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Wildfire influences individual growth and breeding dispersal, but not survival and recruitment in a montane amphibian

Global wildfire regimes are changing rapidly, with widespread increases in the size, frequency, duration, and severity of wildfires. Whereas the effects of wildfire on ecological state variables such as occupancy, abundance, and species diversity are relatively well-documented, changes in population vital rates (e.g., survival, recruitment) and individual responses (e.g., growth, movement) to wildfire are more limited because of the detailed information needed on the same individuals both pre- and post-fire. We capitalized on the 2018 Roosevelt wildfire, which occurred during our six-year (2015–2020) capture-mark-recapture study of boreal toads (Anaxyrus boreas boreas; n = 1415) in the Bridger-Teton National Forest, USA, to evaluate the responses of population vital rates and individual metrics to wildfire. We employed robust design capture-recapture models to compare the growth, dispersal, survival, and recruitment of adult boreal toads pre- and post-fire at burned versus unburned sites. At burned locations, growth increased two-years post-fire compared with the year directly following wildfire and was higher two-years post-fire than any other interval during our study period. Boreal toads dispersed to alternative breeding patches more at burned sites than unburned sites and dispersal increased two-years post-fire compared with the year directly following wildfire. Annual survival and recruitment did not differ between pre- and post-fire years nor among pre-fire years, the year following wildfire, and two-years post-fire. We demonstrate that, in certain contexts, dispersal can play a major role in changes to state variables (e.g., abundance) after wildfire, as opposed to other vital rates such as survival and recruitment. Our study represents an important step towards understanding the biological processes that underlie observed patterns in state variables following wildfire, which ultimately will be critical for the effective management of species in landscapes experiencing shifts in fire activity.

The emblematic South African therocephalian Euchambersia in China: a new link in the dispersal of late Permian vertebrates across Pangea

Therapsids were widely distributed in Pangea in the late Permian. South Africa in Gondwana, and Russia in Laurasia are the principal areas recording tetrapods (including therapsids) of this age. More recent field explorations have increased the importance of Chinese late Permian fossil assemblages. This is clearly reflected in the discovery of several new therocephalians from the Naobaogou Formation in Nei Mongol. Here we report a therocephalian from that unit identified as a new species of the emblematic South African taxon Euchambersia. The new species, E. liuyudongi, is represented by a well-preserved skull and mandible showing a well-developed maxillary fossa and absence of postcanine teeth. This is the third akidnognathid recovered from the Naobaougou Formation, but oddly, the two basal Chinese akidnognathids previously known were recovered from a younger unit of the formation than the derived E. liuyudongi. This is the first time that the same therocephalian genus is recorded in northern and southern continents, making the record of the Naobaougou Formation key to understanding the evolution of late Permian continental faunas in general, and of akidnognathid therocephalians in particular.

Responses of a resident group to an outsider in the blue-breasted quail: a paradigm for studying social resettlement of dispersers

Dispersal is an individual life history trait that can influence the ecological and evolutionary dynamics of both the source and recipient populations. Current studies of animal dispersal have paid little attention to how the responses of residents in a recipient population affect the social resettlement of dispersers into a new habitat. We addressed this question in the blue-breasted quail Synoicus chinensis by designing an outsider introduction experiment to simulate a scenario of interaction between residents and dispersers. In the experiment, we introduced an unfamiliar quail into a group of three differently ranked residents and then examined their behavioral responses to the arrival of the outsider. We found that all residents made negative responses by pecking at the outsider to maintain their pecking order, in which high-ranked residents displayed significantly greater intensity than those of lower ranks. This result highlighted that adverse behavioral responses of residents would prevent outsiders from obtaining hierarchical dominance in the recipient group. Moreover, the residents' sex ratio, their relative ages to the outsiders, and whether outsiders counter-pecked at the residents all influenced the probability of outsiders prevailing against the residents. Those outsiders that displayed counter-peck courage were more likely to gain higher dominance and hence resettle into the recipient group successfully. Our findings suggest that resident groups may impose a selection among dispersers via adverse behavioral responses. Therefore, social factors that can influence the resettlement step of dispersers in a new habitat should be accounted for in future studies of animal dispersal.

