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Persistence and dispersal in a Southern Hemisphere glaciated landscape: the phylogeography of the spotted snow skink (Niveoscincus ocellatus) in Tasmania.

Cliff HB, Wapstra E, Burridge CP - BMC Evol. Biol. (2015)

Bottom Line: There was a high degree of mitochondrial haplotype diversity (96 unique haplotypes) and phylogeographic structure, where spatially distinct groups were associated with Tasmania's Northeast and a large area covering Southeast and Central Tasmania.Expansion in Central and Southeastern areas appears to have been more recent in both demographic and spatial contexts, than in Northeast Tasmania, which is consistent with inferences for other taxa of greater stability and persistence in Northeast Tasmania during the Last Glacial Maximum.These phylogeographic patterns indicate contrasting demographic histories of populations in close proximity to areas directly affected by glaciers in the Southern Hemisphere during the LGM.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia. hcliff11@gmail.com.

ABSTRACT

Background: The aim of this research was to identify the effects of Pleistocene climate change on the distribution of fauna in Tasmania, and contrast this with biotic responses in other temperate regions in the Northern and Southern Hemisphere that experienced glacial activity during this epoch. This was achieved by examining the phylogeographic patterns in a widely distributed Tasmanian endemic reptile, Niveoscincus ocellatus. 204 individuals from 29 populations across the distributional range of N. ocellatus were surveyed for variation at two mitochondrial genes (ND2, ND4), and two nuclear genes (β-globin, RPS8). Phylogenetic relationships were reconstructed using a range of methods (maximum parsimony, Bayesian inference and haplotype networks), and the demographic histories of populations were assessed (AMOVA, Tajima's D, Fu's Fs, mismatch distributions, extended Bayesian skyline plots, and relaxed random walk analyses).

Results: There was a high degree of mitochondrial haplotype diversity (96 unique haplotypes) and phylogeographic structure, where spatially distinct groups were associated with Tasmania's Northeast and a large area covering Southeast and Central Tasmania. Phylogeographic structure was also present within each major group, but the degree varied regionally, being highest in the Northeast. Only the Southeastern group had a signature of demographic expansion, occurring during the Pleistocene but post-dating the Last Glacial Maximum. In contrast, nuclear DNA had low levels of variation and a lack of phylogeographic structure, and further loci should be surveyed to corroborate the mitochondrial inferences.

Conclusions: The phylogeographic patterns of N. ocellatus indicate Pleistocene range and demographic expansion in N. ocellatus, particularly in the Southeast and Central areas of Tasmania. Expansion in Central and Southeastern areas appears to have been more recent in both demographic and spatial contexts, than in Northeast Tasmania, which is consistent with inferences for other taxa of greater stability and persistence in Northeast Tasmania during the Last Glacial Maximum. These phylogeographic patterns indicate contrasting demographic histories of populations in close proximity to areas directly affected by glaciers in the Southern Hemisphere during the LGM.

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Topographic map of Tasmania indicating sampling sites for Niveoscincus ocellatus (filled circles) and species distribution records (open circles). The blue line bounds the maximum extent of Pleistocene glaciation, while that corresponding to the Last Glacial Maximum is bounded by the red line, based on [28]. Black lines demarcate groups defined on the basis of mtDNA variation, with the dashed black line indicating the ambiguous placement of the Lake Mackenzie population either within the Southeast group or on its own. Elevation data were obtained from Geoscience Australia
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Fig1: Topographic map of Tasmania indicating sampling sites for Niveoscincus ocellatus (filled circles) and species distribution records (open circles). The blue line bounds the maximum extent of Pleistocene glaciation, while that corresponding to the Last Glacial Maximum is bounded by the red line, based on [28]. Black lines demarcate groups defined on the basis of mtDNA variation, with the dashed black line indicating the ambiguous placement of the Lake Mackenzie population either within the Southeast group or on its own. Elevation data were obtained from Geoscience Australia

Mentions: During glacial periods, ice was absent or discontinuous across most of the Southern Hemisphere continents with the exception of Antarctica. This has meant that many austral studies have focused on the effects of Pleistocene changes in aridity, in tropical or ice-free temperate regions, rather than the effects of glaciers directly (e.g., [16–19]). Furthermore, Southern Hemisphere studies of the impacts of glacial and periglacial activity on species distributions have concentrated on New Zealand, Patagonia, and Antarctica (e.g., [20–24]), while Tasmania—the focus of Australia’s most extensive Pleistocene glacial activity [25]-has been comparatively neglected. Yet, unlike Patagonia and New Zealand, Tasmania has not experienced recent tectonic activity, which has the ability to confound interpretations regarding the influence of glaciations on species distributions and gene flow [22, 24]. Although not presently glaciated, Tasmania possessed glaciers at least five times during the Pleistocene, and these glaciers were most extensive (covering up to 7000 km2) during the early (~1.8 Myr) and middle Pleistocene (>130 kyr) [26–30] (Fig. 1). During the LGM, smaller ice caps formed at high altitudes, and local summer temperatures are estimated to have been 6–8 °C cooler than present averages [25, 28, 31] (Fig. 1).Fig. 1


Persistence and dispersal in a Southern Hemisphere glaciated landscape: the phylogeography of the spotted snow skink (Niveoscincus ocellatus) in Tasmania.

