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Climate warming and associated extreme temperature fluctuations result in rapid and pronounced changes in the biogeographical ranges of species. However, existing models that predict these climate‐driven range dynamics often fail to adequately account for the intricacies of local adaptation and individual specialization, treating species as having uniform responses without accounting for individual variability. This oversight highlights the need to enhance our understanding of the evolutionary implications of intraspecific and intrageneric variability, particularly with respect to photosynthetic acclimation of plants. To explore how widespread plant species adapt to temperature variability, we used the cosmopolitan genus Phragmites as a model. We assessed the variance–covariance matrix of gene‐based traits to quantify genetic variability and examine correlations among traits associated with intraspecific photosynthetic acclimatization in a thermal gradient that includes low‐, moderate‐, and high‐temperature regimes. Our findings revealed that gene‐based clinal variations, exemplified by increased robustness in plants from lower latitudes, were closely related to the latitudinal origins of genotypes and manifested more prominently in cooler environments. Furthermore, coordination of integrated physiological traits, aimed at preserving whole plant fitness, exhibits a heightened response under cold stress. We observed that plasticity in physiological traits did not increase with latitude in regions of high climatic seasonality, indicating a deviation from expected clinal plasticity patterns. This finding prompted a re‐evaluation of our understanding of phenotypic plasticity. Our findings improved our understanding of the intrageneric variation in physiological acclimation strategies among widespread species, refining predictions of species responses, survival, and distribution amidst global climate change. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The touchstone of the 'New Synthesis' was population cytogenetics –rather than genetics – due to the abundant polymorphic inversions in the genus Drosophila. Grasshoppers were not a material of choice because of their conservative karyotypes. However, nowadays seven species of Acrididae were described for polymorphic centric fusions, five of them in South-America. Leptysma argentina and the likely biocontrol of water-hyacinth Cornops aquaticum are semiaquatic Leptysminae (Acrididae: Orthoptera), polymorphic for centric fusions, supernumerary segments and a B-chromosome. We sought to demonstrate the operation of natural selection on them, by detecting: (I) latitudinal clines; (II) regression on environmental variables; (III) deviation from null models, such as linkage equilibrium; (IV) seasonal variation; (V) comparison between age classes and (VI) selection component analyses. All of them were confirmed in L. argentina , just (I) and (II) in C. aquaticum. Furthermore, the relationship between karyotype, phenotype and recombination was confirmed in both species. Karyotype–phenotype relationship may be due to the body enlargement the fusions are associated with, along with a latitudinal transition in voltinism. Karyotype-related recombination reduction in both species may help explain all fusion clines, although there is probably more than one factor at work. No effects were noticed for a supernumerary segment in L. argentina , but it is ubiquitous and certainly non-neutral. C. aquaticum is poised for introduction in South-Africa as a biocontrol of water-hyacinths; the recent discovery of four more segment polymorphisms may imply more chromosomal markers to make sense of its genetic system. [ABSTRACT FROM AUTHOR]

An understanding of thermal limits and variation across geographic regions is central to predicting how any population may respond to global change. Latitudinal clines, in particular, have been used to demonstrate that populations can be locally adapted to their own thermal environment and, as a result, not all populations will be equally impacted by an increase in temperature. But how robust are these signals of thermal adaptation to the other ecological challenges that animals commonly face in the wild? Seasonal changes in population density, food availability, or photoperiod are common ecological challenges that could disrupt patterns of thermal tolerance along a cline if each population differentially used these signals to anticipate future temperatures and adjust their thermal tolerances accordingly. In this study, we aimed to test the robustness of a cline in thermal tolerance to simulated signals of seasonal heterogeneity. Experimental animals were derived from clones of the Australian water flea, Daphnia carinata, sampled from nine distinct populations along a latitudinal transect in Eastern Australia. We then factorially combined summer (18 h light, 6 h dark) and winter (6 h light, 18 h dark) photoperiods with high (5 million algal cells individual−1 day−1) and low (1 million algal cells individual−1 day−1) food availabilities, before performing static heat shock assays to measure thermal tolerance. We found that the thermal tolerances of the clonal populations were sensitive to both measures of seasonal change. In general, higher food availability led to an increase in thermal tolerances, with the magnitude of the increase varying by clone. In contrast, a switch in photoperiod led to rank‐order changes in thermal tolerances, with heat resistance increasing for some clones, and decreasing for others. Heat resistance, however, still declined with increasing latitude, irrespective of the manipulation of seasonal signals, with clones from northern populations always showing greater thermal resistance, most likely driven by adaptation to winter thermal conditions. While photoperiod and food availability can clearly shape thermal tolerances for specific populations, they are unlikely to overwhelm overarching signals of thermal adaptation, and thus, observed clines in heat resistance will likely have remained robust to these forms of seasonal heterogeneity. [ABSTRACT FROM AUTHOR]

Abstract Aegilops umbellulata Zhuk., a wild diploid wheat-related species, has been used as a genetic resource for several important agronomic traits. However, its genetic variations have not been comprehensively studied. We sequenced RNA from 114 accessions of Ae. umbellulata to evaluate DNA polymorphisms and phenotypic variations. Bayesian clustering and phylogenetic analysis based on SNPs detected by RNA sequencing revealed two divergent lineages, UmbL1 and UmbL2. The main differences between them were in the sizes of spikes and spikelets, and culm diameter. UmbL1 is divided into two sublineages, UmbL1e and UmbL1w. These genetic differences corresponded to geographic distributions. UmbL1e, UmbL1w, and UmbL2 are found in Turkey, Iran/Iraq, and Greece, respectively. Although UmbL1e and UmbL1w were genetically similar, flowering time and other morphological traits were more distinct between these sublineages than those between the lineages. This discrepancy can be explained by the latitudinal and longitudinal differences in habitats. Specifically, latitudinal clines of flowering time were clearly observed in Ae. umbellulata, strongly correlated with solar radiation in the winter season. This observation implies that latitudinal differences are a factor in differences in the flowering times of Ae. umbellulata. Differences in flowering time could influence other morphological differences and promote genetic divergence between sublineages.

