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2,911 results for “dispersal”
Data from: Does long distance pollen dispersal preclude inbreeding in tropical trees? Fragmentation genetics of Dysoxylum malabaricum in an agro-forest landscape
Tropical trees often display long distance pollen dispersal, even in highly fragmented landscapes. Understanding how patterns of spatial isolation influence gene flow and interact with background patterns of fine scale spatial genetic structure are critical for evaluating the genetic consequences of habitat fragmentation. In the endangered tropical timber tree Dysoxylum malabaricum (Meliaceae) we apply eleven microsatellite markers with paternity and parentage analysis to directly estimate contemporary gene flow across a large area (216 km2) in a highly fragmented agro-forest landscape. A comparison of genetic diversity and genetic structure in adult and juvenile life stages indicates an increase of differentiation and fine-scale spatial genetic structure (FSGS) over time. Paternity analysis and parentage analysis demonstrate high genetic connectivity across the landscape by pollen dispersal. A comparison between mother trees in forest patches with low and high densities of adult trees shows that the frequency of short distance mating increases, as does average kinship among mates in low density stands. We interpret this as an early warning sign of potentially negative genetic consequences of forest fragmentation. Single isolated trees, in contrast, frequently receive heterogeneous pollen from distances exceeding five kilometres. We discuss the processes leading to the observed patterns of gene flow and the implications of this for conservation management of D. malabaricum and tropical trees more generally.
Data from: Scatterhoarders drive long- and short-term population dynamics of a nut-producing tree, while pre-dispersal seed predators and herbivores have little effect
1.Both seed predators and herbivores can have profound effects on individual plant growth, reproduction and survival, but their population level effects are less well understood. While most plants interact with a suite of seed predators and herbivores over their life cycle, few studies incorporate the effects of multiple interacting partners and multiple life stages on plant population growth. 2.We constructed a matrix model using six years of data from a rare, seed-producing population of American chestnut (Castanea dentata). We combined field demographic data with published experimental results on the effects of pre-dispersal seed predators (weevils) and post-dispersal seed predators (scatter-hoarding vertebrates) and incorporated the effect of vertebrate herbivores estimated from the field data. We explored the impact of these three different animal interactions for short-term (transient) and long-term (asymptotic) tree population growth. In addition, we used the model to explore the conditions under which scatter-hoarding would function as a mutualism. 3.Seed predators had greater effect on both short- and long-term population growth than herbivores. Although weevil infestation can greatly reduce the probability of germination, pre-dispersal seed predators had smaller effects on both short- or long-term population growth than post-dispersal predators. The elasticities of weevil-related parameters were also small. The effect of browsers on both the short- and long-term population growth rate were the smallest of the effects studied. Post-dispersal seed predation affected population growth the most of the interactions studied. The probability of seed removal was amongst the largest elasticities, similar in magnitude to survival of large trees. 4.Synthesis Our results indicate that neither weevils nor the intensity of browse damage observed at our study site are likely to hinder tree regeneration or reintroduction, though both reduced population growth. Although researchers and forest managers often assume that seeds are unimportant for long-lived tree populations, our test of this assumption shows that scatterhoarders and other post-dispersal seed consumers can significantly limit natural regeneration. Forest management that alters scatterhoarder behaviour could have significant effects on tree population dynamics that are largely unexplored.
Data from: Maintaining genetic diversity and population panmixia through dispersal and not gene flow in a holocyclic heteroecious aphid species
Heteroecious holocyclic aphids exhibit both sexual and asexual reproduction and alternate among primary and secondary hosts. Most of these aphids can feed on several related hosts, and invasions to new habitats may limit the number of suitable hosts. For example, the aphid specialist Aphis glycines survives only on the primary host buckthorn (Rhamnus spp.) and the secondary host soybean (Glycine max) in North America where it is invasive. Owing to this specialization and sparse primary host distribution, host colonization events could be localized and involve founder effects, impacting genetic diversity, population structure and adaptation. We characterized changes in the genetic diversity and structure across time among A. glycines populations. Populations were sampled from secondary hosts twice in the same geographical location: once after secondary colonization (early season), and again immediately before primary host colonization (late season). We tested for evidence of founder effects and genetic isolation in early season populations, and whether or not late-season dispersal restored genetic diversity and reduced fragmentation. A total of 24 single-nucleotide polymorphisms and 6 microsatellites were used for population genetic statistics. We found significantly lower levels of genotypic diversity and more genetic isolation among early season collections, indicating secondary host colonization occurred locally and involved founder effects. Pairwise FST decreased from 0.046 to 0.017 in early and late collections, respectively, and while genetic relatedness significantly decreased with geographical distance in early season collections, no spatial structure was observed in late-season collections. Thus, late-season dispersal counteracts the secondary host colonization through homogenization and increases genetic diversity before primary host colonization.
