Predicting the geography of species' invasions via ecological niche modeling

An Ecosystems Perspective on Virus Evolution and Emergence

Understanding the emergence of pathogenic viruses has dominated studies of virus evolution. However, new metagenomic studies imply that relatively few of an immense number of viruses may lead to overt disease. This suggests a change in emphasis, from viruses as habitual pathogens to integral components of ecosystems. Here we show how viruses alter interactions between host individuals, populations, and ecosystems, impacting ecosystem health, resilience, and function, and how host ecology in turn impacts viral abundance and diversity. Moving to an ecosystems perspective will put virus evolution and disease emergence in its true context, and enhance our understanding of ecological processes.

Increased chilling tolerance of the invasive species Carpobrotus edulis may explain its expansion across new territories

Invasive plants are expanding their geographical distribution across new regions. Expansion modeling is crucial for geographic prioritization in management policies. However, the assumption of niche conservatism and the lack of information of the species physiological response to the environmental factors determining species presence may hinder predictions. In this study, we aimed to understand the expansion of the widely distributed plant Carpobrotus edulis in Europe. We contrasted introduced and native C. edulis ecological niches and explored the experimental response to temperature, a major determining factor for species distribution, of native and invasive individuals in terms of different biochemical markers. Niche analysis revealed an expansion of the introduced niche to occupy colder climates. Introduced and native individuals showed differential mechanisms facing low temperatures. Individuals from the native range showed an increased sensitivity to chilling, as reflected by photosynthetic pigment degradation, increased de-epoxidation of xanthophylls and the accumulation of the lipophilic antioxidant alpha-tocopherol. The found physiological differentiation towards an increased invasive chilling tolerance of invasive C. edulis individuals together with a high propagule pressure may explain the introduced climatic niche shift to colder climates observed, allowing the extensive expansion of this species in Europe.

Meta-modeling on detailed geography for accurate prediction of invasive alien species dispersal

Invasive species are recognized as a significant threat to biodiversity. The mathematical modeling of their spatio-temporal dynamics can provide significant help to environmental managers in devising suitable control strategies. Several mathematical approaches have been proposed in recent decades to efficiently model the dispersal of invasive species. Relying on the assumption that the dispersal of an individual is random, but the density of individuals at the scale of the population can be considered smooth, reaction-diffusion models are a good trade-off between model complexity and flexibility for use in different situations. In this paper we present a continuous reaction-diffusion model coupled with arbitrary Polynomial Chaos (aPC) to assess the impact of uncertainties in the model parameters. We show how the finite elements framework is well-suited to handle important landscape heterogeneities as elevation and the complex geometries associated with the boundaries of an actual geographical region. We demonstrate the main capabilities of the proposed coupled model by assessing the uncertainties in the invasion of an alien species invading the Basque Country region in Northern Spain.

Fundamental niche unfilling and potential invasion risk of the slider turtle Trachemys scripta

Background

How species colonize new environments is still a fundamental question in ecology and evolution, assessable by evaluating range characteristics of invasive species. Here we propose a model approach to evaluate environmental conditions and species features to predict niche changes in non-equilibrium contexts. It incorporates potentially range-limiting processes (fundamental niche), hence allowing for better predictions of range shifts, differentiation of analog and non-analog conditions between the native and non-native (invaded) ranges, and identification of environmental conditions not currently available but likely in the future. We apply our approach with the worldwide invasive slider-turtle Trachemys scripta.

Methods

We estimated the native and non-native realized niches of T. scripta and built its fundamental niche based on key features of the turtle’s temperature physiological tolerance limits and survival-associated factors. We next estimated response functions adjusted to the physiological predictor variables and estimated habitat suitability values, followed by a comprehensive set of analyses and simulations to compare the environmental conditions occupied by T. scripta (at its native and non-native ranges).

