HSP70 expression in the Copper butterfly Lycaena tityrus across altitudes and temperatures

The ability to express heat‐shock proteins (HSP) under thermal stress is an essential mechanism for ectotherms to cope with unfavourable conditions. In this study, we investigate if Copper butterflies originating from different altitudes and/or being exposed to different rearing and induction temperatures show differences in HSP70 expression. HSP70 expression increased substantially at the higher rearing temperature in low‐altitude butterflies, which might represent an adaptation to occasionally occurring heat spells. On the other hand, high‐altitude butterflies showed much less plasticity in response to rearing temperatures, and overall seem to rely more on genetically fixed thermal stress resistance. Whether the latter indicates a higher vulnerability of high‐altitude populations to global warming needs further investigation. HSP70 expression increased with both colder and warmer induction temperatures.     

Phenotypic plasticity and integration in response to flooded conditions in natural accessions of Arabidopsis thaliana (L.) Heynh (Brassicaceae)

Flood response is a crucial component of the life strategy of many plants, but it is seldom studied in non-flooded tolerant species, even though they may be subjected to stressful environmental conditions. Phenotypic plasticity in reaction to environmental stress affects the whole plant phenotype and can alter the character correlations that constitute the phenotypic architecture of the individual, yet few studies have investigated the lability of phenotypic integration to water regime. Moreover, little has been done to date to quantify the sort of selective pressures that different components of a plant's phenotype may be experiencing under contrasting water regimes. Genetic differentiation and phenotypic plasticity at the single-trait and multivariate levels were investigated in 47 accessions of the weedy plant Arabidopsis thaliana, and the relationship of plastic characters to reproductive fitness was quantified. Results indicate that these plants tend to be highly genetically differentiated for all traits, in agreement with predictions made on the basis of environmental variation and mating system. Varied patterns of apparent selection under flooded and non-flooded conditions were also uncovered, suggesting trade-offs in allocation between roots and above-ground biomass, as well as between leaves and reproductive structures. While the major components of the plants' multivariate phenotypic architecture were not significantly affected by environmental changes, many of the details were different under flooded and non-flooded conditions.     

Aerodynamic costs of long tails in male barn swallows Hirundo rustica and the evolution of sexual size dimorphism

Exaggerated tail feathers of birds constitute a standard exampleof evolution of extravagant characters due to sexual selection.Such secondary sexual traits are assumed to be costly to produceand maintain, and they usually are accompanied by morphologicaladaptations that tend to reduce their costs. The aerodynamiccosts for male barn swallows Hirundo rustica of having longtails were quantified using aerodynamics theory applied to morphologicaldata from seven European populations. Latitudinal differencesin tail length were positively correlated with differences inflight costs predicted by aerodynamics theory. A positive relationshipbetween aerodynamic costs of long tails and the degree of sexualsize dimorphism was found among populations. Latitudinal differencesin foraging costs may result in tail length being relativelysimilar in males and females in southern populations, whereasthe low foraging costs for males in northern populations mayallow them to cope with higher aerodynamic costs, giving riseto large sexual size dimorphism. Enlargement of wingspan inmales can alleviate but not eliminate the costs of tail exaggeration,and therefore differences in aerodynamic costs of male ornamentswere maintained among populations. Sexual size dimorphism in thebarn swallow arises as a consequence of latitudinal differencesin the advantages of sexual selection for males and the costsof long tails for males and females.     

Climate warming and the evolution of morphotypes in a reptile

Climate warming is known to have effects on population dynamics through variations in survival, fecundity and density. However, the impacts of climate change on population composition are still poorly documented. Morphotypes are powerful markers to track changes in population composition. In the common lizard, Lacerta vivipara , individuals display two types of dorsal patterns: reticulated (R individuals) and linear (L individuals). We examined how local warming affected intrapopulation frequencies of these morphotypes across 11 years. We observed changes in morph frequency of dorsal patterns across years, paralleling the rise of spring temperatures. The proportion of R individuals increased with June temperatures in juveniles, yearlings, and adult males and females. Three mechanisms could explain these changes: phenotypic plasticity, microevolution and/or dispersal between populations. We investigated the ontogenetic determinism, fitness and recruitment rates associated with dorsal morphotypes. Dorsal pattern ontogeny showed temperature dependence but this relationship was not associated with the warming trend during this study. We found variation by morphotype in survival and clutch size, but these factors did not explain R frequency increases. Among all the parameters considered in this study, only a decrease of immigration, which was more pronounced in the L morphotype, could explain the change in population composition. To our knowledge, this provides the first evidence of the impact of climate warming on population composition due to its effects on immigration.     