Data from: Geographical barriers and dispersal propensity interact to limit range expansions of Himalayan birds
Range expansions are limited by two key factors. These are (1) dispersal, which includes a species' intrinsic mobility, geographical barriers, and their interaction; and (2) the ability of a species to persist beyond its current range. I evaluate the role of these in affecting bird species distributions across the Himalayas, under a hypothesis that many species have recently expanded their range out of an eastern Pleistocene refuge. I measured wing shape as a proxy for dispersal ability and topographic complexity across the Himalayas as a proxy for dispersal barriers. As a factor affecting the potential for persistence in novel locations, I compared similarity of a species' climatic envelope in the east, the hypothesized historical refuge, and the west, the location of recent colonization. Climatic similarity, wing shape, and the interaction of topographic complexity with wing shape all contribute significantly to the range extent of a given species. The result highlights the important interaction between morphological and landscape factors in affecting successful range expansions. The two dispersal-related parameters together explain two times the variance explained by climate, but I present additional evidence that other factors besides climate—notably biotic interactions—affect the ability of a species to persist beyond its range.
Data from: Scale-dependent responses of pollination and seed dispersal mutualisms in a habitat transformation scenario
Transformed habitats are the result of deliberate replacement of native species by an exotic monoculture, involving changes in biotic and abiotic conditions. Despite this, transformed habitats are becoming more common and constitute a major biodiversity change driver, little is known about the scale-dependent responses of plant-animal mutualisms. Aiming to test the multi-scale responses of pollination and seed dispersal in a habitat transformation scenario, we examined a gradient of native and transformed habitats at three spatial scales (0-50, 50-100, and 100-250 m), focused on a highly-specialized mutualistic system composed of a hemiparasitic mistletoe (Tristerix corymbosus) that is almost exclusively pollinated by a hummingbird (Sephanoides sephaniodes) and dispersed by an arboreal marsupial (Dromiciops gliroides). Even though mistletoes were found along the gradient, they were more abundant and more densely aggregated when the transformed habitat was dominant. Disperser and pollinator activity also increased as the transformed habitat become dominant, at the scale of 0-50 m and 50-100 m, respectively. Furthermore, crop size and disperser activity co-varied at broad and intermediate scales, whereas recruitment co-varied at intermediate and fine scales. Moreover, disperser activity and the number of seedlings were spatially associated, stressing D. gliroides' role in the recruitment of the mistletoe. Synthesis: This highly specialized mutualistic system seems to be responding positively to the habitat structure modifications associated with Eucalyptus plantations. However, the actual costs (e.g., reduced gene flow, increased herbivory) in these transformed habitats are yet to be assessed.
Data from: Variation in fine-scale genetic structure and local dispersal patterns between peripheral populations of a South American passerine bird
The distribution of suitable habitat influences natal and breeding dispersal at small spatial scales, resulting in strong micro-geographic genetic structure. Although environmental variation can promote inter-population differences in dispersal behavior and local spatial patterns, the effects of distinct ecological conditions on within-species variation in dispersal strategies and in fine-scale genetic structure remain poorly understood. We studied local dispersal and fine-scale genetic structure in the thorn-tailed rayadito (Aphrastura spinicauda), a South American bird that breeds along a wide latitudinal gradient. We combine capture-mark-recapture data from eight breeding seasons and molecular genetics to compare two peripheral populations with contrasting environments in Chile: Navarino Island, a continuous and low density habitat, and Fray Jorge National Park, a fragmented, densely populated and more stressful environment. Natal dispersal showed no sex bias in Navarino, but was female-biased in the more dense population in Fray Jorge. In the latter, male movements were restricted and some birds seemed to skip breeding in their first year, suggesting habitat saturation. Breeding dispersal was limited in both populations, with males being more philopatric than females. Spatial genetic autocorrelation analyses using 13 polymorphic microsatellite loci confirmed the observed dispersal patterns: a fine-scale genetic structure was only detectable for males in Fray Jorge for distances up to 450 m. Furthermore, two-dimensional autocorrelation analyses and estimates of genetic relatedness indicated that related males tended to be spatially clustered in this population. Our study shows evidence for context-dependent variation in natal dispersal and corresponding local genetic structure in peripheral populations of this bird. It seems likely that the costs of dispersal are higher in the fragmented and higher density environment in Fray Jorge, particularly for males. The observed differences in micro-geographic genetic structure for rayaditos might reflect the genetic consequences of population-specific responses to contrasting environmental pressures near the range limits of its distribution.