Results

Climatic space analysis showed that the T. scripta’s non-native realized niche is 28.6% greater than the native one. Response curves showed that it does not use its entire range of temperature tolerances (density curves for native: 5.3–23.7 °C and non-native: 1.7–28.4 °C ranges). Whether considering the mean temperature of the warmest or the coldest quarter, it occupies a wider range of temperatures along its non-native distribution. Results of the response curves for worldwide (global) and across Mexico (regional) comparisons showed it occupies analog and non-analog conditions between its native and invaded ranges, exhibiting also unoccupied suitable climatic conditions.

Discussion

We demonstrate that T. scripta occupies a wider subset of its fundamental niche along its non-native range (within its physiological tolerances), revealing that the species observed niche shift corresponds to a different subset of its fundamental niche (niche unfilling). We also identified suitable environmental conditions, globally and regionally, where the slider turtle could potentially invade. Our approach allows to accurately predict niche changes in novel or non-equilibrium contexts, which can improve our understanding about ecological aspects and geographic range boundaries in current and potential invasions.

Climatic Niche Shift during Azolla filiculoides Invasion and Its Potential Distribution under Future Scenarios

In order to prevent future biological invasions, it is crucial to know non-native species distributions. We evaluated the potential global distribution of Azolla filiculoides, a free-floating macrophyte native to the Americas by using species distribution models and niche equivalency tests to analyze the degree of niche overlap between the native and invaded ranges of the species. The models were projected under two future emission scenarios, three global circulation models and two time periods. Our results indicate a possible niche shift between the distribution ranges of the species, indicating that A. filiculoides can adapt to novel environmental conditions derived from climatic differences during the invasion process. Our models also show that the future potential distribution of A. filiculoides will decrease globally, although the species could colonize new vulnerable regions where it is currently absent. We highlight that species occurrence records in the invaded area are necessary to generate accurate models, which will, in turn, improve our ability to predict potential invasion risk areas.

Spatiotemporal analysis of the housing bubble's contribution to the proliferation of illegal landfills - The case of Gran Canaria

Illegal landfills are the source of many impacts that can alter the environment and represent a public health risk. This study investigates their spatiotemporal distribution in two representative areas of Gran Canaria: northwest (Zone A) and east (Zone B). Illegal landfill occurrence was simulated between 2000 and 2018, to estimate and spatially locate the surface growth of illegal landfills based on cellular automata, cellular automata-Markov and multiobjective land allocation models. The proliferation of illegal landfills in 2018 was simulated following the calibration and validation of the proposed models. Models' accuracy was assessed using Kappa index and landscape metrics. The cellular automata-Markov model had the best performance. The model simulations predicted an increase of 52.3 ha and 81.5 ha affected by illegal landfills in Zone A and Zone B for 2018, respectively. The interannual growth rate of surfaces affected by illegal landfills for the period between 2000 and 2006 was 4.5% and 9.5% and between 2006 and 2012 it was 6.6% and 6.7%, for Zone A and Zone B respectively. The growth of illegal landfills between 2000 and 2006 was higher in urban areas, construction sites, and industrial zones, and may be closely related to the process of urban expansion linked to the real estate boom. The latter would have a deep impact on the landscape due to the proliferation of illegal construction and demolition waste. The growth rate of illegal landfills in urban environments fell during the later period of urban expansion. Overall, simulation outputs showed the model's ability to correctly reproduce the distribution patterns for illegal landfill proliferation. Even though the simulated spatial location of illegal landfills was not highly accurate, the models built in this study provide an informative tool to policy makers to aid the process creating policies for environmental protection as well as territorial planning.