Evolution of total net fitness in thermal lines: Drosophila subobscura likes it 'warm'

Fisher's fundamental theorem states that heritable variation for net fitness sets a limit to the rate of response to natural selection. How will temperate (i.e. cold‐tolerant) species cope with contemporary rapid global warming? Using three‐fold replicated lines of Drosophila subobscura that had been allowed to evolve for 4 years (between 32 and 59 generations) at 13 °C (cold), 18 °C (the supposed optimum temperature), and 22 °C (warm) I assess here how net fitness changes according to thermal environments. Net fitness was estimated following the classical approach in population genetics of competing over a number of generation in outbred experimental populations multiple wild‐type O chromosomes (homologous to arm 3R in D. melanogaster) independently derived from each base thermal stock in an otherwise homogeneous genetic background against a balancer chromosome. Warm‐adapted populations (‘warm‐adapted O chromosomes’) performed comparatively well at all tested temperatures. However, net fitness was severely reduced in cold‐adapted populations when transferred to warmer conditions. It seems, therefore, that thermal fitness breath for D. subobscura flies is positively associated to temperature. These findings are discussed in relation to the fast world‐wide clinal shifts in the frequency of genetic markers correlated with current climate change.     

Lower plasticity exhibited by high- versus mid-elevation species in their phenological responses to manipulated temperature and drought

Background and Aims Recent global changes, particularly warming and drought, have had worldwide repercussions on the timing of flowering events for many plant species. Phenological shifts have also been reported in alpine environments, where short growing seasons and low temperatures make reproduction particularly challenging, requiring fine-tuning to environmental cues. However, it remains unclear if species from such habitats, with their specific adaptations, harbour the same potential for phenological plasticity as species from less demanding habitats.Methods Fourteen congeneric species pairs originating from mid and high elevation were reciprocally transplanted to common gardens at 1050 and 2000 m a.s.l. that mimic prospective climates and natural field conditions. A drought treatment was implemented to assess the combined effects of temperature and precipitation changes on the onset and duration of reproductive phenophases. A phenotypic plasticity index was calculated to evaluate if mid- and high-elevation species harbour the same potential for plasticity in reproductive phenology.Key Results Transplantations resulted in considerable shifts in reproductive phenology, with highly advanced initiation and shortened phenophases at the lower (and warmer) site for both mid- and high-elevation species. Drought stress amplified these responses and induced even further advances and shortening of phenophases, a response consistent with an ‘escape strategy’. The observed phenological shifts were generally smaller in number of days for high-elevation species and resulted in a smaller phenotypic plasticity index, relative to their mid-elevation congeners.Conclusions While mid- and high-elevation species seem to adequately shift their reproductive phenology to track ongoing climate changes, high-elevation species were less capable of doing so and appeared more genetically constrained to their specific adaptations to an extreme environment (i.e. a short, cold growing season).     

Thermal evolution of pre-adult life history traits, geometric size and shape, and developmental stability in Drosophila subobscura

Replicated lines of Drosophila subobscura originating from a large outbred stock collected at the estimated Chilean epicentre (Puerto Montt) of the original New World invasion were allowed to evolve under controlled conditions of larval crowding for 3.5 years at three temperature levels (13, 18 and 22 degrees C). Several pre-adult life history traits (development time, survival and competitive ability), adult life history related traits (wing size, wing shape and wing-aspect ratio), and wing size and shape asymmetries were measured at the three temperatures. Cold-adapted (13 degrees C) populations evolved longer development times and showed lower survival at the highest developmental temperature. No divergence for wing size was detected following adaptation to temperature extremes (13 and 22 degrees C), in agreement with earlier observations, but wing shape changes were obvious as a result of both thermal adaptation and development at different temperatures. However, the evolutionary trends observed for the wing-aspect ratio were inconsistent with an adaptive hypothesis. There was some indication that wing shape asymmetry has evolutionarily increased in warm-adapted populations, which suggests that there is additive genetic variation for fluctuating asymmetry and that it can evolve under rapid environmental changes caused by thermal stress. Overall, our results cast strong doubts on the hypothesis that body size itself is the target of selection, and suggest that pre-adult life history traits are more closely related to thermal adaptation.