Patterns Of Range Expansion Research Articles

Isolation by environment and its consequences for range shifts with global change: Landscape genomics of the invasive plant common tansy.

Invasive species are a growing global economic and ecological problem. However, it is not well understood how environmental factors mediate invasive range expansion. In this study, we investigated the recent and rapid range expansion of common tansy across environmental gradients in Minnesota, USA. We densely sampled individuals across the expanding range and performed reduced representation sequencing to generate a dataset of 3071 polymorphic loci for 176 individuals. We used non-spatial and spatially explicit analyses to determine the relative influences of geographic distance and environmental variation on patterns of genomic variation. We found no evidence for isolation by distance but strong evidence for isolation by environment, indicating that environmental factors may have modulated patterns of range expansion. Land use classification and soils were particularly important variables related to population structure although they operated on different spatial scales; land use classification was related to broad-scale patterns and soils were related to fine-scale patterns. All analyses indicated a distinctive genetic cluster in the most recently invaded portion of the range. Individuals from the far northwestern range margin were separated from the remainder of the range by reduced migration, which was associated with environmental resistance. This portion of the range was invaded primarily in the last 15 years. Ecological niche models also indicated that this cluster was associated with the expansion of the niche. While invasion is often assumed to be primarily influenced by dispersal limitation, our results suggest that ongoing invasion and range shifts with climate change may be strongly affected by environmental heterogeneity.

Distribution widening of a ground-nesting social bee across Europe favored by climate change and urban setting

Climate change and/or land use change were repeatedly reported as important for both range expansion of alien bee species and range shrinking for native bee species. However, environmental changes may also positively affect native species that may expand across contiguous areas to their native ones. Here, we focused on Halictus scabiosae (Rossi, 1790) (Hymenoptera: Halictidae), a ground-nesting, primitively eusocial wild bee that has its primary distribution in Western-Southern Europe but that was recently recorded in Eastern-Central Europe. In particular, we studied the range expansion patterns of H. scabiosae, and we hypothesized that previously unsuitable areas may be currently colonized because of environmental changes. In the last 5 years, H. scabiosae moved its densest record areas to North-Eastern Europe, but its ecological niche remained almost unchanged from 1970 to date, suggesting that this bee species is following its preferred conditions (high temperature, high temperature seasonality, and low precipitation seasonality). Potential distribution models revealed high suitability in still unoccupied North-Eastern areas, with urbanization increasingly important as potential stepping stones towards the expansion. The relevant role of urbanization is confirmed by the increase in the number of urban records through time and by the fact that cities with greater population density and greater fragmentation are more likely associated with this species’ occurrence. Halictus scabiosae is thus expanding its range because climate change is producing—and urban environment is offering—suitable conditions in areas previously inadequate for its establishment.

First Record of Tricolored Blackbirds in Idaho

Over 99% of Tricolored Blackbirds (Agelaius tricolor) occur in California. However, small populations persist in Oregon, Washington, Nevada, and Baja California. Loss of wetlands that historically served as foraging and breeding habitat has led to their increasing use of agricultural landscapes including silage fields and cattle feedlots. Here we provide the first documentation of the Tricolored Blackbird in Idaho (26 March–13 May and 3 November–16 December 2023), of up to 30 birds observed at five different locations associated with cattle feedlots, each 10–15 km apart, in Payette and Gem counties. Seven observations included recordings of vocalizations (3-23 April and 14 December 2023), largely coinciding with the final observations at each location, presumably before dispersal to breeding grounds. We consider three hypotheses to explain the apparently sudden occurrence of these birds, including their return to some of the same sites in November 2023: (1) a continued pattern of range expansion due to climate change; (2) an undetected long-term population due to low survey effort; or (3) a large-scale movement in response to flooding and extreme weather in the traditional range. We encourage continued monitoring and surveying of these locations in the coming years and surveying for both new wintering locations and for evidence of the Tricolored Blackbird breeding in Idaho.

