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Short-Tandem-Repeat (STR) marker set for Eurasian lynx for article: Genetic analysis indicates spatial-dependent patterns of sex-biased dispersal in Eurasian lynx in Finland
<p>Conservation and management of large carnivores requires knowledge of female and male dispersal. Such information is crucial to evaluate the population's status and thus management actions. This knowledge is challenging to obtain, often incomplete and contradictory at times. The size of the target population and the methods applied can bias the results. Also, population history and biological or environmental influences can affect dispersal on different scales within a study area. We have genotyped Eurasian lynx (180 males and 102 females, collected 2003-2017) continuously distributed in southern Finland (~23,000 km<sup>2</sup>) using 21 short tandem repeats (STR) loci and compared statistical genetic tests to infer local and sex-specific dispersal patterns within and across genetic clusters as well as geographic regions. We tested for sex-specific substructure with individual-based Bayesian assignment tests and spatial autocorrelation analyses. Differences between the sexes in genetic differentiation, relatedness, inbreeding, and diversity were analysed using population-based AMOVA, F-statistics, and assignment indices. Our results showed two different genetic clusters that were spatially structured for females but admixed for males. Similarly, spatial autocorrelation and relatedness was significantly higher in females than males. However, we found weaker sex-specific patterns for the Eurasian lynx when the data were separated in three geographical regions than when divided in the two genetic clusters. Overall, our results suggest male-biased dispersal and female philopatry for the Eurasian lynx in Southern Finland. The female genetic structuring increased from west to east within our study area. In addition, detection of male-biased dispersal was dependent on analytical methods utilized, on whether subtle underlying genetic structuring was considered or not, and the choice of population delineation. Conclusively, we suggest using multiple genetic approaches to study sex-biased dispersal in a continuously distributed species in which population delineation is difficult.</p>
Data from: Native species dispersal reduces community invasibility by increasing species richness and biotic resistance
1. Recent studies indicate that diversity-invasibility relationships can depend upon spatial scale, but the contributing role of native species dispersal among local communities in mediating these relationships remains unaddressed. Metacommunity ecology highlights the effects of species dispersal rates on local diversity, thereby suggesting native species dispersal may influence local biotic resistance to invasion by non-native species. However, effects of native species dispersal rates on local native diversity and invasibility could depend upon any intraspecific differences of the invader that may alter establishment success. 2. Here, I experimentally tested for the influence of native dispersal-diversity relationships on the invasibility of native communities by a non-native species represented by core, midrange, and peripheral regions of the introduced geographic range. 3. In mesocosms, native plankton communities were connected by low or moderate rates of dispersal to yield dispersal-rate driven differences in native species richness prior to invasion by a non-native zooplankter, Daphnia lumholtzi. After invasion, establishment success and effects of the non-native species on native community structure and ecosystem properties were evaluated as a function of dispersal rate and invader source region relative to a control without native species. 4. Native species richness was greater at the moderate dispersal rate than the low dispersal rate, and yielded a dispersal rate dependent diversity-invasibility relationship that was robust to invader source region. There was almost no establishment success of the non-native species at moderate dispersal and reduced success at low dispersal relative to the control. Invader population growth rates were negative only at the moderate dispersal rate. Effects of species dispersal on native community and ecosystem response were more influential than effects of invasion and impacts associated with invader source region. 5. The results demonstrate that dispersal-diversity relationships can influence diversity-invasibility relationships at the local spatial scale. These dispersal-driven responses of invasion were unaffected by any ecological differences associated with invasion history related intraspecific variation of the non-native species. This study emphasizes that dispersal rates of native species in metacommunities can differentially alter local biotic resistance to invasion. Thus, native species dispersal rates have largely been an underappreciated local diversity maintenance mechanism that can confer insurance against biological invasions.
