Climate change and evolutionary adaptations at species' range margins

Exposure of protected areas in Central America to extreme weather events

Central America and the Caribbean are regularly battered by megadroughts, heavy rainfall, heat waves, and tropical cyclones. Although 21st-century climate change is expected to increase the frequency, intensity, and duration of these extreme weather events (EWEs), their incidence in regional protected areas (PAs) remains poorly explored. We examined historical and projected EWEs across the region based on 32 metrics that describe distinct dimensions (i.e., intensity, duration, and frequency) of heat waves, cyclones, droughts, and rainfall and compared trends in PAs with trends in unprotected lands. From the early 21st century onward, exposure to EWEs increased across the region, and PAs were predicted to be more exposed to climate extremes than unprotected areas (as shown by autoregressive model coefficients at p < 0.05 significance level). This was particularly true for heat waves, which were projected to have a significantly higher average (tested by Wilcoxon tests at p < 0.01) intensity and duration, and tropical cyclones, which affected PAs more severely in carbon-intensive scenarios. PAs were also predicted to be significantly less exposed to droughts and heavy rainfall than unprotected areas (tested by Wilcoxon tests at p < 0.01). However, droughts that could threaten connectivity between PAs are increasingly common in this region. We estimated that approximately 65% of the study area will experience at least one drought episode that is more intense and longer lasting than previous droughts. Collectively, our results highlight that new conservation strategies adapted to threats associated with EWEs need to be tailored and implemented promptly. Unless urgent action is taken, significant damage may be inflicted on the unique biodiversity of the region.

An increase in management actions has compensated for past climate change effects on desert locust gregarization in western Africa

In response to high population density, the desert locust, Schistocerca gregaria, becomes gregarious and forms swarms that can cause significant damage to crops and pastures, threatening food security of human populations from western Africa to India. This switch from solitary to gregarious populations is highly dependent on favorable weather conditions. Climate change, which has been hypothesized to shift conditions towards increasing risks of gregarization, is therefore likely to have significant impacts on the spatial distribution and likelihood of outbreak events. However, the desert locust is intensely managed at large scales, which possibly counteracts any increased risk of outbreaks due to a more favorable climate. Consequently, understanding the changes in risks in the future involves teasing out the effects of climate change and management actions. Here we studied the dynamics of gregarization at the very early stages of potential outbreaks, in parallel with trends in climate and management, between 1985 and 2018 in western Africa. We used three different spatial scales, with the goal to have a better understanding of the potential effects of climate change per se while controlling for management. Our first approach was to look at a regional scale, where we observed an overall decrease in gregarization events. However, this scale includes very heterogeneous environments and management efforts. To consider this heterogeneity, we divided the area into a grid of 0.5° cells. For each cell, a climate analysis was performed for rainfall and temperature, with trends obtained by a harmonic decomposition model on monthly data. Analyses of gregarization showed only a few significant trends, both positive and negative, mainly found in western Mauritania where management effort has increased. To improve the statistical power, these cells were then grouped into larger homogeneous climatic clusters, i.e. groups of cells with similar climatic conditions and similar climatic trends over the study period. At this scale, gregarization events depend on the intersection between climate conditions and management efforts. The clusters where gregarization increased were also the ones with the highest increase of management. These results highlight the important effect of preventive management, which may counteract the positive effects of climate change on locust proliferation.

Would future climate warming cause zoonotic diseases to spread over long distances?

Dipus sagitta is a major rodent found in arid environments and desert areas. They feed on plant seeds, young branches and some small insects, and have hibernating habits. Peak Dipus sagitta numbers impact the construction of the plant community in the environment, but also have a human impact as these rodents carry a variety of parasitic fleas capable of spreading serious diseases to humans. Based on 216 present distribution records of Dipus sagitta and seven environmental variables, this article simulates the potential distribution of Dipus sagitta during the Last Glacial Maximum, the mid-Holocene, the present and the future (2070s, RCP4.5, RCP8.5). This study also analyzes the geographic changes of the population distribution and evaluates the importance of climate factors by integrating contribution rate, replacement importance value and the jackknife test using the MaxEnt model. In this study, we opted to assess the predictive capabilities of our model using the receiver operating characteristic (ROC) and partial receiver operating characteristic (pROC) metrics. The findings indicate that the AUC value exceeds 0.9 and the AUC ratio is greater than 1, indicating superior predictive performance by the model. The results showed that the main climatic factors affecting the distribution of the three-toed jerboa were precipitation in the coldest quarter, temperature seasonality (standard deviation), and mean annual temperature. Under the two warming scenarios of the mid-Holocene and the future, there were differences in the changes in the distribution area of the three-toed jerboa. During the mid-Holocene, the suitable distribution area of the three-toed jerboa expanded, with a 93.91% increase in the rate of change compared to the Last Glacial Maximum. The size of the three-toed jerboa's habitat decreases under both future climate scenarios. Compared to the current period, under the RCP4.5 emission scenario, the change rate is -2.96%, and under the RCP8.5 emission scenario, the change rate is -7.41%. This indicates a trend of contraction in the south and expansion in the north. It is important to assess changes in the geographic population of Dipus sagitta due to climate change to formulate population control strategies of these harmful rodents and to prevent and control the long-distance transmission of zoonotic diseases.

Rapid evolution of novel biotic interactions in the UK Brown Argus butterfly uses genomic variation from across its geographical range

Understanding the rate and extent to which populations can adapt to novel environments at their ecological margins is fundamental to predicting the persistence of biological communities during ongoing and rapid global change. Recent range expansion in response to climate change in the UK butterfly Aricia agestis is associated with the evolution of novel interactions with a larval food plant, and the loss of its ability to use an ancestral host species. Using ddRAD analysis of 61,210 variable SNPs from 261 females from throughout the UK range of this species, we identify genomic regions at multiple chromosomes that are associated with evolutionary responses, and their association with demographic history and ecological variation. Gene flow appears widespread throughout the range, despite the apparently fragmented nature of the habitats used by this species. Patterns of haplotype variation between selected and neutral genomic regions suggest that evolution associated with climate adaptation is polygenic, resulting from the independent spread of alleles throughout the established range of this species, rather than the colonization of pre-adapted genotypes from coastal populations. These data suggest that rapid responses to climate change do not depend on the availability of pre-adapted genotypes. Instead, the evolution of novel forms of biotic interaction in A. agestis has occurred during range expansion, through the assembly of novel genotypes from alleles from multiple localities.