Aegilops umbellulata Zhuk., a wild diploid wheat-related species, has been used as a genetic resource for several important agronomic traits. However, its genetic variations have not been comprehensively studied. We sequenced RNA from 114 accessions of Ae. umbellulata to evaluate DNA polymorphisms and phenotypic variations. Bayesian clustering and phylogenetic analysis based on SNPs detected by RNA sequencing revealed two divergent lineages, UmbL1 and UmbL2. The main differences between them were in the sizes of spikes and spikelets, and culm diameter. UmbL1 is divided into two sublineages, UmbL1e and UmbL1w. These genetic differences corresponded to geographic distributions. UmbL1e, UmbL1w, and UmbL2 are found in Turkey, Iran/Iraq, and Greece, respectively. Although UmbL1e and UmbL1w were genetically similar, flowering time and other morphological traits were more distinct between these sublineages than those between the lineages. This discrepancy can be explained by the latitudinal and longitudinal differences in habitats. Specifically, latitudinal clines of flowering time were clearly observed in Ae. umbellulata, strongly correlated with solar radiation in the winter season. This observation implies that latitudinal differences are a factor in differences in the flowering times of Ae. umbellulata. Differences in flowering time could influence other morphological differences and promote genetic divergence between sublineages. [ABSTRACT FROM AUTHOR]

Understanding how species adapt to different temperatures is crucial to predict their response to global warming, and thermal performance curves (TPCs) have been employed recurrently to study this topic. Nevertheless, fundamental questions regarding how thermodynamic constraints and evolution interact to shape TPCs in lineages inhabiting different environments remain unanswered. Here, we study Drosophila simulans along a latitudinal gradient spanning 3000 km to test opposing hypotheses based on thermodynamic constrains (hotter-is-better) versus biochemical adaptation (jack-of-all-temperatures) as primary determinants of TPCs variation across populations. We compare thermal responses in metabolic rate and the egg-to-adult survival as descriptors of organismal performance and fitness, respectively, and show that different descriptors of TPCs vary in tandem with mean environmental temperatures, providing strong support to hotter-is-better. Thermodynamic constraints also resulted in a strong negative association between maximum performance and thermal breadth. Lastly, we show that descriptors of TPCs for metabolism and egg-to-adult survival are highly correlated, providing evidence of co-adaptation, and that curves for egg-to-adult survival are systematically narrower and displaced toward lower temperatures. Taken together, our results support the pervasive role of thermodynamics constraining thermal responses in Drosophila populations along a latitudinal gradient, that are only partly compensated by evolutionary adaptation. [ABSTRACT FROM AUTHOR]

Fruit traits have historically been interpreted as plant adaptations to their seed dispersers. On the other hand, different environmental factors, which vary spatially and temporally, can shape fruit-trait variation. The mistletoe Tristerix corymbosus has a latitudinal distribution along the South American Pacific rim that encompasses two different biomes, the matorral of central Chile and the temperate forest that extends south of the matorral. This mistletoe shows contrasting fruiting phenology (spring vs summer), fruit color (yellow vs green), and seed dispersers (birds vs marsupial) in these two biomes. We characterized geographic variation of morphological and nutritional fruit traits of T. corymbosus to evaluate which macroecological factor, biome or latitude, better explains spatial variation in these variables. For each of 22 populations, we obtained environmental data (temperature, precipitation, and canopy cover), measured fruit and seed morphology traits (size, shape, and weight), and pulp moisture and nutritional content (fiber, protein, fat, carbohydrates, ash, and caloric content). Patterns of variation for each variable were described by fitting and comparing five different simple models varying in slope, intercept or both. Fruit morphology showed a clear biome-related disruptive pattern, seed morphological traits were unrelated to either biome or latitude, whereas nutritional variables showed diverse patterns. Different environmental factors seem to affect fruit development and phenology, determining the observed fruit characteristics, with seed dispersers playing a minor role in shaping these patterns. More generally, the contrasting plant-seed disperser associations we addressed can be interpreted as the outcome of an ecological-fitting rather than of a coevolutionary process. [ABSTRACT FROM AUTHOR]

Within an animal species, the body sizes of individuals at higher latitudes are often different from individuals at lower latitudes. For homeothermic species that maintain a relatively constant body temperature, such as mammals and birds, individuals at higher latitudes tend to be larger. For ectothermic species, such as insects, that do not retain their own body heat and which often do not maintain a relatively constant body temperature, patterns of body size with latitude are highly variable. This has led some authors to contend that patterns in even closely related species cannot be expected to be similar. Indeed, to our knowledge, no studies of invertebrates have found that more closely related species have more similar relationships between body size and latitude. Further, no studies have investigated the potential influence of diet quality on interspecific differences in these clines. We measured wing lengths of specimens (N = 1753) in eight lycaenid butterfly species and one species of the sister family, Riodinidae to determine if more closely related species have similar latitudinal trends. We also estimated the mean nitrogen content of caterpillars' hosts to investigate whether this often‐limiting nutrient influences the strength and direction of latitudinal clines in body size. We found that four species are significantly smaller at higher latitudes, an additional species is marginally smaller at higher latitudes (p <.06), and four species had no significant relationship with latitude. We also found a strong phylogenetic signal for latitudinal clines in body size among our species, which indicates that some closely related species may have similar clines. However, the strength and direction of these clines did not depend on the estimated nitrogen content of caterpillars' hosts. Our results indicate that mean nitrogen content of hosts may not be an important driver in latitudinal clines but that phylogenetic relationships among species should be accounted for when exploring other potential drivers of body‐size clines in invertebrate species. [ABSTRACT FROM AUTHOR]

