Variation in heat shock protein expression at the latitudinal range limits of a widely‐distributed species,the Glanville fritillary butterfly (Melitaea cinxia)

Studies of heat shock response show a correlation with local climate, although this is more often across altitudinal than latitudinal gradients. In the present study, differences in constitutive but not inducible components of heat shock response are detected among populations of the Glanville fritillary butterfly Melitaea cinxia L. that exist at the species' latitudinal range limits (Finland and Spain). The study demonstrates that macroclimatic differences between these sites should cause greater exposure of the Spanish population to higher temperatures. Thermal stress treatments are used to estimate differences in the expression of four genes potentially relevant for tolerating these temperatures. For the analysis, three heat‐shock proteins and glyceraldehyde‐3‐phosphate dehydrogenase (G3PDH), a glycolysis enzyme that also modulates cell growth based on metabolic state, are chosen. Two constitutive differences are found between the sites. First, insects from Spain have higher levels of Hsp 21.4 than those from Finland regardless of thermal stress treatment; this protein is not inducible. Second, insects from Finland have higher levels of G3PDH. The two remaining Hsps, Hsp20.4 and Hsp90, show dramatic up‐regulation at higher temperatures, although there are no significant differences between insects from the different populations in either constitutive levels or inducibility. In nature, differences between the study populations likely occur in the expression of all four genes that were studied, although these differences would be directly climate‐induced in Hsp20.4 and Hsp90 and constitutive in Hsp21.4 and G3PDH. Inducibility may mitigate the need for constitutive variation in traits that adapt insects to local climate.     

Fitness declines towards range limits and local adaptation to climate affect dispersal evolution during climate‐induced range shifts

Dispersal ability will largely determine whether species track their climatic niches during climate change, a process especially important for populations at contracting (low‐latitude/low‐elevation) range limits that otherwise risk extinction. We investigate whether dispersal evolution at contracting range limits is facilitated by two processes that potentially enable edge populations to experience and adjust to the effects of climate deterioration before they cause extinction: (i) climate‐induced fitness declines towards range limits and (ii) local adaptation to a shifting climate gradient. We simulate a species distributed continuously along a temperature gradient using a spatially explicit, individual‐based model. We compare range‐wide dispersal evolution during climate stability vs. directional climate change, with uniform fitness vs. fitness that declines towards range limits (RLs), and for a single climate genotype vs. multiple genotypes locally adapted to temperature. During climate stability, dispersal decreased towards RLs when fitness was uniform, but increased when fitness declined towards RLs, due to highly dispersive genotypes maintaining sink populations at RLs, increased kin selection in smaller populations, and an emergent fitness asymmetry that favoured dispersal in low‐quality habitat. However, this initial dispersal advantage at low‐fitness RLs did not facilitate climate tracking, as it was outweighed by an increased probability of extinction. Locally adapted genotypes benefited from staying close to their climate optima; this selected against dispersal under stable climates but for increased dispersal throughout shifting ranges, compared to cases without local adaptation. Dispersal increased at expanding RLs in most scenarios, but only increased at the range centre and contracting RLs given local adaptation to climate.     

Variation in growth and developmental responses to supraoptimal temperatures near latitudinal range limits of gypsy moth Lymantria dispar (L.), an expanding invasive species

Variation in thermal performance within and between populations provides the potential for adaptive responses to increasing temperatures associated with climate change. Organisms experiencing temperatures above their optimum on a thermal performance curve exhibit rapid declines in function and these supraoptimal temperatures can be a critical physiological component of range limits. The gypsy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is one of the best‐documented biological invasions and factors driving its spatial spread are of significant ecological and economic interest. The present study examines gypsy moth sourced from different latitudes across its North American range for sensitivity to high temperature in constant temperature growth chamber experiments. Supraoptimal temperatures result in higher mortality in northern populations compared with populations from the southern range extent (West Virginia and coastal plain of Virginia, U.S.A.). Sublethal effects of high temperature on traits associated with fitness, such as smaller pupal mass, are apparent in northern and West Virginia populations. Overall, the results indicate that populations near the southern limits of the range are less sensitive to high temperatures than northern populations from the established range. However, southern populations are lower performing overall, based on pupal mass and development time, relative to northern populations. This suggests that there may be a trade‐off associated with decreased heat sensitivity in gypsy moth. Understanding how species adapt to thermal limits and possible fitness trade‐offs of heat tolerance represents an important step toward predicting climatically driven changes in species ranges, which is a particularly critical consideration in conservation and invasion ecology.     