Environmentally independent selection for hybrids between divergent freshwater stickleback lineages in semi-natural ponds

Hybridization following secondary contact of genetically divergent populations can influence the range expansion of invasive species, though specific outcomes depend on the environmental dependence of hybrid fitness. Here, using two genetically and ecologically divergent threespine stickleback lineages that differ in their history of freshwater colonization, we estimate fitness variation of parental lineages and hybrids in semi-natural freshwater ponds with contrasting histories of nutrient loading. In our experiment, we found that fish from the older freshwater lineage (Lake Geneva) and hybrids outperformed fish from the younger freshwater lineage (Lake Constance) in terms of both growth and survival, regardless of the environmental context of our ponds. Across all ponds, hybrids exhibited the highest survival. Although wild-caught adult populations differed in their functional and defence morphology, it is unclear which of these traits underlie the fitness differences observed among juveniles in our experiment. Overall, our work suggests that when hybrid fitness is insensitive to environmental conditions, as observed here, introgression may promote population expansion into unoccupied habitats and accelerate invasion success.

Epigenetic regulations as drivers of insecticide resistance and resilience to climate change in arthropod pests

Arthropod pests are remarkably capable of rapidly adapting to novel forms of environmental stress, including insecticides and climate change. The dynamic interplay between epigenetics and genetics explains the largely unexplored reality underlying rapid climatic adaptation and the development of insecticide resistance in insects. Epigenetic regulation modulates gene expression by methylating DNA and acetylating histones that play an essential role in governing insecticide resistance and adaptation to climate change. This review summarises and discusses the significance of recent advances in epigenetic regulation that facilitate phenotypic plasticity in insects and their symbiotic microbes to cope with selection pressure implied by extensive insecticide applications and climate change. We also discuss how epigenetic changes are passed on to multiple generations through sexual recombination, which remains enigmatic. Finally, we explain how these epigenetic signatures can be utilized to manage insecticide resistance and pest resilience to climate change in Anthropocene.

Modeling climate change impacts on the distribution of an endangered brown bear population in its critical habitat in Iran

Climate change is one of the major challenges to the current conservation of biodiversity. Here, by using the brown bear, Ursus arctos, in the southernmost limit of its global distribution as a model species, we assessed the impact of climate change on the species distribution in western Iran. The mountainous forests of Iran are inhabited by small and isolated populations of brown bears that are prone to extinction in the near future. We modeled the potential impact of climate change on brown bear distribution and habitat connectivity by the years 2050 and 2070 under four representative concentration pathways (RCPs) of two general circulation models (GCMs): BCC-CSM1-1 and MRI-CGCM3. Our projections revealed that the current species' range, which encompasses 6749.8 km² (40.8%) of the landscape, will decline by 10% (2050: RCP2.6, MRI-CGCM3) to 45% (2070: RCP8.5, BCC-CSM1-1). About 1850 km² (27.4%) of the current range is covered by a network of conservation (CAs) and no-hunting (NHAs) areas which are predicted to decline by 0.64% (2050: RCP2.6, MRI-CGCM3) to 15.56% (2070: RCP8.5, BCC-CSM1-1) due to climate change. The loss of suitable habitats falling within the network of CAs and NHAs is a conservation challenge for brown bears because it may lead to bears moving outside the CAs and NHAs and result in subsequent increases in the levels of bear-human conflict. Thus, re-evaluation of the network of CAs and NHAs, establishing more protected areas in suitable landscapes, and conserving vital linkages between habitat patches under future climate change scenarios are crucial strategies to conserve and manage endangered populations of the brown bear.

Small mammals in a mountain ecosystem: the effect of topographic, micrometeorological, and biological correlates on their community structure

An increasing number of studies have investigated spatial and temporal patterns in species richness and assemblage composition in mountain ecosystems along altitudinal gradients. Small mammals have been successfully used as indicators of environmental health and as proxies of biodiversity. However, information about the composition and distribution of species assemblages in the mosaic of habitat and rocky landform types at a high altitude is still lacking for most of the mountain regions. Through the use of live traps and camera trapping, we described the small mammal community living above the treeline of the Western Dolomites (Italian Alps), investigating the species richness, abundance of individuals and community composition in relation to topographic, micrometeorological, mesohabitat, and biological correlates. A total of five species and 50 individuals were sampled, analysed, and released. At the extremes of the analysed altitudinal range (i.e. 1900 vs 2900 m a.s.l.), community composition was completely different and species richness was related to elevation, steepness, and vegetation cover. At the same time, the taxonomic distinctness of ground-dwelling arthropods (namely carabid beetles and spiders), a proxy of habitat complexity, showed higher values in areas with a greater small mammal species richness. We found a positive effect of steepness and rocky landform type “carsism” on the number of captured individuals, showing the importance of the availability of shelters and underground burrows for the sampled species. As a confirmation of the altitudinal shift for these species in relation to the ongoing climate change, we detected a negative impact of sub-surface ground temperature on small mammal abundance during the monitoring period. In conclusion, small mammals represent an excellent model for understanding the evolutionary processes of ecosystems, population dynamics under changing environmental conditions, and habitat vulnerabilities.

Single Amino Acid Substitution the DNA Repairing Gene Radiation-Sensitive 4 Contributes to Ultraviolet Tolerance of a Plant Pathogen

To successfully survive and reproduce, all species constantly modify the structure and expression of their genomes to cope with changing environmental conditions including ultraviolet (UV) radiation. Thus, knowledge of species adaptation to environmental changes is a central theme of evolutionary studies which could have important implication for disease management and social-ecological sustainability in the future but is generally insufficient. Here, we investigated the evolution of UV adaptation in organisms by population genetic analysis of sequence structure, physiochemistry, transcription, and fitness variation in the radiation-sensitive 4 (RAD4) gene of the Irish potato famine pathogen Phytophthora infestans sampled from various altitudes. We found that RAD4 is a key gene determining the resistance of the pathogen to UV stress as indicated by strong phenotype-genotype-geography associations and upregulated transcription after UV exposure. We also found conserved evolution in the RAD4 gene. Only five nucleotide haplotypes corresponding to three protein isoforms generated by point mutations were detected in the 140 sequences analyzed and the mutations were constrained to the N-terminal domain of the protein. Physiochemical changes associated with non-synonymous mutations generate severe fitness penalty to mutants, which are purged out by natural selection, leading to the conserved evolution observed in the gene.

Pesticide resistance in arthropods: Ecology matters too

Pesticide resistance development is an example of rapid contemporary evolution that poses immense challenges for agriculture. It typically evolves due to the strong directional selection that pesticide treatments exert on herbivorous arthropods. However, recent research suggests that some species are more prone to evolve pesticide resistance than others due to their evolutionary history and standing genetic variation. Generalist species might develop pesticide resistance especially rapidly due to pre‐adaptation to handle a wide array of plant allelochemicals. Moreover, research has shown that adaptation to novel host plants could lead to increased pesticide resistance. Exploring such cross‐resistance between host plant range evolution and pesticide resistance development from an ecological perspective is needed to understand its causes and consequences better. Much research has, however, been devoted to the molecular mechanisms underlying pesticide resistance while both the ecological contexts that could facilitate resistance evolution and the ecological consequences of cross‐resistance have been under‐studied. Here, we take an eco‐evolutionary approach and discuss circumstances that may facilitate cross‐resistance in arthropods and the consequences cross‐resistance may have for plant–arthropod interactions in both target and non‐target species and species interactions. Furthermore, we suggest future research avenues and practical implications of an increased ecological understanding of pesticide resistance evolution.