Genetic differentiation among different natural populations of a species depends upon the environmental factors and the evolutionary forces that operate on them. In this study, seven Indian natural populations of D. bipectinata, two from north and five from south India, have been studied for their chromosomal inversion polymorphism. A total of nine paracentric autosomal inversions were recorded from these seven places but only three of them, present on the 2L, 2R and 3L were found to be cosmopolitan in distribution. In all the populations, the frequency of standard gene arrangement was found to be high than their respective cosmopolitan inversion gene arrangement. The average heterozygosity (Ho) of cosmopolitan inversions increases from north to south. There is a latitudinal cline in the distribution of three cosmopolitan inversion arrangements because their frequency increases with the decreasing latitude, i.e. from north to south India. A comparison of the genetic profile of two north Indian and five south Indian natural populations of D. bipectinata reveals the role of natural selection as well as bottleneck effect in the genetic structuring of these populations which may be due to their varying ecological conditions to which they are constantly encountered. Further, the presence of all kinds of paracentric inversions in individual populations was analysed following Poisson distribution to see whether these inversions occur randomly in natural populations or not and the results indicate that north Indian populations show the random occurrence of these inversions than the populations derived from the south. [ABSTRACT FROM AUTHOR]

Aims Field and common garden comparisons are commonly performed to test the rapid evolution of increased vigor in introduced plant populations. Latitudinal clines in phenotypic traits can obscure such evolutionary inferences, particularly when native or introduced populations are distributed across large geographic ranges. We tested whether the latitudinal clines influence comparisons between introduced and native populations of Senecio vulgaris. Methods Senecio vulgaris is native to Europe but has been introduced in northeastern and southwestern China. To evaluate the performance in terms of growth and reproduction between native European populations and introduced Chinese populations, we compared plant height, number of branches and number of capitula in field populations in native and introduced ranges and in a common garden in Switzerland. Important Findings The introduced Chinese populations performed better than the native European populations in the field in terms of plant height and number of capitula, which was consistent with the prediction of the evolution of the increased competitive ability (EICA) hypothesis. The Chinese populations produced more capitula than the European populations when the latitudinal cline was considered in the common garden comparison. When we compared the traits of the northeastern Chinese, southwestern Chinese and European populations in both the field and common garden, the northeastern Chinese populations, at latitudes similar to those of the European populations, exhibited greater plant size and more capitula than the European populations in both the field and common garden. However, the southwestern Chinese populations, at latitudes much lower than those of the European populations, did not perform better than the native populations in terms of reproduction. In conclusion, our results suggest that latitudinal clines in phenotypic traits should be considered in field and common garden comparisons when introduced populations are geographically structured. [ABSTRACT FROM AUTHOR]

Summary: Re‐establishment of heritable latitudinal clines in growth‐related traits has been recognised as evidence for adaptive evolution in invasive plants. However, less information is known about latitudinal clines in defence and joint clinal evolution of growth and defence in invasive plants.We planted 14 native Argentinean populations and 14 introduced Chinese populations of Alternanthera philoxeroides in replicate common gardens in China. We investigated the latitudinal clines of traits related to growth and defence, and plasticity of these traits in relation to experiment site and soil nitrogen.We found that chemical defence decreased with latitude in introduced populations but increased with latitude in native populations. For growth rate, latitudinal clines were positive in introduced populations but nonexistent in native populations. There were also parallel positive latitudinal clines in total/shoot biomass and specific leaf area. Experiment site affected the occurrence or magnitude of latitudinal clines in growth rate, branch intensity and triterpenoid saponins concentration. Introduced populations were more plastic to experiment site and soil nitrogen than native populations.We provide evidence for rapid evolution of clines in growth and defence in an invasive plant. Altered herbivory gradients and trade‐off between growth and defence may explain nonparallel clines between the native and introduced ranges. [ABSTRACT FROM AUTHOR]

Aims Germination is the earliest life-history transition of a plant species. It determines the ecological breadth and geographic ranges of a species and has major effects on its invasion potential. The largest spread of the invasive salt-marsh cordgrass Spartina alterniflora in China, where it extends to latitudes lower than its native range in North America, provides an opportunity to examine germination trait variation across latitudes within and among its invasive and native ranges. Methods We studied seed germination traits of S. alterniflora using seeds collected from 10 locations across latitudes in its invasive range (China, 20°–40° N) and 16 locations across latitudes in its native range (USA, 27°–43° N) in growth chambers with 0 PSU sterilized distilled water. We further evaluated how climate and tide range in the original locations influenced germination traits. Important Findings Native populations showed higher (~10%) germination percentage and significantly higher (~20%) germination index than invasive populations did, but invasive populations germinated significantly earlier (~3 days) than native populations. Germination percentage and germination index increased with latitude in the invasive range but decreased with latitude in the native range. The mean germination time decreased with latitude in the invasive range and paralleled that in the native range. Germination percentage and germination index were negatively correlated with mean daily temperature (Tmean), mean daily maximum temperature (Tmax) and mean daily minimum temperature (Tmin), and inversely correlated with Tmean, Tmax and Tmin in the native range. However, the mean germination time was positively correlated with Tmean, Tmax and Tmean in both ranges. Our results demonstrate that invasive and native populations have evolved different latitudinal clines in germination percentage and index, but the mean germination time of the invasive population mirrored the latitudinal cline observed in the native range, suggesting that germination strategy across latitudes may change during invasion process. [ABSTRACT FROM AUTHOR]

Identifying the environmental drivers of population dynamics is crucial to predict changes in species abundances and distributions under climate change. Populations of the same species might differ in their responses as a result of intraspecific variation. Yet the importance of such differences remains largely unexplored. We examined the responses of latitudinally distant populations of the forest moss Hylocomiastrum umbratum along microclimate gradients in Sweden. We transplanted moss mats from southern and northern populations to 30 sites with contrasting microclimates (i.e., replicated field common gardens) within a forest landscape, and recorded growth and survival of individual shoots over 3 yr. To evaluate the importance of intraspecific variation in responses to environmental factors, we assessed effects of the interactions between population origin and microclimate drivers on growth and survival. Effects on overall performance of transplanted populations were estimated using the product of survival and growth. We found differences between southern and northern populations in the response to summer temperature and snowmelt date in one of three yearly transitions. In this year, southern populations performed better in warm, southern‐like conditions than in cold, northern‐like conditions; and the reverse pattern was true for northern populations. Survival of all populations decreased with evaporation, consistent with the high hydric demands and poikilohydric nature of mosses. Our results are consistent with population adaptation to local climate, and suggest that intraspecific variation among populations can have important effects on the response of species to microclimate drivers. These findings highlight the need to account for differential responses in predictions of species abundance and distribution under climate change. [ABSTRACT FROM AUTHOR]