Climatic niche characteristics of native and invasive Lilium lancifolium

One of the topics currently under discussion in biological invasions is whether the species' climatic niche has been conserved or, alternatively, has diverged during invasions. Here, we explore niche dynamic processes using the complex invasion history model of Lilium lancifolium, which is the first tested case of a native species (Korea) with two hypothesized spatial (regional and intercontinental) and temporal arrivals: (1) as an archaeophyte in East Asia (before AD 1500); and (2) as a neophyte in Europe, North America, Australia, and New Zealand (after AD 1500). Following a niche examination through both environmental and geographical spaces, the species in the archaeophyte range has apparently filled the ancestral native niche and, rather, would have increased it considerably. The species as a neophyte shows a closer climatic match with the archaeophyte range than with the native one. This pattern of niche similarity suggests that the neophyte range was probably colonized by a subset of archaeophyte propagules adapted to local climate that promoted the species' establishment. Overall, niche conservatism is proposed at each colonization step, from native to archaeophyte, and from archaeophyte to neophyte ranges. We detected signals of an advanced invasion stage within the archaeophyte range and traces of an early introduction stage in neophyte ranges.

Ecological Release of the Anna's Hummingbird during a Northern Range Expansion

During range expansions, species can experience rapid population growth if changes in climate or interspecific interactions remove limits on growth rates in novel habitats. Here I document a century of range expansion in the Anna's hummingbird (Calypte anna) and investigate the causes of its recent abundance through a combination of demographic, climatic, and phenological analyses. Christmas Bird Count records indicate that populations have been growing in California since the early twentieth century. Sites across the Pacific Northwest show striking fits to simple models of exponential growth following colonization in the 1960s and 1970s, and nest records indicate that the species now delays the start of the nesting season by at least 16 days in the north. Although the species now occurs in a much wider range of climates than before the range expansion, the fastest growing populations in the northwest are in regions with minimum breeding season temperatures similar to those occupied by the species in its native range. Range expansions in the Anna's hummingbird thus reflect an ecological release likely caused by a mix of introduced plants, human facilitation, and phenological acclimation that allowed a California native to expand across western North America.

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.

Location-level processes drive the establishment of alien bird populations worldwide

Human-mediated translocation of species to areas beyond their natural distribution (here termed aliens1) is a key signature of the Anthropocene2 and a primary driver of global biodiversity loss and environmental change3. Stemming the tide of invasions requires understanding why some species fail to establish alien populations, while others succeed. To achieve this, we need to integrate the impact of features of the introduction site, the species introduced, and the specific introduction event. However, determining which, if any, location-level factors affect establishment success has proved difficult due to the multiple spatial, temporal and phylogenetic axes along which environmental variation may influence population survival. Here, we apply Bayesian hierarchical regression analysis to a global spatially and temporally explicit database of alien bird introduction events4 to show that environmental conditions at the introduction location, notably climatic suitability and the presence of other alien species groups are the primary determinants of establishment success. Species-level traits and founding population size (propagule pressure) exert secondary, but still important, effects on success. Thus, current trajectories of anthropogenic environmental change will most likely facilitate future incursions by alien species, but predicting future invasions will require integrating multiple location, species, and event-level characteristics.

Identification of high-risk habitats of Oncomelania hupensis, the intermediate host of schistosoma japonium in the Poyang Lake region, China: A spatial and ecological analysis

BACKGROUND

Identifying and eliminating snail habitats is the key measure for schistosomiasis control, critical for the nationwide strategy of eliminating schistosomiasis in China. Here, our aim was to construct a new analytical framework to predict high-risk snail habitats based on a large sample field survey for Oncomelania hupensis, providing guidance for schistosomiasis control and prevention.

METHODOLOGY/PRINCIPAL FINDINGS

Ten ecological models were constructed based on the occurrence data of Oncomelania hupensis and a range of variables in the Poyang Lake region of China, including four presence-only models (Maximum Entropy Models, Genetic Algorithm for rule-set Production, Bioclim and Domain) and six presence-absence models (Generalized Linear Models, Multivariate Adaptive Regression Splines, Flexible Discriminant Analysis, as well as machine algorithmic models-Random Forest, Classification Tree Analysis, Generalized Boosted Model), to predict high-risk snail habitats. Based on overall predictive performance, we found Presence-absence models outperformed the presence-only models and the models based on machine learning algorithms of classification trees showed the highest accuracy. The highest risk was located in the watershed of the River Fu in Yugan County, as well as the watershed of the River Gan and the River Xiu in Xingzi County, covering an area of 52.3 km2. The other high-risk areas for both snail habitats and schistosomiasis were mainly concentrated at the confluence of Poyang Lake and its five main tributaries.

