High Dispersal Rates Research Articles

Unveiling the Preparation and Characterization of Lercanidipine Hydrochloride in an Oral Solid Self-Nanoemulsion for Enhancing Oral Delivery.

Chronic kidney disease (CKD) is becoming increasingly prevalent worldwide, particularly among the elderly, along with an increase in the incidence of hypertension and cardiovascular disorders. Developing lipid-based oral dosage forms with a higher expected bioavailability of antihypertensive drugs with nephroprotective effects poses a challenge. Lercanidipine hydrochloride (LRCH) is a newer type of third-generation dihydropyridine calcium channel blocker that functions as an antihypertensive and has significant nephroprotective effects. Due to its extensive first-pass metabolism, its bioavailability is about 10% and increases to 3-4 times when taken with a high-fat meal. Targeting this drug to the lymphatic system using the solid self-nano-emulsifying drug delivery system (SSNEDDS) is a promising approach for improving LRCH's bioavailability and dispersion rate. SSNEDDS combines the benefits of both liquid self-emulsifying and solid dosage forms, improving drug stability and extending storage time. In this study, liquid SNEDDS composed of 10% peppermint oil, 67% Tween 20, and 22.5% propylene glycolwas solidified using two adsorbent agent mixtures (SSNEDDS1: Avicel PH 101 and Aerosil 200) and (SSNEDDS2: Avicel PH 102 and Aerosil 200) separately. The prepared formulations were evaluated for powder flow, drug content, and an in-vitro dispersion test in comparison to the brand-marketed tablet as a standard or pure drug. DSC and X-ray diffraction analysis were also used. The SSNEDDS2 shows excellent flowability, a higher drug content (99.761%), and a significantly higher and faster dispersion rate of 100% within 10 minutes compared to 92% of the marketed LRCH tablet and 18.1% of the pure drug for 60 minutes. The solid-state characterization of the formulation composed of SSNEDDS2 confirmed that the LRCH was in an amorphous form inside the solidified nano system without interacting with the excipient. This study successfully prepared LRCH using the promising strategy of SSNEDDS as a hard gelatin capsule with a higher dispersion rate. It improved its stability and expected bioavailability compared to the brand-marketed tablet as the standard.

A machine-based corpus optimization method for extracting domain-oriented technical words: an example of COVID-19 corpus data

Although natural language processing (NLP) refers to a process involving the development of algorithms or computational models that empower machines to understand, interpret, and generate human language, machines are still unable to fully grasp the meanings behind words. Specifically, they cannot assist humans in categorizing words with general or technical purposes without predefined standards or baselines. Empirically, prior researches have relied on inefficient manual tasks to exclude these words when extracting technical words (i.e., terminology or terms used within a specific field or domain of expertise) for obtaining domain information from the target corpus. Therefore, to enhance the efficiency of extracting domain-oriented technical words in corpus analysis, this paper proposes a machine-based corpus optimization method that compiles an advanced general-purpose word list (AGWL) to serve as the exclusion baseline for the machine to extract domain-oriented technical words. To validate the proposed method, this paper utilizes 52 COVID-19 research articles as the target corpus and an empirical example. After compared to traditional methods, the proposed method offers significant contributions: (1) it can automatically eliminate the most common function words in corpus data; (2) through a machine-driven process, it removes general-purpose words with high frequency and dispersion rates –57% of word types belonging to general-purpose words, constituting 90% of the total words in the target corpus. This results in 43% of word types representing domain-oriented technical words that makes up 10% of the total words in the target corpus are able to be extracted. This allows future researchers to focus exclusively on the remaining 43% of word types in the optimized word list (OWL), enhancing the efficiency of corpus analysis for extracting domain knowledge. (3) The proposed method establishes a set of standard operation procedure (SOP) that can be duplicated and generally applied to optimize any corpus data.

