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1,068 results for “demographic”
Data from: Population genomics through time provides insights into the consequences of decline and rapid demographic recovery through head-starting in a Galapagos giant tortoise
Population genetic theory related to the consequences of rapid population decline is well-developed, but there are very few empirical studies where sampling was conducted before and after a known bottleneck event. Such knowledge is of particular importance for species restoration, given links between genetic diversity and the probability of long-term persistence. To directly evaluate the relationship between current genetic diversity and past demographic events, we collected genome-wide single nucleotide polymorphism data from pre-bottleneck historical (c.1906) and post-bottleneck contemporary (c.2014) samples of Pinzón giant tortoises (Chelonoidis duncanensis; n=25 and 149 individuals, respectively) endemic to a single island in the Galapagos. Pinzón giant tortoises had a historically large population size that was reduced to just 150-200 individuals in the mid 20th century. Since then, Pinzón's tortoise population has recovered through an ex situ head-start program in which eggs or pre-emergent individuals were collected from natural nests on the island, reared ex situ in captivity until they were 4-5 years old, and subsequently repatriated. We found that the extent and distribution of genetic variation in the historical and contemporary samples was very similar, with the latter group not exhibiting the characteristic genetic patterns of recent population decline. No population structure was detected either spatially or temporally. We estimated an effective population size (Ne) of 58 (95% CI = 50-69) for the post-bottleneck population; no pre-bottleneck Ne point estimate was attainable (95% CI = 39-infinity) likely due to the sample size being lower than the true Ne. Overall, the historical sample provided a valuable benchmark for evaluating the head-start captive breeding program, revealing high retention of genetic variation and no skew in representation despite the documented bottleneck event. Moreover, this work demonstrates the effectiveness of head-starting in rescuing the Pinzón giant tortoise from almost certain extinction.
Influence of past climate change on phylogeography and demographic history of narwhals, Monodon monoceros
<p>The Arctic is warming <span>at an unprecedented rate,</span> with unknown consequences for endemic fauna. However, Earth has experienced severe climatic oscillations in the past, and understanding how species responded to them might provide insight into their resilience to near-future climatic predictions. Little is known about the responses of Arctic marine mammals to past climatic shifts, but narwhals (<i>Monodon monoceros</i>) are considered one of the endemic Arctic species most vulnerable to environmental change. Here, we analyze 121 complete mitochondrial genomes from narwhals sampled across their range, and use them in combination with species distribution models to elucidate the influence of past and ongoing climatic shifts on their population structure and demographic history. We find low levels of genetic diversity and limited geographic structuring of genetic clades. We show that narwhals experienced a long-term low effective population size, which increased after the Last Glacial Maximum (LGM), when the amount of suitable habitat expanded. Similar post-glacial habitat release has been a key driver of population size expansion of other Polar marine predators. Our analyses indicate that habitat availability has been critical to the success of narwhals, raising concerns for their fate in an increasingly warming Arctic.</p>
Long-term demographic data on the red-cockaded woodpecker
<p>In cooperative breeding systems, inclusive fitness theory predicts that non-breeding helpers more closely related to the breeders should be more willing to provide costly alloparental care, and thus have more impact on breeder fitness. In the red-cockaded woodpecker (<em>Dryobates borealis</em>), most helpers are the breeders' earlier offspring, but helpers do vary within groups in both relatedness to the breeders (some even being unrelated) and sex, and it can be difficult to parse their separate impacts on breeder fitness. Moreover, most support for inclusive fitness theory has been positive associations between relatedness and behavior, rather than actual fitness consequences. We used functional linear models to evaluate the per capita effects of helpers of different relatedness on eight breeder fitness components measured for up to 41 years at three sites. In support of inclusive fitness theory, helpers more related to the breeding pair made greater contributions to six fitness components. However, male helpers made equal contributions to increasing pre-fledging survival regardless of relatedness. These findings suggest that both inclusive fitness benefits and other, direct benefits may underlie helping behaviors in the red-cockaded woodpecker. Our results also demonstrate the application of an underused statistical approach to disentangle a complex ecological phenomenon.</p>
Demographic mechanisms and anthropogenic drivers of contrasting population dynamics of hummingbirds
