Molecular Systematics, Phylogeography, and the Effects of Pleistocene Glaciation in the Painted Turtle (Chrysemys Picta) Complex

Abstract

The painted turtle, Chrysemys picta, is currently recognized as a continentally distributed polytypic species, ranging across North America from southern Canada to extreme northern Mexico. We analyzed variation in the rapidly evolving mitochondrial control region (CR) in 241 turtles from 117 localities across this range to examine whether the painted turtle represents a continentally distributed species based on molecular analysis. We found strong support for the novel hypothesis that C. p. dorsalis is the sister group to all remaining Chrysemys, with the remaining Chrysemys falling into a single, extremely wide-ranging and genetically undifferentiated species. Given our goal of an evolutionarily accurate taxonomy, we propose that two evolutionary lineages be recognized as species within Chrysemys: C. dorsalis (Agassiz 1857) in the southern Mississippi drainage region, and C. picta (Schneider 1783) from the rest of the range of the genus. Neither molecular nor recent morphological analyses argue for the hybrid origin of C. p. marginata as previously proposed. Within C. picta, we find evidence of at least two independent range expansions into previously glaciated regions of North America, one into New England and the other into the upper Midwest. We further find evidence of a massive extinction/recolonization event across the Great Plains/Rocky Mountain region encompassing over half the continental United States. The timing and extent of this colonization is consistent with a recently proposed regional aridification as the Laurentide ice sheets receded approximately 14,000 years ago, and we tentatively propose this paleoclimatological event as a major factor shaping genetic variation in Chrysemys.

Evolutionary History of the Northern Leopard Frog: Reconstruction of Phylogeny, Phylogeography, and Historical Changes in Population Demography From Mitochondrial Dna

“…We also see a striking pattern of reduced levels of genetic variation in the west (Table 3). Although a selective sweep could be responsible, we see the same pattern of east-west divergence and lower western diversity in painted turtles (Chrysemys picta complex; Starkey et al 2003). The most parsimonious explanation for such similar patterns in both turtles and frogs is some common geologic event, such as repeated glacial oscillations, that resulted in bottlenecks in both taxa in the west.…”

“…That R. pipiens would show a major break across the Mississippi River was not an a priori prediction of our study. However, this result is not surprising because many other species of small mammals, fishes, amphibians, and reptiles also show major phylogeographic breaks in the vicinity of the Mississippi River (Blair 1965;Lansman et al 1983;Burbrink et al 2000 and references therein;Starkey et al 2003) Our analyses also revealed three interesting and unexpected patterns. First, NCA results suggest that the eastern haplotypes were derived from a western haplotype via longdistance colonization (Table 2).…”

“…Second, we predict that within the framework of restricted gene flow, we will be able to detect the genetic signature of a demographic bottleneck and subsequent expansion caused by glacial advance and retreat (Hewitt 1996) including evidence of glacial refugia (Comps et al 2001). This second hypothesis is supported by phylogeographic findings from other species found in temperate North America (e.g., Sage and Wolff 1986;Green et al 1996;Bernatchez and Wilson 1998;Burbrink et al 2000;Conroy and Cook 2000;Nielson et al 2001;Starkey et al 2003). Support for these hypotheses would indicate that anuran evolution is influenced by Pleistocene glaciation in a manner similar to that of other North American species.…”

Morphological and molecular evidence indicates that the Gulf Coast box turtle (Terrapene carolina major) is not a distinct evolutionary lineage in the Florida Panhandle

“…An approximately 700-bp fragment of the mitochondrial displacement loop (d-loop) region was amplified for 114 specimens representing the panhandle and samples from deep within the ranges of each of the subspecies. Amplification and bidirectional sequencing was conducted using primers DES1 and DES2 (Starkey et al, 2003). Polymerase chain reaction (PCR) profile consisted of an initial denaturation for 5 min at 94°C; 35 cycles of 45 s at 94°C, 45 s at 52°C, and 45 s at 72°C; followed by a 5-min extension at 72°C.…”

Influence of drainage divides versus arid corridors on genetic structure and demography of a widespread freshwater turtle, Emydura macquarii krefftii, from Australia

“…Many Northern Hemisphere species, including freshwater fishes and turtles, show clear signatures of genetic bottlenecks and range reductions into isolated glacial refugia, followed by dramatic demographic and range expansion since the end of the last ice age (Starkey et al 2003;Seifertova et al 2012). Cyclic Pleistocene aridity in Australia appears not to have produced molecular signatures of wide-scale contraction to major refugia and subsequent macrogeographical range expansion as seen for temperate Northern Hemisphere biotas (Hewitt 2000).…”