Data from: Phylogeography of Petrolisthes armatus, an invasive species with low dispersal ability
Theoretically, species with high population structure are likely to expand their range, because marginal populations are free to adapt to local conditions; however, meta-analyses have found a negative relation between structure and invasiveness. The crab Petrolisthes armatus has a wide native range, which has expanded in the last three decades. We sequenced 1718 bp of mitochondrial DNA from native and recently established populations to determine the population structure of the former and the origin of the latter. There was phylogenetic separation between Atlantic and eastern Pacific populations, and between east and west Atlantic ones. Haplotypes on the coast of Florida and newly established populations in Georgia and South Carolina belong to a different clade from those from Yucatán to Brazil, though a few haplotypes are shared. In the Pacific, populations from Colombia and Ecuador are highly divergent from those from Panamá and the Sea of Cortez. In general, populations were separated hundreds to million years ago with little subsequent gene flow. High genetic diversity in the newly established populations shows that they were founded by many individuals. Range expansion appears to have been limited by low dispersal rather than lack of ability of marginal populations to adapt to extreme conditions.
Data from: Extreme genetic structure in a social bird species despite high dispersal capacity
Social barriers have been shown to reduce gene flow and contribute to genetic structure among populations in species with high cognitive capacity and complex societies, such as cetaceans, apes and humans. In birds, high dispersal capacity is thought to prevent population divergence unless major geographic or habitat barriers induce isolation patterns by dispersal, colonization or adaptation limitation. We report that Iberian populations of the red-billed chough, a social, gregarious corvid with high dispersal capacity, show a striking degree of genetic structure composed of at least 15 distinct genetic units. Monitoring of marked individuals over 30 years revealed that long-distance movements over hundreds of kilometres are common, yet recruitment into breeding populations is infrequent and highly philopatric. Genetic differentiation is weakly related to geographic distance and habitat types used are overall qualitatively similar among regions and regularly shared by individuals of different populations, so that genetic structure is unlikely to be due solely to isolation by distance or isolation by adaptation. Moreover, most population nuclei showed relatively high levels of genetic diversity, suggesting a limited role for genetic drift in significantly differentiating populations. We propose that social mechanisms may underlie this unprecedented level of genetic structure in birds through a pattern of isolation by social barriers not yet described, which may have driven this remarkable population divergence in the absence of geographic and environmental barriers.
Data from: Proximity to roads disrupts rodents' contributions to seed dispersal services and subsequent recruitment dynamics
1. Seed dispersal and subsequent recruitment dynamics play a crucially important role in regulating species coexistence and structuring tree diversity in diverse forests. Wildlife, which can dually shape the tree recruitment process by simultaneously functioning as natural enemies and seed dispersers, are undergoing widespread changes in population and behaviour due to the detrimental effects of expanding global road networks. However, the impact of these changes on recruitment dynamics through the alteration of seed dispersal processes remains understudied. 2. Here, we assessed how roads affect animal-mediated recruitment dynamics from the seed to adult stages of trees using a ubiquitous vertebrate-seed model: rodents and acorns. To quantify the degree to which proximity to a road alters seed dispersal and regulates subsequent recruitment dynamics, we conducted seed dispersal and predation experiments, and investigated the natural recruitment of a dominant tree species (Quercus aliena) from September 2009 to July 2012 in a subtropical forest of central China. 3. Roads caused a decreased seed dispersal distance and increasing larder hoarding, demonstrating a weakened contribution of rodents to seed dispersal services. These patterns were stronger in the masting year than in the non-masting year. Correspondingly, seedlings, saplings, and adult trees had higher densities near roads than far from roads. Near roads, recruit transition rates (i.e., seedling-to-sapling and sapling-to-juvenile) were low, and the influential strength of conspecific adult density was weakened over these recruit transitions, indicating that space limitation and lottery competition, not conspecific negative density-dependent effects, approximately determined the near-road recruitment process. Furthermore, most adults near roads were young, and their ages matched the road ages. 4. Synthesis. Roads diminished animal-mediated seed dispersal services and disrupted subsequent recruitment dynamics in Q. aliena populations, thus weakening the key process promoting diversity in forest ecosystems. Given that these animal-regulated roles in recruitment dynamics are widespread stabilizing forces for tree coexistence, our findings suggest that the ubiquity of roads and their continued expansion will contribute to the increase in forests dominated by a relatively low number of species. Consequently, the growing expansion of road networks will ultimately cause profound changes in community composition and structure across diverse forests worldwide.