Both local stability and dispersal contribute to metacommunity sensitivity to asynchronous habitat availability

The stability of isolated communities depends on the complexity of their foodwebs. However, it remains unclear how local stability interacts with dispersal in multitrophic metacommunities to shape biodiversity patterns. This lack of understanding is deeper in the more realistic frame of landscapes that exhibit non-trivial and time-varying structures. Therefore, in this study, we aim to evaluate the influence of local stabilizing factors versus dispersal in determining the sensitivity of metacommunity biodiversity to increasing asynchrony of site availability. Additionally, we assess the role of foodweb complexity and landscape structure as modulating factors. To accomplish our goals we developed a model based on random matrices for local communities, which are linked by stochastic dispersal over explicit dynamic landscapes. We ran numerical simulations and computed the effect sizes of foodweb temperature, self-limitation, dispersal ability, and all pairwise combinations, on the sensitivity of biodiversity to landscape asynchrony. In our experiments we explored gradients of species richness, foodweb connectance, number of sites, and landscape modularity. Our results showed that asynchrony among site availability periods reduced α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}-diversity and increased β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document}-diversity. Asynchrony increased γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma$$\\end{document}-diversity at high dispersal rates. Both local and regional stabilizing factors determined the sensitivity of metacommunities to landscape asynchrony. Local factors were more influential in landscapes with fewer sites and lower modularity, as well as in metacommunities composed of complex foodwebs. This research offers insights into the dynamics of metacommunities in dynamic landscapes, providing valuable knowledge about the interplay between local and regional factors in shaping ecological stability and species persistence.

Testing hypotheses of invasion pathways of the ladybird Harmonia axyridis into and across South Africa

Harmonia axyridis is an invasive beetle (Coleoptera: Coccinellidae), native to Asia, that has established on four continents beyond its native range and was first observed in South Africa in 2001. Using microsatellite data and a comprehensive geographic coverage of international (17 locations) and South African (14 locations) beetle samples, we inferred the source of colonists invading South Africa and the beetle’s movement within the country. Genetic structure analyses suggest that this species’ populations in South Africa are derived from admixture between beetles originating from eastern North America (which acted as a bridgehead population) and another population not directly sampled in our study. Genetic admixture prior its invasion into South Africa, along with the possibility of multiple introductions from the bridgehead population, may explain the high genetic diversity estimates for South African H. axyridis (HE = 0.582–0.625) compared to beetles from the native range (HE = 0.440–0.636). Harmonia axyridis appear to be frequently exchanging genetic material across South Africa, with no clear genetic structure between sampled locations. However, evidence of weak isolation-by-distance within South Africa suggests that beetles are dispersing less frequently between locations that are furthest apart. This study supports previous findings on global invasion pathways in this species but provides new insights in the context of the invasion in South Africa. We highlight how mixing of distinct lineages from divergent origins prior to the invasion into South Africa has augmented genetic diversity in the region. The high dispersal rates and large effective population sizes inferred from genetic markers suggest that slowing the spread or reducing population abundances of the species in South Africa will be challenging without an integrated, multi-faceted management approach.

Restoration of an Indigenous aquaculture system can increase reef fish density and fisheries harvest in Hawai‘i

AbstractWhile aquaculture is increasingly considered a globally important source of protein, growing fish for human consumption is not new. Indigenous aquaculture systems, such as loko i‘a (fishponds), were successfully implemented in ancient Hawai‘i and represent a technological advancement designed to sustain a growing human population while maintaining—instead of supplanting—natural ecosystem function in the process of increasing food availability. Biocultural restoration efforts in Hawai‘i, aimed at revitalizing Indigenous stewardship, have included restoration of loko i‘a to sustainably increase the availability of local seafood. While it is clear from historical accounts that loko i‘a can augment fish within estuaries, their role as a nursery ground that supplements surrounding fish populations and fisheries harvest (i.e., providing spillover) remains unstudied in the current literature. This study aimed to test the extent to which loko i‘a restoration can supplement fish populations and fisheries harvest both inside the loko i‘a and in the surrounding waters. A food web model was constructed representing nutrients, phytoplankton, fish, and fisheries in three distinct habitats. The model, set in Kāne‘ohe Bay, O‘ahu, Hawai‘i, revealed that there were interactive effects of the area under loko i‘a management, bay fishing effort, and fish dispersal rates on fish density and fisheries harvest. We found that increasing the area under loko i‘a management not only increased loko i‘a fish density and fisheries harvest but also created the potential to supplement bay fish populations and fisheries harvest under certain scenarios. We also identified a trade‐off whereby at high fish dispersal rates, a larger area under loko i‘a management provided maximal benefits to the bay fish population and fisheries harvest, while at low fish dispersal rates, a smaller area under loko i‘a management was more beneficial to bay fish populations and harvest. As expected, loko i‘a also created a surplus of fish within the pond. Our results support the idea that restoration of Indigenous aquaculture systems can positively impact conservation efforts and food security by increasing local fish availability, through both direct production and supplementation of surrounding fish stocks.

