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2,911 results for “dispersal”
Data from: Relationship type affects the reliability of dispersal distance estimated using pedigree inferences in partially sampled populations: a case study involving invasive American mink in Scotland
Estimating dispersal—a key parameter for population ecology and management—is notoriously difficult. The use of pedigree assignments, aided by likelihood-based software, has become popular to estimate dispersal rate and distance. However, the partial sampling of populations may produce false assignments. Further, it is unknown how the accuracy of assignment is affected by the genealogical relationships of individuals and is reflected by software-derived assignment probabilities. Inspired by a project managing invasive American mink (Neovison vison), we estimated individual dispersal distances using inferred pairwise relationships of culled individuals. Additionally, we simulated scenarios to investigate the accuracy of pairwise inferences. Estimates of dispersal distance varied greatly when derived from different inferred pairwise relationships, with mother–offspring relationship being the shortest (average = 21 km) and the most accurate. Pairs assigned as maternal half-siblings were inaccurate, with 64%–97% falsely assigned, implying that estimates for these relationships in the wild population were unreliable. The false assignment rate was unrelated to the software-derived assignment probabilities at high dispersal rates. Assignments were more accurate when the inferred parents were older and immigrants and when dispersal rates between subpopulations were low (1% and 2%). Using 30 instead of 15 loci increased pairwise reliability, but half-sibling assignments were still inaccurate (>59% falsely assigned). The most reliable approach when using inferred pairwise relationships in polygamous species would be not to use half-sibling relationship types. Our simulation approach provides guidance for the application of pedigree inferences under partial sampling and is applicable to other systems where pedigree assignments are used for ecological inference.
Data from: Wind dispersal is predicted by tree, not diaspore, traits in comparisons of neotropical species
1. The seed shadow created by wind dispersal around parent trees may be affected by functional traits, as well as wind conditions and surrounding vegetation. 2. This study of one mature tree each of 12 Neotropical species determined the extent to which species variation in diaspore traits vs. tree height and crop size explains (1) rate of diaspore descent in still air, (2) distributions of diaspores dispersed from a 40-m tower in the forest, and (3) natural seed shadows around the parent tree. 3. A model of diaspore wing-loading to a fitted power explained 66.9% of the variation among species in the geometric mean rate of descent in still air. For a subset of four species, expected dispersal distance was not correlated with actual dispersal distance from the forest tower. For a subset of seven species, variation in wing-loading1/2 of individual diaspores explained ≤4.3% of the dispersal distance from the parent tree. 4. Measured seed shadows, particularly their distribution edges and area, differed significantly among the 12 species (range in maximum tree height 19–42 m), and were best fit by 12 separate anisotropic dispersal kernels and surveyed fecundities. Measured mean distance was highly correlated with simulated distances from the kernels. 5. The best models, explaining 57.6% of the variation among species in shadow area, and 59.6, 61.6, and 61.7% of variation in mean, median and maximum distances, included maximum tree height, either alone or in combination with crop size, and not diaspore rate of descent. 6. Among 10 species, seed shadow area was not related to rank of seedling shade tolerance. In their highly skewed distributions, most seeds were much closer than the distance of greatest seedling recruitment and in very high density, thus enhancing later density- and/or distance-related seedling mortality. 7. Tree functional traits, rather than the historically emphasized diaspore traits, explain distance distributions of these wind-dispersed species. Additional exploration of diaspore abscission in relation to wind and the influence of wind patterns after release are needed.