No evidence for divergence in male harmfulness or female resistance in response to changes in the opportunity for dispersal
The outcome of sexual conflict can depend on the social environment, as males respond to changes in the inclusive fitness payoffs of harmfulness and harm females less when they compete with familiar relatives. Theoretical models also predict that if limited male dispersal predictably enhances local relatedness while maintaining global competition, kin selection can produce evolutionary divergences in male harmfulness among populations. Experimental tests of these predictions, however, are rare. We assessed rates of dispersal in female and male seed beetles Callosobruchus maculatus, a model species for studies of sexual conflict, in an experimental setting. Females dispersed significantly more often than males, but dispersing males travelled just as far as dispersing females. Next, we used experimental evolution to test whether limiting dispersal allowed the action of kin selection to affect divergence in male harmfulness and female resistance. Populations of C. maculatus were evolved for 20 and 25 generations under one of three dispersal regimens: completely free dispersal, limited dispersal, and no dispersal. There was no divergence among treatments in female reproductive tract scarring, ejaculate size, mating behaviour, fitness of experimental females mated to stock males, or fitness of stock females mated to experimental males. We suggest that this is likely due to insufficient strength of kin selection rather than a lack of genetic variation or time for selection. Limited dispersal alone is therefore not sufficient for kin selection to reduce male harmfulness in this species, consistent with general predictions that limited dispersal will only allow kin selection if local relatedness is independent of the intensity of competition among kin.
Data from: Validating dispersal distances inferred from autoregressive occupancy models with genetic parentage assignments
1.Dispersal distances are commonly inferred from occupancy data but have rarely been validated. Estimating dispersal from occupancy data is further complicated by imperfect detection and the presence of unsurveyed patches. 2.We compared dispersal distances inferred from seven years of occupancy data for 212 wetlands in a metapopulation of the secretive and threatened California black rail (Laterallus jamaicensis coturniculus) to distances between parent-offspring dyads identified with 16 microsatellites. 3.We used a novel autoregressive multi-season occupancy model that accounted for both unsurveyed patches and imperfect detection to quantify patch isolation using buffer radius (BRM) and incidence function (IFM) connectivity measures at 15 scales (1–10, 15, 20, 25, and 30 km). Connectivity measures were then fit as colonization covariates in occupancy models to estimate a model-averaged dispersal distance. 4.As predicted, colonization was more strongly related to connectivity at small spatial scales (< 10 km). AIC weights were greatest at 7 km for BRM and at 4 km for IFM. 5.Model-averaged dispersal distances (BRM = 7.46 km; IFM = 5.48 km) showed good agreement with the mean (± SE) dispersal distance from 23 parent-offspring dyads (5.58 ± 1.92 km), indicating reasonably accurate mean dispersal distances can be inferred from occupancy data when isolation strongly affects colonization.
Data from: Does sex-biased dispersal account for the lack of geographic and host-associated differentiation in introduced populations of an aphid parasitoid?
Host recognition and use in female parasitoids strongly relies on host fidelity, a plastic behavior which can significantly restrict the host preferences of parasitoids, thus reducing the gene flow between parasitoid populations attacking different insect hosts. However, the effect of migrant males on the genetic differentiation of populations has been frequently ignored in parasitoids, despite its known impact on gene flow between populations. Hence, we studied the extent of gene flow mediated by female and male parasitoids by assessing sibship relationships among parasitoids within and between populations, and its impact on geographic and host-associated differentiation in the aphid parasitoid Aphidius ervi. We report evidences of a high gene flow among parasitoid populations on different aphid hosts and geographic locations. The high gene flow among parasitoid populations was found to be largely male mediated, suggested by significant differences in the distribution of full-sib and paternal half-sib dyads of parasitoid populations.
Data from: Resilience of seed production to a severe El Niño‐induced drought across functional groups and dispersal types
More frequent and severe El Niño Southern Oscillations (ENSO) are causing episodic periods of decreased rainfall. Although the effects of these ENSO-induced droughts on tree growth and mortality have been well studied, the impacts on other demographic rates such as reproduction are less well known. We use a four-year seed rain dataset encompassing the most severe ENSO-induced drought in more than 30 years to assess the resilience (i.e. resistance and recovery) of the seed composition and abundance of three forest types in a tropical dry forest. We found that forest types showed distinct differences in the timing, duration and intensity of drought during the ENSO event, which likely mediated seed composition shifts and resilience. Drought-deciduous species were particularly sensitive to the drought with overall poor resilience of seed production, whereby seed abundance of this functional group failed to recover to pre-drought levels even two years after the drought. Liana and wind-dispersed species were able to maintain seed production both during and after drought suggesting that ENSO events promote early successional species or species with a colonization strategy. Combined, these results suggest that ENSO-induced drought mediates the establishment of functional groups and dispersal types suited for early successional conditions with more open canopies and reduced competition among plants. The effects of the ENSO-induced drought on seed composition and abundance were still evident two years after the event suggesting the recovery of seed production requires multiple years that may lead to shifts in forest composition and structure in the long-term, with potential consequences for higher trophic levels like frugivores.