Data from: Local and regional founder effects in lake zooplankton persist after thousands of years despite high dispersal potential
We reconstructed the genetic structure of a planktonic crustacean Daphnia longispina living in high mountain lakes and ponds in the Pyrenees to investigate whether it was shaped by persistent founder effects originating shortly after the last glacial maximum or by ongoing dispersal and effective migration (gene flow). We found that the genetic structure can largely be explained by a single colonization event following gradual deglaciation of the Pyrenees c. 10-15 000 years ago. Nuclear genetic diversity declined steeply from southeast to northwest, suggestive of serial colonization of available habitats with advancing deglaciation. The spatial genetic structure suggests that founder effects were major determinants of the present-day diversity, both at the catchment level and at the level of individual water bodies, further supporting extremely low effective migration rates. This study reveals a prime example of a founder effect that is both long-lasting and maintained at small spatial scales. Our data suggest a process of isolation by colonisation as a result of strong priority effects and monopolisation. We found evidence for the spread of haplotypes with Pyrenean ancestry across the Palearctic over distances up to 5500 km, although the local genetic structure after colonization was hardly influenced by contemporary dispersal. Finally, our data also suggest that mitochondrial mutation rates in the studied populations were seven times higher than typically assumed. Overall, we show that founder effects can persist for centuries even at small spatial scales at which the potential for dispersal is high.
Data from: Patterns of local community composition are linked to large-scale diversification and dispersal of clades
At any location, a group of organisms may be represented by several clades. What determines which clades will dominate local communities in terms of their species richness? Here, this relatively neglected question is addressed by analyzing 166 local assemblages of snakes distributed globally. For most regions, local assemblages are dominated by clades with higher global-scale diversification rates and more frequent dispersal into each region, and not by clades that have been present in that region longer. This result contrasts with many other studies of local richness (in other organisms), which show strong impacts of regional colonization time on overall local species richness of clades. Furthermore, even though local assemblages are assembled independently on different continents, most regions have converged on similar patterns of proportional richness. Specifically, a few rapidly diversifying clades dominate most communities around the world. The high diversification rates of these clades are then linked to their high dispersal rates. Similar patterns may occur in many groups, such as plants, frogs, salamanders, birds, and mammals.
Data from: Resource dispersion and relatedness interact to explain space use in a solitary predator
<p><span><span><span><span><span><span><span><span><span><span><span>Resource dispersion or kin selection are commonly used to explain animal spatial and social organization. Despite this, studies examining how these factors interact in wild populations of solitary animals are rare. We used 16 years of individual-level spatial and genetic data to disentangle how resources and relatedness influence spatial organization of a solitary predator, the Eurasian lynx (<i>Lynx lynx</i>). As expected, space-use overlap between neighbouring individuals increased when food resources were heterogeneous and unpredictably distributed (as predicted from resource dispersion) or when neighbours were closely related (as predicted from kin selection). However, these patterns were highly dependent on each other. Increased spatial overlap was restricted to mother-daughter dyads, with this effect only occurring in areas and during seasons when prey was clumped and irregularly distributed in the landscape.Additionally, full-siblings with similar levels of genetic relatedness did not show these patterns, suggesting that kin selection is mediated through mother-daughter recognition, and is only beneficial under specific resource dispersion circumstances. Our results provide key insights into the flexibility of spatial organization of solitary animals, and clearly show the importance of considering the interaction between resources and kinship when assessing animal space use patterns.</span></span></span></span></span></span></span></span></span></span></span></p>
Data from: Evaluating the influence of different aspects of habitat fragmentation on mating patterns and pollen dispersal in the bird-pollinated Banksia sphaerocarpa var. caesia
Habitat fragmentation can significantly affect mating and pollen dispersal patterns in plant populations, although the differential effects of the various aspects of fragmentation are poorly understood. In this study we used paternity assignment with eight microsatellite loci to investigate the effect of fragmentation on the mating system and pollen dispersal within one large and eight small population remnants of Banksia sphaerocarpa var. caesia, a bird-pollinated shrub in the southern agricultural region of Western Australia. The large population had a much larger neighbourhood size and lower selfing rate, maternal pollen pool differentiation and within-plot mean pollen dispersal distance than the small populations. Outcrossing was consistently high and ranged from 89% ± 0.8 to 98.5% ± 0.3, and mating patterns suggested nearest-neighbour pollination. Pollen immigration into small populations ranged from 6% ± 0.6 to 15% ± 0.6. Using the small populations, we tested for correlations between various fragmentation variables and mating system and pollen dispersal parameters. We found significant positive linear relationships between population size and number of different fathers per seed crop and between population shape and pollen pool differentiation. There were significant negative linear relationships between population isolation and outcrossing rate; population shape and neighbourhood size; and conspecific density and mean pollen dispersal distance. Our results suggest that birds may use a series of fragmented populations as a vegetation corridor while foraging across the landscape and that population connectivity is a critical determinant of pollinator visitation. Our results also suggest that the effect of a linear population shape on the mating system and pollen dispersal is routinely underestimated.