Data from: Crossing the uncrossable: novel trans-valley biogeographic patterns revealed in the genetic history of low dispersal mygalomorph spiders (Antrodiaetidae, Antrodiaetus) from California
Antrodiaetus riversi is a dispersal-limited, habitat specialized mygalomorph spider species endemic to mesic woodlands of northern and central California. Here we build upon prior phylogeographic research using a much larger geographic sample and include additional nuclear genes, providing more detailed biogeographic insights throughout the range of this complex. Of particular interest is the uncovering of unexpected and replicated trans-valley biogeographic patterns, where in two separate genetic clades western haplotypes in the California south Coast Ranges are phylogenetically closely-related to eastern haplotypes from central and northern Sierran foothills. In both instances, these trans-valley phylogenetic patterns are strongly supported by multiple genes. These western and eastern populations are currently separated by the Central Valley, a well-recognized modern-day and historical biogeographic barrier in California. For one clade the directionality is clearly northeast to southwest, and all available evidence is consistent with a jump dispersal event estimated at 1.2-1.3 million years ago. During this time period, paleogeographic data indicate that northern Sierran rivers emptied to the ocean in the south Coast Ranges, rather than at the San Francisco Bay. For the other trans-valley clade genetic evidence is less conclusive regarding the mechanism and directionality of biogeographic exchange, although the estimated timeframe is similar (approximately 1.8 Ma). Despite the large number of biogeographic studies previously conducted in central California, to the best of our knowledge no prior studies have discussed or revealed a northern Sierran to south Coast Range biogeographic connection. This uniqueness may reflect the low-dispersal biology of mygalomorph spiders, where "post-event" gene exchange rarely erases historical biogeographic signal.
Data from: Seasonality and temperature-dependent flight dispersal of Triatoma infestans (Hemiptera: Reduviidae) and other vectors of Chagas disease in western Argentina
Flight dispersal of Triatominae is affected by climatic conditions and determines the spatiotemporal patterns of house invasion and transmission of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae). We investigated the detailed time structure and temperature dependencies of flight occurrence of Triatoma infestans Klug (Hemiptera: Reduviidae) and other triatomine species in a rural village of western Argentina by taking advantage of the attraction of adult triatomines to artificial light sources. Most of the village's streetlight posts were systematically inspected for triatomines twice between sunset and midnight over 425 nights in the spring–summer seasons of 1999–2002, an unprecedented light-trap sampling effort for any triatomine species. In total, 288 adults were captured, including 122 Triatoma guasayana Wygodzinsky and Abalos, 89 T. infestans, 72 Triatoma eratyrusiformis Del Ponte, and 5 Triatoma garciabesi Carcavallo et al. Adult sex ratios were balanced in T. infestans and strongly male-biased in other species. Nearly all flight-dispersing triatomines were caught when temperatures at sunset were >20 °C (range, 16.6–31.7 °C), suggesting a putative threshold around 17–18 °C. Triatomine catches were rare on rainy days. Logistic regression analysis revealed that the proportion of nights in which at least an adult T. infestans was caught increased highly significantly with increasing temperature at sunset and was modified by collection month, with greater catches in early spring and no sex differential. This study confirms that spring represents a previously overlooked, important dispersal period of T. infestans, and shows large variations among and within Triatominae in their temporal patterns of flight occurrence, abundance, and sex ratio.
Data from: Seed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging
The natural regeneration of tree species depends on seed and pollen dispersal. To assess if limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long-distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp=700m, mp=52% immigration rate in 6 km2 plot, s=7% selfing rate) than in E. suaveolens (dp=294m, mp=22% in 2 km2 plot, s=20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds=175m) than in the wind-dispersed D. benthamianus (ds=71m). Yet, seed dispersal appeared much more fat-tailed in the latter species (15-25% seeds dispersing >500m), putatively due to storm winds (papery pods). The reproductive success was correlated to trunk diameter in E. suaveolens and crown dominance in D. benthamianus. Contrary to D. benthamianus, E. suaveolens underwent significant assortative mating, increasing further the already high inbreeding of its juveniles due to selfing, which seems offset by strong inbreeding depression. To achieve sustainable exploitation, seed and pollen dispersal distances did not appear limiting, but the natural regeneration of E. suaveolens might become insufficient if all trees above the minimum legal cutting diameter were exploited. This highlights the importance of assessing the diameter structure of reproductive trees for logged species.