Rapid range expansion and community reorganization in response to warming

Species ranges are expected to expand along their cooler boundaries in response to rising temperatures associated with current global climate change. However, this ‘fingerprint’ of climate change is yet to be assessed for an entire flora. Here, we examine patterns of altitudinal range change in the complete native vascular flora of sub‐Antarctic Marion Island. We demonstrate a rapid mean upslope expansion in the flora since 1966, in response to 1.2 °C warming on the island. The 3.4±0.8 m yr^?1 (mean±SE) upslope expansion rate documented is amongst the highest estimates from partial floras. However, less than half of the species in the flora were responsible for the expansion trend, demonstrating that the global fingerprint of warming may be driven by a highly responsive subset of the species pool. Individual range expansion rates varied greatly, with species‐specific niche requirements explaining some of this variation. As a result of the idiosyncratic expansion rates, altitudinal patterns of species richness and community composition changed considerably, with the formation of no‐analog communities at high and intermediate altitudes. Therefore, both species‐ and community‐level changes have occurred in the flora of Marion Island over a relatively short period of rapid warming, demonstrating the sensitivity of high latitude communities to climate change. Patterns of change within this flora illustrate the range of variation in species responses to climate change and the consequences thereof for species distributions and community reorganization.     

Dryness limits vegetation pace to cope with temperature change in warm regions

Climate change leads to increasing temperature and more extreme hot and drought events. Ecosystem capability to cope with climate warming depends on vegetation's adjusting pace with temperature change. How environmental stresses impair such a vegetation pace has not been carefully investigated. Here we show that dryness substantially dampens vegetation pace in warm regions to adjust the optimal temperature of gross primary production (GPP) ($T_{\mathrm{opt}}^{\mathrm{GPP}}$) in response to change in temperature over space and time. $T_{\mathrm{opt}}^{\mathrm{GPP}}$ spatially converges to an increase of 1.01°C (95% CI: 0.97, 1.05) per 1°C increase in the yearly maximum temperature (T_max) across humid or cold sites worldwide (37^oS–79^oN) but only 0.59°C (95% CI: 0.46, 0.74) per 1°C increase in T_max across dry and warm sites. $T_{\mathrm{opt}}^{\mathrm{GPP}}$ temporally changes by 0.81°C (95% CI: 0.75, 0.87) per 1°C interannual variation in T_max at humid or cold sites and 0.42°C (95% CI: 0.17, 0.66) at dry and warm sites. Regardless of the water limitation, the maximum GPP (GPP_max) similarly increases by 0.23 g C m⁻² day⁻¹ per 1°C increase in $T_{\mathrm{opt}}^{\mathrm{GPP}}$ in either humid or dry areas. Our results indicate that the future climate warming likely stimulates vegetation productivity more substantially in humid than water-limited regions.     

Limited potential for adaptation to climate change in a broadly distributed marine crustacean

The extent to which acclimation and genetic adaptation might buffer natural populations against climate change is largely unknown. Most models predicting biological responses to environmental change assume that species' climatic envelopes are homogeneous both in space and time. Although recent discussions have questioned this assumption, few empirical studies have characterized intraspecific patterns of genetic variation in traits directly related to environmental tolerance limits. We test the extent of such variation in the broadly distributed tidepool copepod Tigriopus californicus using laboratory rearing and selection experiments to quantify thermal tolerance and scope for adaptation in eight populations spanning more than 17° of latitude. Tigriopus californicus exhibit striking local adaptation to temperature, with less than 1 per cent of the total quantitative variance for thermal tolerance partitioned within populations. Moreover, heat-tolerant phenotypes observed in low-latitude populations cannot be achieved in high-latitude populations, either through acclimation or 10 generations of strong selection. Finally, in four populations there was no increase in thermal tolerance between generations 5 and 10 of selection, suggesting that standing variation had already been depleted. Thus, plasticity and adaptation appear to have limited capacity to buffer these isolated populations against further increases in temperature. Our results suggest that models assuming a uniform climatic envelope may greatly underestimate extinction risk in species with strong local adaptation.     