Data from: Seed-dispersal networks in tropical forest fragments: area effects, remnant species, and interaction diversity
<p>Seed dispersal interactions involve key ecological processes in tropical forests that help to maintain ecosystem functioning. Yet this functionality may be threatened by increasing habitat loss, defaunation and fragmentation. However, generalist species, and their interactions, can benefit from the habitat change caused by human disturbance while more specialized interactions mostly disappear. Therefore changes in the structure of the local, within fragment, networks can be expected. Here we investigated how the structure of seed-dispersal networks changes along a gradient of increasing habitat fragmentation. We analysed 16 bird seed-dispersal assemblages from forest fragments of a biodiversity-rich ecosystem. We found significant species-, interaction- and network-area relationships, yet the later was determined by the number of species remaining in each community. The number of frugivorous bird and plant species, their interactions, and the number of links per species decreases as area is lost in the fragmented landscape. In contrast, network nestedness has a negative relationship with fragment area, suggesting an increasing generalization of the network structure in the gradient of fragmentation. Network specialization was not significantly affected by area, indicating that some network properties may be invariant to disturbance. Still, the local extinction of partner species, paralleled by a loss of interactions and specialist-specialist bird-plant seed dispersal associations suggests the functional homogenization of the system as area is lost. Our study provides empirical evidence for network-area relationships driven by the presence/absence of remnant species and the interactions they perform.</p>
Data from: Varieties of the highly dispersible and hypervariable tree, Metrosideros polymorpha, differ in response to mechanical stress and light across a sharp ecotone
PREMISE OF THE STUDY: The drivers of isolation between sympatric populations of long-lived and highly-dispersible conspecific plants are not well understood. In the Hawaiian Islands the landscape-dominant tree, Metrosideros polymorpha, displays extraordinary phenotypic differences among sympatric varieties despite high dispersibility of its pollen and seeds, thereby presenting a unique opportunity to investigate how disruptive selection alone can maintain incipient forms. Stenophyllous M. polymorpha var. newellii is a recently evolved tree endemic to the waterways of east Hawai'i Island that shows striking neutral genetic differentiation from its ancestor, wet-forest var. glaberrima, despite sympatry of these forms. We looked for evidence for, and drivers of, differential local adaptation of these varieties across the range of var. newellii. METHODS: For paired populations of these varieties, we compared seedling performance under contrasting light conditions and a strong water current characteristic of the riparian zone. We also conducted a reciprocal transplant experiment and contrasted adult leaf anatomy. KEY RESULTS: Results suggest that the riparian zone is harsh and that selection involving the mechanical stress of rushing water, and secondarily light, lead to significant reciprocal immigrant inviability in adjacent forest and riparian environments. The strongest adaptive divergence between varieties was seen in leaves and seedlings from the site with the sharpest ecotone, coincident with the strongest genetic isolation of var. newellii observed previously. CONCLUSIONS: These findings suggest that disruptive selection across a sharp ecotone contributes to the maintenance of an incipient riparian ecotype from within a continuous population of a long-lived and highly dispersible tree species.