Drivers of zooplankton dispersal in a pond metacommunity

Dispersal success is integral to survival of species in metacommunities. For species that disperse passively like zooplankton, reliance on dispersal vectors is paramount for colonization of water bodies. Zooplankton species engage in dispersal in time (resting eggs) and space (overland). For dispersal in time, resting eggs are deposited in the sediment during adverse conditions and recolonize aquatic systems when beneficial conditions resume

Dispersals from the West Tethys as the source of the Indo-West Pacific diversity hotspot in comatulid crinoids

Conspicuous centers of biodiversity are frequently attributed to local conditions that promote speciation or resistance to extinction, but recent diversification studies indicate this mode of explanation might not be very general, so it may be fruitful to revisit the role of dispersal in concentrating biodiversity. Here we consider the processes underlying the marine diversity hotspot in the Indo-West Pacific among comatulid crinoids, suspension-feeding echinoderms conspicuous on modern tropical reefs. We used ancestral range reconstruction on a phylogeny of extant crinoids, assembled a new occurrence database of fossil comatulids and interrogated it with probabilistic preservational models, and developed a morphological character matrix to estimate the relationships among living and fossil comatulids. Ancestral range reconstruction on a phylogeny of extant comatulids recovers an origin outside the Indo-Pacific and elevated dispersal into it. A new occurrence database records the comatulid clade spreading out gradually from origin in the Early Jurassic of the West Tethys. They do not appear in their modern hotspot until the Oligocene, and taphonomic analyses show these results cannot be explained solely as a result of inadequate sampling in Asia and Oceania. Finally, phylogenetic analyses demonstrate that deeply nested crown-group comatulids had originated before the clade became well-established in the East Tethys, implying many independent dispersals into the modern hotspot. These consilient results suggest a biodiversity hotspot that owes its existence to dispersals out of the ancient West Tethys rather than to elevated in situ diversification.

opencc-zeroJul 2022View details →

Environmentally associated variation in dispersal distance affects inbreeding risk in a stream salamander

Avoiding inbreeding is considered a key driver of dispersal evolution, and dispersal distances should be especially important in mediating inbreeding risk because the likelihood of mating with relatives decreases with dispersal distance. However, a lack of direct data on dispersal distances has limited empirical tests of this prediction, particularly in the context of the multiple selective forces that can influence dispersal. Using a headwater salamander system, we tested whether spatial variation in environmental conditions leads to differences in dispersal distances, resulting in spatial variation in the effect of dispersal on inbreeding risk. Using capture-recapture and population genomic data from 5 streams, we found that dispersal distances were greater in downstream reaches than upstream reaches. Inbreeding risk was lower for dispersers than non-dispersers in downstream reaches, but not in upstream reaches. Furthermore, stream reaches did not differ in spatial patterns of individual relatedness, indicating that variation in inbreeding risk was in fact due to differences in dispersal distances. These results demonstrate that environmentally associated variation in dispersal distances can cause the inbreeding consequences of dispersal to vary at fine spatial scales. They also show that selective pressures other than inbreeding avoidance maintain phenotypic variation in dispersal, underscoring the importance of addressing alternative hypotheses in dispersal research.

opencc-by-4.0Jul 2022View details →

Data for "Workhorse minimally-empirical dispersion-corrected density functional, with tests for weakly-bound systems: r2 SCAN + rVV10"

VASP inputs and outputs for the: <ul> <li>Ar2 binding energy curve (Ar2_bpara.tar.gz)</li> <li>L28 set of layered-solid geometries and interlayer binding energies (L28.tar.gz)</li> <li>S22 set of interaction energies of weakly-bound complexes (S22.tar.gz)</li> </ul> All POTCAR files have been replaced by "potcar.txt" files containing the title(s) of the POTCAR(s) needed to reproduce the calculations. A preprint is available from the arXiv:2204.11717 (<a href="https://arxiv.org/abs/2204.11717">link</a>).

opencc-by-4.0Jul 2022View details →

FIGURE 4 in A late Turolian giant panda from Bulgaria and the early evolution and dispersal of the panda lineage

FIGURE 4. Dental ratio of P4 of Ailuropodini. Abbreviations: L, length; W, width, in mm.

opencc-by-4.0Jul 2022View details →

FIGURE 1 in A late Turolian giant panda from Bulgaria and the early evolution and dispersal of the panda lineage

FIGURE 1. Location of Ognyanovo in Bulgaria.