<p>Conserving species requires knowledge of demographic rates (survival, recruitment) that govern population dynamics to allow the allocation of limited resources to the most vulnerable stages of target species' life cycles. Additionally, quantifying drivers of demographic change facilitates the enactment of specific remediation strategies. However, knowledge gaps persist in how similar environmental changes lead to contrasting population dynamics through demographic rates. For sympatric hummingbird species, the population of urban-associated partial-migrant Anna's hummigbird (<em>Calypte anna</em>) has increased, yet the populations of Neotropical migrants including rufous, calliope, and black-chinned hummingbirds have decreased. Here, we developed an integrated population model to jointly analyze 25 years of mark-recapture data and population survey data for these four species. We examined the contributions of demographic rates on population growth and evaluated the effects of anthropogenic stressors including human population density and crop cover on demographic change in relation to species' life histories. While recruitment appeared to drive the population increase of urban-associated Anna's hummingbirds, decreases in juvenile survival contributed most strongly to population declines of Neotropical migrants and highlight a potentially vulnerable phase in their life-history. Moreover, rufous hummingbird adult and juvenile survival rates were negatively impacted by human population density. Mitigating threats associated with intensively modified anthropogenic environments is a promising avenue for slowing further hummingbird population loss. Overall, our model grants critical insight into how anthropogenic modification of habitat affects the population dynamics of species of conservation concern.</p>
Fig. 5. Demographic inference from cyt b in Echinoderes galadrielae Grzelak & Sørensen 2022, sp. nov.
Fig. 5. Demographic inference from cyt b sequences of Rhodeus ocellatus in East Asia. (A) Mismatch distribution of total population. The abscissa and ordinate of the histograms indicate the number of pairwise difference between specimens and the frequency of each value, respectively. The black and gray bars represent the frequency distribution of the observed and expected pairwise difference respectively under the sudden expansion model. (B) Bayesian skyline plot (BSP) of total population estimated by 1.05% per site per million year of evolutionary rate. The black line indicates the mean curve of BSP. The dotted line indicates the 95% highest posterior density intervals of the BSP. The x-axis indicates the time (million years ago, mya). The y-axis is the estimated effective population size.
Additional simulations for "Demographic interactions of the last hunter-gatherers and the first farmers"
<p>These are the complete results for the article "Demographic interactions of the last hunter-gatherers and the first farmers". Due to space constrains, they have been uploaded here, and not at the main github repo (https://github.com/acortell3/Demographic_interactions). Nevertheless, these are the discarded results, and are not necessary to reproduce the paper.</p>
Data from: Demographic inference from whole-genome and RAD sequencing data suggests alternating human impacts on goose populations since the last ice age
We investigated how population changes and fluctuations in the pink-footed goose might have been affected by climatic and anthropogenic factors. First, genomic data confirmed the existence of two separate populations: western (Iceland) and eastern (Svalbard/Denmark). Second, emographic inference suggests that the species survived the last glacial period as a single ancestral population with a low population size (100-1,000 individuals) that split into the current populations at the end of the Last Glacial Maximum with Iceland being the most plausible glacial refuge. While population changes during the last glaciation were clearly environmental, we hypothesize that more recent demographic changes are human-related: (1) the inferred population increase in the Neolithic is due to deforestation to establish new lands for agriculture, increasing available habitat for pink-footed geese (2) the decline inferred during the Middle Ages is due to human persecution and (3) improved protection explains the increasing demographic trends during the 20th century. Our results suggest both environmental (during glacial cycles) and anthropogenic effects (more recent) can be a threat to species survival.
Fig. 10 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 10. Yearly number of stag beetles found dead by predation at the Jagersveld CMR site during the period 2001- 2023. Areas in grey refer to predation by Corvids, areas in yellow to predation by hedgehogs. The annual sex-ratio measured on these beetle remains is indicated, as is the yearly total number of beetles killed by predators and the total number of natural deaths.
Fig. 9 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 9. Variation, as a function of year, of the mean and standard error of head width (KB) of males found dead at the Jagersveld CMR site. Numbers indicate the size of the samples, and letters and colors indicate samples not significantly differing in size from each other at the P = 0.05 threshold, by using the non-parametric Kruskal-Wallis test for multiple comparisons. Samples of years 1924 and 2021 were excluded from the K-W analysis.
Fig. 8 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 8. Box plots of total length (TL) of stag beetles measured in the order of their first appearance at the Jagersveld site during the capture-mark-recapture exercise of 2007. Median, quartiles and extremes of male sizes over successive weeks and of female sizes over successive ten-day periods.