Predicting the spatio-temporal pattern of range expansion under lack of equilibrium with climate

Early detection of invasive species in regions under threat is key for biodiversity conservation. Here we conduct a retrospective study to assess whether correlative Species Distribution Models (SDMs) can predict the spatio-temporal range of expansion in an invasive species, the Asian hornet. Given that modelling invasive species distributions defies one of the main assumptions of SDMs, the equilibrium with climate, we also introduce a quantitative assessment of climatic disequilibrium in the invaded area based on hypervolume comparison between the native and invaded areas (both unoccupied and occupied territories). We evaluate the ability of three different modelling approaches (presence-only, presence-background and presence-absence) calibrated with data until 2013 to predict the species distribution observed the following years (2015, 2017, 2019, and 2021). Our results show that presence-only models based on the BIOCLIM algorithm can effectively predict the spatio-temporal pattern of invasion when predictions are rescaled based on percentiles (i.e. ranked suitability) and the model is calibrated with data from both native and invaded areas. These models predicted higher suitability values for sites that were invaded earlier in time and, importantly, they did not predict low suitability values for sites that were eventually occupied years later. Thus, they can be very useful for decision-makers and managers, as they provide a probabilistic prediction of both (i) the temporal dimension of species range expansion, and (ii) the potential distribution range in the long term. Such information would allow prioritizing monitoring efforts in the short term without losing sight of the potential risks in the long term.

Anthropogenic driven range expansion of Asian elephant Elephas maximus in an agricultural landscape and its consequences in South West Bengal, India

Alterations of the geographical ranges of animals have become a reason for interactions with humans, leading to various consequences. We describe the pattern of range expansion of Asian elephants (Elephas maximus) and implications for human-elephant interactions in the agricultural landscape of South West Bengal, India. We enquired about past and current sightings of Asian elephants from local people to gather information on range expansion from the 1950 s to 2018. We also collected the records of human deaths and injuries by elephants from 2010 to 2018 from the records of the Forest Department. We employed an occupancy framework to understand the probability of the occurrence of elephants in the landscape from 2010 to 2018. The range of elephants in the landscape increased from ∼ 1200 km2 in the 1950–60 s to ∼ 13200 km2 by 2010–18. The calculated probability of use of grid cells was 36 % and the forest edge had a high influence on the space usage by the elephants. Elephants occurred in an average of 26 grid cells per month, and the number of grid cells with elephants did not differ between the months. A total of 640 attacks on humans occurred, which significantly varied between the years. The probability of elephant occurrence in a grid cell was the major determinant factor for the elephant attacks on humans. Although people respect elephants, there is a sense of intolerance towards them if they enter the crop fields, owing to the small land holdings and the incapacity to endure the monetary losses of the farmers.

Inferring past refugia and range dynamics through the integration of fossil, niche modelling and genomic data

AbstractAimReconstructing species' glacial refugial history and demographic changes over time has greatly relied on comparing inferences from multiple methods while not sufficiently acknowledging their limitations. Here, we aim to integrate as fully as possible complementary methods in ecology, genomics and palaeobiology to improve the reconstruction of species biogeographical history.LocationSouth‐western Europe.TaxonCabrera vole (Microtus cabrerae).MethodsWe compiled and mapped the raw fossil data of the Cabrera vole for the Last Glacial Maximum (LGM) and Mid‐Holocene (MH). Alongside, we projected the calibrated ecological niche model (ENM) of the species' current distribution for the LGM, the Younger Dryas and the MH. Complementarily, we used previously obtained Genotyping‐by‐Sequencing data to evaluate the demographic history and range expansion patterns of all four Evolutionarily Significant Units of the species, in an integrative framework.ResultsENM‐inferred refugial areas and genomic modelling consistently supported northern Iberian glacial refugia for the Cabrera vole. This contrasted with the higher fossil abundance of the species in southern and eastern Iberia and southern France from the LGM to the MH. Our results suggest that populations in areas with high fossil abundance went extinct, and were later replaced by northern Iberian populations such that they did not contribute significantly to the current gene pool.Main conclusionsOur integrative approach indicates how the range of the Cabrera vole fluctuated in response to environmental change during and following the LGM. Despite methodological limitations, the ENM and genomic approaches produced generally congruent results. Instead, the fossil record may misrepresent the ancestral distribution of this species and should be considered cautiously for ancestral distribution reconstruction, considering that it also reflects the fossilization conditions. Overall, our study supports the idea that integrative approaches are essential to provide an accurate and well‐supported picture of historical refugial areas and range dynamics.

Spatial Variation of Acanthophlebia cruentata (Ephemeroptera), a Mayfly Endemic to Te Ika-a-Māui-North Island of Aotearoa, New Zealand.