Plant dispersal characteristics shape the relationship of diversity with area and isolation

Aim This study disentangles how plant dispersal syndromes influence the relationship of species richness with area and isolation while also accounting for the human impact on island biodiversity. It builds on the potential of islands at the mesoscale and of similar origin to contribute to the ongoing discussion in island biogeography on what determines species richness and filtering. Location Denmark, 54 saltwater and brackish water islands in the North and Baltic Sea Taxon Vascular plants, including pteridophytes (ferns, clubmosses and horsetails) Methods Generalized linear models (GLMs) and linear regressions are used to analyse how dispersal syndromes influence the relationships of species numbers with island area and isolation, as well as island inhabitation and human density, respectively. Results Species numbers, as well as mean seed mass and the proportion of zoochore and anemochore species, are positively related to island area while the share of water-dispersed species decreases with increasing area. The slope of the regression line representing the species-area relationship (SAR) was 0.34 and lies within the common range for this relationship. Isolation is weakly related to mean seed mass but has no explaining power for species numbers and the presence of specific dispersal syndrome on the target islands. Species richness and seed mass was positively related to human presence. Main conclusions Human impact for centuries has not overwritten the strong relationship of species richness with area on the Danish Islands but is affecting the shape of this relationship. Island area constitutes a strong filter for different dispersal syndromes and leads to the assumption that heavier and animal-dispersed seeds are positively related to island area due to the presence of more bird and mammal species. Human-induced loss of isolation caused by ongoing traffic and the connection of landmasses by bridges and ferries may be a reason for the overall low explanatory power of island isolation. Higher species richness on inhabited islands may further be linked to higher habitat diversity in human modified landscapes.

opencc-by-4.0Apr 2022View details →

Data supporting "Dispersal of bacteria and stimulation of permafrost decomposition by Collembola"

This archive contains the processed sequencing data, processed CO2 flux data and the script used to generate figures and tables presented in "Dispersal of bacteria and stimulation of permafrost decomposition by Collembola" by Monteux S., Mariën J., and Krab E.J., Biogeosciences 2022, 19, 4089-4105, https://doi.org/10.5194/bg-19-4089-2022 . A more exhaustive repository including bioinformatics processing is found at https://git.bolin.su.se/bolin/monteux-2022-collembola and the raw DNA data is deposited at ENA under accession number PRJEB51992

Seasonal variation in impact of non-native species on tropical seed dispersal networks

Invasive non-native species can alter animal-mediated seed dispersal interactions and ultimately affect the stability of recipient communities. The degree of such disturbances, however, is highly variable and depends on several factors, two of which have received little attention: the relative timing of native and non-native fruiting phenologies, and the associated variation in relative resource availability across the fruiting period. Both are likely to alter plant-seed disperser interactions threatened by biological invasions. Here we investigated the impact of plant invasions on the seasonal dynamics of frugivory and seed dispersal networks across a large-scale experimental setup and a plant invasion gradient on a tropical island. We recorded fruit and frugivore abundances, and plant-frugivore interactions across 8 inselbergs (i.e. rocky outcrops) with different levels of plant invasion during 10 months on the island of Mahé, Seychelles. By combining four sampling methods of plant-frugivore interactions we constructed quantitative seed dispersal networks at all sites across two 5-month seasons: the on-peak and off-peak fruiting season. Our findings showed that, by fruiting mostly synchronously with natives, non-native plants compete with natives for dispersal services, predominantly carried out by native frugivores. Variation in native seed dispersal was driven by plant invasion and seasonality. Specifically, native seed dispersal declined with the degree of invasion; dispersal frequency increased with fruit abundance more strongly during the off-peak fruiting season; and networks became increasingly specialised during off-peak. These results indicated that during the main fruiting peak seed dispersal services were saturated, which likely intensified the competition between native and non-native fruits. When resources were scarce during off-peak fruiting season, native and non-native frugivores were more selective in their fruit choice at sites dominated by non-native plants. We showed that native plant and frugivore populations and native seed dispersal interactions were more vulnerable in invaded plant communities, where non-native plants compete with natives for dispersal services potentially reducing native recruitment. As invasive non-native plants dominate many ecosystems worldwide, particularly on islands, our findings showed that controlling plant invasions in vulnerable native communities can be critical to maintain native ecosystem functions and biodiversity.

opencc-by-4.0Apr 2022View details →

dataset for "A Scintillation Arc Survey of 22 Pulsars with Low to Moderate Dispersion Measures"

These are the 54 Dynamic Spectrum files (.FITS format) behind the paper "A Scintillation Arc Survey of 22 Pulsars with Low to Moderate Dispersion Measures," submitted to the AAS Journals on 2022 April 06. We also include the Tables, Figures, and Text from the work, as well as some explanatory README files.