Aim: Introduced species may display or foster novel latitudinal clines because they are not well adapted to their new habitats. We tested the hypothesis that the latitudinal cline in nematode diversity in salt marshes would differ between the native (United States) and introduced (China) ranges of Spartina alterniflora. Location: East Coasts of the United States (30.32–43.33°N) and China (30.36–39.14°N). Methods: We extracted nematodes from soil samples collected at 32 sites along the United States East Coast and 41 sites along the Chinese coast. We compared latitudinal patterns in nematode diversity and composition between the native and introduced ranges. Results: In the native range of S. alterniflora, nematode richness at lower latitudes was almost twice as high as that at higher latitudes. In contrast, we found no latitudinal pattern in nematode richness or diversity in the introduced range of S. alterniflora. Nematode genus richness at all sites in China was about half that at lower latitudes in the United States. Beta diversity of nematodes increased with geographic distance in the United States, but not China. Main conclusions: Nematode diversity did not show latitudinal clines in salt marshes dominated by introduced S. alterniflora in China. A likely explanation is that the recently introduced populations are still relatively genetically homogenous, whereas in the native range, genetic variation in plant populations across latitude drives different nematode communities. We suggest that future studies of introduced species will gain additional insights by taking an explicitly geographic perspective. [ABSTRACT FROM AUTHOR]

Highlights • A positive relationship was detected between growth performance and temperature of NEA saithe. • Body weight, length, Fulton's condition factor (K), and specific growth rate (SGR) all increased under positive temperature anomalies. • Acclimatization to local temperatures per se was likely minor. • Individuals in the field show far from optimal growth performance. Abstract It is well known that marine fish dynamics relate with climate variability, and predicting future population developments have become increasingly urgent with on-going climate change. One approach in widespread populations is to study how individuals from different parts of the distribution area respond to climate, thereby testing for potential resilience in terms of local adaptions against environmental change. In this study, we collated extensive survey data on size-at-age for Northeast Arctic saithe (Pollachius virens) (1992–2013; 62–70 °N; ages 0–3 years) and detailed hydrographic information from three fixed, coastal stations along the Norwegian coast (at ≈63, 68 and 71 °N). Dedicated ad libitum feeding experiments were additionally performed to further strengthen the insight in saithe growth dynamics, also including adults (≥4 years). Likely temperature-mediated effects on whole body weight (W), total length, Fulton's K , and specific growth rate (SGR) of wild saithe were explored using generalized linear models with age and region as fixed factors. A positive relationship with temperature was found, as evidenced by the before-mentioned body metrics of saithe age 2–3 years all becoming higher at positive local annual temperature anomalies, i.e. the deviation from the long-term mean temperature. The direct use of corresponding, absolute temperature instead of temperature anomalies gave comparable results. Hence, acclimatization to local temperatures per se was likely minor. Furthermore, examination of GLM interaction terms indicated that dissimilar feeding conditions in part of the study area, using K as a proxy, were not a confounding factor. Taken together, the present material provided an excellent opportunity to scrutinize temperature-mediated effects on growth dynamics across age classes, regions, and years. However, data sets pooled over years turned out to be more informative: SGR from age 0 to 1 year was clearly highest in the warmer, southern region but individuals in the colder, northern region gradually caught up and thereby showed higher W at age 3 years. This pattern mechanistically speaks for a gradual displacement of response curves for growth towards lower temperatures as saithe become larger or older. Although the present feeding experiments evidenced steady declines in SGR with W for younger individuals while this size effect faded away in the adults, the results also implied that saithe in the field show far from optimal growth performance, according to standard physiological principles. Thus, the term "optimal growth" should be treated with caution. Nevertheless, further studies are merited in this research area, potentially aiding body growth predictions and thereby management routines of this productive stock. [ABSTRACT FROM AUTHOR]

Summary: Biological invasions provide opportunities to study evolutionary processes occurring over contemporary timescales. To explore the speed and repeatability of adaptation, we examined the divergence of life‐history traits to climate, using latitude as a proxy, in the native North American and introduced European and Australian ranges of the annual plant Ambrosia artemisiifolia.We explored niche changes following introductions using climate niche dynamic models. In a common garden, we examined trait divergence by growing seeds collected across three ranges with highly distinct demographic histories. Heterozygosity–fitness associations were used to explore the effect of invasion history on potential success. We accounted for nonadaptive population differentiation using 11 598 single nucleotide polymorphisms.We revealed a centroid shift to warmer, wetter climates in the introduced ranges. We identified repeated latitudinal divergence in life‐history traits, with European and Australian populations positioned at either end of the native clines.Our data indicate rapid and repeated adaptation to local climates despite the recent introductions and a bottleneck limiting genetic variation in Australia. Centroid shifts in the introduced ranges suggest adaptation to more productive environments, potentially contributing to trait divergence between the ranges. [ABSTRACT FROM AUTHOR]

Cold tolerance plays a critical role in determining the geographical range limits of species. Previous studies have found that range shifts in response to climate warming are facilitated, paradoxically, by cold acclimation capacities, due to increasingly colder and variable weather at high latitudes. However, the evolutionary dynamics of this process are poorly understood. In this study we combined experiments and field studies to investigate the social and ecological factors affecting cold tolerances in range-shifting populations of the female-polymorphic damselfly Ischnura elegans in north-east Scotland, and their consequences for evolutionary change. In the field, we observed both environmental and social effects on cold tolerance and female colour morph frequencies. This process results in a latitudinal cline in female morph frequencies, due to positive feedback between social stress and thermal tolerances. Density manipulations in the laboratory provide experimental evidence that social interactions directly impact cold tolerance. Reciprocal effects of social environments on thermal acclimation may be important but commonly overlooked aspects of allee effects that contribute to the formation of range margins. Moreover, there is a wider need to consider the role of evolving social dynamics to reciprocally shape both the thermal physiology of individuals and the thermal niches of species. [ABSTRACT FROM AUTHOR]

