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45 results for “glaciations”
Data from: Glaciation as an historical filter of below-ground biodiversity
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Fine-scale genome-wide signature of Pleistocene glaciation in Thitarodes moths (Lepidoptera: Hepialidae), host of Ophiocordyceps fungus in the Hengduan Mountains
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Persisting in a glaciated landscape: Pleistocene microrefugia evidenced by the tree wētā Hemideina maori in central South Island, New Zealand
<p><span><span><b>Aim:</b> Repeated cycles of Pleistocene glaciation have influenced phylogeographic structure of taxa on New Zealand's South Island. Many taxa became restricted to refugia at either end of the island during glaciation, resulting in an area of low endemicity in central South Island. This area of low endemism is typified by the so-called beech (or biotic) gap, where the absence of <i>Nothofagus </i>forest (and many other plant and invertebrate taxa) has been attributed to repeated glaciation. Some taxa, however, appear to have persisted <i>in situ</i> in localized refugia within the biotic gap. We test these alternative hypotheses in a large flightless alpine wētā (grasshopper).</span></span></p> <p><span><span><b>Location:</b> Southern Alps, South Island, New Zealand</span></span></p> <p><b>Taxon:</b> <i>Hemideina maori</i> <span>Pictet & Saussure, 1891 </span>(Orthoptera: Anostostomatidae)</p> <p><span><span><b>Methods:</b> We used phylogeographic analysis of mitochondrial cytochrome<i> c </i>oxidase I (<i>cox1</i>) and twenty-five nuclear DNA (nuDNA) markers to test for Pleistocene glacial microrefugia within the current montane South Island range of <i>Hemideina maori.</i></span></span></p> <p><span><span><b>Results:</b> We identified eight deeply differentiated mtDNA lineages with limited sharing of haplotypes among populations. Genetic differentiation assessed using nuDNA revealed a similar pattern, with three groups broadly corresponding to the deepest mtDNA splits. The central South Island region exhibits substantial endemic mtDNA diversity and a distinctive nuclear lineage.</span></span></p> <p><span><span><b>Main conclusions: </b>These results indicate that <i>H. maori </i>likely<i> </i>persisted in microrefugia<i> </i>within the biotic gap during glaciation. These deep lineages are estimated to have started diverging prior to the initiation of glaciation, up to 3 Ma. These results add to a growing number of Southern Hemisphere examples of deep phyleogeographic differentiation in glaciated regions compared to Europe and North America, probably reflecting less intense glaciation. We suggest that other Southern Alps species showing northern and southern clades alone, are more montane than alpine, and were reliant on warmer habitat to the north and south during glacial eras. Thus, there are species-specific responses to climatic processes, influenced by distinctive habitat requirements and physiological traits.</span></span></p>
Data from: How to survive a glaciation: the challenge of estimating biologically realistic potential distributions under freezing conditions
Correlative ecological niche models are increasingly used to estimate potential distributions during the Last Glacial Maximum (LGM) for biogeographical research. In the case of presence-background/pseudoabsences techniques, cold environments that are poorly represented in existing geography can complicate the process of model calibration and transfer into more extreme cold environments that were very common during the LGM (non-analog conditions). This may lead to biologically unrealistic estimations. Using one cold-adapted North American mammal, we explore a real scenario to better understand the effect of restricting the range of environmental conditions over which niche models are calibrated and then transferred to LGM conditions. We performed two sets of experiments in MAXENT: (1) we calibrated models in the context of only present‐day climate conditions, which is the most common practice, and compared predictions under LGM conditions based on two extrapolation methods (clamping vs unconstrained); (2) we calibrated single models using both present‐day and LGM conditions as part of the same background in order to include more extreme environments in the model calibration. Our experiments led to dramatically different estimates of species' potential distributions, showing notable differences with respect to latitudinal and elevational shifts during the LGM. Models calibrated using present‐day climates yielded biologically unrealistic estimations, suggesting that species survived in the glaciers during the LGM. Even more unrealistic estimations were achieved when clamping was enforced as the method to extrapolate. Models calibrated in the context of both modern and past climates reduced the required degree of extrapolation and allowed more realistic potential distributions, suggesting that the species avoided extremely cold conditions during the LGM. This study alerts to the possibility of obtaining implausible potential distributions during the LGM due to restricted background datasets and offers recommendations that should promote better strategies to estimate distributional changes during glaciations.