Mitochondrial composition of and diffusion limiting factors of three social wasp genera Polistes, Ropalidia, and parapolybia (Hymenoptera: Vespidae)

Background

Social wasps Polistes, Ropalidia, and Parapolybia, belonging to the subfamily Polistinae, have obviously different distribution patterns, yet the factors leading to this difference remain unknown.

Results

The 17 newly sequenced mitogenomes of Polistes, Ropalidia, and Parapolybia contain 37 genes, and there are obvious differences among the compositions of the three genera. The monophyly of the genus Polistes and a monophyletic Ropalidiini: (Ropalidia + Parapolybia) are concordant with previous morphological analysis of the subfamily Polistinae. Our inferred divergence time demonstrates Polistes (at around 69 Ma) was diverged earlier than Ropalidia and Parapolybia (at around 61 Ma). The rearrangement of both trnY and trnL1 are shared by all the Polistinae. In addition, the unique rearrangement of TDRL derived at 69 Ma is detected in Polistes, and Ropalidia contains a Reversal which may derive at 61 Ma. Hereafter, the possibility is elaborated that Polistes originated in Aisa and then dispersed from Africa to South America, and Polistes and Ropalidia spread from Southeast Asia to Australia. At last, continental drift and Quaternary Ice Ages are inferred to be two main limiting factors in the current distributions of the three genera.

Conclusions

Obvious differences occur in the mitochondrial composition of Polistes, Ropalidia, and Parapolybia. According to the reconstructed time-calibrated framework, it is inquired that the continental drifts and the climate are mainly diffusion limiting factors of the three genera.

Supplementary information

The online version contains supplementary material available at 10.1186/s12862-022-02017-6.

Introduction to the theme issue 'Species' ranges in the face of changing environments'

Understanding where, when and how species’ ranges will be modified is both a fundamental problem and essential to predicting how spatio-temporal environmental changes in abiotic and biotic factors impact biodiversity. Notably, different species may respond disparately to similar environmental changes: some species may overcome an environmental change only with difficulty or not at all, while other species may readily overcome the same change. Ranges may contract, expand or move. The drivers and consequences of this variability in species' responses remain puzzling. Importantly, changes in a species’ range creates feedbacks to the environmental conditions, populations and communities in its previous and current range, rendering population genetic, population dynamic and community processes inextricably linked. Understanding these links is critical in guiding biodiversity management and conservation efforts. This theme issue presents current thinking about the factors and mechanisms that limit and/or modify species' ranges. It also outlines different approaches to detect changes in species’ distributions, and illustrates cases of range modifications in several taxa. Overall, this theme issue highlights the urgency of understanding species' ranges but shows that we are only just beginning to disentangle the processes involved. One way forward is to unite ecology with evolutionary biology and empirical with modelling approaches.

This article is part of the theme issue ‘Species’ ranges in the face of changing environments (Part II)’.

Genetic divergence and range expansion in a western North Pacific coral

Coral poleward range expansions have recently been observed in response to warming oceans. Range expansion can lead to reduced genetic diversity and increased frequency of deleterious mutations that were rare in core populations, potentially limiting the ability for adaptation and persistence in novel environments. Successful expansions that overcome these founder effects and colonize new habitat have been attributed to multiple introductions from different sources, hybridization with native populations, or rapid adaptive evolution. Here, we investigate population genomic patterns of the reef-building coral Acropora hyacinthus along a latitudinal cline that includes a well-established range expansion front in Japan using 2b-RAD sequencing. A total of 184 coral samples were collected across seven sites spanning from ~24°N to near its northern range front at ~33°N. We uncover the presence of three cryptic lineages of A. hyacinthus, which occupy discrete reefs within this region. Only one lineage is present along the expansion front and we find evidence for its historical occupation of marginal habitats. Within this lineage we also find evidence of bottleneck pressures associated with expansion events including higher clonality, increased linkage disequilibrium, and lower genetic diversity in range edge populations compared to core populations. Asymmetric migration between populations was also detected with lower migration from edge sites. Lastly, we describe genomic signatures of local adaptation potentially attributed to lower winter temperatures experienced at the more recently expanded northern populations. Together these data illuminate the genomic consequences of range expansion in a coral and highlight how adaptation to discrete environments along expansion fronts may facilitate further range expansion in this temperate coral lineage.

Seasonal and microclimatic effects on leaf beetles (Coleoptera, Chrysomelidae) in a tropical forest fragment in northeastern Mexico

Leaf beetles (Coleoptera: Chrysomelidae) constitute a family of abundant, diverse, and ecologically important herbivorous insects, due to their high specificity with host plants, a close association with vegetation and a great sensitivity to microclimatic variation (factors that are modified gradually during the rainy and dry seasons). Therefore, the effects of seasonality (rainy and dry seasons) and microclimate on the community attributes of chrysomelids were evaluated in a semideciduous tropical forest fragment of northeastern Mexico. Monthly sampling was conducted, between March 2016 and February 2017, with an entomological sweep net in 18 plots of 20 × 20 m, randomly distributed from 320 to 480 m a.s.l. Seven microclimatic variables were simultaneously recorded during each of the samplings, using a portable weather station. In total, 216 samples were collected at the end of the study, of which 2,103 specimens, six subfamilies, 46 genera, and 71 species were obtained. The subfamily Galerucinae had the highest number of specimens and species in the study area, followed by Cassidinae. Seasonality caused significant changes in the abundance and number of leaf beetle species: highest richness was recorded in the rainy season, with 60 species, while the highest diversity (lowest dominance and highest H’ index) was obtained in the dry season. Seasonal inventory completeness of leaf beetles approached (rainy season) or was higher (dry season) than 70%, while the faunistic similarity between seasons was 0.63%. The outlying mean index was significant in both seasons; of the seven microclimatic variables analyzed, only temperature, heat index, evapotranspiration and wind speed were significantly related to changes in abundance of Chrysomelidae. Association between microclimate and leaf beetles was higher in the dry season, with a difference in the value of importance of the abiotic variables. The results indicated that each species exhibited a different response pattern to the microclimate, depending on the season, which suggests that the species may exhibit modifications in their niche requirements according to abiotic conditions. However, the investigations must be replicated in other regions, in order to obtain a better characterization of the seasonal and microclimatic influence on the family Chrysomelidae.