Body size latitudinal clines have been widley explained by the Bergmann's rule in homeothermic vertebrates. However, there is no general consensus in poikilotherms organisms in particular in insects that represent the large majority of wildlife. Among them, bees are a highly diverse pollinators group with high economic and ecological value. Nevertheless, no comprehensive studies of species assemblages at a phylogenetically larger scale have been carried out even if they could identify the traits and the ecological conditions that generate different patterns of latitudinal size variation. We aimed to test Bergmann's rule for wild bees by assessing relationships between body size and latitude at continental and community levels. We tested our hypotheses for bees showing different life history traits (i.e. sociality and nesting behaviour). We used 142 008 distribution records of 615 bee species at 50 × 50 km (CGRS) grids across the West Palearctic. We then applied generalized least squares fitted linear model (GLS) to assess the relationship between latitude and mean body size of bees, taking into account spatial autocorrelation. For all bee species grouped, mean body size increased with higher latitudes, and so followed Bergmann's rule. However, considering bee genera separately, four genera were consistent with Bergmann's rule, while three showed a converse trend, and three showed no significant cline. All life history traits used here (i.e. solitary, social and parasitic behaviour; ground and stem nesting behaviour) displayed a Bergmann's cline. In general there is a main trend for larger bees in colder habitats, which is likely to be related to their thermoregulatory abilities and partial endothermy, even if a ‘season length effect’ (i.e. shorter foraging season) is a potential driver of the converse Bergmann's cline particularly in bumblebees. [ABSTRACT FROM AUTHOR]

Understanding adaptations to climatic stresses has been a longstanding issue in evolutionary biology. Clinal patterns for stress tolerance traits at interspecific as well as intraspecific levels provide an opportunity to comprehend the adaptive divergence acquired in the closely related species among different geographical populations. In the present study, we investigated the geographical differences for basal as well as induced thermal tolerance (hardening) in two sympatric sibling Drosophila species ( D. leontia and D. kikkawai) along a latitudinal transect (South: 8°06′N to North: 32°40′N) across India. A higher relative abundance of D. leontia was observed in the southern localities (tropical) while D. kikkawai was more abundant in the northern localities (sub-tropical). Both the species showed a negative cline for heat tolerance along the latitude i.e. following a trend of increased tolerance level in the southern populations compared to northern ones. Contrarily, a positive cline for cold tolerance was evident in D. kikkawai, while such intra-specific population differences were non-significant in D. leontia. Further, we found the evidence for heat and cold hardening effects only in D. kikkawai. In D. kikkawai, higher hardening capacity for heat as well as cold tolerance was observed in northern populations compared to southern populations, despite lower basal heat tolerance in northern populations. In conclusion, clinal patterns for hardening capacity for heat and cold tolerance in D. kikkawai while absence of the same in D. leontia suggest divergent evolutionary history of these two sympatric sibling species. [ABSTRACT FROM AUTHOR]

Large male body size is typically favored by directional sexual selection through competition for mates. However, alternative male life-history phenotypes, such as "sneakers," should decrease the strength of sexual selection acting on body size of large "fighter" males. We tested this prediction with salmon species; in southern populations, where sneakers are common, fighter males should be smaller than in northern populations, where sneakers are rare, leading to geographical clines in sexual size dimorphism (SSD). Consistent with our prediction, fighter male body size and SSD (fighter male:female size) increase with latitude in species with sneaker males (Atlantic salmon Salmo salar and masu salmon Oncorhynchus masou) but not in species without sneakers (chum salmon Oncorhynchus keta and pink salmon Oncorhynchus gorbuscha). This is the first evidence that sneaker males affect SSD across populations and species, and it suggests that alternative male mating strategies may shape the evolution of body size. [ABSTRACT FROM AUTHOR]

Populations arrayed along broad latitudinal gradients often show patterns of clinal variation in phenotype and genotype. Such population differentiation can be generated and maintained by both historical demographic events and local adaptation. These evolutionary forces are not mutually exclusive and can in some cases produce nearly identical patterns of genetic differentiation among populations. Here, we investigate the evolutionary forces that generated and maintain clinal variation genome-wide among populations of Drosophila melanogaster sampled in North America and Australia. We contrast patterns of clinal variation in these continents with patterns of differentiation among ancestral European and African populations. Using established and novel methods we derive here, we show that recently derived North America and Australia populations were likely founded by both European and African lineages and that this hybridization event likely contributed to genome-wide patterns of parallel clinal variation between continents. The pervasive effects of admixture mean that differentiation at only several hundred loci can be attributed to the operation of spatially varying selection using an F ST outlier approach. Our results provide novel insight into the well-studied system of clinal differentiation in D. melanogaster and provide a context for future studies seeking to identify loci contributing to local adaptation in a wide variety of organisms, including other invasive species as well as temperate endemics. [ABSTRACT FROM AUTHOR]

The roach Rutilus rutilus is a eurythermal generalist that has been translocated and introduced mainly beyond the southern limits of its native Eurasian range of distribution. Although largely studied in most aspects of its ecology, no global assessment is available on its growth. Such information is critical for management purposes, especially in view of further dispersal of this 'potential pest' and climate change predictions. To address this knowledge gap, a meta-analysis was carried out of the age and growth of 301 roach populations from 231 water bodies across the species' native and translocated/introduced Eurasian range of distribution with the aim to identify habitat and climate-related differences in growth patterns, latitudinal clines, and the possible presence of countergradient growth variation (CGV). Faster growth rates were identified under warm relative to temperate and cold climates, and these were related to optimised resource allocation. Latitudinal clines indicated decreasing trends with increasing latitude in growth and body size, in line with life-history theory. However, the presence of thresholds encompassing the previously-reported 50°N latitude value suggested a 'plateau' or decrease in growth at lower latitudes, and CGV was identified for 1+ to 10+ fish. It is argued that increased water temperatures are likely to cause a northern shift in the observed thresholds and a 'homogenisation' of the species' population dynamics resulting in faster growth rates, but with more pronounced effects in continental Eurasia. [ABSTRACT FROM AUTHOR]

Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦ β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST- FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change. [ABSTRACT FROM AUTHOR]

Neotropical passion-vine butterflies in the tribe Heliconiini ( Lepidoptera: Nymphalidae) are a major focus of research in ecology and evolution because of their diverse, aposematic wing patterns, extensive Müllerian mimicry, and coevolution with their Passifloraceae host-plants. However, the basic taxonomy of this group, which is essential to evolutionary ecology research, has been built over the last two centuries using primarily gross morphological comparisons, with most species identification being based on wing colour pattern variation. For some taxa, such as the genus Philaethria Billberg, even the most basic information, such as species limits and geographical distributions, remains uncertain. Furthermore, descriptions of new species, within Philaethria and beyond, have generally been based on small sample sizes collected from a restricted area of the full geographical distribution. To address these issues in the genus Philaethria, here we used an integrative taxonomic approach involving both morphology (genitalia ultrastructure; linear and geometric morphometric analyses of wing shape) and molecular data (multilocus DNA sequence data and amplified fragment length polymorphisms). Specifically, we tested the taxonomic validity of two Philaethria species, Philaethria pygmalion and Philaethria wernickei, described in the literature as having disjunct distributions, corresponding to the Amazon Basin and the Atlantic Rain Forest of Brazil, respectively. Our analyses revealed that these two Philaethria species cannot be delimited and diagnosed using metric and nonmetric morphological characters. Furthermore, they occur in sympatry in the Cerrado biome of central Brazil, and appear to form a latitudinal cline in wing colour variation across their combined distribution. These results are further supported by limited genetic differentiation and a lack of reciprocal monophyly between Amazon and Atlantic Rain Forest populations based on DNA sequence data, and unstructured amplified fragment length polymorphism variation. Our combined results allow us to clarify species-level limits within the genus Philaethria, whereby we propose that P. pygmalion is conspecific with P. wernickei (new synonym), and reassess the spatial range of P. wernickei by providing a refined mapping of its geographical distribution. Beyond clarifying the taxonomy of Philaethria, our results provide a solid, integrative framework that could be applied to fully characterize the taxonomy of other species in the Heliconiini and beyond. © 2014 The Linnean Society of London [ABSTRACT FROM AUTHOR]

Evolution has contributed to the successful invasion of exotic plant species in their introduced ranges, but how evolution affects particular control strategies is still under evaluation. For instance, classical biological control, a common strategy involving the utilization of highly specific natural enemies to control exotic pests, may be negatively affected by host hybridization because of shifts in plant traits, such as root allocation or chemical constituents. We investigated introgression between two parent species of the invasive shrub tamarisk (Tamarix spp.) in the western United States, and how differences in plant traits affect interactions with a biological control agent. Introgression varied strongly with latitude of origin and was highly correlated with plant performance. Increased levels of T. ramosissima introgression resulted in both higher investment in roots and tolerance to defoliation and less resistance to insect attack. Because tamarisk hybridization occurs predictably on the western U.S. landscape, managers may be able to exploit this information to maximize control efforts. Genetic differentiation in plant traits in this system underpins the importance of plant hybridization and may explain why some biological control releases are more successful than others. [ABSTRACT FROM AUTHOR]

Over the series of articles on circadian rhythms, we saw that living organisms exhibit daily rhythms in multiple behaviours and physiological processes. Although some rhythms may be passive responses to 24 h environmental cycles, many are regulated by endogenous-rhythmgenerating machinery called circadian clocks. We have introduced the concept of circadian clocks, their organization and the underlying molecular mechanisms. In this article, we will dwell upon one of the most fundamental questions pertaining to circadian clocks, 'Why do we have them?'. The aim of this article is not to provide answers, but to discuss the efforts and strategies used to address this question and critically evaluate explanations proposed till date. [ABSTRACT FROM AUTHOR]

Species with a wide distribution over latitudinal gradients often exhibit increasing growth and development rates towards higher latitudes. Ecological theory predicts that these fast-growing genotypes are, in the absence of trade-offs with fast growth, better competitors than low-latitude conspecifics. While knowledge on key ecological traits along latitudinal clines is important for understanding how these clines are maintained, the relative competitive ability of high latitude individuals against low latitude conspecifics has not been tested. Growth and development rates of the common frog Rana temporaria increase along the latitudinal gradient across Scandinavia. Here we investigated larval competition over food resources within and between two R. temporaria populations originating from southern and northern Sweden in an outdoor common garden experiment. We used a factorial design, where southern and northern tadpoles were reared either as single populations or as mixes of the two populations at two densities and predator treatments (absence and non-lethal presence of Aeshna dragonfly larvae). Tadpoles from the high latitude population grew and developed faster and in the beginning of the experiment they hid less and were more active than tadpoles from the low latitude population. When raised together with high latitude tadpoles the southern tadpoles had a longer larval period, however, the response of high latitude tadpoles to the competition by low latitude tadpoles did not differ from their response to intra-population competition. This result was not significantly affected by density or predator treatments. Our results support the hypothesis that high latitude populations are better competitors than their low latitude conspecifics, and suggest that in R. temporaria fast growth and development trade off with other fitness components along the latitudinal gradient across Scandinavia. [ABSTRACT FROM AUTHOR]

Shorter season length and lower temperature towards higher latitudes and altitudes often select for intraspecific clines in development and growth rates. However, the physiological mechanisms enabling these clines are not well understood. We studied the relationship between routine metabolic rate (RMR) and larval life-history traits along a 1500-km latitudinal gradient across Sweden. In a laboratory common garden experiment, we exposed eight common frog Rana temporaria populations to two experimental temperatures (15 and 18 °C) and measured RMR using flow-through respirometry. We found significant differences among populations in RMR, but there was no evidence for a linear relationship between latitude and RMR in either temperature treatment. However, we found a concave relationship between latitude and RMR at the lower experimental temperature. RMR was not correlated with growth rate at population or at individual levels. The results obtained suggest that, unlike in growth and development rates, there is no latitudinal cline in RMR in R. temporaria tadpoles. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 217–224. [ABSTRACT FROM AUTHOR]