High inter-population connectivity and occasional gene flow between subspecies improves recovery potential for the endangered Least Bell’s Vireo

Abstract Increasingly, genomic data are being used to supplement field-based ecological studies to help evaluate recovery status and trends in endangered species. We collected genomic data to address 2 related questions regarding the Least Bell’s Vireo (Vireo bellii), an endangered migratory songbird restricted to southern California riparian habitat for breeding. First, we sought to delineate the range limits and potential overlap between Least Bell’s Vireo and its sister subspecies, the Arizona Bell’s Vireo, by analyzing samples from the deserts of eastern California, southwestern Nevada, Utah, and Arizona. Second, we evaluated genetic structure among Least Bell’s Vireo populations in coastal California and estimated effective population size. Clustering analyses based on 10,571 single-nucleotide polymorphisms (SNPs) from 317 samples supported 2 major groups that aligned closely to the previously defined subspecies ranges. The first cluster included birds in the Central Valley, all coastal drainages, and westernmost deserts of California, with no further sub-structuring among coastal drainages. Almost all birds from the Amargosa River in eastern California and eastward assigned to the second cluster; however, low levels of gene flow were detected across the subspecies groups, with greater rates of gene flow from Arizona Bell’s Vireo to Least Bell’s Vireo than the reverse. Admixed individuals occurred in the California deserts; and although smaller than coastal populations, desert populations may be important for maintaining and replenishing genetic diversity and facilitating the movement of potentially adaptive genes between subspecies. Within Least Bell’s Vireo, local populations in coastal drainages comprised a single genetic population, with some evidence of close relatives distributed across drainages, suggesting that these could function as a well-connected metapopulation. These results are consistent with previous Least Bell’s Vireo banding studies that reported high rates of dispersal among drainages. Effective population size for both subspecies was high, suggesting that adaptive potential has been maintained despite previous declines.

Osmoregulatory Plasticity in Oreochromis niloticus-Nile Tilapia, and it’s Possible Estuary Use for Rivers Dispersion

Nile tilapia is a widely farmed species globally, due to its resistance to environmental challenges. Additionally, it is a generalist consumer and a prolific breeder. In Brazil, this fish is recognized as an invasive species because of its high dispersion and establishment rates, which compromise native biota. Estuarine waters (0.06 - 32‰) are being used in tilapia aquaculture, which is a promisor fish farming for euryahalinity species. The tilapia’s euryhalinity is well-know, but most protocols are based on gradual exposure. This research showed the tolerance of Nile tilapia on abrupt exposure to 0‰ (FW), and 10, 20, 30, 35 or 40‰, over in 6, 12 and 24 hours. An abrupt exposure resistance demonstrate that this fish can use estuaries to disperse for other watersheds. After experimental design the blood sample was taken after anesthesia was administered. Subsequently, fish was euthanized by spinal section, for muscle and gills samples collections. All samples were keep freezing until ionic, dehydration and enzyme measurement. Nile tilapia survived 24h until 30‰, 12h at 35‰ and 9h at 40‰. Osmolality increase and muscle dehydration decrease both above 20‰. While sodium levels keep regulated in all salinities, chloride, potassium and magnesium levels also increased above 20‰. These results prove that tilapia can easily tolerate abrupt exposure until 20‰ without an osmotic stressor. Gill carbonic anhydrase (C.A.) activity decreased at 30‰, and NKA did not change along salinities and times. These results complements plasma and dehydration averages, showing the large tolerance of this specie to salinity challenges, even in abrupt exposure. Then, these results can be used for discuss about the estuary fish farming system for tilapia, as this species may use estuarine waters to nearby rivers and also can harm the native ecosystem.

Tidal gradients, fine-scale homing and a potential cryptic ecotype of wild spawning pink salmon (Oncorhynchus gorbuscha).