Collapse of dispersal trait diversity across a long-term chronosequence reveals a strong negative impact of frugivore extinctions on forest resilience
<p><span><b>1. </b></span><span>Understanding how seed dispersal disruption may alter plant community diversity and dynamics over a large temporal scale remains a challenge. Here, we use a long-term chronosequence to compare changes in the richness and composition of different dispersal trait assemblages in communities established before and after human colonisation in the Mascarene archipelago.</span></p> <p><span><b>2. </b></span><span>Our study was located on Réunion on the slopes of the Piton de la Fournaise, one of the most active volcanoes worldwide. We analysed 151 vegetation surveys on lava flows dated between 1401-AD and 1956-AD and in tropical rainforests established on older substrata. We defined five classes of substratum age, according to the well-known chronology of native frugivore defaunation: "old substrata" and </span>[1401, 1665[ when frugivores were abundant and diverse <span>before permanent human settlement</span>; [1665, 1800[ when large-bodied frugivore populations were strongly reduced; [1800, 1900[ when large-bodied frugivores went extinct and small-bodied frugivores were still abundant; [1900, 1956] <span>decline in the population of small-bodied frugivores. Based on dispersal traits, we categorised 146 native woody species as anemochorous, small fleshy-fruited or large fleshy-fruited, i.e. plant of which fruit could not theoretically be dispersed by extant frugivores.</span></p> <p><span><b>3. </b></span><span>Changes in dispersal trait diversity strongly correlated with the chronology of defaunation. Species-rich communities settled before human colonisation were strongly dominated by fleshy-fruited species. </span>L<span>arge fleshy-fruited plants in the oldest communities </span>settled after human colonisation <span>declined markedly and almost disappeared after 1800. The richness of small fleshy-fruited plants decreased less rapidly across the chronosequence, with medium levels on </span>[1665, 1800[ and [1800, 1900[ <span>lava flows and low levels on </span>[1900, 1956] lava flows<span>. Conversely, the richness of anemochorous plants remained unchanged. Communities settled before human colonisation had a similar composition. Fleshy-fruited assemblages showed strong species loss across the chronosequence, while anemochorous assemblages showed strong species turnover, which was probably due to lower dispersal limitation.</span></p> <p><span><b>4. Synthesis. </b></span><span>Our results provide the first insights into the tremendous impact that frugivore extinction has on plant colonisation dynamics over 300 years. The dramatic loss of fleshy-fruited plant diversity on historical lava flows highlights the irreplaceable dispersal role played by frugivores, especially large-bodied species. The conservation of </span>plant-animal mutualistic interactions<span> is invaluable and refaunation efforts need to be undertaken in areas where frugivores have been extirpated.</span></p>
Data from: Prey exploitation and dispersal strategies vary among natural populations of a predatory mite
When predators commonly overexploit local prey populations, dispersal drives the dynamics in local patches, which together form a metapopulation. Two extremes in a continuum of dispersal strategies are distinguished: the "Killer" strategy, where predators only start dispersing when all prey are eliminated, and the "Milker" strategy, in which predator dispersal occurs irrespective of prey availability. Theory shows that the Milker strategy is not evolutionarily stable if local populations are well connected by dispersal. Using strains of the predatory mite Phytoseiulus persimilis, collected from 11 native populations from coastal areas in Turkey and Sicily, we investigated whether these two strategies occur in nature. In small wind tunnels, we measured dispersal rates and population dynamics of all populations in a system consisting of detached rose leaves, spider mites (Tetranychus urticae) as prey, and P. persimilis. We found significant variation in the exploitation and dispersal strategies among predator populations, but none of the collected strains showed the extreme Killer or Milker strategy. The results suggest that there is genetic variation for prey exploitation and dispersal strategies. Thus, different dispersal strategies in the Milker–Killer continuum may be selected for under natural conditions. This may affect the predator–prey dynamics in local populations and is likely to determine persistence of predator–prey systems at the metapopulation level.