Data from: Inverse dispersal patterns in a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae) and their ant hosts
When postulating evolutionary hypotheses for diverse groups of taxa using molecular data, there is a tradeoff between sampling large numbers of taxa with a few Sanger sequenced genes or sampling fewer taxa with hundreds to thousands of next-generation sequenced genes. High taxon sampling enables the testing of evolutionary hypotheses that are sensitive to sampling bias (i.e. dating, biogeography, and diversification analyses), whereas high character sampling improves resolution of critical nodes. In a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae), we analyze both of these types of datasets independently (203 taxa with 5 Sanger loci; 92 taxa with 348 Anchored Hybrid Enrichment loci) and in combination (229 taxa, 353 loci) to explore divergence dating, biogeography, host relationships, and differential rates of diversification. Oraseminae specialize as parasitoids of the immature stages of ants in the subfamily Myrmicinae (Hymenoptera: Formicidae), with ants in the genus Pheidole being their most common and presumed ancestral host. A general assumption is that the distribution of the parasite must be limited by any range contraction or expansion of its host. Recent studies support a single New World to Old World dispersal pattern for Pheidole approximately 11–22 Ma. Using multiple phylogenetic inference methods (parsimony, maximum likelihood, dated Bayesian, and coalescent analyses), we provide a robust phylogeny showing that Oraseminae dispersed in the opposite direction, from Old World to New World, approximately 24–33 Ma, which implies that they existed in the Old World prior to their presumed ancestral hosts. Their dispersal into the New World appears to have promoted an increased diversification rate. Both the host and parasitoid show single unidirectional dispersals in accordance with the presence of the Beringian Land Bridge during the Oligocene, a time when the changing northern climate likely limited the dispersal ability of such tropically adapted groups.
Data from: Gene expression shifts in yellow-bellied marmots prior to natal dispersal
The causes and consequences of vertebrate natal dispersal have been studied extensively, yet little is known about the molecular mechanisms involved. We used RNA-seq to quantify transcriptomic gene expression in blood of wild yellow-bellied marmots (Marmota flaviventer) prior to dispersing from or remaining philopatric to their natal colony. We tested three predictions. First, we hypothesized dispersers and residents will differentially express genes and gene networks since dispersal is physiologically demanding. Second, we expected differentially expressed genes to be involved in metabolism, circadian processes, and immune function. Finally, in dispersing individuals, we predicted differentially expressed genes would change as a function of sampling date relative to dispersal date. We detected 150 differentially expressed genes, including genes that have critical roles in lipid metabolism and antigen defense. Gene network analysis revealed a module of 126 co-expressed genes associated with dispersal that was enriched for extra-cellular immune function. Of the dispersal-associated genes, 22 altered expression as a function of days until dispersal, suggesting that dispersal-associated genes do not initiate transcription on the same time scale. Our results provide novel insights into the fundamental molecular changes required for dispersal and suggest evolutionary conservation of functional pathways during this behavioral process.
A large-scale assessment of plant dispersal mode and seed traits across human-modified Amazonian forests
1. Quantifying the impact of habitat disturbance on ecosystem function is critical for understanding and predicting the future of tropical forests. Many studies have examined post-disturbance changes in animal traits related to mutualistic interactions with plants, but the effect of disturbance on plant traits in diverse forests has received much less attention. 2. Focusing on two study regions in the eastern Brazilian Amazon, we used a trait-based approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging. 3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size. 4. Disturbance reduced tree diversity and increased the proportion of lower wood-density and smaller-seeded tree species in study plots. Unexpectedly, disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had functionally similar plant communities to the most heavily disturbed primary forests. 5. <i>Synthesis</i>. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The higher importance of animal-mediated seed dispersal in disturbed and recovering forests highlights the importance of avoiding defaunation or promoting faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasising the importance of developing a comprehensive plant traits database for the Amazon and other biomes.
Data from: Dispersal is associated with morphological innovation, but not increased diversification, in Cyphostemma (Vitaceae)
Multiple processes - including dispersal, morphological innovation, and habitat change - are frequently cited as catalysts for increased diversification. We investigate these processes and the causal linkages among them in the genus Cyphostemma (Vitaceae), a clade comprising ~200 species that is unique in the Vitaceae for its diversity of growth habits. We reconstruct time-calibrated evolutionary relationships among 64 species in the genus using five nuclear and chloroplast markers, and infer the group's morphological and biogeographic history. We test for changes in speciation rate, and evaluate the temporal association and sequencing of events with respect to dispersal, habitat change, and morphological evolution using a Monte Carlo simulation approach. In Cyphostemma, neither dispersal nor morphological evolution is associated with shifts in speciation rate, but dispersal is associated with evolutionary shifts in growth form. Evolution of stem succulence, in particular, is associated with adaptation to local, pre-existing conditions following long-distance dispersal, not habitat change in situ. We suggest that the pattern of association between dispersal, morphological innovation, and diversification may depend on the particular characters under study. Lineages with evolutionarily labile characters, such as stem succulence, do not necessarily conform to the notion of niche conservatism and instead demonstrate remarkable morphological adaptation to local climate and edaphic conditions following dispersal.