Simple SummaryPatterns of variation within a widespread species can provide evidence of population history. Adjacent stable populations with gene flow show clinal genetic divergence forming a pattern of isolation by distance. Populations that have grown due to an increase in potential habitat such as forest cover since the last glacial maximum will have low genetic variation showing patterns of range expansion. The mayfly Acanthophlebia cruentata of Aotearoa, New Zealand, is widespread in streams of North Island but absent from the cooler South Island. Mayfly nymphs are restricted to streams but adults fly, facilitating gene flow among catchments. We detected higher genetic diversity at lower latitudes of this mayfly’s range compared to most of its distribution, concordant with predictions of limited forest cover in New Zealand during Pleistocene glacial periods. A signature of recent range expansion was observed in the higher latitudes. Despite initial observation suggesting mayfly size correlated with latitude, we found sex, elevation and sampling date were significant predictors of size, and some size variation is also explained by three regional groups based on haplotype distribution.The mayfly Acanthophlebia cruentata of Aotearoa, New Zealand, is widespread in Te Ika-a-Māui North Island streams, but has never been collected from South Island despite land connection during the last glacial maximum. Population structure of this mayfly might reflect re-colonisation after volcanic eruptions in North Island c1800 years ago, climate cycling or conceal older, cryptic diversity. We collected population samples from 33 locations to estimate levels of population genetic diversity and to document phenotypic variation. Relatively low intraspecific haplotype divergence was recorded among mitochondrial cytb sequences from 492 individuals, but these resolved three geographic-haplotype regions (north, west, east). We detected a signature of isolation by distance at low latitudes (north) but evidence of recent population growth in the west and east. We did not detect an effect of volcanic eruptions but infer range expansion into higher latitudes from a common ancestor during the last glacial period. As judged from wing length, both sexes of adult mayflies were larger at higher elevation and we found that haplotype region was also a significant predictor of Acanthophlebia cruentata size. This suggests that our mitochondrial marker is concordant with nuclear genetic differences that might be explained by founder effect during range expansion.

Drivers of genetic differentiation and recent evolutionary history of an Eurasian wild pea

AbstractAimGenetic diversity is a major determinant for the capacity of species to persist and adapt to their environments. Unravelling the factors affecting genetic differentiation is crucial to understand how genetic diversity is shaped and species may react to changing environments. We investigated the drivers of genetic differentiation and their interplay with the evolutionary history in a wild pea to test how those may have affected the distribution of genetic diversity.LocationMediterranean basin, western Asia.TaxonPisum sativum (Fabaceae).MethodsWe employed restriction site associated DNA (RAD) sequencing of a collection of 81 wild pea samples. The influence of environmental factors on genetic differentiation was tested by estimating the association of these factors and genetic variation using gradient forest analysis. Stairwayplots were used to estimate past effective population sizes and clines of allele frequencies were analysed to detect past expansion patterns. Association of single nucleotide polymorphisms with environmental variables was tested to find signatures of local adaptation.ResultsThe effect of the tested factors influencing genetic differentiation was variable among genetic clusters. Climate predictors were most important in all clusters. Land cover was more important in clusters from areas strongly influenced by human land use. We found statistically significant associations of 3623 SNPs with environmental variables. Most of these SNPs were correlated with latitude followed by temperature. Wild peas went through a genetic bottleneck during the last glacial period followed by population recovery. The detected range expansion patterns suggested an eastward range expansion of the European cluster to Turkey and thereof southwards and eastwards.Main conclusionDrivers of genetic differentiation do not act in a uniform manner within a species. The distribution of genetic variation and the processes affecting this distribution have to be viewed in the context of the hierarchical structure of genetic variation and the environment of its entities to understand how genetic diversity was shaped and may change in the future.