Body and wing size, but not wing shape, vary along a large-scale latitudinal gradient in a damselfly

Large-scale latitudinal studies that include both north and south edge populations and address sex differences are needed to understand how selection has shaped trait variation. We quantified the variation of flight-related morphological traits (body size, wing size, ratio between wing size and body size, and wing shape) along the whole latitudinal distribution of the damselfly Lestes sponsa, spanning over 2700 km. We tested predictions of geographic variation in the flight-related traits as a signature of: (1) stronger natural selection to improve dispersal in males and females at edge populations; (2) stronger sexual selection to improve reproduction (fecundity in females and sexual behaviors in males) at edge populations. We found that body size and wing size showed a U-shaped latitudinal pattern, while wing ratio showed the inverse shape. However, wing shape varied very little along the latitudinal gradient. We also detected sex-differences in the latitudinal patterns of variation. We discuss how latitudinal differences in natural and sexual selection regimes can lead to the observed quadratic patterns of variation in body and wing morphology via direct or indirect selection. We also discuss the lack of latitudinal variation in wing shape, possibly due to aerodynamic constraints.

Bumblebee resilience to climate change, through plastic and adaptive responses

Bumblebees are ubiquitous, cold-adapted eusocial bees found worldwide from subarctic to tropical regions of the world. They are key pollinators in most temperate and boreal ecosystems, and both wild and managed populations are significant contributors to agricultural pollination services. Despite their broad ecological niche at the genus level, bumblebee species are threatened by climate change, particularly by rising average temperatures, intensifying seasonality and the increasing frequency of extreme weather events. While some temperature extremes may be offset at the individual or colony level through temperature regulation, most bumblebees are expected to exhibit specific plastic responses, selection in various key traits, and/or range contractions under even the mildest climate change. In this review, we provide an in-depth and up-to-date review on the various ways by which bumblebees overcome the threats associated with current and future global change. We use examples relevant to the fields of bumblebee physiology, morphology, behaviour, phenology, and dispersal to illustrate and discuss the contours of this new theoretical framework. Furthermore, we speculate on the extent to which adaptive responses to climate change may be influenced by bumblebees' capacity to disperse and track suitable climate conditions. Closing the knowledge gap and improving our understanding of bumblebees' adaptability or avoidance behaviour to different climatic circumstances will be necessary to improve current species climate response models. These models are essential to make correct predictions of species vulnerability in the face of future climate change and human-induced environmental changes to unfold appropriate future conservation strategies.

The role of climate change in pollinator decline across the Northern Hemisphere is underestimated

Pollinator biodiversity loss occurs at unprecedented rates globally, with particularly sharp declines documented in the North Temperate Zone. There is currently no consensus on the main drivers of the decline. Although climate change is expected to drive biodiversity loss in the future, current warming is often suggested to have positive impacts on pollinator assemblages in higher latitudes. Consequently, pollinator conservation initiatives in Europe and the USA tend to lack climate adaptation initiatives, an omission of which may be risky if climate change has significant negative impacts on pollinators. To gain an understanding of the impacts of climate change on pollinator biodiversity in the Northern Hemisphere, we conducted a literature review on genetic, species and community level diversity. Our findings suggest that global heating most likely causes homogenization of pollinator assemblages at all levels of pollinator biodiversity, making them less resilient to future stochasticity. Aspects of biodiversity that are rarely measured (e.g. genetic diversity, β-diversity, species evenness) tend to be most affected, while some dimensions of climate change, such as fluctuations in winter weather conditions, changes in the length of the vegetational season and increased frequency of extreme weather events, that seldom receive attention in empirical studies, tend to be particularly detrimental to pollinators. Negative effects of global heating on pollinator biodiversity are most likely exacerbated by homogenous and fragmented landscapes, widespread across Europe and the US, which limit opportunities for range-shifts and reduce micro-climatic buffering. This suggests the need for conservation initiatives to focus on increasing landscape connectivity and heterogeneity at multiple spatial scales.

Coffee Berry Borer (Hypothenemus hampei) Emergence from Ground Fruits Across Varying Altitudes and Climate Cycles, and the Effect on Coffee Tree Infestation

During coffee harvest, picked berries fall to the ground where they serve as a reservoir for the coffee berry borer (CBB) which then infest coffee berries on the trees. This study tested the effect of fallen CBB-infested coffee berries on the infestation of coffee trees (Coffea arabica). Three-year-old trees were treated with either 0, 1, 5, 10, 15, or 20 CBB-infested berries placed on the root vicinity. The CBB infestation of coffee trees was sampled every 30 days during 6 months for four coffee productive cycles. The experiment was set up at four different locations comprising different altitudes (1,218; 1,381; 1,470; and 1,700 m.a.s.l.) and the measurements were taken during 4 years where the climatic events of El Niño, La Niña, Neutral, and transitions El Niño/La Niña were present. The results show that CBB-infested berries left on the ground are a reservoir of CBB for 140 ± 8.2 days and infest developing healthy coffee berries. In a climate Neutral year, one CBB-infested ground berry left on the ground infested on average 590.2 ± 142.2 berries in coffee trees grown at 1,218 m.a.s.l. At the same altitude, one CBB-infested ground berry resulted in 151.5 ± 29.1 infested tree berries during La Niña year and 959.0 ± 89.6 during El Niño year. The CBB infestation was positively correlated with temperature and negatively correlated with altitude (R²= 0.99 and R²= -0.96, respectively). This study highlights the importance of careful harvesting practices to prevent berries from falling to the ground, followed by ground sanitation to limit later infestation of the coffee crop.

How Dispersal Evolution and Local Adaptation Affect the Range Dynamics of Species Lagging Behind Climate Change

AbstractAs climate changes, species' ability to spatially track suitable climate depends on their spread velocity, a function of their population growth and dispersal capacity. When climate changes faster than species can spread, the climate experienced at species' expanding range edges may ameliorate as conditions become increasingly similar to those of the range core. When this boosts species' growth rates, their spread accelerates. Here, we use simulations of a spreading population with an annual life history to explore how climatic amelioration interacts with dispersal evolution and local adaptation to determine the dynamics of spread. We found that depending on the timing of dispersal evolution, spread velocity can show contrasting trajectories, sometimes transiently exceeding the climate velocity before decelerating. Climatic amelioration can also accelerate the spread of populations composed of genotypes best adapted to local climatic conditions, but the exact dynamics depends on the pattern of climatic adaptation. We conclude that failing to account for demographic variation across climatic gradients can lead to erroneous conclusions about species' capacity to spatially track suitable climate.

The Effect of the Recombination Rate between Adaptive Loci on the Capacity of a Population to Expand Its Range

AbstractPrevious theoretical work on range expansions over heterogeneous environments showed that there is a critical environmental gradient where range expansion stops. For populations with freely recombining loci underlying the trait under selection (hereafter, "adaptive loci"), the critical gradient in one-dimensional habitats depends on the fitness cost of dispersal and the strength of selection relative to genetic drift. Here, we extend the previous work in two directions and ask, What is the role of the recombination rate between the adaptive loci during range expansions? And what effect does the ability of selfing as opposed to obligate outcrossing have on range expansions? To answer these questions, we use computer simulations. We demonstrate that while reduced recombination rates between adaptive loci slow down range expansions as a result of poor purging of locally deleterious alleles at the expansion front, they may also allow a species to occupy a greater range. In addition, we find that the allowance of selfing may improve the ability of populations to expand their ranges, for example, because selfing among potentially rare high-fitness individuals facilitates the establishment and maintenance of locally well-adapted genotypes. We conclude that during range expansions there is a trade-off between positive and negative effects of recombination within and between individuals.