Data from: Building genetic networks using relatedness information: a novel approach for the estimation of dispersal and characterization of group structure in social animals
Natal dispersal is an important life history trait driving variation in individual fitness and, therefore, a proper understanding of the factors underlying dispersal behaviour is critical to many fields including population dynamics, behavioural ecology and conservation biology. However, individual dispersal patterns remain difficult to quantify despite many years of research using direct and indirect methods. Here, we quantify dispersal in a single intensively-studied population of the cooperatively breeding chestnut-crowned babbler (Pomatostomus ruficeps) using genetic networks created from the combination of pairwise relatedness data and social networking methods and compare this to dispersal estimates from re-sighting data. Not only does this novel approach identify movements between social groups within our study sites but also provides an estimation of immigration rates of individuals originating outside the study site. Both genetic and re-sighting data indicated that dispersal was strongly female-biased, but the magnitude of dispersal estimates was much greater using genetic data. This suggests that many previous studies relying on mark-recapture data may have significantly underestimated dispersal. An analysis of spatial genetic structure within the sampled population also supports the idea that females are more dispersive, with females having no structure beyond the bounds of their own social group while male genetic structure expands for 750 meters from their social group. Although the genetic network approach we have used is an excellent tool for visualising the social and genetic microstructure of social animals and identifying dispersers, our results also indicate the importance of applying them in parallel with behavioural and life history data.
Data from: Fire-induced population reduction and landscape opening increases gene flow via pollen dispersal in Pinus halepensis
Population reduction and disturbances may alter dispersal, mating patterns and gene flow. Rather than taking the common approach of comparing different populations or sites, here we studied gene flow via wind-mediated effective pollen dispersal on the same plant individuals before and after a fire-induced population drop, in a natural stand of Pinus halepensis. The fire killed 96% of the pine trees in the stand and cleared the vegetation in the area. Thirteen trees survived in two groups separated by ~80 m, and seven of these trees had serotinous (closed) pre-fire cones that did not open despite the fire. We analyzed pollen from closed pre- and post-fire cones using microsatellites. The two groups of surviving trees were highly genetically differentiated, and the pollen they produced also showed strong among-group differentiation and very high kinship both before and after the fire, indicating limited and very local pollen dispersal. The pollen not produced by the survivors also showed significant pre-fire spatial genetic structure and high kinship, indicating mainly within-population origin and limited gene flow from outside, but became spatially homogeneous with random kinship after the fire. We suggest that post-fire gene flow via wind-mediated pollen dispersal increased by two putative mechanisms: 1) a drastic reduction in local pollen production due to population thinning, effectively increasing pollen immigration; 2) an increase in wind speeds in the vegetation-free post-fire landscape. This research shows that dispersal can alleviate negative genetic effects of population size reduction, and that disturbances might enhance gene flow, rather than reduce it.
Data from: Exploring potential establishment of marine rafting species after transoceanic long-distance dispersal
Aim On March 11, 2011, the Great East Japan Earthquake triggered a massive tsunami that resulted in the largest known rafting event in recorded history. By spring 2012, marine debris began washing ashore along the Pacific Coast of the U.S. and Canada with a wide-range of Asian coastal species attached. We used this unique dataset, where the source region, date of dislodgment, and landing location are known, to assess the potential for species invasions by transoceanic rafting on marine debris. Location Northeast Pacific from 20 to 60°N Time period Current Major taxa studied Forty-eight invertebrate and algal species recorded on Japanese tsunami marine debris. Methods We developed Maximum Entropy (MaxEnt) species distribution models for 48 species recorded on Japanese tsunami marine debris to predict establishment potential along the Pacific Coast from 20-60°N. Models were compared within the context of historical marine introductions from Japan to this region to validate the emergence of marine debris as a novel vector for species transfer. Results Overall, 27% (13 species) landed with debris at locations with suitable environmental conditions for establishment and survival, indicating that these species may be able to establish new populations or introduce greater genetic diversity to already established non-native populations. A further 22 species have environmental match in areas where tsunami debris likely landed, but was not extensively sampled. Nearly 100 Japanese marine species previously invaded the northeastern Pacific, demonstrating this region's environmental suitability for rafting Japanese biota. Historical invasions from Asia are highest in California and largely known from bays and harbors. Main conclusions Marine debris is a novel and growing vector for non-native species introduction. By utilizing a unique dataset of Japanese tsunami marine debris species, our predictive models show capacity for new transoceanic invasions and can focus monitoring priorities to detect successful long-distance dispersal across the world's oceans.