The homing behaviour of salmon is a remarkable natural phenomenon, critical for shaping the ecology and evolution of populations yet the spatial scale at which it occurs is poorly understood. This study investigated the spatial scale and mechanisms driving homing as depicted by spawning site-choice behaviour in pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, Alaska. Molecular pedigree analyses of over 30,000 adult spawners in four streams revealed that pink salmon exhibit fine-scale site fidelity within a stream, returning to within <100 m of their parents. Homing behaviours were driven in part by a salinity gradient between intertidal and freshwater environments, with individuals incubated in freshwater environments more than twice as likely to spawn upstream of tidal influence than those incubated in the intertidal. Our findings challenge the traditional view that pink salmon populations are genetically and phenotypically homogenous due to their short freshwater residency as juveniles and high rates of dispersal as returning adults (i.e. straying). This study has important implications for rates of inbreeding, local adaptation and gene flow within populations, and is particularly relevant to the management of salmon hatcheries, given the high incidence of hatchery-origin pink salmon, reared in freshwater hatchery environments, that stray into wild populations of Prince William Sound.

Biogeographic patterns and environmental drivers of species richness in the globally distributed Millettioid/Phaseoloid clade (Fabaceae, subfamily Papilionoideae)

IntroductionThe Millettioid/Phaseoloid (MP) clade of Fabaceae is globally distributed, economically important, and highly diverse, making it an attractive system for studying biogeographic and macroecological patterns at a global scale. We conducted the first global macroecological study to map and explore the environmental drivers of the MP clade's species richness patterns.MethodsWe compiled 116,212 species occurrences (161 genera) for the MP clade and 20 environmental variables (19 bioclimatic variables and elevation). Geospatial analyses were performed to estimate species richness patterns and biogeographic heterogeneity. The effects of environmental variables on the species richness of the MP clade were measured through multiple regression models.ResultsOur study identified the megathermal regions as hotspots of species richness for the MP clade. While species distributions and richness largely fit the latitudinal diversity gradient pattern, there was a significant negative relationship between the species richness of the MP clade along the latitude and longitude. The Afrotropic biogeographic realm had the highest alpha diversity (~36%); in terms of biome types, tropical and subtropical moist broadleaf forests had the highest alpha diversity (25%), while the beta diversity revealed a high dispersal rate and habitat tracking. Furthermore, the species richness was positively influenced by multiple climatic factors, with the mean diurnal range of temperatures and precipitation in the warmest quarter having strongest influence.DiscussionOverall, the staggering species richness patterns could be explained by multiple diversity gradient hypotheses. Particularly, colder climates play a crucial role in shaping the species richness pattern by limiting the ecological opportunities for MP clade species in the higher latitudes of the Northern Hemisphere. This suggests that the species richness patterns of the MP clade can be described as "when dispersal meets adaptation." Our study provides a new basis for identifying priority regions for conservation of legumes.

High-efficiency PdNi single-atom alloy catalyst toward cross-coupling reaction

The preparation of Pd-based catalysts with rich electrons and a high atom dispersion rate is of great significance for improving the reactivity of cross-coupling reactions, which is a powerful tool for pharmaceutical and fine chemical synthesis. Here, we report a PdNi single-atom alloy (SAA) catalyst in which isolated Pd single atoms are anchored onto the surface of Ni nanoparticles (NPs) applied for Suzuki coupling reactions and Heck coupling reactions. The 0.1% PdNi SAA exhibits extraordinary catalytic activity (reaction rate: 17,032.25 mmol h−1 gPd−1) toward the Suzuki cross-coupling reaction between 4-bromoanisole and phenylboronic acid at 80 °C for 1 h. The excellent activity is supposed to attribute to the 100 percent utilization rate of Pd atoms and the highly stable surface zero-valance Pd atoms, which provides abundant sites and electrons for the adsorption and fracture of the C-X (X = Cl, Br, I) bond. Moreover, our work demonstrates the excellent application prospect of SAAs for cross-coupling reactions.

Colonization-persistence trade-offs in natural bacterial communities.