Living at the edge: lower success of eggs and hatchlings at lower elevation may shape range limits in an alpine lizard

Studies on range limits clarify the factors involved in the extent of species occurrence and shed light on the limits to adaptation. We studied the effects of elevational variation on the thermal dependence of fitness‐related traits (incubation time, hatching rate, and survivorship, size, and condition of hatchlings) to assess the role of incubation requirements in distribution range limits of the alpine endemic Iberolacerta cyreni. We captured gravid females from two core (summit) and two marginal (low‐elevation edge) populations, we incubated their eggs at three temperatures (22, 26, and 30 °C), and we monitored phenotypic effects. Viability of eggs and hatchlings decreased, independently of elevation, as incubation temperature increased. Hatching success and embryo survivorship were lower for clutches from low‐elevation areas than for those from mountain summits, showing that lizards face difficulties thriving at the low‐elevation edge of their range. Such difficulties were partly counterbalanced by faster postnatal growth at lower elevations, leading to increased adult size and higher fecundity. High incubation temperature had detrimental effects also at low‐elevation areas, and no elevational variation in the thermal dependence of hatchling traits was detected. We suggest that temperature effects on egg development and the lack of selective pressures strong enough to foster local adaptation at marginal areas, combined with extended egg retention, may contribute to shape the range limits of these alpine oviparous reptiles.     

Heritable variation in heat shock gene expression: a potential mechanism for adaptation to thermal stress in embryos of sea turtles

The capacity of species to respond adaptively to warming temperatures will be key to their survival in the Anthropocene. The embryos of egg-laying species such as sea turtles have limited behavioural means for avoiding high nest temperatures, and responses at the physiological level may be critical to coping with predicted global temperature increases. Using the loggerhead sea turtle (Caretta caretta) as a model, we used quantitative PCR to characterise variation in the expression response of heat-shock genes (hsp60, hsp70 and hsp90; molecular chaperones involved in cellular stress response) to an acute non-lethal heat shock. We show significant variation in gene expression at the clutch and population levels for some, but not all hsp genes. Using pedigree information, we estimated heritabilities of the expression response of hsp genes to heat shock and demonstrated both maternal and additive genetic effects. This is the first evidence that the heat-shock response is heritable in sea turtles and operates at the embryonic stage in any reptile. The presence of heritable variation in the expression of key thermotolerance genes is necessary for sea turtles to adapt at a molecular level to warming incubation environments.     

Evolutionary responses to environmental change: trophic interactions affect adaptation and persistence

According to recent reviews, the question of how trophic interactions may affect evolutionary responses to climate change remains unanswered. In this modelling study, we explore the evolutionary dynamics of thermal and plant–herbivore interaction traits in a warming environment. We find the herbivore usually reduces adaptation speed and persistence time of the plant by reducing biomass. However, if the plant interaction trait and thermal trait are correlated, herbivores can create different coevolutionary attractors. One attractor has a warmer plant thermal optimum, and the other a colder one compared with the environment. A warmer plant thermal strategy is given a head start under warming, the only case where herbivores can increase plant persistence under warming. Persistence time of the plant under warming is maximal at small or large thermal niche width. This study shows that considering trophic interactions is necessary and feasible for understanding how ecosystems respond to climate change.     

Interrogating recent range changes in South African birds: confounding signals from land use and climate change present a challenge for attribution

Aim Apparent anthropogenic warming has been underway in South Africa for several decades, a period over which significant range shifts have been observed in some indigenous bird species. We asked whether these range shifts by birds are clearly consistent with either climate change or land use change being the primary driver. Location South Africa. Methods We categorized recent range changes among 408 South African terrestrial bird species and, using generalized linear mixed models, analysed ecological attributes of those species that have and have not changed their ranges. Results Fifty‐six of the 408 taxa studied have undergone significant range shifts. Most extended their ranges towards the south (towards cooler latitudes, consistent with climate‐change drivers) or west (towards drier and warmer habitats, inconsistent with climate drivers but consistent with land use drivers); very few moved east or north. Both southward and westward movers were habitat generalists. Furthermore, southward movers were mobile taxa (migrants and nomads), whereas westward movers were associated with human‐modified elements in the landscape, such as croplands, plantations or buildings. Main conclusions The results suggest that both land use changes and climate change may simultaneously be influencing dynamic range shifts by South African birds, but separating the relative strengths of these two drivers is challenging, not least because both are operating concurrently and may influence some species simultaneously. Those species that respond to land use change by contracting their ranges are likely to be among the species that will be most impacted by climate change if land use practices with negative impacts are occurring in areas anticipated to become climatic refugia for these species. This highlights a pressing need to develop dynamic models of species’ potential range shifts and changing abundances that incorporate population and dispersal processes, as well as ecological processes that influence habitat suitability.     