Aims: The superior performance of many non-indigenous species in a new range can be attributed to different factors such as pre-adaptation to environmental conditions in new areas or to factors inherent to displacement mechanisms such as loss of co-evolved pathogens and herbivores that increase the speed of evolutionary change towards a shift in allocation from defence to growth and reproduction. To assess the importance of the different mechanisms governing the success of Conyza canadensis, a globally successful invader, we simultaneously tested several recent hypotheses potentially explaining the factors leading to biological invasion. [ABSTRACT FROM PUBLISHER]

Abstract: We report here on two complementary experiments examining the effect of climate on morphological and life-history traits of antlion adults. We first examined whether body size and wing loading of emerging adults are plastic by raising larvae, collected from five antlion populations along Israel''s sharp climatic gradient, in two environmental chambers simulating temperature and humidity of desert and Mediterranean climates. The variance in adult morphology was mostly related to body size, with adults of Mediterranean populations being larger than those of desert populations. Wing-to-thorax ratio was negatively correlated with temperature, compensating for the decrease in wing-beat frequency in colder environments. Differences between climatic treatments were significant for body size but not for the wing-to-thorax ratio, suggesting that body size is more plastic than the ratio between different body components. We next investigated how the exposure of antlion pupae to different climatic conditions influences the emerging adults. Adult body mass increased with final larval body mass at a faster rate when exposed to Mediterranean rather than desert conditions. Duration of the pupa stage was positively correlated with final larval mass, but only under Mediterranean conditions. Adult survival increased with initial mass (after eclosion), but was lower under desert conditions. Similarly, adults lost mass at a faster rate when exposed to desert conditions. Notably, the exposure of the pupae to varying climatic conditions had no effect on adult morphology. Climate is a major factor affecting insect life span and body size. Since body size is strongly linked to fecundity and survival, climate thus has a twofold effect on fitness: directly, and indirectly through body size. [Copyright &y& Elsevier]

Body size of many animals varies with latitude: body size is either larger at higher latitudes (Bergmann's rule) or smaller at higher latitudes (converse Bergmann's rule). However, the causes underlying these patterns are poorly understood. Also, studies rarely explore how sexual size dimorphism varies with latitude. Here we investigate geographic variation in body size and sexual size dimorphism of the seed-feeding beetle Stator limbatus, collected from 95 locations along a 38° range in latitude. We examine 14 variables to test whether clines in environmental factors are adequate to explain geographic patterns of body size. We found that body size and sexual size dimorphism of S. limbatus varied considerably with latitude; beetles were smaller but more dimorphic at lower latitudes. Body size was not correlated with a gradient in mean temperature, contrary to the commonly accepted hypothesis that clines are produced by latitudinal gradients in temperature. Instead, we found that three factors were adequate to explain the cline in body size: clinal variation in host plant seed size, moisture (humidity), and seasonality (variance in humidity, precipitation, and temperature). We also found that the cline in sexual size dimorphism was partially explainable by a gradient in moisture, though moisture alone was not sufficient to explain the cline. Other ecological or environmental variables must necessarily contribute to differences in selection on male versus female body size. The main implications of our study are that the sexes differ in the magnitude of clinal variation in body size, creating latitudinal variation in sexual size dimorphism, and that clines in body size of seed beetles are likely influenced by variation in host seed size, water availability, and seasonality. [ABSTRACT FROM AUTHOR]

How introduced plants, which may be locally adapted to specific climatic conditions in their native range, cope with the new abiotic conditions that they encounter as exotics is not well understood. In particular, it is unclear what role plasticity versus adaptive evolution plays in enabling exotics to persist under new environmental circumstances in the introduced range. We determined the extent to which native and introduced populations of St. John's Wort (Hypericum perforatum) are genetically differentiated with respect to leaf-level morphological and physiological traits that allow plants to tolerate different climatic conditions. In common gardens in Washington and Spain, and in a greenhouse, we examined clinal variation in percent leaf nitrogen and carbon, leaf δ13C values (as an integrative measure of water use efficiency), specific leaf area (SLA), root and shoot biomass, root/shoot ratio, total leaf area, and leaf area ratio (LAR). As well, we determined whether native European H. perforatum experienced directional selection on leaf-leve! traits in the introduced range and we compared, across gardens, levels of plasticity in these traits. In field gardens in both Washington and Spain, native populations formed latitudinal dines in percent leaf N. In the greenhouse, native populations formed latitudinal clines in root and shoot biomass and total leaf area. and in the Washington garden only, native populations also exhibited latitudinal clines in percent leaf C and leaf δ13C. Traits that failed to show consistent latitudinal clines instead exhibited significant phenotypic plasticity. Introduced St. John's Wort populations also formed significant or marginally significant latitudinal clines in percent leaf N in Washington and Spain, percent leaf C in Washington, and in root biomass and total leaf area in the greenhouse. In the Washington common garden, there was strong directional selection among European populations for higher percent leaf N and leaf δ13C, but no selection on any other measured trait. The presence of convergent, genetically based latitudinal dines between native and introduced H. perforatum, together with previously published molecular data, suggest that native and exotic genotypes have independently adapted to a broad-scale variation in climate that varies with latitude. [ABSTRACT FROM AUTHOR]

Abstract: Much has been made of body-size variability with latitude, and extreme body sizes in polar waters, but body size has never been investigated along a latitudinal gradient within polar waters. The Scotia arc and Antarctic Peninsula are ideal for latitudinal studies, and a number of species extend along the length of this region. We studied body size in two gastropod molluscs, Margarella antarctica and Nacella concinna, an echinoid, Sterechinus neumayeri, and two bryozoans, Celleporella bougainvillea and Inversiula nutrix, at six sites from South Georgia to Adelaide Island (54–68°S). We hypothesised that size, age, and growth would not correlate with latitude, given the uniformity of conditions (i.e. temperature, dissolved oxygen, etc.) within the Polar Frontal Zone. We found significant differences in size of all five species among our study sites, but not a linear trend, nor one that correlated with latitude. In bryozoans, this result was because growth was positively and age negatively correlated with latitude—resulting in little difference in overall size. In the grazer organisms (the two gastropods and the echinoid) a correlation with local food availability (chlorophyll a concentration) did not correlate with latitude. Fecundity in the gastropod M. antarctica was positively correlated with body size, and body size also was influenced by food availability. We conclude that variation in body size in all five study taxa was governed by local factors such as food availability and competition and not by latitude. [Copyright &y& Elsevier]

