 2018

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In wide-ranging taxa with historically dynamic ranges, past allopatric isolation and range expansion can both influence the current structure of genetic diversity. Considering alternate historical scenarios involving expansion from either a single refugium or from multiple refugia can be useful in differentiating the effects of isolation and expansion. Here, we examined patterns of genetic variability in the trans-continentally distributed painted turtle (Chrysemys picta). We utilized an existing phylogeographic dataset for the mitochondrial control region and generated additional data from nine populations for the mitochondrial control region (n = 302) and for eleven nuclear microsatellite loci (n = 247). We created a present-day ecological niche model (ENM) for C. picta and hindcast this model to three reconstructions of historical climate to define three potential scenarios with one, two, or three refugia. Finally, we employed spatially-explicit coalescent simulations and an approximate Bayesian computation (ABC) framework to test which scenario best fit the observed genetic data. Simulations indicated that phylogeographic and multilocus population-level sampling both could differentiate among refugial scenarios, although inferences made using mitochondrial data were less accurate when a longer coalescence time was assumed. Furthermore, all empirical genetic datasets were most consistent with expansion from a single refugium based on ABC. Our results indicate a stronger role for post-glacial range expansion, rather than isolation in allopatric refugia followed by range expansion, in structuring diversity in this species. To distinguish among complex historical scenarios, we recommend explicitly modeling the effects of range expansion and evaluating alternate refugial scenarios for wide-ranging taxa.

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“…Four subspecies of painted turtle are recognized (Ernst and Lovich 2009), but the genus is undergoing taxonomic revision due to recent genetic work that potentially elevates Chrysemys picta dorsalis to species status [as C. dorsalis (Crother 2012;Jensen et al 2014a)]. For convenience in this paper, we refer to subspecies, but we acknowledge the unresolved taxonomy.…”

Section: Methodsmentioning

confidence: 99%

Rethinking biogeographic patterns: high local variation in relation to latitudinal clines for a widely distributed species

Tesche

Hodges

2015

Oecologia

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Wide-ranging species typically differ morphologically across their ranges. Bergmann's rule suggests that taxa in colder environments are bigger than related taxa in warmer locations. We examined 767 painted turtles (Chrysemys picta) in ten populations near their northwestern range edge in south-central British Columbia, Canada, in conjunction with previous data, to test the hypotheses of (1) a Bergmann's latitudinal cline, and (2) that males and females show similar latitudinal variation in size. We also explicitly test the impact of high local variation on range-wide inference. Female and male turtles showed similar latitudinal clines in body size; the degree of sexual dimorphism did not change across the range. Importantly, local variation in sexual dimorphism across ponds was nearly as high as the previously observed continental variation. Indeed, we found both the lowest and the highest degrees of sexual size dimorphism that have ever been reported for this species. Further, differing criteria in the literature for identifying mature females compound the difficulty of interpreting latitudinal clines in size or dimorphism. Our results highlight the need for much more systematic local and regional sampling as inputs for latitudinal or other comparative analyses such as Rensch's rule because insufficient sampling of high local variation may mask important ecological and evolutionary patterns.

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Genetic Assessment of Taxonomic Uncertainty in Painted Turtles

Cited by 14 publications

References 29 publications

Breadth of the thermal response captures individual and geographic variation in temperature‐dependent sex determination

Breadth of the thermal response captures individual and geographic variation in temperature‐dependent sex determination

Disentangling the genetic effects of refugial isolation and range expansion in a trans-continentally distributed species

Rethinking biogeographic patterns: high local variation in relation to latitudinal clines for a widely distributed species

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