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32 results for “Demographic expansion”
FIG. 5. Correlation between the spatial distribution index and population density. A in Demographic and spatial structure at the stage of expansion in the populations of some alien land snails in Belgorod city (Central Russian Upland)
FIG. 5. Correlation between the spatial distribution index and population density. A. For Brephulopsis cylindrica and Xeropicta derbentina at 160 plots for three years. B. For Harmozica ravergiensis in nine sites×20 plots for two years. РИС. 5. Корреляция меЖду индексом пространственного распределения и плотностью популяции. А. Для Brephulopsis cylindrica и Xeropicta derbentina на 160 плоЩадках За три года. В. Для Harmozica ravergiensis на девяти участках по 20 плоЩадок За два года.
FIG. 4 in Demographic and spatial structure at the stage of expansion in the populations of some alien land snails in Belgorod city (Central Russian Upland)
FIG. 4. Boxplots for estimating the density of different age classes in the Xeropicta derbentina population in warm months of 2017, 2019, and 2020 for 160 test plots. Adult snails are represented by red boxes; juvenile snails are represented by blue boxes. РИС. 4. Боксплоты для оценок плотности раЗличных воЗрастных классов в популяции Xeropicta derbentina в раЗные теплые месяцы 2017, 2019 и 2020 гг. для 160 пробных плоЩадок. ВЗрослые особи покаЗаны красным цветом, ювенильные особи покаЗаны голубым цветом.
FIG. 3 in Demographic and spatial structure at the stage of expansion in the populations of some alien land snails in Belgorod city (Central Russian Upland)
FIG. 3. Boxplots for estimating the density of different age classes in the Brephulopsis cylindrica population in warm months of 2017, 2019, and 2020 for 160 test plots. Adult snails are represented by red boxes; juvenile snails are represented by blue boxes. РИС. 3. Боксплоты для оценок плотности раЗличных воЗрастных классов в популяции Brephulopsis cylindrica в раЗные теплые месяцы 2017, 2019 и 2020 гг. для 160 пробных плоЩадок. ВЗрослые особи покаЗаны красным цветом, ювенильные особи покаЗаны голубым цветом.
FIG. 2 in Demographic and spatial structure at the stage of expansion in the populations of some alien land snails in Belgorod city (Central Russian Upland)
FIG. 2. Scheme of plots in a regular grid. A. Study site. B. Brephulopsis cylindrica and Xeropicta derbentina in the field. C. Scheme of plots in a regular grid. РИС. 2. Регулярная сетка плоЩадок. A. РасполоЖение исследуемого участка. B. Brephulopsis cylindrica и Xeropicta derbentina в месте обитания. C. Схема регулярной сетки плоЩадок.
Data from: Demographic expansion and panmixia in a St. Martin endemic, Anolis pogus, coincides with the decline of a competitor
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FIG. 1 in Demographic and spatial structure at the stage of expansion in the populations of some alien land snails in Belgorod city (Central Russian Upland)
FIG. 1. Map of study sites. РИС. 1. Карта раЗмеЩения исследуемых участков.