Increasing efficiency and reducing bias in the detection of seed-dispersal interactions based on mist-netted birds

Efficient and unbiased sampling of ecological interactions is essential to our understanding of the functions they mediate. Seed dispersal by frugivorous birds is a key mutualism for plant regeneration and community dynamics. Mist-netting is one of the most widely used methods to sample avian seed dispersal through the identification of seeds in droppings of captured birds kept inside cloth bags. However, birds may drop seeds on the ground before being extracted from the net, leading to a fraction of missing information due to ineffective sampling. Worryingly, this fraction could be unevenly distributed across bird and plant species, leading to sampling biases. Here, we assess the effectiveness of using a 1- m wide mesh below mist nets to sample seeds dropped by entangled birds. We used data from birds mist-netted during one-year-round. We sampled nearly 50% of interaction events and 75% of dispersed seeds on the mesh band below the mist nets (i.e. lost information without this optimization). The proportion of seeds sampled on the mesh bands was not evenly distributed among bird species but strongly related to bird size, ranging from 57-63% in warblers to 84-94% in thrushes. Moreover, the proportion of seeds sampled on the mesh was negatively related to seed size, although this relationship was weaker. We also evaluated accumulation curves of species and pairwise interactions with increasing sampling effort, both with and without using the mesh bands. The number of seed species sampled increased by 21% when using the mesh bands and the number of pairwise interactions by 36%. Our findings provide strong evidence on how inefficient and biased traditional mist-netting can be for sampling community-wide seed-dispersal interactions. We thus urge the use of mesh bands in future studies to increase sampling effectiveness and avoid biases, which will ultimately improve our understanding of the seed dispersal function.

Data from: Resident-disperser differences and genetic variability affect communities in microcosms

Dispersal is a key process mediating ecological and evolutionary dynamics. Its effects on the dynamics of spatially-structured systems, population genetics, or species range distribution can depend on phenotypic differences between dispersing and non-dispersing individuals. However, scaling up the importance of resident-disperser differences to communities and ecosystems has rarely been considered, in spite of intraspecific phenotypic variability being an important factor mediating community structure and productivity. Here, we used the ciliate Tetrahymena thermophila, in which phenotypic traits are known to differ between residents and dispersers, to test (i) whether these resident-disperser differences affect biomass and composition in competitive communities composed of four other Tetrahymena species, and (ii) whether these effects are genotype-dependent. We found that dispersers led to lower community biomass compared to residents. This effect was highly consistent across the twenty T. thermophila genotypes used, despite intraspecific variability in resident-disperser phenotypic differences. We also found a significant genotypic effect on biomass production, showing that intraspecific variability has consequences for communities. Our study suggests that individual dispersal strategy can scale up to community productivity in a predictable way, opening new perspectives to the functioning of spatially structured ecosystems.

Data for: Stronger niche than dispersal effects on α- and β-diversity of stream algae, insects, and fish across latitudes in the US

Aim: Niche and dispersal processes influence biodiversity, but their relative importance along latitude is unclear. We predicted that: i) niche processes would dominate at high latitudes due to increased climatic stress, consistent with the physiological tolerance hypothesis and the Dobzhansky-MacArthur hypothesis and ii) dispersal limitation would prevail at low latitudes due to narrower niches and smaller range sizes, as postulated by the dispersal-ecological specialization tradeoff hypothesis, the latitude-niche breadth hypothesis, and Rapoport's rule. Location: Central United States Time Period: 1993-2019 Major taxa studied: Stream algae, insects, and fish Methods: We examined the relative effects of environment (climate and physicochemistry) vs. space on stream biodiversity in seven latitudinal zones, spanning 19 latitudinal degrees. In each zone, species richness (α-diversity) was analyzed with multiple regression and variance partitioning. Compositional dissimilarity (β-diversity) within zones was assessed with distance-based RDA and variance partitioning. Results: For α-diversity, latitudinal variability of niche and dispersal processes conformed to our predictions in all three groups, except for dispersal processes in insects. However, the drivers of β-diversity did not follow our predictions. The latitude-niche breadth hypothesis and Rapoport's rule were weakly supported only in fish. Main Conclusions: The importance of niche and dispersal processes varied predictably along the latitudinal gradient only for α-diversity. However, the niche effects were driven mostly by physicochemistry, and the dispersal effects were not always linked with ecological specialization and range size. This suggests that climate-based biodiversity theories do not have particular relevance for the streams in our study. Niche processes had a greater impact than dispersal processes across species groups and diversity metrics, emphasizing the primary role of the environment.