CONCLUSIONS/SIGNIFICANCE

This study developed a new distribution map of snail habitats in the Poyang Lake region, and demonstrated the critical role of ecological models in risk assessment to directing local field investigation of Oncomelania hupensis. Moreover, this study could also contribute to the development of effective strategies to prevent further spread of schistosomiasis from endemic areas to non-endemic areas.

Velocity and geometry of propagating fronts in complex convective flow fields

We numerically study the propagation of reacting fronts through three-dimensional flow fields composed of convection rolls that include time-independent cellular flow, spatiotemporally chaotic flow, and weakly turbulent flow. We quantify the asymptotic front velocity and determine its scaling with system parameters including the local angle of the convection rolls relative to the direction of front propagation. For cellular flow fields, the orientation of the convection rolls has a significant effect upon the front velocity and the front geometry remains relatively smooth. However, for chaotic and weakly turbulent flow fields, the front velocity depends upon the geometric complexity of the wrinkled front interface and does not depend significantly upon the local orientation of the convection rolls. Using the box counting dimension we find that the front interface is fractal for chaotic and weakly turbulent flows with a dimension that increases with flow complexity.

Muddy Boots Beget Wisdom: Implications for Rare or Endangered Plant Species Distribution Models

Species distribution models (SDMs) are popular tools for predicting the geographic ranges of species. It is common practice to use georeferenced records obtained from online databases to generate these models. Using three species of Phaedranassa (Amaryllidaceae) from the Northern Andes, we compare the geographic ranges as predicted by SDMs based on online records (after standard data cleaning) with SDMs of these records confirmed through extensive field searches. We also review the identification of herbarium collections. The species’ ranges generated with corroborated field records did not agree with the species’ ranges based on the online data. Specifically, geographic ranges based on online data were significantly inflated and had significantly different and wider elevational extents compared to the ranges based on verified field records. Our results suggest that to generate accurate predictions of species’ ranges, occurrence records need to be carefully evaluated with (1) appropriate filters (e.g., altitude range, ecosystem); (2) taxonomic monographs and/or specialist corroboration; and (3) validation through field searches. This study points out the implications of generating SDMs produced with unverified online records to guide species-specific conservation strategies since inaccurate range predictions can have important consequences when estimating species’ extinction risks.

Climatic niche shift and possible future spread of the invasive South African Orchid Disa bracteata in Australia and adjacent areas

Orchids are generally regarded as plants with an insignificant invasive potential and so far only one species has proved to be harmful for native flora. However, previous studies on Epipactis helleborine and Arundina graminifolia indicate that the ecological aspects of range extension in their non-native geographical range are not the same for all species of orchids. Disa bracteata in its native range, South Africa, is categorized as of little concern in terms of conservation whereas in Australia it is naturalized and considered to be an environmental weed. The aim of this research was to determine the ecological preferences enabling the spread of Disa bracteata in Western and South Australia, Victoria and Tasmania and to evaluate the effect of future climate change on its potential range. The ecological niche modeling approach indicates that most of the accessible areas are already occupied by this species but future expansion will continue based on four climate change scenarios (rcp26, rcp45, rcp60, rcp85). Further expansion is predicted especially in eastern Australia and eastern Tasmania. Moreover, there are some unpopulated but suitable habitats in New Zealand, which according to climate change scenarios will become even more suitable in the future. The most striking result of this study is the significant difference between the environmental conditions recorded in the areas which D. bracteata naturally inhabits and invasive sites-that indicates a possible niche shift. In Australia the studied species continues to populate a new niche or exploit habitats that are only moderately represented in South Africa.