Demographic, physiological, and genetic factors linked to poleward range expansion along the shoreline of China
<p><span>Distribution </span><span>range expansion is one of the most significant consequences of climate change in the Anthropocene. During range expansion, the former biogeographic barrier can be broken and then a new biogeographic pattern might appear. A comprehensive study, including demographic pattern, physiological performance and genetic features, is crucial for understanding how the expanding population occupies and survives in the new habitat, within which it formerly did not occur. In the present study, we investigated the demographic, physiological, and genetic features of the intertidal gastropod </span><span><em>Nerita yoldii</em>, which has extended its northern limit by ~200 km into areas that are warming up faster than the historical distribution over the former biogeographic break of the Yangtze River Estuary (YRE) during recent decades. The neutral SNPs data showed that the new marginal populations formed a distinct cluster established by a few founders. Demographic modeling analysis revealed that the new marginal populations experienced strong genetic bottlenecks followed by recent demographic expansion. Successful expansion that overcomes the founder effect (reduced genetic variation) might be attributed to its high capacity of rapid population growth and multiple introductions. According to the non-neutral SNPs under diversifying selection, there were high levels of heterozygosity in the new marginal populations, which might be beneficial for adapting to the novel thermal conditions. The common garden experiment showed that the new marginal populations have evolved divergent transcriptomic and physiological responses to heat stress, allowing them to occupy and survive in the novel environment. Our study also reveals a fast loss of </span><span>transcriptional</span><span> plasticity in the new marginal populations, potentially contributing to local adaptation. These results suggest a new biogeographic pattern for the snail <em>N. yoldii</em> has formed with the occurrence of demographic, physiologic and genetic changes, and emphasize the roles of adaptation of marginal populations during distribution range expansion.</span></p>
Data from: Integrating demographic niches and black spruce range expansion at subarctic treelines
<p>When investigating relationships between species' niches and distributions, niches can be divided demographically, resulting in unique niches for different life stages. This approach can identify changing substrate requirements throughout a species' life cycle. Using non-metric multidimensional scaling, we quantified microsite conditions associated with successful recruitment in the tundra landscape and successful seed production amongst adult trees of black spruce (<em>Picea mariana</em>) at subarctic treeline in Yukon, Canada to assess how life stage-specific requirements may impact the distribution of this widespread boreal tree species. Treeline ecotones in this region showed high heterogeneity in tundra microsites available for establishment. Black spruce exhibited changing microsite associations from germination to reproductive maturity, which were mainly driven by changes in plant community and soil moisture. These associations limit the microsites where individuals can establish and reproduce to a subset available within the heterogeneous landscape. Overall, we suggest that (1) substrates suitable for early recruitment are limited at the range edge; and (2) reproductive adults have a narrow niche, limiting successful seed production in adults and forming sink populations where suitable conditions are limited. Our multivariate assessment of microsite suitability can provide valuable insights into the spatial distribution of a species throughout its life cycle and identify life stage-specific constraints to range expansion.</p>
Data from: Integrating demographic niches and black spruce range expansion at subarctic treelines
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Demographic, physiological, and genetic factors linked to poleward range expansion along the shoreline of China
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Data from: Mitochondrial introgressive hybridization following a demographic expansion in the tomato frogs of Madagascar, genus Dyscophus
Madagascar is a biodiversity hotspot with a unique fauna and flora largely endemic at the species level and highly threatened by habitat destruction. The processes underlying population-level differentiation in Madagascar's biota are poorly understood and have been proposed to be related to Pleistocene climatic cycles, yet the levels of genetic divergence observed are often suggestive of ancient events. We combined molecular markers of different variability to assess the phylogeography of Madagascar's emblematic tomato frogs (Dyscophus guineti and D. antongilii) and interpret the observed pattern as resulting from ancient and recent processes. Our results suggest that the initial divergence between these taxa is probably old as reflected by protein-coding nuclear genes and by a strong mitochondrial differentiation of the southernmost population. Dramatic changes in their demography appear to have been triggered by the end of the last glacial period and possibly by the short return of glacial conditions known as the 8K event. This dramatic change resulted in an approximately 50-fold reduction of the effective population size in various populations of both species. We hypothesize these species' current mitochondrial DNA diversity distribution reflects a swamping of the mitochondrial genetic diversity of D. guineti by that of D. antongilii previous to the populations' bottlenecks during the Holocene, and probably as a consequence of D. antongilii demographic expansion approximately 1 million years ago. Our data support the continued recognition of D. antongilii and D. guineti as separate species and flag D. guineti as the more vulnerable species to past and probably also future environmental changes.