Fig. 6 A-B in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 6 A-B. Survivorship curves of marked male stag beetles during (A) the 2001 and (B) 2007 CMR exercises, in function of death as end event. Kaplan-Meyer step-curves with 95% upper and lower confidence bounds. The arrows indicate the medians of the known life span. A Weibull curve is drawn over the K-M curve. C: illustrating the lack of statistical difference between the 2001 and 2007 K-M curves.
Fig. 4 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 4. Cumulative number of new individuals at the Jagersveld site during the CMR sessions of 2001 and 2007. (a): appearance of the first males. (b): geometric increase of new individuals during a short period. The graphs in the right insets show this increase in semi-logarithmic coordinates. (i): inflection point. (c): more regular increase of new individuals until reaching (d) a plateau (p). The increase of new females was more progressive.
Fig. 3 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 3. Calendar of male capture and recapture histories at the Jagersveld site. The marked individuals are sorted by date of first capture and by known duration of longevity. 1: captured. 0: not encountered in the interval where the individual was known to be alive. +: found dead by predation on the sampling site. *: natural death. MNA: minimum number known alive.
Fig. 5 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 5. Distribution of the number of males confirmed to be still alive, as a function of the number of days elapsed since they were marked during the 2001 and 2007 CMR exercises. The construction of the curves is based on the first two columns of Table 1 and is limited to 23 days for the year 2007.
Fig. 1 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 1. Aerial view of part of the locality of Boitsfort, a suburb in the south-east of the city of Brussels, with, encircled in yellow, the stag beetle brood sites as they were known for at least the years 2000-2010. Larval sites were (and are) mainly located outside densely wooded plots, and even in the alignments of ornamental cherry trees along certain avenues. Note also the dispersion of these sites, whose circle size do not prejudge the size of their beetle population. Orthophoto plan from UrbIS datastore.brussels.
Fig. 7 in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 7. Daily estimates of the number of beetles at the Jagersveld site in 2001 and 2007 according to the POPAN formulation of the Jolly-Seber method, under the acceptance of constant survival and capture probabilities over time. Minimum daily number of known survivors (MNA). Rainy periods and, for 2001, stormy evening episodes, are figured at the bottom of the graphs.
Fig. 2. A in Demographic data on a stag beetle (Lucanus cervus) population self-established in an artificial suburban habitat
Fig. 2. A, The ramp to the playground of the Jagersveld school, with its central staircase in 2001. B, The palisade of beams of the east side of the ramp in its 2007 state, however photographed in 2013, the staircase having been removed in the meantime. C, The earthen platform at the top of the ramp in 2002, with the alignment of short beams separating it from the concrete of the ramp. D, The same platform fenced and overgrown with maple saplings, as viewed in 2022. E - F, Stag beetle larvae and a pupa found in 2005 when some of the beams were replaced. G - H, damage to the paling, west side and east side, in 2021. © E and F, courtesy Olivier Beck.
Data on the demographics of public preferences for ten carbon removal and solar geoengineering interventions in 30 countries
<p><span>Data used in the analysis for 'The demographics of public preferences for ten carbon removal and solar geoengineering interventions in 30 countries' in the academic journal <em>Communications Earth and Environment.</em></span></p>
The Demographics of Giant Exoplanets and Brown Dwarfs in Wide Stellar Binaries
<p>While numerous exoplanets have now been uncovered in stellar binaries, the impact of companion stars on planet formation and evolution is still not understood. In this talk, I will present results of population trends seen among the known sample of planets in wide multiple star systems, which allows us to investigate the effects of stellar binarity on the resulting planetary architectures. In particular, observations of stars hosting close-in giant planets and brown dwarfs find an excess of binary companions on few hundred AU separations, and different planet demographics for these systems, suggesting that such binaries may provide favourable conditions for the formation of the observed inner companions. I will show results from simulations of self-gravitating protoplanetary disks adapted to binary-star environments, which show that certain binary configurations may trigger gravitational fragmentation and lead to the formation of giant planets in otherwise-stable disks.</p>
MICCAI 2021 MSSEG-2 challenge demographics data
<p>This dataset will include all demographics and dataset constitution information for the MICCAI 2021 challenge.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
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DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
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.