Altitudinal Heterogeneity of UV Adaptation in Phytophthorainfestans Is Associated with the Spatial Distribution of a DNA Repair Gene

Climate change is considered a major threat to society and nature. UV irradiation is the most important environmental genotoxic agent. Thus, how elevated UV irradiation may influence human health and ecosystems has generated wide concern in the scientific community, as well as with policy makers and the public in general. In this study, we investigated patterns and mechanisms of UV adaptation in natural ecosystems by studying a gene-specific variation in the potato late blight pathogen, Phytophthora infestans. We compared the sequence characteristics of radiation sensitive 23 (RAD23), a gene involved in the nucleotide excision repair (NER) pathway and UV tolerance, in P. infestans isolates sampled from various altitudes. We found that lower genetic variation in the RAD23 gene was caused by natural selection. The hypothesis that UV irradiation drives this selection was supported by strong correlations between the genomic characteristics and altitudinal origin (historic UV irradiation) of the RAD23 sequences with UV tolerance of the P. infestans isolates. These results indicate that the RAD23 gene plays an important role in the adaptation of P. infestans to UV stress. We also found that different climatic factors could work synergistically to determine the evolutionary adaptation of species, making the influence of climate change on ecological functions and resilience more difficult to predict. Future attention should aim at understanding the collective impact generated by simultaneous change in several climate factors on species adaptation and ecological sustainability, using state of the art technologies such as experimental evolution, genome-wide scanning, and proteomics.

Latitudinal clines in sexual selection, sexual size dimorphism and sex-specific genetic dispersal during a poleward range expansion

Range expansions can be shaped by sex differences in behaviours and other phenotypic traits affecting dispersal and reproduction. Here, we investigate sex differences in morphology, behaviour and genomic population differentiation along a climate-mediated range expansion in the common bluetail damselfly (Ischnura elegans) in northern Europe. We sampled 65 sites along a 583-km gradient spanning the I. elegans range in Sweden and quantified latitudinal gradients in site relative abundance, sex ratio and sex-specific shifts in body size and mating status (a measure of sexual selection). Using single nucleotide polymorphism (SNP) data for 426 individuals from 25 sites, we further investigated sex-specific landscape and climatic effects on neutral genetic connectivity and migration patterns. We found evidence for sex differences associated with the I. elegans range expansion, namely (a) increased male body size with latitude, but no latitudinal effect on female body size, resulting in reduced sexual dimorphism towards the range limit, (b) a steeper decline in male genetic similarity with increasing geographic distance than in females, (c) male-biased genetic migration propensity and (d) a latitudinal cline in migration distance (increasing migratory distances towards the range margin), which was stronger in males. Cooler mean annual temperatures towards the range limit were associated with increased resistance to gene flow in both sexes. Sex ratios became increasingly male biased towards the range limit, and there was evidence for a changed sexual selection regime shifting from favouring larger males in the south to favouring smaller males in the north. Our findings suggest sex-specific spatial phenotype sorting at the range limit, where larger males disperse more under higher landscape resistance associated with cooler climates. The combination of latitudinal gradients in sex-biased dispersal, increasing male body size and (reduced) sexual size dimorphism should have emergent consequences for sexual selection dynamics and the mating system at the expanding range front. Our study illustrates the importance of considering sex differences in the study of range expansions driven by ongoing climate change.

Evolution of cold tolerance and thermal plasticity in life history, behaviour and physiology during a poleward range expansion

Many species that are moving polewards encounter novel thermal regimes to which they have to adapt. Therefore, rapid evolution of thermal tolerance and of thermal plasticity in fitness-related traits in edge populations can be crucial for the success and speed of range expansions. We tested for adaptation in cold tolerance and in life history, behavioural and physiological traits and their thermal plasticity during a poleward range expansion. We reconstructed the thermal performance curves of life history (survival, growth and development rates), behaviour (food intake) and cold tolerance (chill coma recovery time) in the aquatic larval stage of the damselfly Ischnura elegans that is currently showing a poleward range expansion in northern Europe. We studied larvae from three edge and three core populations using a common-garden experiment. Consistent with the colder annual temperatures, larvae at the expansion front evolved an improved cold tolerance. The edge populations showed no overall (across temperatures) evolution of a faster life history that would improve their range-shifting ability. Moreover, consistent with damselfly edge populations from colder latitudes, edge populations evolved at the highest rearing temperature (28°C) a faster development rate, likely to better exploit the rare periods with higher temperatures. This was associated with a higher food intake and a lower metabolic rate. In conclusion, our results suggest that the edge populations rapidly evolved adaptive changes in trait means and thermal plasticity to the novel thermal conditions at the edge front. Our results highlight the importance of considering besides trait plasticity and the evolution of trait means, also the evolution of trait plasticity to improve forecasts of responses to climate change.

Range expansion, habitat use, and choosiness in a butterfly under climate change: Marginality and tolerance of oviposition site selection

Poleward range shifts under climate change involve the colonization of new sites and hence the foundation of new populations at the expanding edge. We studied oviposition site selection in a butterfly under range expansion (Lycaena dispar), a key process for the establishment of new populations. We described and compared the microhabitats used by the species for egg laying with those available across the study sites both in edge and in core populations. We carried out an ecological niche factor analysis (ENFA) to estimate (1) the variety of microhabitats used by the butterfly for egg laying (tolerance) and (2) the extent to which these selected microhabitats deviated from those available (marginality). Microhabitat availability was similar in edge and core populations. Ambient temperature recorded at the site level above the vegetation was on average lower at core populations. In contrast with what is often assumed, edge populations did not have narrower microhabitat use compared to core populations. Females in edge populations even showed a higher degree of generalism: They laid eggs under a wider range of microhabitats. We suggest that this pattern could be related to an overrepresentation of fast deciding personalities in edge populations. We also showed that the thermal time window for active female behavior was reduced in edge populations, which could significantly decrease the time budget for oviposition and decrease the threshold of acceptance during microhabitat selection for oviposition in recently established populations.