Fitness equalizing mechanisms, such as trade-offs, are recognized as one of the main factors promoting species coexistence in community ecology. However, they have rarely been explored in microbial communities. Although microbial communities are highly diverse, the coexistence of their multiple taxa is largely attributed to niche differences and high dispersal rates, following the principle 'everything is everywhere, but the environment selects'. We use a dynamical stochastic model based on the theory of island biogeography to study highly diverse bacterial communities over time across three different systems (soils, alpine lakes and shallow saline lakes). Assuming fitness equalization mechanisms, here we newly analytically derive colonization-persistence trade-offs, and report a signal of such trade-offs in natural bacterial communities. Moreover, we show that different subsets of species in the community drive this trade-off. Rare taxa, which are occasional and more likely to follow independent colonization/extinction dynamics, drive this trade-off in the aquatic communities, while the core sub-community did it in the soils. We conclude that equalizing mechanisms may be more important than previously recognized in bacterial communities. Our work also emphasizes the fundamental value of dynamical models for understanding temporal patterns and processes in highly diverse communities.

Spatial Habitat Structure Assembles Willow-Dependent Communities across the Primary Successional Watersheds of Mount St. Helens, USA

The eruption of Mount St. Helens in 1980 resulted in a cataclysmic restructuring of its surrounding landscapes. The Pumice Plain is one of these landscapes, where tree species such as Sitka willow (Salix sitchensis) and their dependent communities have been established along newly-formed streams. Thus, the study of these dependent communities provides a unique and rare opportunity to investigate factors influencing metacommunity assembly during true primary succession. We analyzed the influence of landscape connectivity on metacommunity assembly through a novel application of circuit theory, alongside the effects of other factors such as stream locations, willow leaf chemistry, and leaf area. We found that landscape connectivity structures community composition on willows across the Pumice Plain, where the least connected willows favored active flyers such as the western tent caterpillar (Malacosoma fragilis) or the Pacific willow leaf beetle (Pyrrhalta decora carbo). We also found that multiple levels of spatial habitat structure linked via landscape connectivity can predict the presence of organisms lacking high rates of dispersal, such as the invasive stem-boring poplar weevil (Cryptorhynchus lapathi). This is critical for management as we show that the maintenance of a heterogeneous mixture of landscape connectivity and resource locations can facilitate metacommunity dynamics to promote ecosystem function and mitigate the influences of invasive species.

Constraints to speciation despite divergence in an old haplochromine cichlid lineage.

Most of the 500+ cichlid species of Lake Victoria evolved very rapidly in the wake of an adaptive radiation within the last 15,000 years. All 500 species have evolved from just one out of five old cichlid lineages that colonized the lake. Endemic to the Lake Victoria region, Astatoreochromis alluaudi is a member of an old haplochromine lineage that never speciated in the region. Even though the species occurs in a wide range of habitats, there were no indications of evolutionary diversification. Here, we tested predictions of several hypothetical mechanisms that might constrain speciation, including high dispersal rates, a generalist life style and the lack of behavioral assortative mating. Genomic analyses of individuals from 13 populations revealed several genomically distinct groups, associated with major habitat classes, indicating the existence of two distinct ecotypes. We found significant phenotypic differences between these ecotypes in the wild, which were retained under common-garden conditions, potentially indicating heritable phenotypic adaptations. Female mate choice experiments revealed the absence of behavioral assortative mating despite genetic and phenotypic differentiation between ecotypes. We suggest that the lack of coupling between behavioral mating preferences and phenotypic and genetic divergence constrains speciation in this cichlid.

Population level genetic divergence and phylogenetic placement of Mexican shortfin mollies (Mollienesia: Poecilia: Poeciliidae)

Abstract Mexico is a megadiverse region with a complex geological history, but it remains unclear to what extent the distribution of freshwater fish has been influenced by geographic barriers. This study examines the population level genetic divergence and phylogenetic relationships of species in the shortfin group of the subgenus Mollienesia (genus Poecilia), a group of live-bearing fishes that are widely distributed across Mexico, with sampling at a small geographic scale. Samples from over 50 locations were analyzed for six species by using phylogenetic and haplotype network approaches to assess genetic diversity across geographic ranges and to refine the distributions of species in this group. The results indicate that Mexican species have diversified following multiple, independent invasions from Middle America. Two species found north of the Trans-Mexican Volcanic Belt (TMVB) and one transversal species exhibited weak phylogenetic structure, likely due to the lack of physiographic barriers, recent colonization, and high dispersal rates among regions. In contrast, three species found south of the TMVB exhibited strong phylogenetic structure, reflecting a longer presence in the area and multiple physiographic barriers that isolated populations. This study identified mechanisms driving divergence and speciation, expanded the known range of several species, and resolved taxonomic uncertainties of populations.