Reconstructing Ecological Niche Evolution When Niches Are Incompletely Characterized

Evolutionary dynamics of abiotic ecological niches across phylogenetic history can shed light on large-scale biogeographic patterns, macroevolutionary rate shifts, and the relative ability of lineages to respond to global change. An unresolved question is how best to represent and reconstruct evolution of these complex traits at coarse spatial scales through time. Studies have approached this question by integrating phylogenetic comparative methods with niche estimates inferred from correlative and other models. However, methods for estimating niches often produce incomplete characterizations, as they are inferred from present-day distributions that may be limited in full expression of the fundamental ecological niche by biotic interactions, dispersal limitations, and the existing set of environmental conditions. Here, we test whether incomplete niche characterizations inherent in most estimates of species' niches bias phylogenetic reconstructions of niche evolution, using simulations of virtual species with known niches. Results establish that incompletely characterized niches inflate estimates of evolutionary change and lead to error in ancestral state reconstructions. Our analyses also provide a potential mechanism to explain the frequent observation that maximum thermal tolerances are more conserved than minimum thermal tolerances: populations and species experience more spatial variation in minimum temperature than in maximum temperature across their distributions and, consequently, may experience stronger diversifying selection for cold tolerance.

Potential invasion of exotic ambrosia beetles Xyleborus glabratus and Euwallacea sp. in Mexico: A major threat for native and cultivated forest ecosystems

We analyze the invasive potential of two Asian ambrosia beetles, Xyleborus glabratus and Euwallacea sp., into Mexico and the southern United States. The fungal symbionts of these beetles have been responsible for damage to trees of the family Lauraceae, including Persea americana and other non-cultivated tree species on both coasts of the United States. We estimate their potential threat using ecological niche modeling and spatial multi-criteria evaluation protocols to incorporate plant and beetle suitabilities as well as forest stress factors across Mexico. Mexico contains higher climatic and habitat suitability for X. glabratus than for Euwallacea sp. Within this country, the neotropical region is most vulnerable to invasion by both of these species. We also identify a corridor of potential invasion for X. glabratus along the Gulf of Mexico coast where most Lauraceae and native Xyleborus species are present; dispersal of either X. glabratus or Euwallacea sp. into this region would likely lead to major disease spread. However, the overall potential damage that these beetles can cause may be a function of how many reproductive hosts and how many other ambrosia beetles are present, as well as of their capacity to disperse. This work can also alert relevant managers and authorities regarding this threat.

Highly structured genetic diversity of Bixa orellana var. urucurana, the wild ancestor of annatto, in Brazilian Amazonia

Annatto (Bixa orellana L.) is a tropical American crop, commercially valuable due to its application in the food and cosmetics industries as a natural dye. The wild ancestor of cultivated annatto is B. orellana var. urucurana. Although never cultivated, this variety occurs in open forests and anthropogenic landscapes, and is always associated with riparian environments. In this study, we evaluated the genetic diversity and structure of B. orellana var. urucurana populations in Brazilian Amazonia using 16 microsatellite loci. We used Ecological Niche Modeling (ENM) to characterize the potential geographical range of this variety in northern South America. We analyzed 170 samples from 10 municipalities in the states of Rondônia, Pará and Roraima. A total of 194 alleles was observed, with an average of 12.1 alleles per locus. Higher levels of expected (H_E) than observed (H_O) heterozygosities were found for all populations. Bayesian analysis, Neighbor-Joining dendrograms and PCAs suggest the existence of three strongly structured groups of populations. A strong and positive correlation between genetic and geographic distances was found, suggesting that genetic differentiation might be caused by geographic isolation. From species distribution modelling, we detected that South Rondônia, Madre di Dios River basin, Llanos de Mojos, Llanos de Orinoco and eastern Ecuador are highly suitable areas for wild annatto to occur, providing additional targets for future exploration and conservation. Climatic adaptation analyses revealed strong differentiation among populations, suggesting that precipitation plays a key role in wild annatto’s current and potential distribution patterns.