Data from: A Cretaceous aged Paleotropical dispersal established an endemic lineage of Caribbean praying mantises
Recent phylogenetic advances have uncovered remarkable biogeographic histories that have challenged traditional concepts of dispersal, vicariance and diversification in the Greater Antilles. Much of this focus has centred on vertebrate lineages despite the high diversity and endemism of terrestrial arthropods, which account for 2.5 times the generic endemism of all Antillean plants and non-marine vertebrates combined. In this study, we focus on three Antillean endemic praying mantis genera, Callimantis, Epaphrodita and Gonatista, to determine their phylogenetic placement and geographical origins. Each genus is enigmatic in their relation to other praying mantises due to their morphological affinities with both Neotropical and Old World groups. We recovered the three genera as a monophyletic lineage among Old World groups, which was supported by molecular and morphological evidence. With a divergence at approximately 107 Ma, the lineage originated during the break-up of Gondwana. Ancestral range reconstruction indicates the lineage dispersed from an African + Indomalayan range to the Greater Antilles, with a subsequent extinction in the Old World. The profound ecomorphic convergence with non-Caribbean groups obscured recognition of natural relationships within the same geographical distribution. To the best of our knowledge, the lineage is one of the oldest endemic animal groups in the Greater Antilles and their morphological diversity and restricted distribution mark them as a critical taxon to conserve.
African wild dog dispersal and implications for management
Successful conservation of species that roam and disperse over large areas requires detailed understanding of their movement patterns and connectivity between subpopulations. But empirical information on movement, space use, and connectivity is lacking for many species, and data acquisition is often hindered when study animals cross international borders. The African wild dog (Lycaon pictus) exemplifies such species that require vast undisturbed areas to support viable, self‐sustaining populations. To study wild dog dispersal and investigate potential barriers to movements and causes of mortality during dispersal, between 2016 and 2019 we followed the fate of 16 dispersing coalitions (i.e., same‐sex group of ≥1 dispersing African wild dogs) in northern Botswana through global positioning system (GPS)‐satellite telemetry. Dispersing wild dogs covered ≤54 km in 24 hours and traveled 150 km to Namibia and 360km to Zimbabwe within 10 days. Wild dogs were little hindered in their movements by natural landscape features, whereas medium to densely human‐populated landscapes represented obstacles to dispersal. Human‐caused mortality was responsible for >90% of the recorded deaths. Our results suggest that a holistic approach to the management and conservation of highly mobile species is necessary to develop effective research and evidence‐based conservation programs across transfrontier protected areas, including the need for coordinated research efforts through collaboration between national and international conservation authorities.