Data from: Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages
Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
Data from: A multispecies approach reveals hot-spots and cold-spots of diversity and connectivity in invertebrate species with contrasting dispersal modes
Genetic diversity is crucial for species' maintenance and persistence, yet is often overlooked in conservation studies. Species diversity is more often reported due to practical constraints, but it is unknown if these measures of diversity are correlated. In marine invertebrates, adults are often sessile or sedentary and populations exchange genes via dispersal of gametes and larvae. Species with a larval period are expected to have more connected populations than those without larval dispersal. We assessed the relationship between measures of species and genetic diversity, and between dispersal ability and connectivity. We compiled data on genetic patterns and life history traits in nine species across five phyla. Sampling sites spanned 600 km in the northwest Mediterranean Sea and focused on a 50 km area near Marseilles, France. Comparative population genetic approaches yielded three main results. (1) Species without larvae showed higher levels of genetic structure than species with free-living larvae but the role of larval type (lecithotrophic or planktotrophic) was negligible. (2) A narrow area around Marseilles, subject to offshore advection, limited genetic connectivity in most species. (3) We identified sites with significant positive contributions to overall genetic diversity across all species, corresponding with areas near low human population densities. In contrast, high levels of human activity corresponded with a negative contribution to overall genetic diversity. Genetic diversity within species was positively and significantly linearly related with local species diversity. Our study suggests that local contribution to overall genetic diversity should be taken into account for future conservation strategies.
Data from: Female-biased dispersal in a bat with a female-defence mating strategy
The ultimate causes for predominant male-biased dispersal (MBD) in mammals and female-biased dispersal (FBD) in birds are still subject to much debate. Studying exceptions to general patterns of dispersal, for example, FBD in mammals, provides a valuable opportunity to test the validity of proposed evolutionary pressures. We used long-term behavioural and genetic data on individually banded Proboscis bats (Rhynchonycteris naso) to show that this species is one of the rare mammalian exceptions with FBD. Our results suggest that all females disperse from their natal colonies prior to first reproduction and that a substantial proportion of males are philopatric and reproduce in their natal colonies, although male immigration has also been detected. The age of females at first conception falls below the tenure of males, suggesting that females disperse to avoid father–daughter inbreeding. Male philopatry in this species is intriguing because Proboscis bats do not share the usual mammalian correlates (i.e. resource-defence polygyny and/or kin cooperation) of male philopatry. They have a mating strategy based on female defence, where local mate competition between male kin is supposedly severe and should prevent the evolution of male philopatry. However, in contrast to immigrant males, philopatric males may profit from acquaintance with the natal foraging grounds and may be able to attain dominance easier and/or earlier in life. Our results on Proboscis bats lent additional support to the importance of inbreeding avoidance in shaping sex-biased dispersal patterns and suggest that resource defence by males or kin cooperation cannot fully explain the evolution of male philopatry in mammals.
Data from: Successional status, seed dispersal mode and overstorey species influence tree regeneration in tropical rain-forest fragments in Western Ghats, India
The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.
Data from: The interactive effects of competition and predation risk on dispersal in an insect.
Dispersal dynamics have significant consequences for ecological and evolutionary processes. Previous work has demonstrated that dispersal can be context-dependent. However, factors affecting dispersal are typically considered in isolation, despite the probability that individuals make dispersal decisions in response to multiple, possibly interacting factors. We examined whether two ecological factors, predation risk and intraspecific competition, have interactive effects on dispersal dynamics. We performed a factorial experiment in mesocosms using backswimmers (Notonecta undulata), flight-capable, semi-aquatic insects. Emigration rates increased with density, and increased with predation risk at intermediate densities; however, predation had minimal effects on emigration at high and low densities. Our results indicate that factorial experiments may be required to understand dispersal dynamics under realistic ecological conditions.
Data from: Signals of selection in outlier loci in a widely dispersing species across an environmental mosaic
Local adaptation reflects a balance between natural selection and gene flow and is classically thought to require the retention of locally adapted alleles. However, organisms with high dispersal potential across a spatially or temporally heterogeneous landscape pose an interesting challenge to this view requiring local selection every generation or when environmental conditions change to generate adaptation in adults. Here, we test for geographical and sequence-based signals of selection in five putatively adaptive and two putatively neutral genes identified in a previous genome scan of the highly dispersing purple sea urchin, Strongylocentrotus purpuratus. Comparing six populations spanning the species' wide latitudinal range from Canada to Baja California, Mexico, we find positive tests for selection in the putative adaptive genes and not in the putative neutral genes. Specifically, we find an excess of low-frequency and nonsynonymous polymorphisms in two transcription factors and a transporter protein, and an excess of common amino acid polymorphisms in the two transcription factors, suggestive of spatially balancing selection. We test for a genetic correlation with temperature, a dominant environmental variable in this coastal ecosystem. We find mild clines and a stronger association of genetic variation with temperature than latitude in four of the five putative adaptive loci and a signal of local adaptation in the Southern California Bight. Overall, patterns of genetic variation match predictions based on spatially or temporally balancing selection in a heterogeneous landscape and illustrate the value of geographical and coalescent tests on candidate loci identified in a genome-wide scan for selection.