Rising environmental temperatures and biogeography: poleward range contraction of the blue mussel,Mytilus edulis L., in the western Atlantic

Aim We tested whether the contraction of the equatorward boundary of an intertidal organism, the blue mussel, Mytilus edulis, was due to high summer temperatures limiting mortality. Location The Atlantic coast of the United States. Methods Field transplant experiments were conducted at three locations along the US Atlantic coast. Survival and heat shock protein 70 expression were determined at biweekly intervals. Air and water temperature profiles were used to model current and historical patterns of mortality, and to determine rates of temperature change. Results High levels of mortality and expression of the inducible heat shock protein 70 were observed after multiple consecutive aerial exposures of 32 °C or greater. Since 1960, seasonal air and water temperatures have increased along the eastern US seaboard, and south of Lewes, DE (38.8° N) summer sea surface temperature increases have exceeded the upper lethal limits of this organism. Main conclusions Along the southern portion of its range, intertidal populations of M. edulis have experienced catastrophic mortality directly associated with summer high temperatures. Over the past 50 years, a geographic contraction of the southern, equatorward range edge of M. edulis has occurred, shifting the range edge approximately 350 km north of the previous limit at Cape Hatteras, NC (35.2° N).     

Climate change and freshwater biodiversity: detected patterns, future trends and adaptations in northern regions

Current rates of climate change are unprecedented, and biological responses to these changes have also been rapid at the levels of ecosystems, communities, and species. Most research on climate change effects on biodiversity has concentrated on the terrestrial realm, and considerable changes in terrestrial biodiversity and species’ distributions have already been detected in response to climate change. The studies that have considered organisms in the freshwater realm have also shown that freshwater biodiversity is highly vulnerable to climate change, with extinction rates and extirpations of freshwater species matching or exceeding those suggested for better‐known terrestrial taxa. There is some evidence that freshwater species have exhibited range shifts in response to climate change in the last millennia, centuries, and decades. However, the effects are typically species‐specific, with cold‐water organisms being generally negatively affected and warm‐water organisms positively affected. However, detected range shifts are based on findings from a relatively low number of taxonomic groups, samples from few freshwater ecosystems, and few regions. The lack of a wider knowledge hinders predictions of the responses of much of freshwater biodiversity to climate change and other major anthropogenic stressors. Due to the lack of detailed distributional information for most freshwater taxonomic groups and the absence of distribution‐climate models, future studies should aim at furthering our knowledge about these aspects of the ecology of freshwater organisms. Such information is not only important with regard to the basic ecological issue of predicting the responses of freshwater species to climate variables, but also when assessing the applied issue of the capacity of protected areas to accommodate future changes in the distributions of freshwater species. This is a huge challenge, because most current protected areas have not been delineated based on the requirements of freshwater organisms. Thus, the requirements of freshwater organisms should be taken into account in the future delineation of protected areas and in the estimation of the degree to which protected areas accommodate freshwater biodiversity in the changing climate and associated environmental changes.     

Local adaptation of a parasite to solar radiation impacts disease transmission potential,spore yield,and host fecundity*

Environmentally transmitted parasites spend time in the abiotic environment, where they are subjected to a variety of stressors. Learning how they face this challenge is essential if we are to understand how host–parasite interactions may vary across environmental gradients. We used a zooplankton–bacteria host–parasite system where availability of sunlight (solar radiation) influences disease dynamics to look for evidence of parasite local adaptation to sunlight exposure. We also examined how variation in sunlight tolerance among parasite strains impacted host reproduction. Parasite strains collected from clearer lakes (with greater sunlight penetration) were most tolerant of the negative impacts of sunlight exposure, suggesting local adaptation to sunlight conditions. This adaptation came with both a cost and a benefit for parasites: parasite strains from clearer lakes produced relatively fewer transmission stages (spores) but these strains were more infective. After experimental sunlight exposure, the most sunlight-tolerant parasite strains reduced host fecundity just as much as spores that were never exposed to sunlight. Sunlight availability varies greatly among lakes around the world. Our results suggest that the selective pressure sunlight exposure exerts on parasites may impact both parasite and host fitness, potentially driving variation in disease epidemics and host population dynamics across sunlight availability gradients.     

Evidence of genomic adaptation to climate in Eucalyptus microcarpa: Implications for adaptive potential to projected climate change

Understanding whether populations can adapt in situ or whether interventions are required is of key importance for biodiversity management under climate change. Landscape genomics is becoming an increasingly important and powerful tool for rapid assessments of climate adaptation, especially in long‐lived species such as trees. We investigated climate adaptation in Eucalyptus microcarpa using the DArTseq genomic approach. A combination of F_ST outlier and environmental association analyses were performed using >4200 genomewide single nucleotide polymorphisms (SNPs) from 26 populations spanning climate gradients in southeastern Australia. Eighty‐one SNPs were identified as putatively adaptive, based on significance in F_ST outlier tests and significant associations with one or more climate variables related to temperature (70/81), aridity (37/81) or precipitation (35/81). Adaptive SNPs were located on all 11 chromosomes, with no particular region associated with individual climate variables. Climate adaptation appeared to be characterized by subtle shifts in allele frequencies, with no consistent fixed differences identified. Based on these associations, we predict adaptation under projected changes in climate will include a suite of shifts in allele frequencies. Whether this can occur sufficiently rapidly through natural selection within populations, or would benefit from assisted gene migration, requires further evaluation. In some populations, the absence or predicted increases to near fixation of particular adaptive alleles hint at potential limits to adaptive capacity. Together, these results reinforce the importance of standing genetic variation at the geographic level for maintaining species’ evolutionary potential.     