RangeShifter 2.0: an extended and enhanced platform for modelling spatial eco‐evolutionary dynamics and species' responses to environmental changes

Process‐based models are becoming increasingly used tools for understanding how species are likely to respond to environmental changes and to potential management options. RangeShifter is one such modelling platform, which has been used to address a range of questions including identifying effective reintroduction strategies, understanding patterns of range expansion and assessing population viability of species across complex landscapes. Here we introduce a new version, RangeShifter 2.0, which incorporates important new functionality. It is now possible to simulate dynamics over user‐specified, temporally changing landscapes. Additionally, we integrated a new genetic module, notably introducing an explicit genetic modelling architecture, which allows for simulation of neutral and adaptive genetic processes. Furthermore, emigration, transfer and settlement traits can now all evolve, allowing for sophisticated simulation of the evolution of dispersal. We illustrate the potential application of RangeShifter 2.0's new functionality by two examples. The first illustrates the range expansion of a virtual species across a dynamically changing UK landscape. The second demonstrates how the software can be used to explore the concept of evolving connectivity in response to land‐use modification, by examining how movement rules come under selection over landscapes of different structure and composition. RangeShifter 2.0 is built using object‐oriented C++ providing computationally efficient simulation of complex individual‐based, eco‐evolutionary models. The code has been redeveloped to enable use across operating systems, including on high performance computing clusters, and the Windows graphical user interface has been enhanced. RangeShifter 2.0 will facilitate the development of in‐silico assessments of how species will respond to environmental changes and to potential management options for conserving or controlling them. By making the code available open source, we hope to inspire further collaborations and extensions by the ecological community.

Modeling potential hotspots of invasive Prosopis juliflora (Swartz) DC in India

Prosopis juliflora (Swartz) DC has become one of the world's 100 most dominant invasive species. It is spreading quickly in different parts of the country leading to growing public concern. Effective management of invasive plants requires information regarding their spatial distributions and identifying areas vulnerable to Invasive Alien Plant Species (IAPS). This study combines Worldclim bioclimatic data with Global Biodiversity Information Facility (GBIF) and Indian biodiversity portal mediated occurrence points to model climatic suitability for P. juliflora in India under current and future climatic conditions using MaxEnt. For evaluating the importance of the environmental variables for predictive modeling, the Jack-knife test was performed. MaxEnt model was highly accurate with a statistically significant AUC value of 0.92. We observed that a larger extent of the Indian landscape currently invaded will remain suitable for P. juliflora growth and patterns of range expansion will take place soon unless management measures are initiated. Some states of North, North-western, and Southern India are projected to have higher climatic suitability for P. juliflora in the future. The findings of this study could be used as an early warning tool for the environmental monitoring of the areas which are highly vulnerable to the invasion of the species.

Influence of niche breadth and position on the historical biogeography of seafaring scincid lizards

AbstractNiche breadth and position can influence diversification among closely related species or populations, yet limited empirical data exist concerning the predictability of the outcomes. We explored the effects of these factors on the evolution of the Emoia atrocostata species group, an insular radiation of lizards in the western Pacific Ocean and Indo-Australasia composed of both endemic and widespread species that differ in niche occupancy. We used molecular data and phylogeographical diffusion models to estimate the timing and patterns of range expansion, and ancestral reconstruction methods to infer shifts in ecology. We show evidence of multidirectional spread from a centre of origin in western Micronesia, and that the phyletic diversity of the group is derived from a putative habitat specialist that survives in the littoral zone. This species is composed of paraphyletic lineages that represent stages or possible endpoints in the continuum toward speciation. Several descendant species have transitioned to either strand or interior forest habitat, but only on remote islands with depauperate terrestrial faunas. Our results suggest that the atrocostata group might be in the early phases of a Wilsonian taxon cycle and that the capacity to tolerate salt stress has promoted dispersal and colonization of remote oceanic islands. Divergence itself, however, is largely driven by geographical isolation rather than shifts in ecology.

Genetic analysis of invasive populations of Ventenata dubia (Poaceae): an assessment of propagule pressure and pattern of range expansion in the Western United States

Molecular markers prove to be an invaluable tool in assessing the introduction dynamics, pattern of range expansion, and population genetics of an invasive species. Ventenata dubia (Leers) Coss. (Aveneae; ventenata) is a diploid, primarily self-pollinating, annual grass native to Eurasia and Northern Africa. The grass has a detailed herbarium collection history in the western United States since its discovery in eastern Washington in 1952. Genetic analysis of 51 invasive populations (1636 individuals) of V. dubia, coupled with historical records, suggests moderate propagule pressure from multiple introductions, followed by local or regional range expansion. Allozyme analysis detected nine multilocus genotypes (MLGs) across eight western US states. A single MLG, referred to as the most common genotype, was detected in 37 of 51 (72.5%) invasive populations across all states. The other eight MLGs were generally found in fewer populations, with limited geographic distributions. Despite multiple introductions, invasive populations exhibit low levels of genetic admixture, low levels of genetic diversity within populations (A = 1.03, %P = 2.94, Hexp = 0.007) and high genetic differentiation among populations (GST= 0.864). The apparent reduced evolutionary potential of most V. dubia populations did not preclude the initial establishment and rapid spread of this species across its new range in the western US.