Data from: Leap-frog dispersal and mitochondrial introgression: phylogenomics and biogeography of Limnonectes fanged frogs in the Lesser Sundas Archipelago of Wallacea
Aim: The Lesser Sunda Islands are situated between the Sunda and Sahul Shelves, with a linear arrangement that has functioned as a two-way filter for taxa dispersing between the Asian and Australo-Papuan biogeographic realms. Distributional patterns of many terrestrial vertebrates suggest a stepping-stone model of island colonization. Here we investigate the timing and sequence of island colonization in Asian-origin fanged frogs from the volcanic Sunda Arc islands with the goal of testing the stepping-stone model of island colonization. Location: The Indonesian islands of Java, Lombok, Sumbawa, Flores, and Lembata. Taxon: Limnonectes dammermani and L. kadarsani (Family: Dicroglossidae) Methods: Mitochondrial DNA was sequenced from 153 frogs to identify major lineages and to select samples for an exon-capture experiment. We designed probes to capture sequence data from 974 exonic loci (1,235,981 bp) from 48 frogs including the outgroup species, L. microdiscus. The resulting data were analyzed using phylogenetic, population genetic, and biogeographical model testing methods. Results: The mtDNA phylogeny finds L. kadarsani paraphyletic with respect to L. dammermani, with a pectinate topology consistent with the stepping-stone model. Phylogenomic analyses of 974 exons recovered the two species as monophyletic sister taxa that diverged ~7.6 Ma with no detectable contemporary gene flow, suggesting introgression of the L. dammermani mitochondrion into L. kadarsani on Lombok resulting from an isolated ancient hybridization event ~4 Ma. Within L. kadarsani, the Lombok lineage diverged first while the Sumbawa and Lembata lineages are nested within a Flores assemblage composed of two parapatrically distributed lineages meeting in central Flores. Biogeographical model comparison found strict stepping-stone dispersal to be less likely than models involving leap-frog dispersal events. Main conclusions: These results suggest that the currently accepted stepping-stone model of island colonization might not best explain the current patterns of diversity in the archipelago. The high degree of genetic structure, large divergence times, and absent or low levels of migration between lineages suggests that L. kadarsani represents five distinct species.
Data from: Phoretic dispersal influences parasite population genetic structure
Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift, and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be done in the proper comparative context. Here we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host-specific feather lice (Phthiraptera: Ischnocera) that co-occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, "wing lice" (Columbicola columbae) disperse phoretically by "hitchhiking" on pigeon flies (Diptera: Hippoboscidae), while "body lice" (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host-parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host-parasite cospeciation.
Data from: Global geographic patterns in the colours and sizes of animal‐dispersed fruits
Aim. Fruit colours attract animal seed dispersers, yet the causes of fruit colour diversity remain controversial. The lack of knowledge of large-scale spatial patterns in fruit colours has limited our ability to formulate and test alternative hypotheses to explain fruit colour, fruit size, and fruit colour diversity. We describe spatial (especially latitudinal) variation in fruit colour, colour diversity, and length, and test for correlations between fruit colour, length, and plant habit. Location. Global. Time period. Present-day. Major taxa studied. Seed plants. Methods. We assembled a database of fruit traits for 13,178 fleshy-fruited plant species spanning 136 sites around the world. To assess whether fruit colour categories correspond with spectral reflectances, we tested for clustering of hue, chroma, and saturation for 236 species for which we had reflectance data. We then quantified latitudinal gradients in fruit colour, fruit length, and fruit colour diversity while controlling for the effects of plant habit, and whether colour categories varied with respect to average fruit size. Results. Colour categories corresponded well with reflectance data. The tropics show high colour diversity, while red fruits progressively constitute a higher proportion of the fleshy-fruited plant community towards high latitudes. All mammal-associated colours (green, orange, brown, and yellow) are more common in the tropics than at high latitudes. Fruit length also increases towards the tropics. Main conclusions. Tropical communities tend to have diverse fruit colours, including many mammal-associated fruit colours, while high latitude communities contain a higher percentage of red-fruited species. The correlation between colour and size is strong, and some latitudinal patterns may be partly driven by changes in fruit size. Differences in geography and in the history of plant lineages in the southern versus the northern hemisphere may help to explain some biogeographic patterns, but alternative hypotheses related to fruit defence, development, and metabolic costs are plausible.