Data from: Space use and social association in a gregarious ungulate: testing the conspecific attraction and resource dispersion hypotheses
Animals use a variety of proximate cues to assess habitat quality when resources vary spatiotemporally. Two nonmutually exclusive strategies to assess habitat quality involve either direct assessment of landscape features or observation of social cues from conspecifics as a form of information transfer about forage resources. The conspecific attraction hypothesis proposes that individual space use is dependent on the distribution of conspecifics rather than the location of resource patches, whereas the resource dispersion hypothesis proposes that individual space use and social association are driven by the abundance and distribution of resources. We tested the conspecific attraction and the resource dispersion hypotheses as two nonmutually exclusive hypotheses explaining social association and of adult female caribou (Rangifer tarandus). We used location data from GPS collars to estimate interannual site fidelity and networks representing home range overlap and social associations among individual caribou. We found that home range overlap and social associations were correlated with resource distribution in summer and conspecific attraction in winter. In summer, when resources were distributed relatively homogeneously, interannual site fidelity was high and home range overlap and social associations were low. Conversely, in winter when resources were distributed relatively heterogeneously, interannual site fidelity was low and home range overlap and social associations were high. As access to resources changes across seasons, caribou appear to alter social behavior and space use. In summer, caribou may use cues associated with the distribution of forage, and in winter caribou may use cues from conspecifics to access forage. Our results have broad implications for our understanding of caribou socioecology, suggesting that caribou use season‐specific strategies to locate forage. Caribou populations continue to decline globally, and our finding that conspecific attraction is likely related to access to forage suggests that further fragmentation of caribou habitat could limit social association among caribou, particularly in winter when access to resources may be limited.
Data from: Inferring contemporary dispersal processes in plant metapopulations: comparison of direct and indirect estimates of dispersal for the annual species Crepis sancta
Analyzing population dynamics in changing habitats is a prerequisite for population dynamics forecasting. The recent development of metapopulation modeling allows the estimation of dispersal kernels based on the colonization pattern but the accuracy of these estimates compared with direct estimates of the seed dispersal kernel has rarely been assessed. In this study, we used recent genetic methods based on parentage analysis (spatially explicit mating models) to estimate seed and pollen dispersal kernels as well as seed and pollen immigration in fragmented urban populations of the plant species Crepis sancta with contrasting patch dynamics. Using two independent networks, we documented substantial seed immigration and a highly restricted dispersal kernel. Moreover, immigration heterogeneity among networks was consistent with previously reported metapopulation dynamics, showing that colonization was mainly due to external colonization in the first network (propagule rain) and local colonization in the second network. We concluded that the differences in urban patch dynamics are mainly due to seed immigration heterogeneity, highlighting the importance of external population source in the spatio-temporal dynamics of plants in a fragmented landscape. The results show that indirect and direct methods were qualitatively consistent, providing a proper interpretation of indirect estimates. This study provides attempts to link genetic and demographic methods and show that patch occupancy models may provide simple methods for analyzing population dynamics in heterogeneous landscapes in the context of global change.