Diaspore traits specialized to animal adhesion and sea current dispersal are positively associated with the naturalization of European plants across the World

Understanding what drives non-native species naturalization (the establishment of a self-sustainable population outside its native range) is a central question in invasion science. Plants' capacity for long distance dispersal (LDD) is likely to influence the spread and naturalization of non-native species differently according to their introduction pathways. These pathways include intentional introductions (for economic use, e.g. for agriculture), unintentional introductions (e.g. seed contaminants), plant dispersal via human infrastructures (e.g. roads), and plant spread from an adjacent region where the species was previously introduced. Herein, we tested the relationship between sets of LDD traits (syndromes) of 10,308 European plant species and their global naturalization incidence (i.e. whether a species has become naturalized or not) and extent (i.e. the number of regions where a species has become naturalized) using the most comprehensive database of naturalized plants worldwide (GloNAF). Diaspore traits allowed the identification of four traditional LDD syndromes, namely those with specializations for dispersal by: wind (anemochorous), animal ingestion (endozoochorous), attached to animals (epizoochorous), and sea currents (thalassochorous). These evolutionary specializations have been historically interpreted by biologists even though actual dispersal is not always related to diaspore syndromes. We found that while epizoochorous and thalassochorous traits are positively associated with global plant naturalization incidence, anemochorous and endozoochorous traits show a negative relationship. Species´ residence time outside their native range, their economic use and presence of epizoochorous traits (such as hooks, hairs and adhesive substances) are positively associated with global naturalization extent. Furthermore, we found that plants' economic use reduces the influence of LDD syndromes on the naturalization incidence of intentionally introduced plants. While the success of non-native plants is influenced by a broad array of species- and context-specific factors, LDD syndromes play an important role in this context depending on the economic use of plants.

opencc-by-4.0Sep 2022View details →

Transient Nuclear Criticality Excursion Analysis of Highly Dispersed Particulate Three-Phase Fluidised Systems

The aim of this study was to perform sensitivity analysis, investigating how different fluidisation and sedimentation characteristics of three-phase, wetted UO2 powder beds, may affect a transient nuclear criticality excursion initiated through the addition of water into a fissile powder bed. This type of postulated nuclear criticality accident scenario may occur in nuclear fuel fabrication facilities when a fire is fought through the use of water, supplied via an automatic or manual fire-suppression system. A similar scenario may also develop as a result of water leaks or flooding of the process area housing UO2 powder. The article introduces a model for gas-bubble induced fluidisation of a UO2 powder bed and examines how this phenomenon may affect the neutron kinetic response of a three-phase fluidised fissile powder system. Empirical analysis has shown that fissile suspensions form agglomerated structures when suspended in water, at agglomerate sizes that range from 18 µm to 40 µm. Simulation results indicate that both the critical gas velocity and rate of fluidisation may significantly affect transient nuclear criticality excursion dynamics. The re-distribution of fissile mass into a highly dispersed suspension generally reduces the reactivity of the system, however, depending on the H/U ratio, a positive reactivity may be added to the system. Low Péclet numbers in the suspension suggest that gas-bubble induced motion of the suspension causes a highly dispersive flow field. An oscillatory power response is predicted for low critical gas velocities where the reactivity of the system is predominantly governed by the re-distribution of fissile mass within the system. The frequency of these oscillations is greater for a higher hindered settling rate of powder particles. At higher critical gas velocity, the transient nuclear criticality excursion is governed by the voidage reactivity feedback, making the response quite independent of fluidisation. In all cases, large volumes of UO2 powder may leave the domain due to overflowing of the suspension. Transient nuclear criticality excursions in UO2 powder beds with a low critical gas velocity are terminated once the bed becomes fully saturated.

opencc-by-4.0Sep 2022View details →

Data and script for "Dispersal syndromes in challenging environments: a cross-species experiment"

Datset and R scripts for all analysis of the manuscript "Dispersal syndromes in challenging environments: a cross-species experiment" published in Ecology Letters.