Confronting species distribution model predictions with species functional traits

The influence of scale-dependent geodiversity on species distribution models in a biodiversity hotspot

Improving models of species' distributions is essential for conservation, especially in light of global change. Species distribution models (SDMs) often rely on mean environmental conditions, yet species distributions are also a function of environmental heterogeneity and filtering acting at multiple spatial scales. Geodiversity, which we define as the variation of abiotic features and processes of Earth's entire geosphere (inclusive of climate), has potential to improve SDMs and conservation assessments, as they capture multiple abiotic dimensions of species niches, however they have not been sufficiently tested in SDMs. We tested a range of geodiversity variables computed at varying scales using climate and elevation data. We compared predictive performance of MaxEnt SDMs generated using CHELSA bioclimatic variables to those also including geodiversity variables for 31 mammalian species in Colombia. Results show the spatial grain of geodiversity variables affects SDM performance. Some variables consistently exhibited an increasing or decreasing trend in variable importance with spatial grain, showing slight scale-dependence and indicating that some geodiversity variables are more relevant at particular scales for some species. Incorporating geodiversity variables into SDMs, and doing so at the appropriate spatial scales, enhances the ability to model species-environment relationships, thereby contributing to the conservation and management of biodiversity. This article is part of the Theo Murphy meeting issue 'Geodiversity for science and society'.

Cost effectiveness of spread mitigation strategies for polyphagous shot hole borer Euwallacea fornicatus (Coleoptera: Curculionidae: Scolytinae)

Polyphagous shot hole borer Euwallacea fornicatus Eichhoff was detected in Western Australia in September 2021, and an eradication campaign funded by the Commonwealth government is underway. As part of contingency planning, we examined the cost effectiveness of alternative control strategies that could be used to mitigate urban forest impacts and maintain the benefits of trees to the local communities if eradication was not feasible. At the time this work was undertaken, decision-makers were concerned about the potential need to replace all urban trees susceptible to attack. We considered this strategy alongside less destructive strategies and assessed their cost effectiveness in terms of material and labor costs and the loss of ecosystem services resulting from reduced tree foliage. Using a stochastic simulation model, we found that a strategy that involved pruning necrotic limbs and treating trees biennially with systemic insecticide was almost always more cost effective than removing infested trees and replanting to resistant varieties. We estimated this strategy would cost A$55-110 million over 50 years, while tree removal would cost $105-195 million. A third strategy using a mix of chemical suppression and tree removal was also considered in light of new information about the pest's host preferences. With an estimated cost of $60-110 million, this strategy was only slightly more expensive than using chemical suppression alone and could actually lead to eradication if the host range is as narrow as recent survey data suggests.

Predicting the Current and Future Distributions of Frankliniella occidentalis (Pergande) Based on the MaxEnt Species Distribution Model

Climate change has a highly significant impact on the distribution of species. As the greenhouse effect intensifies each year, the distribution of organisms responds to this challenge in diverse ways. Therefore, climatic environmental variables are a key entry point for capturing the current and future distribution trends of pests. Frankliniella occidentalis is an invasive pest attested worldwide. Its damage is mainly divided into two aspects, including mechanical damage caused by its feeding and egg laying and the spread of tomato spotted wilt virus (TSWV). TSWV is the most dominant transmitted virulent disease. Moreover, F. occidentalis is the major vector for the transmission of this virus, which poses a grave threat to the yield and survival of our crops. In this study, the distribution pattern of this pest was explored using 19 bioclimatic variables based on the Maxent model. The results indicated that in the future, high-suitability areas of F. occidentalis will be widely distributed in 19 provinces of China, with Hebei, Henan, Shandong, Tianjin and Yunnan being the most abundant. Among the 19 bioclimatic variables, the five variables of annual mean temperature (Bio 1), temperature seasonality (standard deviation × 100) (Bio 4), min temperature of the coldest month (Bio 6), mean temperature of the driest quarter (Bio 9) and precipitation of the coldest quarter (Bio 19) were selected as the key environmental variables affecting the distribution of F. occidentalis. In summary, temperature and precipitation are vital factors for the study of the species' distribution, and this study aims to provide new perspectives for the control of this pest in China.