Data from: Persistence and dispersal in a Southern Hemisphere glaciated landscape: the phylogeography of the spotted snow skink (Niveoscincus ocellatus) in Tasmania
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.
Last interglacial (MIS 5e) sea level proxies in the glaciated Northern Hemisphere
<p>This dataset contains known preserved last interglacial (Marine Isotope Stage 5e - 130-115 ka) sea level proxies in glaciated regions of North America and Europe, including Greenland and Iceland. We have excluded deposits that show evidence of glaciotectonism. In total there are 88 sea level proxies in this dataset. The sea level proxies have been dated using electron spin resonance, U-series, amino acid racemization, luminescence and radiocarbon techniques. In many cases, fossil assemblages and pollen records that indicate warmer-than-present conditions provide support for a last interglacial assignment.</p>
FIGURE 15. Maximum glaciation 18,000 in A molecular phylogenetic hypothesis for the Asian agamid lizard genus Phrynocephalus reveals discrete biogeographic clades implicated by plate tectonics
FIGURE 15. Maximum glaciation 18,000 years before present. Much of northern Asia was never fully glaciated, unlike most of high-latitude North America and Europe, lending the possibility of an old history in the north. The map is redrawn from McIntrye et al. (1976).
Model output for Chester et al. (2024): On the origin of Holocene sea-level transgressions in formerly glaciated regions
<p>Model output files and post-processing/plotting scripts for Chester et al. (2024, QSR). </p> <p>This repository contains:</p> <p>Files for reproducing figures:</p> <ol> <li> hingeline_tracker_zenodo.m. This code takes GIA model output and identifies the hinge line for a given transect following Chester et al. (2024) (e.g. Figures 4-6). </li> <li> transgression_magnitude_id_loop_zenodo.m. This code takes GIA model output and identifies and magnitude of a transgression and timing of the highstand for a given region (e.g. Figures 9, 10 and 12 in Chester et al., 2024). </li> </ol> <p>Zip files with GIA model output in .mat form:</p> <ol> <li>LN-SL_ICE7G_100km_plusBestFitting.zip: output from the LN-SL model with the ICE7G reconstruction, a 100 km lithosphere, and the mantle viscosities indicated in Table 1. The folder also includes the output from the two best-fitting simulations used to create Figures 9 and 10 in Chester et al. (2024). </li> <li>LN-NO_ICE7G_100km.zip: output from the LN-NO model with the ICE7G reconstruction, a 100 km lithosphere and the mantle viscosities indicated in Table 1. </li> <li>FN-NO_discload.zip: output from simulations with the FN-NO model. The model was run with the disc load ice sheet and the Earth structures indicated in Table 1. </li> </ol> <p>For GIA model runs with different parameter combinations please contact me at schester@ldeo.columbia.edu. </p> <p>Note on file labeling: 'rsl_ice7g.l60CC.ump1.lm10.mat' translates to, ice model: ICE7G, lithospheric thickness: 60 km, upper mantle viscosity: 0.1 * 10^21 Pa s, lower mantle viscosity: 10 * 10^21 Pa s. </p> <p> </p> <p> </p>
Data from: Spatially explicit models of dynamic histories: examination of the genetic consequences of Pleistocene glaciation and recent climate change on the American Pika.
A central goal of phylogeography is to identify and characterize the processes underlying divergence. One of the biggest impediments currently faced is how to capture the spatiotemporal dynamic under which a species evolved. Here we described an approach that couples species distribution models (SDMs), demographic and genetic models in a spatiotemporally explicit manner. Analyses of American Pika (Ochotona priniceps) from the sky islands of the central Rocky Mountains of North America are used to provide insights into key questions about integrative approaches in landscape genetics, population genetics and phylogeography. This includes (i) general issues surrounding the conversion of time-specific SDMs into simple continuous, dynamic landscapes from past to current, and (ii) the utility of SDMs to inform demographic models with deme-specific carrying capacities and migration potentials, as well as (iii) the contribution of the temporal dynamic of colonization history in shaping genetic patterns of contemporary populations. Our results support that the inclusion of a spatiotemporal dynamic is an important factor when studying the impact of distributional shifts on patterns of genetic data. Our results also demonstrate the utility of SDMs to generate species-specific predictions about patterns of genetic variation that account for varying degrees of habitat specialization and life-history characteristics of taxa. Nevertheless, the results highlight some key issues when converting SDMs for use in demographic models. Because the transformations have direct affects on the genetic consequence of population expansion by prescribing how habitat heterogeneity and spatiotemporal variation is related to the species-specific demographic model, it is important to consider alternative transformations when studying the genetic consequences of distributional shifts.