Current and future climatic regions favourable for a globally introduced wild carnivore, the raccoon Procyon lotor

Invasive species are considered as one of the major threats to biodiversity and represent a major challenge in the conservation of natural ecosystems, in preventing damage to agricultural production, and human health risks. Environmental Niche Modelling has emerged as a powerful tool to predict the patterns of range expansion of non-native species and to direct effective strategies for managing biological invasions. The raccoon, Procyon lotor, is a wild mesocarnivore presenting a high adaptability and showing successful introduced populations worldwide. Here, we modelled the current and future climatically favourable areas for the raccoon using two protocols, based on data sets filtrated in geographic and environmental spaces. Projections from these models show extensive current favourable geographical areas covering extensive regions of temperate biomes. Moreover, predictions for 2050 reveals extensive new favourable areas north of the current favourable regions. However, the results of the two modeling approaches differ in the extent of predicted favourable spaces. Protocols using geographically filtered data present more conservative forecasts, while protocol using environmental filtration presents forecasts across greater areas. Given the biological characteristics and the ecological requirements of a generalist carnivore such as the raccoon, the latter forecasts appears more relevant and should be privileged in the development of conservation plans for ecosystems.

Late Pleistocene range expansion of North American topminnows accompanied by admixture and introgression

AbstractAimWe used genome‐scale sampling to assess the phylogeography of a group of topminnows in the Fundulus notatus species complex. Two of the species have undergone extensive range expansions resulting in broadly overlapping distributions, and sympatry within drainages has provided opportunities for hybridization and introgression. We assessed the timing and pattern of range expansion in the context of late Pleistocene–Holocene drainage events and evaluated the evidence for introgressive hybridization between species.LocationCentral and southern United States including drainages of the Gulf of Mexico Coastal Plain and portions of the Mississippi River drainage in and around the Central Highlands.TaxonTopminnows, Genus Fundulus, subgenus Zygonectes—Fundulus notatus, Fundulus olivaceus, Fundulus euryzonus.MethodsWe sampled members of the F. notatus species complex throughout their respective ranges, including numerous drainage systems where species co‐occur. We collected genome‐wide single nucleotide polymorphisms (SNPs) using the genotype‐by‐sequencing (GBS) method and subjected data to population genetic analyses to infer the population histories of both species, including explicit tests for admixture and introgression. The methods employed included STRUCTURE, principal coordinates analysis, TreeMix and approximate Bayesian computation.ResultsGenetic data are presented for 749 individuals sampled from 14 F. notatus, 20 F. olivaceus and 2 F. euryzonus populations. Members of the species complex differed in phylogeographic structure, with F. notatus exhibiting geographic clusters corresponding to Pleistocene coastal drainages and F. olivaceus comparatively lacking in phylogeographic structure. Evidence for interspecific introgression varied by drainage.Main conclusionsPopulations of F. notatus and F. olivaceus exhibited contrasting patterns of lineage diversity among coastal drainages, indicating interspecific differences in their Pleistocene southern refugia. Phylogeographic patterns in both species indicated that range expansions into the northern limits of contemporary distributions coincided with and continued subsequent to the Last Glacial Maximum. There was evidence of introgression between species in some, but not all drainages where the species co‐occur, in a pattern that is correlated with previous estimates of hybridization rates.