The Distribution and Habitat Affinities of the Invasive Ant Myrmica rubra (Hymenoptera: Formicidae) in Southern New England

The Eurasian ant Myrmica rubra (L.) (Hymenoptera: Formicidae) was first discovered in North America in the early 1900s in Massachusetts. Populations have since appeared in at least seven states within the United States and in seven Canadian provinces. We conducted a systematic search for the ant across southern New England-the states of Connecticut, Massachusetts, and Rhode Island-where M. rubra is spreading from multiple loci. The species occurs in two large regions in Massachusetts, each spanning approximately 75 km, and in several smaller populations in Massachusetts and Rhode Island. No populations were discovered anywhere in Connecticut or across large expanses of central Massachusetts and northern Rhode Island, despite the presence of apparently favorable habitat. This pattern of distribution suggests a combination of long-distance dispersal by human transport coupled with slow local spread. Resurveys of sites previously known to support M. rubra showed that populations persist for decades. Within invaded areas, M. rubra was strongly associated with particular habitats. Colonies were most prevalent in freshwater wetlands and in moist forests near wetlands and water; they were uncommon in drier forests and were rare in open habitats outside of wetlands. The slow rate of spread over the last 110 yr suggests that the ants do not easily disperse between patches of suitable habitat.

Ecological niche modeling for a cultivated plant species: a case study on taro (Colocasia esculenta) in Hawaii

Under the threat of ongoing and projected climate change, communities in the Pacific Islands face challenges of adapting culture and lifestyle to accommodate a changing landscape. Few models can effectively predict how biocultural livelihoods might be impacted. Here, we examine how environmental and anthropogenic factors influence an ecological niche model (ENM) for the realized niche of cultivated taro (Colocasia esculenta) in Hawaii. We created and tuned two sets of ENMs: one using only environmental variables, and one using both environmental and cultural characteristics of Hawaii. These models were projected under two different Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (RCPs) for 2070. Models were selected and evaluated using average omission rate and area under the receiver operating characteristic curve (AUC). We compared optimal model predictions by comparing the percentage of taro plots predicted present and measured ENM overlap using Schoener's D statistic. The model including only environmental variables consisted of 19 Worldclim bioclimatic variables, in addition to slope, altitude, distance to perennial streams, soil evaporation, and soil moisture. The optimal model with environmental variables plus anthropogenic features also included a road density variable (which we assumed as a proxy for urbanization) and a variable indicating agricultural lands of importance to the state of Hawaii. The model including anthropogenic features performed better than the environment-only model based on omission rate, AUC, and review of spatial projections. The two models also differed in spatial projections for taro under anticipated future climate change. Our results demonstrate how ENMs including anthropogenic features can predict which areas might be best suited to plant cultivated species in the future, and how these areas could change under various climate projections. These predictions might inform biocultural conservation priorities and initiatives. In addition, we discuss the incongruences that arise when traditional ENM theory is applied to species whose distribution has been significantly impacted by human intervention, particularly at a fine scale relevant to biocultural conservation initiatives.