Data from: Long-distance dispersal suppresses introgression of local alleles during range expansions
During range expansions, even low levels of interbreeding can lead to massive introgression of local alleles into an invader's genome. Nonetheless, this pattern is not always observed in human populations. For instance, European Americans in North America are barely introgressed by Amerindian genes in spite of known contact and admixture. With coalescent spatially explicit simulations, we examined the impact of long-distance dispersal (LDD) events on introgression of local alleles into the invading population using a set of different demographic scenarios applicable to a diverse range of natural populations and species. More specifically, we consider two distinct LDD models: one where LDD events originate in the range core and targets only the expansion front and a second one where LDD events can occur from any area to any other. We find that LDD generally prevents introgression, but that LDD events specifically targeting the expansion front are most efficient in suppressing introgression. This is likely due to the fact that LDD allows for the presence of a larger number of invader alleles at the wave front, where effective population size is thus increased and local introgressed alleles are rapidly outnumbered. We postulate that the documented settlement of pioneers directly on the wave front in North America has contributed to low levels of Amerindian admixture observed in European Americans and that this phenomenon may well explain the lack of introgression after a range expansion in natural populations without the need to evoke other mechanisms such as natural selection.
Data from: Evidence for high dispersal ability and mito-nuclear discordance in the small brown planthopper, Laodelphax striatellus
Understanding dispersal ability in pest species is critical for both theoretical aspects of evolutionary and population biology and from a practical standpoint, such as implementing effective forecasting systems. The small brown planthopper (SBPH), Laodelphax striatellus (Fallén), is an economically important pest, but few data exist on its dispersal ability. Here, we used mitochondrial and nuclear markers to elucidate the population genetic structure of SBPH and of the parasitic bacterium Wolbachia throughout temperate and subtropical China. Our results showed that the SBPH populations in China lack significant differences in genetic structure, suggesting extensive gene flow. Multilocus sequence typing revealed that Wolbachia infection was systematic and due to the same strain (wStri) within and across populations. However, the mtDNA haplogroups had a nonrandom distribution across the sampling localities, which correlated to latitudinal and climatic gradients. We explain this mito-nuclear discordance as a result of historical population recolonization or mitochondria adaptation to climate.
Data from: Response of ants to human-altered habitats with reference to seed dispersal of Corydalis giraldii Fedde (Papaveraceae)
Anthropogenic habitat disturbance has potential consequences for ant communities. However, there is limited information on the effects of ant responses on associated ecological processes such as seed dispersal. We investigated the effect of disturbance on the abundance, richness, and composition of ant communities and the resulting seed‐dispersal services for a herbaceous myrmecochore, Corydalis giraldii (Papaveraceae), in an undisturbed habitat (forest understory), moderately disturbed habitat (abandoned farm field), and highly disturbed habitat (road verge) on Qinling Mountains, China. In total, we recorded 13 ant species, and five out of these were observed to transport seeds. The community composition of dispersers was significantly different amongst habitats. The richness of the dispersers did not differ among the habitats, but their total abundance significantly varied across habitats and was recorded to decrease in the road verge by 21%, in comparison to abandoned farm fields. The major seed‐dispersing ant species in both the forest understory and abandoned farm field were large‐bodied (Myrmica sp. and Formica fusca, respectively), whereas the major seed‐dispersing ants found in the road verge were small‐bodied (Lasius alienus). This difference resulted in lower seed removal rates and dispersal distances in the road verge than in the other two habitats. The different dispersal patterns were attributed primarily to differences in dispersing ant abundance and identity, most likely in response to habitats with different degree of anthropogenic disturbance. The possible influence of disturbance on the ecological specialization of ant‐seed dispersal interaction was also discussed.