Comparing the Performance of CMCC-BioClimInd and WorldClim Datasets in Predicting Global Invasive Plant Distributions

Species distribution modeling (SDM) has been widely used to predict the distribution of invasive plant species based on bioclimatic variables. However, the specific selection of these variables may affect the performance of SDM. This investigation elucidates a new bioclimate variable dataset (i.e., CMCC-BioClimInd) for its use in SDM. The predictive performance of SDM that includes WorldClim and CMCC-BioClimInd was evaluated by AUC and omission rate and the explanatory power of both datasets was assessed by the jackknife method. Furthermore, the ODMAP protocol was used to record CMCC-BioClimInd to ensure reproducibility. The results indicated that CMCC-BioClimInd effectively simulates invasive plant species' distribution. Based on the contribution rate of CMCC-BioClimInd to the distribution of invasive plant species, it was inferred that the modified and simplified continentality and Kira warmth index from CMCC-BioClimInd had a strong explanatory power. Under the 35 bioclimatic variables of CMCC-BioClimInd, alien invasive plant species are mainly distributed in equatorial, tropical, and subtropical regions. We tested a new bioclimate variable dataset to simulate the distribution of invasive plant species worldwide. This method has great potential to improve the efficiency of species distribution modeling, thereby providing a new perspective for risk assessment and management of global invasive plant species.

Prediction of global potential suitable habitats of Nicotiana alata Link et Otto based on MaxEnt model

Nicotiana alata Link et Otto, widely used in landscaping, is not only of great ornamental value but also of high commercial and medical value. The global potential habitat of N. alata and the environmental factors affecting its distribution are not that clear at present. To provide a reference for the reasonable and extensive planting of N. alata now and in the future, the MaxEnt model was used to predict its global suitable habitats under current and future climate conditions, respectively, based on global geographic distribution data of N. alata and the current and future world bioclimatic variables. The results showed that mean temperature of the driest quarter (bio9), precipitation of driest month (bio14), precipitation seasonality (bio15) and max temperature of warmest month (bio5), were the key bioclimatic variables governing the distribution of N. alata. The global suitable habitats of N. alata were mainly distributed in Europe, the United States, southeastern South America, and China under current climate conditions. Compared with current climate conditions, the future climate decreased suitable habitats of N. alata under SSP1-2.6, and SSP2-4.5 scenario and increased suitable habitats of N. alata under SSP3-7.0, and SSP5-8.5 climatic scenarios. The results provided valuable information and theoretical reference for the reasonable planting of N. alata.

Analysis of niche shift and potential suitable distributions of Dendrobium under the impact of global climate change

Dendrobium is a valuable traditional Chinese herb that contains active ingredients such as polysaccharides and alkaloids that have anti-aging, antioxidant, and immunomodulating effects. The appropriate distribution range of Dendrobium should be predicted from the perspective of ecological niche theory in order to preserve and utilize medicinal plant resources. In this study, Dendrobium nobile, Dendrobium officinale, and Dendrobium moniliforme were selected to predict the potential suitable distributions and ecological niche shifts. A comparison of 19 environmental variables of the three Dendrobium species revealed three climatic factors that differed significantly when the species were compared two at a time. The principal component analysis was carried out in order to screen seven climatic factors for ecological niche shift analysis. All three Dendrobium species were found to have a very similar ecological niche, but with a relatively small range of variability regarding certain climatic factors. Finally, the current and future suitable areas for these three Dendrobium species in China were predicted using the MaxEnt model and ArcGIS using the two representative concentration pathways (RCP 2.6 and 8.5). Overall, the analysis of the climatic factors' comparisons, niche shift, and current and future suitable areas of these three Dendrobium species provides a basis for medicinal plant resource conservation and utilization, and our methods could be applied to the study of other similar valuable medicinal plants.

Linking ecological niche models and common garden experiments to predict phenotypic differentiation in stressful environments: Assessing the adaptive value of marginal populations in an alpine plant

Environmental variation within a species' range can create contrasting selective pressures, leading to divergent selection and novel adaptations. The conservation value of populations inhabiting environmentally marginal areas remains in debate and is closely related to the adaptive potential in changing environments. Strong selection caused by stressful conditions may generate novel adaptations, conferring these populations distinct evolutionary potential and high conservation value under climate change. On the other hand, environmentally marginal populations may be genetically depauperate, with little potential for new adaptations to emerge. Here, we explored the use of ecological niche models (ENMs) linked with common garden experiments to predict and test for genetically determined phenotypic differentiation related to contrasting environmental conditions. To do so, we built an ENM for the alpine plant Silene ciliata in central Spain and conducted common garden experiments, assessing flowering phenology changes and differences in leaf cell resistance to extreme temperatures. The suitability patterns and response curves of the ENM led to the predictions that: (1) the environmentally marginal populations experiencing less snowpack and higher minimum temperatures would have delayed flowering to avoid risks of late-spring frosts and (2) those with higher minimum temperatures and greater potential evapotranspiration would show enhanced cell resistance to high temperatures to deal with physiological stress related to desiccation and heat. The common garden experiments revealed the expected genetically based phenotypic differentiation in flowering phenology. In contrast, they did not show the expected differentiation for cell resistance, but these latter experiments had high variance and hence lower statistical power. The results highlight ENMs as useful tools to identify contrasting putative selective pressures across species ranges. Linking ENMs with common garden experiments provides a theoretically justified and practical way to study adaptive processes, including insights regarding the conservation value of populations inhabiting environmentally marginal areas under ongoing climate change.