Data from: Post-Pleistocene demographic history of the North Atlantic endemic Irish moss Chondrus crispus: glacial survival, spatial expansion and gene flow
Range expansions and gene flow as micro-evolutionary processes played a leading role in the population demographic history of marine organisms. Herein, we sequenced partial mtDNA Cox1 gene from 26 assigned geographic populations in order to understand how Irish moss (Chondrus crispus) responded to severe climatic oscillations during the Pleistocene glaciations and contemporary forces such as gene flow. Phylogeographic patterns indicated that haplotype frequency distributions were strongly skewed, with nearly half found only in single samples and thus restricted to a single population. Analysis of molecular variance revealed that most of the variation was within populations with no significant genetic structuring on either side of the Atlantic. Demographic analyses indicated that ISI (Irish Sea and Ireland) and NS (the North Sea) areas experienced a slight trend of increase in population size over time, whereas EC (the English Channel) area experienced expansion beginning approximately 170,000-360,000 BP. The observed complex genetic pattern of C. crispus is consistent with a scenario of multiple unrelated founding events by survival of this species in at least three putative Pleistocene refugia along the European coastline, and subsequent trans-Atlantic dispersal combined with contiguous northward population expansion predating the LGM and geographically gene flow.
Fig. 6 in From glacial refugia to wide distribution range: demographic expansion of Loropetalum chinense (Hamamelidaceae) in Chinese subtropical evergreen broadleaved forest
Fig. 6 Mismatch distribution analysis detected unimodel distributions with SSD and HRag statistics at the species level
Fig. 4 a in From glacial refugia to wide distribution range: demographic expansion of Loropetalum chinense (Hamamelidaceae) in Chinese subtropical evergreen broadleaved forest
Fig. 4 a Genetic admixture analysis conducted on AFLP data for L. chinense, L. chinense var. rubrum (CUL), and L. subcordatum (LS). Each vertical bar represents an individual and its assignment proportion into one of six population clusters. b Genetic structuring of populations based on AFLP data. The map of the individual assignment in each population to K = 6 clusters (C1–C6) is based on STRUCTURE analysis of the AFLP data. Each cluster is represented by a different color
Data from: Demographic expansion and genetic load of the halophyte model plant Eutrema salsugineum
Eutrema salsugineum is a widely distributed species, which provide a good model to study long-distance dispersal and accumulation of deleterious mutations. Based on population genomic data, we clarified demographic history of E. salsugineum and showed how deleterious alleles accumulated.
Data from: Colonization and demographic expansion of freshwater fauna across the Hawaiian Archipelago
It is widely accepted that insular terrestrial biodiversity progresses with island age because colonization and diversification proceed over time. Here we assess whether this principle extends to oceanic island streams. We examined range-wide mtDNA sequence variation in four stream-dwelling species across the Hawaiian archipelago to characterize the relationship between colonization and demographic expansion, and to determine whether either factor reflects island age. We found that colonization and demographic expansion are not related and that neither correspond to island age. The snail Neritina granosa exhibited the oldest colonization time (~2.713 mya) and time since demographic expansion (~282 kya), likely reflecting a preference for lotic habitats most prevalent on young islands. Conversely, gobioid fishes (Awaous stamineus, Eleotris sandwicensis and Sicyopterus stimpsoni) colonized the archipelago only ~0.411-0.935 mya, suggesting ecological opportunities for colonization in this group were temporally constrained. These findings indicate that stream communities form across colonization windows, underscoring the importance of ecological opportunities in shaping island freshwater diversity.
Data from: Demographic expansion and genetic load of the halophyte model plant Eutrema salsugineum
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Data from: Post-Pleistocene demographic history of the North Atlantic endemic Irish moss Chondrus crispus: glacial survival, spatial expansion and gene flow
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Data from: A phylogeographic, demographic and historical analysis of the short-tailed pit viper (Gloydius brevicaudus): evidence for early divergence and late expansion during the Pleistocene
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Data from: Genetic structure and post-glacial expansion of Cornus florida L. (Cornaceae): integrative evidence from phylogeography, population demographic history, and species distribution modeling
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