Data from: Declining demographic performance and dispersal limitation influence the geographic distribution of the perennial forb, Astragalus utahensis (fabaceae)
1. A central goal of ecology is understanding the determinants of species' distributions. 'Metapopulation' models for the existence of distributional boundaries predict that species' geographic ranges arise from the landscape-scale deterioration of habitat suitability towards the range edge (i.e. niche mechanisms), which simultaneously hinders demographic performance and limits dispersal to suitable habitat beyond the edge (i.e. dispersal limitation). However, few studies have examined both of these mechanisms for the same species by examining abundance and comprehensive measures of demographic performance across the distribution and beyond its boundary. 2. We tested the predictions of metapopulation models for range limits by contrasting abundance, demographic performance, and population growth (λ) of the perennial forb Astragalus utahensis in central and northern range edge populations. We tested for dispersal limitation by transplanting individuals at and beyond the northern range boundary and monitoring their demographic performance. 3. Astragalus abundance and stochastic λ decreased from the range center to the northern range edge, with stochastic λ falling to or below replacement in range edge populations. However, transplants at some sites beyond the northern range edge survived and reproduced at levels similar to transplants within the range. Thus, in addition to deteriorating conditions at the range edge, dispersal limitation appears to contribute to limiting A. utahensis' northern distribution. 4. Synthesis: Our results support metapopulation models for range limits by suggesting that decreased demographic performance constrains the viability of range edge populations while contributing to dispersal limitation of A. utahensis' distribution. Thus, the tandem action of niche and dispersal processes appears to play an important role in constraining this species' northern latitudinal range.
Data from: Rare long-distance dispersal of a marine angiosperm across the Pacific Ocean
Aim: Long-distance dispersal (LDD) events occur rarely but play a fundamental role in shaping species biogeography. Lying at the heart of island biogeography theory, LDD relies on unusual events to facilitate colonisation of new habitats and range expansion. Despite the importance of LDD, it is inherently difficult to quantify due to the rarity of such events. We estimate the probability of LDD of the seagrass Heterozostera nigricaulis, a common Australian species, across the Pacific Ocean to colonise South America.Location: Coastal Chile, Australia and the Pacific Ocean. Methods: Genetic analysis of H. nigricaulis collected from Chile and Australia were used to assess the relationship between the populations and levels of clonality. Ocean surface current models were used to predict the probability of propagules dispersing from South East Australia to Central Chile and shipping data used to determine the likelihood of anthropogenic dispersal. Results: Our study infers that the seagrass H. nigricaulis dispersed from Australia across the entire width of the Pacific (~14,000 km) to colonise South America on two occasions. Genetic analyses reveal that these events led to two large isolated clones, one of which covers a combined area of 3.47 km2. Oceanographic models estimate the arrival probability of a dispersal propagule within 3 years to be at most 0.00264%. Early shipping provides a potential alternative dispersal vector, yet few ships sailed from SE Australia to Chile prior to the first recording of H. nigricaulis and the lack of more recent and ongoing introductions demonstrate the rarity of such dispersal. Main Conclusion: These findings demonstrate LDD does occur over extreme distance despite very low probabilities. The large number of propagules (100s of millions) produced over 100s of years suggests that the arrival of propagules in Chile was inevitable and confirms the importance of LDD for species distributions and community ecology.
Data from: Natal dispersal of tree sloths in a human-dominated landscape: implications for tropical biodiversity conservation
1. Habitat loss and fragmentation resulting from the conversion of tropical forests are among the most important threats to biodiversity globally. Habitat specialists and species with low dispersal capacity are expected to be the most sensitive to such changes. Relatively little is known, however, about how habitat change and life history interact to impact natal dispersal and population viability in tropical species. 2. Here, we characterized natal dispersal patterns, habitat selection, and survival rates in two-toed (Choloepus hoffmanni) and three-toed (Bradypus variegatus) sloths within a human-dominated tropical landscape in Costa Rica consisting of a shade-grown cacao plantation surrounded by riparian forests and cattle pastures. 3. Radio-marked individuals of both species preferentially selected tropical forests during natal dispersal and were commonly observed using riparian forest buffers for dispersal. The more specialized and sedentary three-toed sloth, however, avoided both pastures and shade-grown cacao for dispersal, whereas two-toed sloths only avoided pastures. 4. Juvenile survival was lower for three-toed than two-toed sloths, and was lowest immediately following maternal independence for both species. Despite interspecific differences, juvenile survival was high and sufficient to maintain stable populations of both species. 5. Synthesis and applications. Our results indicate that tropical forest conversion is more likely to impact the natal dispersal success of specialized and dispersal-limited species. Moreover, riparian forest buffers appear to provide critical corridors for maintaining such species, and biodiversity more broadly, in modified tropical landscapes.07-Feb-2018
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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
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OpenNeuro
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