Assessing the complex relationship between landscape, gene flow, and range expansion of a Mediterranean carnivore

Landscape resistance is often disregarded in studies of range expansions and population connectivity. To assess those effects, we simulated the expansion of the Egyptian mongoose (Herpestes ichneumon) in relation to landscape resistance through kernel resistance modeling, confronting it with previously published data regarding the observed pattern of expansion and genetic diversity of the population in Portugal. We modeled population expansion as a function of shrub cover and elevation through iterative simulation of a resistance model and a null model. We then performed an overlap analysis to assess the congruence between the observed pattern of expansion and both resistance and null models across 30 years. We also tested whether there is an effect of allelic surfing or the central-marginal hypothesis by correlating observed allelic richness (1) with the number of simulated years that each location with sampled genotypes had been occupied by the mongoose population and (2) with the cumulative resistant kernel density (which is a measure of population centrality). Results indicated a higher similarity between observed range expansion and the simulation using the null model and a marginally significant correlation between observed allelic richness and number of years of the simulated presence of the species in the null model. The pattern of range expansion in this population is most consistent with a neutral model of uniform resistance, and genetic diversity is most correlated with null model as well. This suggests that range expansion and genetic diversity patterns in expanding populations may not always be predicted by landscape resistance models developed through association of observed genetic differentiation with landscape features.

Brown rat demography reveals pre-commensal structure in eastern Asia before expansion into Southeast Asia.

Fossil evidence indicates that the globally distributed brown rat (Rattus norvegicus) originated in northern China and Mongolia. Historical records report the human-mediated invasion of rats into Europe in the 1500s, followed by global spread because of European imperialist activity during the 1600s–1800s. We analyzed 14 genomes representing seven previously identified evolutionary clusters, and tested alternative demographic models to infer patterns of range expansion, divergence times, and changes in effective population (Ne) size for this globally important pest species. We observed three range expansions from the ancestral population that produced the Pacific (diverged ∼16.1 kya), eastern China (∼17.5 kya), and Southeast (SE) Asia (∼0.86 kya) lineages. Our model shows a rapid range expansion from SE Asia into the Middle East and then continued expansion into central Europe 788 yr ago (1227 AD). We observed declining Ne within all brown rat lineages from 150–1 kya, reflecting population contractions during glacial cycles. Ne increased since 1 kya in Asian and European, but not in Pacific, evolutionary clusters. Our results support the hypothesis that northern Asia was the ancestral range for brown rats. We suggest that southward human migration across China between the 800s–1550s AD resulted in the introduction of rats to SE Asia, from which they rapidly expanded via existing maritime trade routes. Finally, we discovered that North America was colonized separately on both the Atlantic and Pacific seaboards, by evolutionary clusters of vastly different ages and genomic diversity levels. Our results should stimulate discussions among historians and zooarcheologists regarding the relationship between humans and rats.

Environmental niche unfilling but limited options for range expansion by active dispersion in an alien cavity-nesting wasp

BackgroundPredicting the patterns of range expansion of alien species is central to develop effective strategies for managing potential biological invasions. Here, we present a study on the potential distribution of the American cavity-nesting, Orthoptera-hunting and solitary wasp, Isodontia mexicana (Hymenoptera: Sphecidae), which was first detected as alien species in France in 1960 and now is present in many European countries. After having updated its current distribution, we estimated the environmental space (based on bioclimatic data and altitude) occupied by the species and subsequently predicted its environmental potential distribution under both present and future climatic conditions at global scale.ResultsThe wasp lives in low-altitude areas of the Northern hemisphere with moderate temperatures and precipitation. The environmental space occupied in the invaded area is practically just a subset (42%) of that occupied in the native area, showing a process of environmental niche unfilling (i.e. the species only partially fills its environmental niche in the invaded range). Besides, I. mexicana could also live in other temperate areas, mainly in the Southern hemisphere, particularly close to the coasts. However, geographic (oceans) and/or climatic (tropical areas, mountain chains) barriers would prevent the species to reach these potential areas unless through human trade activity. The species could thus only reach, by active dispersion, the remaining invadable areas of Europe. Estimations for the future (2050 and 2070) predict an expansion through active dispersion towards North in the native range and towards North and East in the invaded range, but future conditions would not break down the current climatic barriers in the Southern hemisphere.ConclusionsIsodontia mexicana has not shifted its environmental niche in the invaded area. It could still occupy some new areas by active dispersion, but confined to Europe. The conspicuous niche unfilling shown by this wasp species could reflect the likely single introduction in Europe just a few decades ago. Furthermore, results stay in line with other studies that found niche unfilling rather than niche expansion in insects.