The role of forest structure and composition in driving the distribution of bats in Mediterranean regions

Forests are key native habitats in temperate environments. While their structure and composition contribute to shaping local-scale community assembly, their role in driving larger-scale species distributions is understudied. We used detailed forest inventory data, an extensive dataset of occurrence records, and species distribution models integrated with a functional approach, to disentangle mechanistically how species-forest dependency processes drive the regional-scale distributions of nine forest specialist bats in a Mediterranean region in the south of Spain. The regional distribution patterns of forest bats were driven primarily by forest composition and structure rather than by climate. Bat roosting ecology was a key trait explaining the strength of the bat-forest dependency relationships. Tree roosting bats were strongly associated with mature and heterogeneous forest with large trees (diameters > 425 mm). Conversely, and contrary to what local-scale studies show, our results did not support that flight-related traits (wing loading and aspect ratio) drive species distributional patterns. Mediterranean forests are expected to be severely impacted by climate change. This study highlights the utility of disentangling species-environment relationships mechanistically and stresses the need to account for species-forest dependency relationships when assessing the vulnerability of forest specialists towards climate change.

Different life stage, different risks: Thermal performance across the life cycle of Salmo trutta and Salmo salar in the face of climate change

Extending assessments of climate change-induced range shifts via correlative species distribution models by including species traits is crucial for conservation planning. However, comprehensive assessments of future distribution scenarios incorporating responses of biotic factors are poorly investigated. Therefore, the aim of our study was to extend the understanding about the combined usage of species traits data and species distribution models for different life stages and distribution scenarios. We combine global model predictions for the 2050s and thermal performances of Salmo trutta and Salmo salar under consideration of different life stages (adults, juveniles, eggs), timeframes (monthly, seasonally, yearly), and dispersal scenarios (no dispersal, free dispersal, restricted dispersal). We demonstrate that thermal performances of different life stages will either increase or decrease for certain time periods. Model predictions and thermal performances imply range declines and poleward shifts. Dispersal to suitable habitats will be an important factor mitigating warming effects; however, dams may block paths to areas linked to high performances. Our results emphasize enhanced inclusion of critical periods for species and proper dispersal solutions in conservation planning.

Environmental Factors Are Stronger Predictors of Primate Species’ Distributions Than Basic Biological Traits

Understanding the neutral, biological, and environmental processes driving species distributions is valuable in informing conservation efforts because it will help us predict how species will respond to changes in environmental conditions. Environmental processes affect species differently according to their biological traits, which determine how they interact with their environment. Therefore, functional, trait-based modeling approaches are considered important for predicting distributions and species responses to change but even for data-rich primate communities our understanding of the relationships between traits and environmental conditions is limited. Here we use a large-scale, high-resolution data set of African diurnal primate distributions, biological traits, and environmental conditions to investigate the role of biological traits and environmental trait filtering in primate distributions. We collected data from published sources for 354 sites and 14 genera with 57 species across sub-Saharan Africa. We then combined a three-table ordination method, RLQ, with the fourth-corner approach to test relationships between environmental variables and biological traits and used a mapping approach to visually assess patterning in primate genus and species’ distributions. We found no significant relationships between any groups of environmental variables and biological traits, despite a clear role of environmental filtering in driving genus and species’ distributions. The most important environmental driver of species distributions was temperature seasonality, followed by rainfall. We conclude that the relative flexibility of many primate genera means that not any one particular set of traits drives their species–environment associations, despite the clear role of such associations in their distribution patterns.

Combining niche shift and population genetic analyses predicts rapid phenotypic evolution during invasion

The rapid evolution of non-native species can facilitate invasion success, but recent reviews indicate that such microevolution rarely yields expansion of the climatic niche in the introduced habitats. However, because some invasions originate from a geographically restricted portion of the native species range and its climatic niche, it is possible that the frequency, direction, and magnitude of phenotypic evolution during invasion have been underestimated. We explored the utility of niche shift analyses in the red seaweed Gracilaria vermiculophylla, which expanded its range from the northeastern coastline of Japan to North America, Europe, and northwestern Africa within the last 100 years. A genetically informed climatic niche shift analysis indicates that native source populations occur in colder and highly seasonal habitats, while most non-native populations typically occur in warmer, less seasonal habitats. This climatic niche expansion predicts that non-native populations evolved greater tolerance for elevated heat conditions relative to native source populations. We assayed 935 field-collected and 325 common-garden thalli from 40 locations, and as predicted, non-native populations had greater tolerance for ecologically relevant extreme heat (40°C) than did Japanese source populations. Non-native populations also had greater tolerance for cold and low-salinity stresses relative to source populations. The importance of local adaptation to warm temperatures during invasion was reinforced by evolution of parallel clines: Populations from warmer, lower-latitude estuaries had greater heat tolerance than did populations from colder, higher-latitude estuaries in both Japan and eastern North America. We conclude that rapid evolution plays an important role in facilitating the invasion success of this and perhaps other non-native marine species. Genetically informed ecological niche analyses readily generate clear predictions of phenotypic shifts during invasions and may help to resolve debate over the frequency of niche conservatism versus rapid adaptation during invasion.