Nest survival and productivity of translocated and resident burrowing owls in Arizona

AbstractDevelopment activities associated with urbanization can directly displace animals, causing high mortality and dispersal rates. Wildlife managers have attempted to mitigate the impacts of development on burrowing owls (Athene cunicularia), a species susceptible to ground‐disturbing activities, by translocating them away from areas slated for development. In this study, we evaluated the effects of translocation on burrowing owl reproduction by comparing nest survival and productivity of owls involved in an ongoing translocation program in Arizona, USA, with that of resident owls. We used nest survival models to evaluate differences in nest survival and generalized linear models with Poisson error to assess differences in productivity. In 2017, cumulative nest survival (CNS) was lower among current‐year translocated owls (i.e., owls translocated within the last year; CNS = 0.34, 95% CI = 0.18, 0.51) compared to non‐translocated resident owls (0.83, 95% CI = 0.71, 0.94), but CNS was similar between previously translocated owls (i.e., those translocated &gt;1 yr ago, CNS = 0.81, 95% CI = 0.64, 0.98) and residents. Likewise, in 2018, CNS was lower for current‐year translocated owls (CNS = 0.12, 95% CI = 0.00, 0.24) compared to residents (CNS = 0.68, 95% CI = 0.50, 0.87) and previously translocated owls (CNS = 0.65, 95% CI = 0.40, 0.90). Productivity was significantly lower for current‐year translocated owls ( = 0.5 fledglings/nest) compared to residents ( = 2.4 fledglings/nest) and previously translocated owls ( = 1.5 fledglings/nest) across sites and years. With the current methods of translocation, owls had poor reproductive success in the first year after release, but if they survived 2 years after release, they had similar nest survival and productivity compared to residents. Our results demonstrate that the current practice of releasing translocated burrowing owls in the Phoenix, Arizona area during the breeding season depresses reproduction and should be substantially changed. Nest survival was low and this was mainly attributed to nest establishment of translocated owls within release tents (acclimation structures used in translocations that involve soft release) where 85% of nests failed following tent removal. Translocation approaches that reflect a closer fit to the timing and behavior of the species should be tested to determine whether they result in better success. In particular, future studies should examine the translocation results of releasing owls as male‐female pairs or single birds during the nonbreeding period.

High dispersal rates in hybrids drive expansion of maladaptive hybridization

Hybridization between native and invasive species, a major cause of biodiversity loss, can spread rapidly even when hybrids have reduced fitness. This paradox suggests that hybrids have greater dispersal rates than non-hybridized individuals, yet this mechanism has not been empirically tested in animal populations. Here, we test if non-native genetic introgression increases reproductive dispersal using a human-mediated hybrid zone between native cutthroat trout (&lt;i&gt;Oncorhynchus clarkii&lt;/i&gt;) and invasive rainbow trout (&lt;i&gt;Oncorhynchus mykiss&lt;/i&gt;) in a large and connected river system. We quantified the propensity for individuals to migrate from natal rearing habitats (migrate), reproduce in non-natal habitats (stray), and the joint probability of dispersal as a function of genetic ancestry. Hybrid trout with predominantly non-native rainbow trout ancestry were more likely to migrate as juveniles and to stray as adults. Overall, hybrids with greater than 50% rainbow trout ancestry were 5.7 times more likely to disperse than native or hybrid trout with small amounts of rainbow trout ancestry. Our results show a genetic basis for increased dispersal in hybrids that is likely contributing to the rapid expansion of invasive hybridization between these species. Management actions that decrease the probability of hybrid dispersal may mitigate the harmful effects of invasive hybridization on native biodiversity.