Community structure informs species geographic distributions

Understanding what determines species’ geographic distributions is crucial for assessing global change threats to biodiversity. Measuring limits on distributions is usually, and necessarily, done with data at large geographic extents and coarse spatial resolution. However, survival of individuals is determined by processes that happen at small spatial scales. The relative abundance of coexisting species (i.e. ‘community structure’) reflects assembly processes occurring at small scales, and are often available for relatively extensive areas, so could be useful for explaining species distributions. We demonstrate that Bayesian Network Inference (BNI) can overcome several challenges to including community structure into studies of species distributions, despite having been little used to date. We hypothesized that the relative abundance of coexisting species can improve predictions of species distributions. In 1570 assemblages of 68 Mediterranean woody plant species we used BNI to incorporate community structure into Species Distribution Models (SDMs), alongside environmental information. Information on species associations improved SDM predictions of community structure and species distributions moderately, though for some habitat specialists the deviance explained increased by up to 15%. We demonstrate that most species associations (95%) were positive and occurred between species with ecologically similar traits. This suggests that SDM improvement could be because species co-occurrences are a proxy for local ecological processes. Our study shows that Bayesian Networks, when interpreted carefully, can be used to include local conditions into measurements of species’ large-scale distributions, and this information can improve the predictions of species distributions.

Climate change and vector-borne diseases of public health significance

There has been much debate as to whether or not climate change will have, or has had, any significant effect on risk from vector-borne diseases. The debate on the former has focused on the degree to which occurrence and levels of risk of vector-borne diseases are determined by climate-dependent or independent factors, while the debate on the latter has focused on whether changes in disease incidence are due to climate at all, and/or are attributable to recent climate change. Here I review possible effects of climate change on vector-borne diseases, methods used to predict these effects and the evidence to date of changes in vector-borne disease risks that can be attributed to recent climate change. Predictions have both over- and underestimated the effects of climate change. Mostly under-estimations of effects are due to a focus only on direct effects of climate on disease ecology while more distal effects on society's capacity to control and prevent vector-borne disease are ignored. There is increasing evidence for possible impacts of recent climate change on some vector-borne diseases but for the most part, observed data series are too short (or non-existent), and impacts of climate-independent factors too great, to confidently attribute changing risk to climate change.

Compatible ecological niche signals between biological and archaeological datasets for late-surviving Neandertals

OBJECTIVES

To assess ecological niche similarity for biological and archaeological samples representing late-surviving Neandertals in Europe to evaluate the validity of combining these two types of data in ecological niche modeling analyses.

MATERIALS AND METHODS

Tests of niche conservatism were used to assess niche similarity and niche identity of samples of morphologically diagnostic Neandertal remains and Middle Paleolithic (MP) archaeological sites dating to the time period leading up to Neandertal extinction. Paleoenvironmental reconstructions for the Pre-H4 (43.3-40.2 ky cal BP) were used as environmental space analyses.

RESULTS

Null hypotheses of niche similarity and identity of the two types of samples could not be rejected.

CONCLUSIONS

As primary and secondary evidence of Neandertal occurrence during the Pre-H4 show high levels of niche similarity and identity, combining the two types of occurrence data to create larger samples for niche analyses is justified without the concern that different environmental signals could complicate future research.

Spatial Niche Separation on the Periphery Range of Argiope bruennichi and Its Effect With Araneus quadratus (Araneae: Araneidae)

Recent decades have witnessed an intensified expansion of thermophilic organisms from southern into northern Europe. Argiope bruennichi, an orb-weaver spider species, is extending its range relatively fast and gradually becoming a common species in Europe. The aim of this study was to investigate how this relatively newly-come taxon is affecting another orb-weaver spider species and whether it demonstrates features of an invasive species. Interactions were examined between this species and another dominant species with similar body and web size, Araneus quadratus. The study areas were located in two adjacent regions in northeast Poland: the warmer Mazury Lake District and the colder Suwalki Lake District. The areas differed in both population density of the studied species as well as in climatic conditions. Six study sites were selected in each region. In the Mazury Lake District, A. bruennichi was more frequent than A. quadratus; this relationship was reversed in the Suwalki Lake District. We measured the height of the web hub above the ground and the height of the plants to which webs were fixed. Web location height was chosen as an indicator of the interaction. The results indicate that A. quadratus located its webs higher than A. bruennichi, regardless of species abundance and region. A. bruennichi does not exert a significant negative impact on A. quadratus web placement. The two species clearly prefer different heights, which in turn may determine the kind of prey they catch.