Species' traits as predictors of range shifts under contemporary climate change: A review and meta-analysis

A growing body of literature seeks to explain variation in range shifts using species' ecological and life-history traits, with expectations that shifts should be greater in species with greater dispersal ability, reproductive potential, and ecological generalization. Despite strong theoretical support for species' traits as predictors of range shifts, empirical evidence from contemporary range shift studies remains limited in extent and consensus. We conducted the first comprehensive review of species' traits as predictors of range shifts, collecting results from 51 studies across multiple taxa encompassing over 11,000 species' responses for 54 assemblages of taxonomically related species occurring together in space. We used studies of assemblages that directly compared geographic distributions sampled in the 20th century prior to climate change with resurveys of distributions after contemporary climate change and then tested whether species traits accounted for heterogeneity in range shifts. We performed a formal meta-analysis on study-level effects of body size, fecundity, diet breadth, habitat breadth, and historic range limit as predictors of range shifts for a subset of 21 studies of 26 assemblages with sufficient data. Range shifts were consistent with predictions based on habitat breadth and historic range limit. However, body size, fecundity, and diet breadth showed no significant effect on range shifts across studies, and multiple studies reported significant relationships that contradicted predictions. Current understanding of species' traits as predictors of range shifts is limited, and standardized study is needed for traits to be valid indicators of vulnerability in assessments of climate change impacts.

Phenotypic distribution models corroborate species distribution models: A shift in the role and prevalence of a dominant prairie grass in response to climate change

Phenotypic distribution within species can vary widely across environmental gradients but forecasts of species' responses to environmental change often assume species respond homogenously across their ranges. We compared predictions from species and phenotype distribution models under future climate scenarios for Andropogon gerardii, a widely distributed, dominant grass found throughout the central United States. Phenotype data on aboveground biomass, height, leaf width, and chlorophyll content were obtained from 33 populations spanning a ~1000 km gradient that encompassed the majority of the species' environmental range. Species and phenotype distribution models were trained using current climate conditions and projected to future climate scenarios. We used permutation procedures to infer the most important variable for each model. The species-level response to climate was most sensitive to maximum temperature of the hottest month, but phenotypic variables were most sensitive to mean annual precipitation. The phenotype distribution models predict that A. gerardii could be largely functionally eliminated from where this species currently dominates, with biomass and height declining by up to ~60% and leaf width by ~20%. By the 2070s, the core area of highest suitability for A. gerardii is projected to shift up to ~700 km northeastward. Further, short-statured phenotypes found in the present-day short grass prairies on the western periphery of the species' range will become favored in the current core ~800 km eastward of their current location. Combined, species and phenotype models predict this currently dominant prairie grass will decline in prevalence and stature. Thus, sourcing plant material for grassland restoration and forage should consider changes in the phenotype that will be favored under future climate conditions. Phenotype distribution models account for the role of intraspecific variation in determining responses to anticipated climate change and thereby complement predictions from species distributions models in guiding climate adaptation strategies.

Phenotypic plasticity in life-history traits of Daphnia galeata in response to temperature - a comparison across clonal lineages separated in time

Climatic changes are projected to result in rapid adaptive events with considerable phenotypic shifts. In order to reconstruct the impact of increased mean water temperatures during past decades and to reveal possible thermal micro‐evolution, we applied a resurrection ecology approach using dormant eggs of the freshwater keystone species Daphnia galeata. To this end, we compared the adaptive response of D. galeata clones from Lake Constance of two different time periods, 1965–1974 (“historical”) versus 2000–2009 (“recent”), to experimentally increased temperature regimes. In order to distinguish between genetic versus environmentally induced effects, we performed a common garden experiment in a flow‐through system and measured variation in life‐history traits. Experimental thermal regimes were chosen according to natural temperature conditions during the reproductive period of D. galeata in Central European lakes, with one additional temperature regime exceeding the currently observable maximum (+2°C). Increased water temperatures were shown to significantly affect measured life‐history traits, and significant “temperature × clonal age” interactions were revealed. Compared to historical clones, recent clonal lineages exhibited a shorter time to first reproduction and a higher survival rate, which may suggest temperature‐driven micro‐evolution over time but does not allow an explicit conclusion on the adaptive nature of such responses.