Genetic Diversity of Ligidium Isopods in Hokkaido and Niigata, Northern Japan, Based on Mitochondrial DNA Analysis

The genetic diversity of the genus Ligidium in Hokkaido and Niigata, northern Japan, was investigated by analyzing the cytochrome c oxidase subunit 1 (CO1) region in the mitochondrial DNA (mtDNA). The genetic diversity in Hokkaido was much lower than that in Niigata. Nine different operational taxonomic units (OTUs) were identified. Only a single OTU, most likely Ligidium japonicum, was found in Hokkaido, whereas all nine OTUs were found in Niigata. Using the mtDNA evolutionary rate determined for the marine invertebrate Haptosquilla pulchella (Miers, 1880), population expansion for OTU1 in Hokkaido was estimated to have occurred at 12,600 years BP, suggesting that Ligidium underwent a bottleneck due to glacial cooling, and the population then expanded after postglacial warming. Assuming that the expansion of the OTU1 population occurred at 9600 years BP, when the sea surface temperature rose offshore of Tokachi in the Northwestern Pacific, the evolutionary rate (µ) of the mtDNA CO1 region in Ligidium is calculated as: 0.087 (95% confidence intervals: min: 0.042-max: 0.12) (substitutions/site/million years). The presence of a haplotype common to Hokkaido and Niigata implies that the haplotype migrated across the Tsugaru Strait. Considering that geological evidence indicates that the Tsugaru Strait was continuously present even during the last glacial maximum when the sea level was at its lowest, accidental transport by human beings or animals might have been critical to the migration of Ligidium.

Translocation of an arctic seashore plant reveals signs of maladaptation to altered climatic conditions

Ongoing anthropogenic climate change alters the local climatic conditions to which species may be adapted. Information on species' climatic requirements and their intraspecific variation is necessary for predicting the effects of climate change on biodiversity. We used a climatic gradient to test whether populations of two allopatric varieties of an arctic seashore herb (Primula nutans ssp. finmarchica) show adaptation to their local climates and how a future warmer climate may affect them. Our experimental set-up combined a reciprocal translocation within the distribution range of the species with an experiment testing the performance of the sampled populations in warmer climatic conditions south of their range. We monitored survival, size, and flowering over four growing seasons as measures of performance and, thus, proxies of fitness. We found that both varieties performed better in experimental gardens towards the north. Interestingly, highest up in the north, the southern variety outperformed the northern one. Supported by weather data, this suggests that the climatic optima of both varieties have moved at least partly outside their current range. Further warming would make the current environments of both varieties even less suitable. We conclude that Primula nutans ssp. finmarchica is already suffering from adaptational lag due to climate change, and that further warming may increase this maladaptation, especially for the northern variety. The study also highlights that it is not sufficient to run only reciprocal translocation experiments. Climate change is already shifting the optimum conditions for many species and adaptation needs also to be tested outside the current range of the focal taxon in order to include both historic conditions and future conditions.

Wing morphological responses to latitude and colonisation in a range expanding butterfly

Populations undergoing rapid climate-driven range expansion experience distinct selection regimes dominated both by increased dispersal at the leading edges and steep environmental gradients. Characterisation of traits associated with such expansions provides insight into the selection pressures and evolutionary constraints that shape demographic and evolutionary responses. Here we investigate patterns in three components of wing morphology (size, shape, colour) often linked to dispersal ability and thermoregulation, along latitudinal gradients of range expansion in the Speckled Wood butterfly (Pararge aegeria) in Britain (two regions of expansion in England and Scotland). We measured 774 males from 54 sites spanning 799 km with a 10-year mean average temperature gradient of 4 °C. A geometric morphometric method was used to investigate variation in size and shape of forewings and hindwings; colour, pattern, and contrast of the wings were examined using a measure of lightness (inverse degree of melanism). Overall, wing size increased with latitude by ∼2% per 100 km, consistent with Bergmann’s rule. Forewings became more rounded and hindwings more elongated with history of colonisation, possibly reflecting selection for increased dispersal ability. Contrary to thermal melanism expectations, wing colour was lighter where larvae developed at cooler temperatures and unrelated to long-term temperature. Changes in wing spot pattern were also detected. High heterogeneity in variance among sites for all of the traits studied may reflect evolutionary time-lags and genetic drift due to colonisation of new habitats. Our study suggests that temperature-sensitive plastic responses for size and colour interact with selection for dispersal traits (wing size and shape). Whilst the plastic and evolutionary responses may in some cases act antagonistically, the rapid expansion of P. aegeria implies an overall reinforcing effect between these two mechanisms.

Latitudinal variation in climate-associated genes imperils range edge populations

The ecological impacts of increasing global temperatures are evident in most ecosystems on Earth, but our understanding of how climatic variation influences natural selection and adaptive resilience across latitudes remains largely unknown. Latitudinal gradients allow testing general ecosystem-level theories relevant to climatic adaptation. We assessed differences in adaptive diversity of populations along a latitudinal region spanning highly variable temperate to subtropical climates. We generated and integrated information from environmental mapping, phenotypic variation and genome-wide data from across the geographical range of the rainbowfish Melanotaenia duboulayi, an emerging aquatic system for studies of climate change. We detected, after controlling for spatial population structure, strong interactions between genotypes and environment associated with variation in stream flow and temperature. Some of these hydroclimate-associated genes were found to interact within functional protein networks that contain genes of adaptive significance for projected future climates in rainbowfish. Hydroclimatic selection was also associated with variation in phenotypic traits, including traits known to affect fitness of rainbowfish exposed to different flow environments. Consistent with predictions from the "climatic variability hypothesis," populations exposed to extremes of important environmental variables showed stronger adaptive divergence and less variation in climate-associated genes compared to populations at the centre of the environmental gradient. Our findings suggest that populations that evolved at environmental range margins and at geographical range edges may be more vulnerable to changing climates, a finding with implications for predicting adaptive resilience and managing biodiversity under climate change.

Genomic Signatures of Selection along a Climatic Gradient in the Northern Range Margin of the White-Footed Mouse (Peromyscus leucopus)

Identifying genetic variation involved in thermal adaptation is likely to yield insights into how species adapt to different climates. Physiological and behavioral responses associated with overwintering (e.g., torpor) are thought to serve important functions in climate adaptation. In this study, we use 2 isolated Peromyscus leucopus lineages on the northern margin of the species range to identify single nucleotide polymorphisms (SNPs) showing a strong environmental association and test for evidence of parallel evolution. We found signatures of clinal selection in each lineage, but evidence of parallelism was limited, with only 2 SNPs showing parallel allele frequencies across transects. These parallel SNPs map to a gene involved in protection against iron-dependent oxidative stress (Fxn) and to a gene with unknown function but containing a forkhead-associated domain (Fhad1). Furthermore, within transects, we find significant clinal patterns in genes enriched for functions associated with glycogen homeostasis, synaptic function, intracellular Ca2+ balance, H3 histone modification, as well as the G2/M transition of cell division. Our results are consistent with recent literature on the cellular and molecular basis of climate adaptation in small mammals and provide candidate genomic regions for further study.