Data from: Pre-dispersal seed predators and fungi differ in their effect on Luehea seemannii capsule development, seed germination and dormancy across two Panamanian forests
Pre-dispersal seed predation can greatly reduce crop size affecting recruitment success. Additionally, non-fatal damage by seed predators may allow infection by fungi responsible for post-dispersal seed losses. The objectives of this study were (1) to quantify pre-dispersal seed predation and fungal infection in a Neotropical tree species, Luehea seemannii, that produces dehiscent fruits and wind-dispersed seeds, and (2) to link pre-dispersal effects on seed quality to seed survival in the soil. To examine how seed predators and fungi influence seed losses, mesh exclosures, fungicide and the combination of both treatments were applied to separate branches in the canopy of trees in Gamboa and Parque Natural Metropolitano (PNM), Panama. To determine if treatments affect seed viability and survival in the soil, half of the seeds collected from each treatment were buried for four weeks in forest soils and subsequently allowed to germinate before and after the breaking of dormancy. Overall, 24 percent of developing fruit were lost to insect attack. In contrast, fungi infected only 3 percent of seeds at the pre-dispersal stage. For seeds germinated directly after collection, fungicide significantly increased germination in the wetter site (Gamboa) but decreased germination in the drier site (PNM). The pre-dispersal insect exclosure treatment increased the fraction of seeds that remained dormant after burial in the soil. This result suggests that exposure to insect predators may cause physical damage to seeds that results in the loss of physical dormancy but does not necessarily increase the susceptibility of seeds to pathogen attack in the soil.
Data from: Divergent effects of forest edges on host distribution and seed disperser activity influence mistletoe distribution and recruitment
1. Species interactions define functional diversity and community stability across ecosystems, and depend on the spatial distribution, the habitat requirements, and the sensitivity to disturbances of all interacting partners. Hence, assessing the effects of such anthropogenic disturbances on multi-species interactions may be essential to improve adaptation and mitigation measures for biodiversity conservation. 2. We determined the importance of edge effects on the interaction and distribution of three keystone species in South American temperate rainforests: the hemiparasitic mistletoe Tristerix corymbosus, its main host (the liana Campsidium valdivianum) and its only seed disperser (the marsupial Dromiciops gliroides). 3. The discordant impacts of forest edges on host (positive) and seed disperser (negative) affected mistletoe distribution at large spatial scales, owing to the combined effects of increased dispersal limitation and decreased host availability. More importantly, marsupial abundance had contrasting effects on mistletoe abundance at small and large spatial scales – suggesting a potential trade-off between local and long-distance dispersal. 4. We found the number of adult mistletoes per host increased with host size, which likely indicates that mistletoe colonization accumulated over the host's life-span. However, the number of juveniles found per host peaked at medium-sized hosts, increased with marsupial abundance and host availability and showed a negligible response to edges. 5. Synthesis: The lack of spatial congruence between host and seed disperser probably explains the scarcity of mistletoes in the study area, although the discordant drivers of juvenile and adult distributions suggest that there is a trade-off between recruitment patterns but also potential dispersal limitation at small scales. In essence, the interdependence among species linked by (mutualistic and antagonistic) interactions makes them more sensitive to anthropogenic disturbance, exacerbating its impact on the diversity and functioning of forest ecosystems.
Data from: Long-distance dispersal maximizes evolutionary potential during rapid geographic range expansion
Conventional wisdom predicts that sequential founder events will cause genetic diversity to erode in species with expanding geographic ranges, limiting evolutionary potential at the range margin. Here, we show that invasive European starlings (Sturnus vulgaris) in South Africa preserve genetic diversity during range expansion, possibly as a result of frequent long-distance dispersal events. We further show that unfavourable environmental conditions trigger enhanced dispersal, as indicated by signatures of selection detected across the expanding range. This brings genetic variation to the expansion front, counterbalancing the cumulative effects of sequential founding events and optimizing standing genetic diversity and thus evolutionary potential at range margins during spread. Therefore, dispersal strategies should be highlighted as key determinants of the ecological and evolutionary performances of species in novel environments and in response to global environmental change.
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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.
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