Agouti reintroduction recovers seed dispersal of a large-seeded tropical tree
<p>The aim of animal reintroductions has mainly been species recovery; only few reintroduction initiatives focus on ecosystem restoration. Therefore, reintroduction consequences on ecological interactions are seldom assessed. We used the interaction between a reintroduced population of agoutis (<i>Dasyprocta leporina</i>) and a vulnerable tropical endemic tree (<i>Joannesia princeps</i>) to examine reintroduction effects on seed dispersal and seedling establishment. To test the outcomes of this interaction we tracked seeds of <i>J. princeps</i> in two adjacent forest areas with and without reintroduced agoutis. We also assessed if dispersal distances affected seedling survival. To determine seed fate and dispersal distance we used spool-and-line tracking, together with camera traps to identify dispersers. Agoutis were the only species removing <i>J. princeps</i> seeds, thus dispersal only occurred where agoutis had been reintroduced; in the area without agoutis, all seeds remained intact on the soil, even one year after the experiment's beginning. At the reintroduction area, most seeds were preyed upon by agoutis but 7% remained dispersed and 2% germinated after ten months. Only seeds buried by agoutis were able to germinate. Most dispersed seeds were disperse 15 m or farther and longer dispersal distances benefited <i>J. princeps</i>, since seedlings farther from a conspecific adult tree had greater survival probability. Agoutis were also seen burying seeds of two other plant species; these mammals have the potential to benefit dozens of large-seeded species in our study system<span>. </span>Agouti reintroduction thus exemplifies the value of trophic rewilding programs to re-establish ecological interactions and restore ecosystem functioning.</p>
Global diversification of Anelosimus spiders driven by long distance overwater dispersal and Neogene climate oscillations
Vicariance and dispersal events, combined with intricate global climatic history, have left an imprint on the spatiotemporal distribution and diversity of many organisms. Anelosimus cobweb spiders (Theridiidae), are solitary-social organisms with a cosmopolitan distribution in temperate- to-tropical areas. Their evolutionary history and the discontinuous distribution of species richness suggest that 1) long distance overwater dispersal, and 2) climate change during the Neogene (23–2.6 Ma), may be major factors in explaining their distribution and diversification. Here we test these hypotheses, and explicitly test if global Miocene/Pliocene climatic cooling in the last 8 Ma affected Anelosimus radiation in parallel in South America and Madagascar. To do so, we investigate the phylogeny and spatiotemporal biogeography of Anelosimus through a culmination of a 20-year comprehensive global sampling at the species level (69 species, including 84% of the known 75 species worldwide, represented by 268 individuals) using nucleotide data from seven loci (5.5 kb). Our results strongly support the monophyly of Anelosimus with an Oligocene (~30 Ma) South American origin. Major clades on other continents originate via multiple, long-distance dispersal events, of solitary or subsocial—but not social—lineages, from the Americas. These intercontinental dispersals were to Africa, Madagascar (twice), and SE Asia/Australasia. The early diversification of Anelosimus spiders coincides with a sudden thermal increase in the late Oligocene (~27–25 Ma), though no causal connection can be made. Our results, however, strongly support the hypothesis that global Neogene climatic cooling in the last 8 Ma drove Anelosimus radiation in parallel in S. America and Madagascar, offering a rare empirical evidence for diversification of a socially diverse group driven by an interplay between long distance dispersal and global Neogene climatic changes.
Data from: Comparative analysis of adaptive and neutral markers of Drosophila mediopunctata populations dispersed among forest fragments
Comparison of adaptive and neutral genetic markers is a valuable approach to characterize the evolutionary consequences of populations living in environments threatened by anthropogenic disturbances, such as forest fragmentation. Shifts in allele frequencies, low genetic variability, and a small effective population size can be considered clear signs of forest fragmentation effects (due to genetic drift) over natural populations, while adaptive responses correlate with environmental variables. Brazilian Atlantic Forest had its landscape drastically reduced and fragmented. Now, several forest remnants are isolated from each other by urban and crop areas. We sampled Drosophila mediopunctata populations from eight forest remnants dispersed on two adjacent geomorphological regions, which are physiognomic and climatically quite distinct. Microsatellite data of inversion‐free chromosomes (neutral genetic marker) indicate low structuration among populations suggesting that they were panmictic and greatly influenced by gene flow. Moreover, significant differences in chromosomal inversion frequencies (adaptive genetic marker) among populations and their correlations with climatic and geographical variables indicate that genetic divergence among populations could be an adaptive response to their environment. Nonetheless, we observed a significant difference in inversion frequencies of a population in two consecutive years that may be associated with edge and demographic effects. Also, it may be reflecting seasonal changes of inversion frequencies influenced by great temperature variation due to edge effects. Moreover, the forest fragment size does not affect genetic variation of neutral markers. Our data indicate that despite oscillations in chromosomal inversion frequencies, D. mediopunctata populations from Brazilian Atlantic Forest and their divergence may be driven by adaptive factors to local differences, perhaps because it is a small flying insect easily carried by the wind increasing its migration rates.
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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)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
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.