Patterns and drivers of intraspecific variation in avian life history along elevational gradients: a meta‐analysis

Elevational gradients provide powerful natural systems for testing hypotheses regarding the role of environmental variation in the evolution of life‐history strategies. Case studies have revealed shifts towards slower life histories in organisms living at high elevations yet no synthetic analyses exist of elevational variation in life‐history traits for major vertebrate clades. We examined (i) how life‐history traits change with elevation in paired populations of bird species worldwide, and (ii) which biotic and abiotic factors drive elevational shifts in life history. Using three analytical methods, we found that fecundity declined at higher elevations due to smaller clutches and fewer reproductive attempts per year. By contrast, elevational differences in traits associated with parental investment or survival varied among studies. High‐elevation populations had shorter and later breeding seasons, but longer developmental periods implying that temporal constraints contribute to reduced fecundity. Analyses of clutch size data, the trait for which we had the largest number of population comparisons, indicated no evidence that phylogenetic history constrained species‐level plasticity in trait variation associated with elevational gradients. The magnitude of elevational shifts in life‐history traits were largely unrelated to geographic (altitude, latitude), intrinsic (body mass, migratory status), or habitat covariates. Meta‐population structure, methodological issues associated with estimating survival, or processes shaping range boundaries could potentially explain the nature of elevational shifts in life‐history traits evident in this data set. We identify a new risk factor for montane populations in changing climates: low fecundity will result in lower reproductive potential to recover from perturbations, especially as fewer than half of the species experienced higher survival at higher elevations.     

Parallel evolution of an alpine type ecomorph in a scorpionfly: Independent adaptation to high‐altitude environments in multiple mountain locations

Elucidation of the diversification process of organisms is one of the important tasks of biology. From the viewpoint of species diversity, insects are the most successful group among the diverse organisms on earth and evolutionary adaptation is one of the important factors driving this pattern. Evolutionary adaptation is one of the important factors in the diversification of insects. One of the representative examples of environmental adaptation in insects is the shortening and loss of wings in subalpine and alpine zones. In this study, we focused on the Japanese scorpionfly, Panorpodes paradoxus. In this species, individuals that inhabit mountainous regions and subalpine zones have long wings (the “general type”), and individuals that inhabit higher altitudinal ranges have short wings (the “alpine type”). We collected samples of all Japanese Panorpodes species and one Korean Panorpodes species, and conducted molecular phylogenetic analyses of the mtDNA COI (610 bp), COII (688 bp), and 16S rRNA (888 bp) and nuDNA EF1‐α (658 bp) and 28S rRNA (524 bp) regions in order to reveal the evolutionary history of the alpine type of P. paradoxus. As a result of molecular phylogenetic analyses, it was revealed that the alpine type of P. paradoxus was polyphyletic, and had evolved to become the alpine type at least twice independently at separate mountain locations. In addition, the result of divergence time estimation suggested that the alpine type is an “ecomorph”, having recently adapted to low temperature habitats following mountain uplift within the Japanese Archipelago and subsequent glacial‐interglacial cycles.     

Physiological tolerance, climate change, and a northward range shift in the spittlebug, Philaenus spumarius

Abstract.  1. Considerable evidence indicates that the Earth's climate has warmed over the past 20 years and most models predict that this process will continue or accelerate. Previous studies involving butterflies and other species have shown that ranges have shifted towards the poles although the mechanisms responsible for these range shifts have not been demonstrated conclusively.
2. Here it is reported that the range of the meadow spittlebug has moved northward along the California coast since 1988.
3. Survival and reproduction of this species in previous laboratory experiments were very sensitive to humidity and temperature. Small deviations from optimal conditions resulted in high mortality.
4. These laboratory results were corroborated by annual field censuses from one location since 1983 in which population densities of spittlebug nymphs were positively correlated with summer humidity and negatively correlated with temperature deviations from the published optimum. Thus it is shown that there are strong links between physiological tolerance and a geographic range shift associated with climatic change.