Assessing ecological and physiological costs of melanism in North American Papilio glaucus females: two decades of dark morph frequency declines

Polymorphisms for melanic form of insects may provide various selective advantages. However, melanic alleles may have significant/subtle pleiotrophic "costs." Several potential pleiotrophic effects of the W (=Y)-linked melanism gene in Papilio glaucus L. (Lepidoptera) showed no costs for melanic versus yellow in adult size, oviposition preferences, fecundity, egg viability, larval survival/growth rates, cold stress tolerance, or postdiapause emergence times. Sexual selection (males choosing yellow rather than mimetic dark females) had been suggested to provide a balanced polymorphism in P. glaucus, but spermatophore counts in wild females and direct field tethering studies of size-matched pairs of virgin females (dark and yellow), show that male preferences are random or frequency-dependent from Florida to Michigan, providing no yellow counter-advantages. Recent frequency declines of dark (melanic/mimetic) females in P. glaucus populations are shown in several major populations from Florida (27.3°N latitude) to Ohio (38.5° N). Summer temperatures have increased significantly at all these locations during this time (1999-2018), but whether dark morphs may be more vulnerable (in any stage) to such climate warming remains to be determined. Additional potential reasons for the frequency declines in mimetic females are discussed: (i) genetic introgression of Z-linked melanism suppressor genes from P. canadensis (R & J) and the hybrid species, P. appalachiensis (Pavulaan & Wright), (ii) differential developmental incompatibilities, or Haldane effects, known to occur in hybrids, (iii) selection against intermediately melanic ("dusty") females (with the W-linked melanic gene, b+) which higher temperatures can cause.

The genetics of evolutionary radiations

With the realization that much of the biological diversity on Earth has been generated by discrete evolutionary radiations, there has been a rapid increase in research into the biotic (key innovations) and abiotic (key environments) circumstances in which such radiations took place. Here we focus on the potential importance of population genetic structure and trait genetic architecture in explaining radiations. We propose a verbal model describing the stages of an evolutionary radiation: first invading a suitable adaptive zone and expanding both spatially and ecologically through this zone; secondly, diverging genetically into numerous distinct populations; and, finally, speciating. There are numerous examples of the first stage; the difficulty, however, is explaining how genetic diversification can take place from the establishment of a, presumably, genetically depauperate population in a new adaptive zone. We explore the potential roles of epigenetics and transposable elements (TEs), of neutral process such as genetic drift in combination with trait genetic architecture, of gene flow limitation through isolation by distance (IBD), isolation by ecology and isolation by colonization, the possible role of intra-specific competition, and that of admixture and hybridization in increasing the genetic diversity of the founding populations. We show that many of the predictions of this model are corroborated. Most radiations occur in complex adaptive zones, which facilitate the establishment of many small populations exposed to genetic drift and divergent selection. We also show that many radiations (especially those resulting from long-distance dispersal) were established by polyploid lineages, and that many radiating lineages have small genome sizes. However, there are several other predictions which are not (yet) possible to test: that epigenetics has played a role in radiations, that radiations occur more frequently in clades with small gene flow distances, or that the ancestors of radiations had large fundamental niches. At least some of these may be testable in the future as more genome and epigenome data become available. The implication of this model is that many radiations may be hard polytomies because the genetic divergence leading to speciation happens within a very short time, and that the divergence history may be further obscured by hybridization. Furthermore, it suggests that only lineages with the appropriate genetic architecture will be able to radiate, and that such a radiation will happen in a meta-population environment. Understanding the genetic architecture of a lineage may be an essential part of accounting for why some lineages radiate, and some do not.

The development of Anthropocene biotas

Biodiversity has always responded dynamically to environmental perturbations in the geological past, through changes to the abundances and distributions of genes and species, to the composition of biological communities, and to the cover and locations of different ecosystem types. This is how the 'nature' that exists today has survived. The same is true in the Anthropocene. The entire planet surface has been altered by humans, ranging from direct vegetation transformation and removal of most of the world's megafauna, through to atmospheric changes in greenhouse gasses and consequent climatic changes and ocean acidification. These anthropogenic perturbations have led to the establishment of genes and species in new locations, thus generating novel communities and ecosystems. In this historical context, recent biological changes should be seen as responses to multiple drivers of change, rather than being a problem per se. These changes are the means by which the biosphere is adjusting to and will ultimately survive the Anthropocene. Thus, management and conservation of the biological world, and our place in it, requires a transition from trying to minimize biological change to one in which we facilitate dynamism that accelerates the rates at which species and ecosystems adjust to human-associated drivers of change. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.

Does range expansion modify trait covariation? A study of a northward expanding dragonfly

The adaptive value of correlations among phenotypic traits depends on the prevailing environmental conditions. Differences in selection pressures during species range expansions may therefore shape phenotypic integration. In this study, we assessed variation in behavioral and morphological traits, as well as their covariations, in replicated southern and northern European populations of the northward expanding dragonfly Crocothemis erythraea. Larvae from northern populations were, on average, darker in color, and therefore, better camouflaged than larvae from southern populations. However, there was no difference in activity level. Darkness and activity were positively correlated in larvae from northern populations, whereas this trait covariation was missing in southern populations. This suggests the emergence of alternative strategies in time-limited northern populations, a higher activity level that required better camouflage through darker coloration, while less active larvae benefited from an energy-saving strategy by reducing the investment in costly traits, such as body darkness. We further found that larger larvae emerged into larger adults, with a higher investment in flight morphology. Our findings imply that phenotypic integration is associated with the northward range shift, potentially differentially shaping fitness consequences, and ecological interactions in southern versus northern populations.

Dispersal and life-history traits in a spider with rapid range expansion

BACKGROUND

Dispersal and reproduction are key life-history traits that jointly determine species' potential to expand their distribution, for instance in light of ongoing climate change. These life-history traits are known to be under selection by changing local environmental conditions, but they may also evolve by spatial sorting. While local natural selection and spatial sorting are mainly studied in model organisms, we do not know the degree to which these processes are relevant in the wild, despite their importance to a comprehensive understanding of species' resistance and tolerance to climate change.

METHODS

The wasp spider Argiope bruennichi has undergone a natural range expansion - from the Mediterranean to Northern Europe during the recent decades. Using reciprocal common garden experiments in the laboratory, we studied differences in crucial traits between replicated core (Southern France) and edge (Baltic States) populations. We tested theoretical predictions of enhanced dispersal (ballooning behaviour) and reproductive performance (fecundity and winter survival) at the expansion front due to spatial sorting and local environmental conditions.

RESULTS

Dispersal rates were not consistently higher at the northern expansion front, but were impacted by the overwintering climatic conditions experienced, such that dispersal was higher when spiderlings had experienced winter conditions as occur in their region. Hatching success and winter survival were lower at the range border. In agreement with theoretical predictions, spiders from the northern leading edge invested more in reproduction for their given body size.

CONCLUSIONS

We found no evidence for spatial sorting leading to higher dispersal in northern range edge populations of A. bruennichi. However, reproductive investment and overwintering survival between core and edge populations differed. These life-history traits that directly affect species' expansion rates seem to have diverged during the recent range expansion of A. bruennichi. We discuss the observed changes with respect to the species' natural history and the ecological drivers associated with range expansion to northern latitudes.