Supervised forecasting of the range expansion of novel non‐indigenous organisms: Alien pest organisms and the 2009 H1N1 flu pandemic

AbstractAimWe propose a simple supervised method for forecasting the expansion of the geographical range of non‐indigenous species without any detailed information on the pathway mechanisms. The models currently used, such as metapopulation models, population dynamics [e.g., the susceptible‐infected‐recovered (SIR) model] with diffusion process, and models using individual‐based mechanisms, require specific parameters according to the assumed mechanisms. These parameters are difficult to obtain immediately after the first infestation is detected, although subsequent pandemics of novel pathogens and non‐indigenous pest organisms can be fatal to humans and damage agriculture and native ecosystems.InnovationA simple machine‐learning approach was developed. The future distribution of the target species was predicted by composing the spreading patterns of the previous range expansions of various alien species similar to the target species. A matrix representing the early–late relationship of infestation between regions was used to compare and compose various range expansion patterns. The eigenvector of the composed matrix gives the predicted order of infestation. Spreading speed was considered using the standard deviation of infestation dates, and future infestation dates were calculated by a reduced major axis with the eigenvector. In the feasibility assessment, the study area (Japan) was divided into many small regions (prefectures), and the dates of infestation in these regions were predicted. Our method successfully predicted the infestation dates of various alien species and the novel H1N1 influenza pandemic in 2009.Main conclusionsOur method is less complex and requires simpler information than other methods and is applicable to all organisms. Constructing a database of the range expansions of alien species, including novel pathogens and agricultural and environmental pests, at the global level and with high spatial resolution, such as at the county or city level, will facilitate the prediction of future range expansions of hazardous organisms.

Spatial genetic patterns indicate mechanism and consequences of large carnivore cohabitation within development.

Patterns of human development are shifting from concentrated housing toward sprawled housing intermixed with natural land cover, and wildlife species increasingly persist in close proximity to housing, roads, and other anthropogenic features. These associations can alter population dynamics and evolutionary trajectories. Large carnivores increasingly occupy urban peripheries, yet the ecological consequences for populations established entirely within urban and exurban landscapes are largely unknown. We applied a spatial and landscape genetics approach, using noninvasively collected genetic data, to identify differences in black bear spatial genetic patterns across a rural‐to‐urban gradient and quantify how development affects spatial genetic processes. We quantified differences in black bear dispersal, spatial genetic structure, and migration between differing levels of development within a population primarily occupying areas with >6 houses/km2 in western Connecticut. Increased development disrupted spatial genetic structure, and we found an association between increased housing densities and longer dispersal. We also found evidence that roads limited gene flow among bears in more rural areas, yet had no effect among bears in more developed ones. These results suggest dispersal behavior is condition‐dependent and indicate the potential for landscapes intermixing development and natural land cover to facilitate shifts toward increased dispersal. These changes can affect patterns of range expansion and the phenotypic and genetic composition of surrounding populations. We found evidence that subpopulations occupying more developed landscapes may be sustained by male‐biased immigration, creating potentially detrimental demographic shifts.

Molecular population structure for feral swine in the United States

ABSTRACTFeral swine (Sus scrofa) have invaded most of the United States and continue to expand throughout North America. Given the ecological and economic threats posed by increasing feral swine abundance, it is imperative to develop an understanding of their patterns of natural range expansion and human‐mediated introductions. Towards this goal, we used molecular markers to elucidate the genetic structure of feral swine populations throughout the United States and evaluated the association between historical introductions and contemporary patterns of genetic organization. We used STRUCTURE and discriminant analysis of principal components (DAPC) to delineate genetic clusters for 959 individuals genotyped at 88 single nucleotide polymorphism loci. We identified 10 and 12 genetic clusters for the 2 clustering approaches, respectively. We observed strong agreement in clusters across approaches, with both describing clusters having strong geographic association at regional levels reflecting past introduction and range expansion patterns. In addition, we evaluated patterns of isolation by distance to test for and estimate spatial scaling of population structure within western, central, and eastern regions of North America. We found contrasting spatial patterns of genetic relatedness among regions, suggesting differences in the invasion process, likely as a result of regional variation in landscape heterogeneity and the influence of human‐mediated introductions. Our results indicate that molecular analyses of population genetic structure can provide reliable insights into the invasion processes of feral swine, thus providing a useful basis for management focused on minimizing continued range expansion by this problematic species. © 2018 The Wildlife Society.