Predictable invasion dynamics in North American populations of the Eurasian collared dove Streptopelia decaocto

Species invasions represent a significant dimension of global change yet the dynamics of invasions remain poorly understood and are considered rather unpredictable. We explored interannual dynamics of the invasion process in the Eurasian collared dove (Streptopelia decaocto) and tested whether the advance of the invasion front of the species in North America relates to centrality (versus peripherality) within its estimated fundamental ecological niche. We used ecological niche modelling approaches to estimate the dimensions of the fundamental ecological niche on the Old World distribution of the species, and then transferred that model to the New World as measures of centrality versus peripherality within the niche for the species. Although our hypothesis was that the invasion front would advance faster over more favourable (i.e. more central) conditions, the reverse was the case: the invasion expanded faster in areas presenting less favourable (i.e. more peripheral) conditions for the species as it advanced across North America. This result offers a first view of a predictive approach to the dynamics of species' invasions, and thereby has relevant implications for the management of invasive species, as such a predictive understanding would allow better anticipation of coming steps and advances in the progress of invasions, important to designing and guiding effective remediation and mitigation efforts.

Assessing global range expansion in a cryptic species complex: insights from the red seaweed genus Asparagopsis (Florideophyceae)

The mitochondrial genetic diversity, distribution and invasive potential of multiple cryptic operational taxonomic units (OTUs) of the red invasive seaweed Asparagopsis were assessed by studying introduced Mediterranean and Hawaiian populations. Invasive behavior of each Asparagopsis OTU was inferred from phylogeographic reconstructions, past historical demographic dynamics, recent range expansion assessments and future distributional predictions obtained from demographic models. Genealogical networks resolved Asparagopsis gametophytes and tetrasporophytes into four A. taxiformis and one A. armata cryptic OTUs. Falkenbergia isolates of A. taxiformis L3 were recovered for the first time in the western Mediterranean Sea and represent a new introduction for this area. Neutrality statistics supported past range expansion for A. taxiformis L1 and L2 in Hawaii. On the other hand, extreme geographic expansion and an increase in effective population size were found only for A. taxiformis L2 in the western Mediterranean Sea. Distribution models predicted shifts of the climatically suitable areas and population expansion for A. armata L1 and A. taxiformis L1 and L2. Our integrated study confirms a high invasive risk for A. taxiformis L1 and L2 in temperate and tropical areas. Despite the differences in predictions among modelling approaches, a number of regions were identified as zones with high invasion risk for A. taxiformis L2. Since range shifts are likely climate-driven phenomena, future invasive behavior cannot be excluded for the rest of the lineages.

Changes in habitat associations during range expansion: disentangling the effects of climate and residence time

The distributions of many species are not at equilibrium with their environment. This includes spreading non-native species and species undergoing range shifts in response to climate change. The habitat associations of these species may change during range expansion as less favourable climatic conditions at expanding range margins constrain species to use only the most favourable habitats, violating the species distribution model assumption of stationarity. Alternatively, changes in habitat associations could result from density-dependent habitat selection; at range margins, population densities are initially low so species can exhibit density-independent selection of the most favourable habitats, while in the range core, where population densities are higher, species spread into less favourable habitat. We investigate if the habitat preferences of the non-native common waxbill Estrilda astrild changed as they spread in three directions (north, east and south-east) in the Iberian Peninsula. There are different degrees of climatic suitability and colonization speed across range expansion axes, allowing us to separate the effects of climate from residence time. In contrast to previous studies we find a stronger effect of residence time than climate in influencing the prevalence of common waxbills. As well as a strong additive effect of residence time, there were some changes in habitat associations, which were consistent with density-dependent habitat selection. The combination of broader habitat associations and higher prevalence in areas that have been colonised for longer means that species distribution models constructed early in the invasion process are likely to underestimate species’ potential distribution.