Impact of global warming scenarios on life-history traits of Tetranychus evansi (Acari: Tetranychidae)

Background

The tomato red spider mite, Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae), is an agricultural pest of solanaceous crops. Although T. evansi is of South American subtropical origin, it has recently expanded its distribution range to many tropical and temperate areas around the world. Its potential distribution range in response to scenarios of global warming was recently modeled, confirming its current and possible future distributions. Here, we experimentally investigated the biological traits of T. evansi in the context of the current and future global warming (2100) scenarios. Using an environmental simulation system, we tested the life-history traits of T. evansi under current summer temperatures (as of June, July, and August 2016) and under expected temperature increases based on two IPCC scenarios: RCP2.6 (+ 1 °C) and RCP8.5 (+ 3.7 °C). The mites were introduced into each scenario on 1 June and their sequential progeny were used for testing in each following month.

Results

The mite could develop and reproduce under all scenarios. There was a decrease in the duration of lifespan and female fecundity at RCP8.5 during June and August, but this may be compensated for by the high intrinsic rate of increase, which implies faster population growth and shorter generation time.

Conclusion

Our study and other reports reveal the high adaptability of T. evansi to a wide range of summer temperatures; this may explain its current distribution. We anticipate that global warming will favor the spread of T. evansi and may further expand its distribution to a large area of the globe. These findings should be of ecological and practical relevance for designing prevention and control strategies.

Intraspecific mating system evolution and its effect on complex male secondary sexual traits: Does male-male competition increase selection on size or shape?

Sexual selection is generally held responsible for the exceptional diversity in secondary sexual traits in animals. Mating system evolution is therefore expected to profoundly affect the covariation between secondary sexual traits and mating success. Whereas there is such evidence at the interspecific level, data within species remain scarce. We here investigate sexual selection acting on the exaggerated male fore femur and the male wing in the common and widespread dung flies Sepsis punctum and S. neocynipsea (Diptera: Sepsidae). Both species exhibit intraspecific differences in mating systems and variation in sexual size dimorphism (SSD) across continents that correlates with the extent of male-male competition. We predicted that populations subject to increased male-male competition will experience stronger directional selection on the sexually dimorphic male foreleg. Our results suggest that fore femur size, width and shape were indeed positively associated with mating success in populations with male-biased SSD in both species, which was not evident in conspecific populations with female-biased SSD. However, this was also the case for wing size and shape, a trait often assumed to be primarily under natural selection. After correcting for selection on overall body size by accounting for allometric scaling, we found little evidence for independent selection on any of these size or shape traits in legs or wings, irrespective of the mating system. Sexual dimorphism and (foreleg) trait exaggeration is therefore unlikely to be driven by direct precopulatory sexual selection, but more so by selection on overall size or possibly selection on allometric scaling.

A Conceptual Framework for Range-Expanding Species that Track Human-Induced Environmental Change

For many species, human-induced environmental changes are important indirect drivers of range expansion into new regions. We argue that it is important to distinguish the range dynamics of such species from those that occur without, or with less clear, involvement of human-induced environmental changes. We elucidate the salient features of the rapid increase in the number of species whose range dynamics are human induced, and review the relationships and differences to both natural range expansion and biological invasions. We discuss the consequences for science, policy and management in an era of rapid global change and highlight four key challenges relating to basic gaps in knowledge, and the transfer of scientific understanding to biodiversity management and policy. We conclude that range-expanding species responding to human-induced environmental change will become an essential feature for biodiversity management and science in the Anthropocene. Finally, we propose the term neonative for these taxa.

Maladapted Prey Subsidize Predators and Facilitate Range Expansion

Dispersal of prey from predator-free patches frequently supplies a trophic subsidy to predators by providing more prey than are produced locally. Prey arriving from predator-free patches might also have evolved weaker defenses against predators and thus enhance trophic subsidies by providing easily captured prey. Using local models assuming a linear or accelerating trade-off between defense and population growth rate, we demonstrate that immigration of undefended prey increased predator abundances and decreased defended prey through eco-evolutionary apparent competition. In individual-based models with spatial structure, explicit genetics, and gene flow along an environmental gradient, prey became maladapted to predators at the predator's range edge, and greater gene flow enhanced this maladaptation. The predator gained a subsidy from these easily captured prey, which enhanced its abundance, facilitated its persistence in marginal habitats, extended its range extent, and enhanced range shifts during environmental changes, such as climate change. Once the predator expanded, prey adapted to it and the advantage disappeared, resulting in an elastic predator range margin driven by eco-evolutionary dynamics. Overall, the results indicate a need to consider gene flow-induced maladaptation and species interactions as mutual forces that frequently determine ecological and evolutionary dynamics and patterns in nature.

Evolutionary genomics of gypsy moth populations sampled along a latitudinal gradient

The European gypsy moth (Lymantria dispar L.) was first introduced to Massachusetts in 1869 and within 150 years has spread throughout eastern North America. This large-scale invasion across a heterogeneous landscape allows examination of the genetic signatures of adaptation potentially associated with rapid geographical spread. We tested the hypothesis that spatially divergent natural selection has driven observed changes in three developmental traits that were measured in a common garden for 165 adult moths sampled from six populations across a latitudinal gradient covering the entirety of the range. We generated genotype data for 91,468 single nucleotide polymorphisms based on double digest restriction-site associated DNA sequencing and used these data to discover genome-wide associations for each trait, as well as to test for signatures of selection on the discovered architectures. Genetic structure across the introduced range of gypsy moth was low in magnitude (F_ST  = 0.069), with signatures of bottlenecks and spatial expansion apparent in the rare portion of the allele frequency spectrum. Results from applications of Bayesian sparse linear mixed models were consistent with the presumed polygenic architectures of each trait. Further analyses indicated spatially divergent natural selection acting on larval development time and pupal mass, with the linkage disequilibrium component of this test acting as the main driver of observed patterns. The populations most important for these signals were two range-edge populations established less than 30 generations ago. We discuss the importance of rapid polygenic adaptation to the ability of non-native species to invade novel environments.

Host specificity pattern and chemical deception in a social parasite of ants

In natural ecosystems, relationships between organisms are often characterised by high levels of complexity, where vulnerabilities in multi-trophic systems are difficult to identify, yet variation in specific community modules can be traceable. Within the complex community interactions, we can shed new light on dynamics by which co-evolutionary outcomes can inform science-led conservation. Here we assessed host-ant use in six populations of the butterfly Phengaris (=Maculinea) rebeli, an obligate social parasite of Myrmica ants and a model system in evolutionary and conservation ecology. Starting from the initial distribution of eggs, we estimated the survival of the parasite in the wild in nests of seven Myrmica ant species, and analysed the chemical cues evolved by the parasites to subvert its host defences. We found local variations in host specificity that are consistent with similarities found in the chemical profiles of hosts and parasites on different sites. At some sites, only one ant species is successfully exploited; at others, multiple-host populations are used. Understanding how stable or adaptable these associations are is essential knowledge when devising conservation measures to maintain keystone species of ant and locally adapted populations of Phengaris butterfly species, which are rare, threatened and a high priority for conservation worldwide.