Clinal patterns over broad geographic regions provide a way of identifying characteristics of species under selection and are increasingly being used in quantitative trait locus mapping of adaptive genetic variation in Drosophila. However, interpretations of clinal patterns can be complicated by inversions that also vary clinally and reduce recombination in some parts of the genome. Drosophila serrata (Malloch) is an Australian endemic species being used to investigate the genetic basis of geographic variation in climatic adaptation and mate recognition. Here we describe inversions in D. serrata populations from the east coast of Australia, covering tropical and temperate regions. Seven autosomal paracentric inversions and 1 apparently complex X chromosome arrangement were identified from these populations. All inverted arrangements were relatively more common in tropical populations; 2 common inversions showed clinal patterns over part of the range of D. serrata. Inversion polymorphism was relatively higher in tropical populations and almost absent in populations near the cooler southern border, in agreement with findings on other Drosophila species. While these patterns will complicate mapping of adaptive variation in D. serrata, they suggest that this species will be useful in investigatingthe dynamics of inversion-trait associations in natural populations. [ABSTRACT FROM AUTHOR]

Some models, based on the latitudinal variation in sun angle distribution, predict that trees at high latitudes have narrowly conical crowns and constitute simple-layered forests, whereas trees at low latitudes have shallowly dome-shaped and form more structurally complex multilayered forests. There is a hypothesis that structurally complex habitats can harbor potentially more species than simple ones. In this study, we examined latitudinal correlations between tree shape, forest structure and diversity in drosophilid communities, comparing boreal and cool-temperate forests. We selected secondary birch forests with a common canopy tree species, white birch (Betula platyphylla Sukatchev), as study sites. The crown shape of white birch tended to be spherical in the cool-temperate forest, but narrowly conical in the boreal forest. The foliage structure differed between the two forests. The cool-temperate forest was characterized by a clearly two-layered structure, whereas foliage in the boreal forest was less clearly stratified, being distributed somewhat continuously from the ground to the canopy at lower densities. The structural complexity expressed by foliage height diversity was greater in the cool-temperate forest than in the boreal forest. Various measures of drosophilid diversity were higher in the cool-temperate forest than in the boreal forest, probably resulting from the impoverishment of the canopy subcommunity in the boreal forest. Thus, a physical environmental factor (i.e. the angle of solar inclination) could be a potentially important factor in structuring latitudinal patterns of sylvan animal communities through changes in plant structure at the individual and community levels. [ABSTRACT FROM AUTHOR]

The octanol dehydrogenase ( Odh) and acid phosphatase ( Acph) loci of Drosophila melanogaster are each polymorphic for two electrophoretically detectable alleles. The frequencies of the Odh and Acph alleles have been analysed in populations sampled from up to a 40 ° latitudinal range in each of Australasia, North America and Europe/Asia. Odh frequency is found to be significantly negatively associated with distance from the equator in all three zones. The relationship of Acph frequency to distance from the equator is significant and negative in Australasia but neither significant nor consistent in sign in North America and Europe/Asia. [ABSTRACT FROM AUTHOR]

Procambarus clarkii is one of the worst invasive and best-studied crayfish species worldwide, but its life history at higher latitudes is poorly understood. In the present study, the population ecology of P. clarkii was studied for the first time within its northeastern range limit in Europe (southern Germany) for a two-year period, and the findings are used to discuss several life-history parameters across different latitudes of its current distribution range. The reproductive cycle was tracked using the gonadosomatic index and reproductive traits in females and the reproductive form in males. Life-history parameters were estimated using Von Bertalanffy’s growth function. Reproduction was univoltine and occurred from late summer to autumn. A small proportion of females carried eggs throughout the winter. This contrasts with the species’ multi-voltine life cycle at lower latitudes, with year-round breeding and several reproduction peaks per year. Growth was estimated to be slower than at lower latitudes, whereas longevity, mean lifetime and size increased. These changes in life history probably reflect a general phenomenon at higher latitudes and, thus, latitudinal clines. The presented findings provide evidence that P. clarkii is able to cope well with new cold habitats by modulating its life history.

A major goal of evolutionary biology is to understand how variation within populations gets partitioned into differences between reproductively isolated species. Here, we examine the degree to which diapause life history timing, a critical adaptation promoting population divergence, explains geographic and host-related genetic variation in ancestral hawthorn and recently derived apple-infesting races of Rhagoletis pomonella. Our strategy involved combining experiments on two different aspects of diapause (initial diapause intensity and adult eclosion time) with a geographic survey of genomic variation across four sites where apple and hawthorn flies co-occur from north to south in the Midwestern USA. The results demonstrated that the majority of the genome showing significant geographic and host-related variation can be accounted for by initial diapause intensity and eclosion time. Local genomic differences between sympatric apple and hawthorn flies were subsumed within broader geographic clines; allele frequency differences within the races across the Midwest were two to three-fold greater than those between the races in sympatry. As a result, sympatric apple and hawthorn populations displayed more limited genomic clustering compared to geographic populations within the races. The findings suggest that with reduced gene flow and increased selection on diapause equivalent to that seen between geographic sites, the host races may be recognized as different genotypic entities in sympatry, and perhaps species, a hypothesis requiring future genomic analysis of related sibling species to R. pomonella to test. Our findings concerning the way selection and geography interplay could be of broad significance for many cases of earlier stages of divergence-with-gene flow, including (1) where only modest increases in geographic isolation and the strength of selection may greatly impact genetic coupling and (2) the dynamics of how spatial and temporal standing variation is extracted by selection to generate differences between new and discrete units of biodiversity. [ABSTRACT FROM AUTHOR]