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

Accelerated invasion through the evolution of dispersal behaviour

AbstractAimThe continuous spread of invasive species is attributed to demographic processes and high dispersal rates. Both can change and evolve during range expansion, eventually accelerating spread dynamics. Here, we document such an accelerated spread for one of the most invasive spiders in Europe, the dwarf spider Mermessus trilobatus, and test whether dispersal, reproduction or competitive ability is at the source of this pattern.LocationEurope.Time period1981–2021.Major taxon studiedMermessus trilobatus (Arachnida: Araneae: Linyphiidae).MethodsFirst, we collected records from 21 countries across Europe to document the speed of progression of the invasion front over the last 40 years. Second, we collected live individuals from populations in the longest and more recently invaded areas and compared the dispersal propensity of offspring raised under standardized conditions. Third, we compared the reproduction and competitive ability of females derived from the populations of long‐invaded areas against areas with more recent establishment.ResultsThe progression of the invaded range increased from about 150 km in the 1980s to some 400 km between 2010 and 2020. Dispersal‐related behaviour was nearly twice as frequent in offspring from invasion front populations compared to the core area. By contrast, we found no differences in reproduction or competitive ability among the studied populations. Further, neither joint inheritance nor trade‐offs of dispersal, reproduction or competitive ability were identified.Main conclusionAs high dispersal is recessively inherited in M. trilobatus, our results suggest that the accelerated invasion is due to the accumulation of dispersive but not more reproductive or competitive genotypes in newly colonized areas. Given the high climatic amplitude of the species in North America, we expect it to spread over the remaining parts of Europe and large parts of Asia in the coming decades. Accelerated range expansion through the evolution of dispersal behaviour could play a role in numerous arthropod invasions worldwide.

A spatially implicit model fails to predict the structure of spatially explicit metacommunities under high dispersal

Metacommunities are the product of species dispersal and topology. Metacommunity studies often use spatially implicit models, implemented by fully connected topologies, in which the precise spatial arrangement of habitat patches is not specified. Few studies use spatially explicit models, even though real-world metacommunities are likely structured by topology. Here, we test whether a spatially implicit resource consumption model based on a fully connected topology could predict the structure of spatially explicit metacommunities. Having controlled for environmental heterogeneity, we focus specifically on the effects of species dispersal and topology on metacommunity structure. We classified the topologies according to the shortest path between the most distant nodes (i.e. the graph diameter). Topologies with small diameters are tightly connected, whereas large diameter graphs are loosely connected. Some general trends emerged with increasing dispersal rate, such as a hump-shaped pattern in α-diversity, and a plateau followed by a decline in γ- diversity. However, the importance of topology was also apparent: α-diversity peaked at low dispersal rates in small diameter topologies, but at high dispersal rates in large diameter topologies. At low dispersal rates, α-diversity was higher in spatially implicit than in spatially explicit metacommunities. At medium dispersal we detected stronger species sorting in the small diameter than in the large diameter topologies. Increasing dispersal caused α-diversity to decline more dramatically in small diameter topologies. Smaller metacommunities were dominated by regional competitors, whereas larger communities exhibited patterns of species biomass distribution leading to emergent niche structures. Increasing dispersal caused the mean productivity of each patch to undergo partial declines in spatially implicit metacommunities but continue to decline sharply in spatially explicit metacommunities. We conclude that spatially implicit models should be used cautiously when predicting the biodiversity, community composition or ecosystem functions of spatially explicit metacommunities at medium, and especially at high dispersal rates.

Extensive gene flow in a threatened bat (Rhinonicteris aurantia) in an arid landscape

The bat fauna of Australia comprises some 25% of all terrestrial species, yet we know very little of the demography, dispersal, and movement dynamics of most bat species. The Pilbara leaf-nosed bat ( Rhinonicteris aurantia Pilbara form) is a threatened microbat that roosts exclusively in caves that occur in mineral rich deposits in the Pilbara region. Due to their specific roost microclimate requirements these bats cannot survive for long without a suitable roost and are sensitive to roost disturbance. Understanding the connectivity of roosts throughout the Pilbara is crucial for informed decisions to mitigate potential impacts to persistence of this species in areas under economic development. Along with mitochondrial DNA (mtDNA) markers, we used reduced representation genomic sequencing of over 150 individuals from eight roost sites throughout the Pilbara and tested for landscape-scale population differentiation associated with the two major subregions — the Hamersley and Chichester, as well as finer-scale among roost variation. We found evidence of high rates of dispersal and low population structure within the Pilbara, indicating one panmictic population, with mtDNA results suggesting evidence of some female philopatry. Our results highlight the ongoing need for detailed genetic studies to provide critical insight to species dispersal, particularly in multi-use landscapes. We discuss the importance of identifying and retaining connectivity of key habitat to maintain genetic diversity and gene flow throughout panmictic populations.