Figure 1 in The European spring snail genus Marstoniopsis (Gastropoda: Amnicolidae): Eastward extension likely driven by Pleistocene glaciations
Figure 1. Map showing the distribution area of Marstoniopsis (solid line). Details of numbered localities are given in Table 1. The dashed line shows the extent of the Riss-Saale-Dnieper glaciation, the dotted line – the Würm-Weichsel-Valdai glaciation (compiled after Ehlers and Gibbard 2004). Asterisks indicate the locations of Holocene fossil records (after Horsák et al. 2013).
Effects of glaciation and whole genome duplication on the distribution of the Campanula rotundifolia polyploid complex
<div class="article-section__content en main"> Premise Of The Study <p>Both intrinsic and extrinsic factors contribute to a species distribution. Among plants, the extrinsic effects of glaciation and intrinsic effects of whole genome duplication are powerful drivers of biogeographical patterns, but the interplay of these factors is poorly understood. Here, we investigate the roles glaciation and whole-genome duplication have played in the evolution of the widespread polyploid complex <i>Campanula rotundifolia</i>.</p> Methods <p>We assessed the cytotype of 37 populations that spanned the geographic and cytotypic range of the <i>C. rotundifolia</i> complex. We constructed a chloroplast phylogeny for these populations and used RAD-seq to create nuclear phylogenies and networks for a subset of 23 populations; and estimated divergence times of major clades using Bayesian estimation of substitution rates.</p> Key Results <p><i>Campanula rotundifolia</i> originated in south-central Europe and underwent range expansion throughout much of Europe and North America. Multiple genome duplications have occurred in <i>C. rotundifolia</i>—at least two tetraploid and three hexaploid formations.</p> Conclusions <p>Nuclear and chloroplast phylogenies are largely congruent with a history of populations surviving glacial maxima in known Pleistocene refugia in Europe and North America. Divergent European clades are consistent with two disjunct glacial refugia within Europe. North America was colonized by hexaploids derived from Western European lineages. A glacial refugium in Midwestern North America likely facilitated post-glacial recolonization of North America and limited genetic divergence. These results implicate both glaciation and whole-genome duplication as contributing factors to the extant biogeography of <i>C. rotundifolia</i>.</p> </div>
Data from: Genetic relationships between Atlantic and Pacific populations of the notothenioid fish Eleginops maclovinus: the footprints of Quaternary glaciations in Patagonia
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Data from: Rethinking refugia: tree topology, divergence dates, and demographic history trace the distribution of the endangered Plymouth gentian (Sabatia kennedyana) from the Pleistocene glaciation to present day
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Persisting in a glaciated landscape: Pleistocene microrefugia evidenced by the tree wētā Hemideina maori in central South Island, New Zealand
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Data from: How to survive a glaciation: the challenge of estimating biologically realistic potential distributions under freezing conditions
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Data from: Phylogeographic heterogeneity of the brown macroalga Sargassum horneri (Fucaceae) in the northwestern Pacific in relation to late Pleistocene glaciation and tectonic configurations
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Data from: Spatially explicit models of dynamic histories: examination of the genetic consequences of Pleistocene glaciation and recent climate change on the American Pika.
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Data from: Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment
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Data from: Persistence and dispersal in a Southern Hemisphere glaciated landscape: the phylogeography of the spotted snow skink (Niveoscincus ocellatus) in Tasmania
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Effects of glaciation and whole genome duplication on the distribution of the Campanula rotundifolia polyploid complex
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Allen Brain Atlas
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OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.