Cliff HB, Wapstra E, Burridge CP - BMC Evol. Biol. (2015)

Topographic map of Tasmania indicating sampling sites for Niveoscincus ocellatus (filled circles) and species distribution records (open circles). The blue line bounds the maximum extent of Pleistocene glaciation, while that corresponding to the Last Glacial Maximum is bounded by the red line, based on [28]. Black lines demarcate groups defined on the basis of mtDNA variation, with the dashed black line indicating the ambiguous placement of the Lake Mackenzie population either within the Southeast group or on its own. Elevation data were obtained from Geoscience Australia
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4482293&req=5

Fig1: Topographic map of Tasmania indicating sampling sites for Niveoscincus ocellatus (filled circles) and species distribution records (open circles). The blue line bounds the maximum extent of Pleistocene glaciation, while that corresponding to the Last Glacial Maximum is bounded by the red line, based on [28]. Black lines demarcate groups defined on the basis of mtDNA variation, with the dashed black line indicating the ambiguous placement of the Lake Mackenzie population either within the Southeast group or on its own. Elevation data were obtained from Geoscience Australia
Mentions: During glacial periods, ice was absent or discontinuous across most of the Southern Hemisphere continents with the exception of Antarctica. This has meant that many austral studies have focused on the effects of Pleistocene changes in aridity, in tropical or ice-free temperate regions, rather than the effects of glaciers directly (e.g., [16–19]). Furthermore, Southern Hemisphere studies of the impacts of glacial and periglacial activity on species distributions have concentrated on New Zealand, Patagonia, and Antarctica (e.g., [20–24]), while Tasmania—the focus of Australia’s most extensive Pleistocene glacial activity [25]-has been comparatively neglected. Yet, unlike Patagonia and New Zealand, Tasmania has not experienced recent tectonic activity, which has the ability to confound interpretations regarding the influence of glaciations on species distributions and gene flow [22, 24]. Although not presently glaciated, Tasmania possessed glaciers at least five times during the Pleistocene, and these glaciers were most extensive (covering up to 7000 km2) during the early (~1.8 Myr) and middle Pleistocene (>130 kyr) [26–30] (Fig. 1). During the LGM, smaller ice caps formed at high altitudes, and local summer temperatures are estimated to have been 6–8 °C cooler than present averages [25, 28, 31] (Fig. 1).Fig. 1

Bottom Line: There was a high degree of mitochondrial haplotype diversity (96 unique haplotypes) and phylogeographic structure, where spatially distinct groups were associated with Tasmania's Northeast and a large area covering Southeast and Central Tasmania.Expansion in Central and Southeastern areas appears to have been more recent in both demographic and spatial contexts, than in Northeast Tasmania, which is consistent with inferences for other taxa of greater stability and persistence in Northeast Tasmania during the Last Glacial Maximum.These phylogeographic patterns indicate contrasting demographic histories of populations in close proximity to areas directly affected by glaciers in the Southern Hemisphere during the LGM.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia. hcliff11@gmail.com.

ABSTRACT

Background: The aim of this research was to identify the effects of Pleistocene climate change on the distribution of fauna in Tasmania, and contrast this with biotic responses in other temperate regions in the Northern and Southern Hemisphere that experienced glacial activity during this epoch. This was achieved by examining the phylogeographic patterns in a widely distributed Tasmanian endemic reptile, Niveoscincus ocellatus. 204 individuals from 29 populations across the distributional range of N. ocellatus were surveyed for variation at two mitochondrial genes (ND2, ND4), and two nuclear genes (β-globin, RPS8). Phylogenetic relationships were reconstructed using a range of methods (maximum parsimony, Bayesian inference and haplotype networks), and the demographic histories of populations were assessed (AMOVA, Tajima's D, Fu's Fs, mismatch distributions, extended Bayesian skyline plots, and relaxed random walk analyses).

Results: There was a high degree of mitochondrial haplotype diversity (96 unique haplotypes) and phylogeographic structure, where spatially distinct groups were associated with Tasmania's Northeast and a large area covering Southeast and Central Tasmania. Phylogeographic structure was also present within each major group, but the degree varied regionally, being highest in the Northeast. Only the Southeastern group had a signature of demographic expansion, occurring during the Pleistocene but post-dating the Last Glacial Maximum. In contrast, nuclear DNA had low levels of variation and a lack of phylogeographic structure, and further loci should be surveyed to corroborate the mitochondrial inferences.

Conclusions: The phylogeographic patterns of N. ocellatus indicate Pleistocene range and demographic expansion in N. ocellatus, particularly in the Southeast and Central areas of Tasmania. Expansion in Central and Southeastern areas appears to have been more recent in both demographic and spatial contexts, than in Northeast Tasmania, which is consistent with inferences for other taxa of greater stability and persistence in Northeast Tasmania during the Last Glacial Maximum. These phylogeographic patterns indicate contrasting demographic histories of populations in close proximity to areas directly affected by glaciers in the Southern Hemisphere during the LGM.

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