Thermal Adaptation (thermal + adaptation)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Thermal adaptation of Arctic charr: experimental studies of growth in eleven charr populations from Sweden, Norway and Britain

FRESHWATER BIOLOGY, Issue 2 2005
S. LARSSON
Summary 1. Experimental growth data for Arctic charr (Salvelinus alpinus L.), all fed on excess rations, from 11 European watercourses between 54 and 70N were analysed and fitted to a new general growth model for fish. The model was validated by comparing its predictions with the growth rate of charr in the wild. 2. Growth performance varied among populations, mainly because of variation in the maximum growth potential, whereas the thermal response curves were similar. The estimated lower and upper temperatures for growth varied between ,1.7 to 5.3 and 20.8,23.2 C, respectively, while maximum growth occurred between 14.4 and 17.2 C. 3. There was no geographical or climatic trend in growth performance among populations and therefore no indication of thermal adaptation. The growth potential of charr from different populations correlated positively with fish body length at maturity and maximum weight in the wild. Charr from populations including large piscivorous fish had higher growth rates under standardised conditions than those from populations feeding on zoobenthos or zooplankton. Therefore, the adaptive variation in growth potential was related to life-history characteristics and diet, rather than to thermal conditions. [source]


Genetic variation in thermal tolerance among natural populations of Drosophila buzzatii: down regulation of Hsp70 expression and variation in heat stress resistance traits

FUNCTIONAL ECOLOGY, Issue 3 2001
J. G. Srensen
Summary 1,Thermal adaptation was investigated in the fruitfly Drosophila buzzatii Patterson and Wheeler. Two natural populations originating from a high- and a low-temperature environment, respectively, were compared with respect to Hsp70 (heat shock protein) expression, knock-down resistance and heat shock resistance. 2,Three main hypotheses were tested: (i) The expression level of Hsp70 in flies from the high-temperature habitat should be down-regulated relative to flies from the colder habitat. (ii) Flies having higher Hsp70 expression levels should be weakened most by a hardening treatment and go faster into coma, as Hsp70 level reflects stress intensity, and therefore display reduced heat knock-down resistance. (iii) Heat shock resistance should be increased in the population with highest Hsp70 expression because the level of Hsp70 is positively associated with this trait. 3,The results generally matched the hypotheses. Hsp70 expression was reduced in the high-temperature population. Knock-down resistance was higher in the high-temperature population and survival after heat shock was lower in the high-temperature population. 4,This study showed genetic differences in thermal tolerance between populations, indicating that high temperature in nature may be an important selective factor. Moreover, knock-down resistance in this study seems to be a more relevant trait than standard heat shock resistance for identifying thermal adaptation in natural populations. [source]


Thermal adaptation of Arctic charr: experimental studies of growth in eleven charr populations from Sweden, Norway and Britain

FRESHWATER BIOLOGY, Issue 2 2005
S. LARSSON
Summary 1. Experimental growth data for Arctic charr (Salvelinus alpinus L.), all fed on excess rations, from 11 European watercourses between 54 and 70N were analysed and fitted to a new general growth model for fish. The model was validated by comparing its predictions with the growth rate of charr in the wild. 2. Growth performance varied among populations, mainly because of variation in the maximum growth potential, whereas the thermal response curves were similar. The estimated lower and upper temperatures for growth varied between ,1.7 to 5.3 and 20.8,23.2 C, respectively, while maximum growth occurred between 14.4 and 17.2 C. 3. There was no geographical or climatic trend in growth performance among populations and therefore no indication of thermal adaptation. The growth potential of charr from different populations correlated positively with fish body length at maturity and maximum weight in the wild. Charr from populations including large piscivorous fish had higher growth rates under standardised conditions than those from populations feeding on zoobenthos or zooplankton. Therefore, the adaptive variation in growth potential was related to life-history characteristics and diet, rather than to thermal conditions. [source]


Cold adaptation in geographical populations of Drosophila melanogaster: phenotypic plasticity is more important than genetic variability

FUNCTIONAL ECOLOGY, Issue 5 2004
A. AYRINHAC
Summary 1According to their geographical distribution, most Drosophila species may be classified as either temperate or tropical, and this pattern is assumed to reflect differences in their thermal adaptation, especially in their cold tolerance. We investigated cold tolerance in a global collection of D. melanogaster by monitoring the time adults take to recover from chill coma after a treatment at 0 C. 2Flies grown at an intermediate temperature (21 C) showed a significant linear latitudinal cline: recovery was faster in populations living in colder climates. 3The role of growth temperature was analysed in a subset of tropical and temperate populations. In all cases, recovery time decreased when growth temperature was lowered, and linear reaction norms were observed. This adaptive phenotypic plasticity explained more than 80% of the total variation, while genetic latitudinal differences accounted for less than 4%. 4The beneficial effect observed in adults grown at a low temperature contrasts with other phenotypic effects which, like male sterility, appear as harmful and pathological. Our results point to the difficulty of finding a general interpretation to the diversity of plastic responses that are induced by growth temperature variations. [source]


Thermal performance of juvenile Atlantic Salmon, Salmo salar L.

FUNCTIONAL ECOLOGY, Issue 6 2001
B. JONSSON
Summary 1,Experimental data for maximum growth and food consumption of Atlantic Salmon (Salmo salar L.) parr from five Norwegian rivers situated between 59 and 70N were analysed and modelled. The growth and feeding models were also applied to groups of Atlantic Salmon growing and feeding at rates below the maximum. The data were fitted to the Ratkowsky model, originally developed for bacterial growth. 2,The rates of growth and food consumption varied significantly among populations but the variation appeared unrelated to thermal conditions in the river of population origins. No correlation was found between the thermal conditions and limits for growth, thermal growth optima or maximum growth, and hypotheses of population-specific thermal adaptation were not supported. Estimated optimum temperatures for growth were between 16 and 20 C. 3, Model parameter estimates differed among growth-groups in that maximum growth and the performance breadth decreased from fast to slow growing individuals. The optimum temperature for growth did not change with growth rate. 4, The model for food consumption (expressed in energy terms) peaked at 19,21 C, which is only slightly higher than the optimal temperature for growth. Growth appeared directly related to food consumption. Consumption was initiated ,2 C below the lower temperature for growth and terminated ,15 C above the upper critical temperature for growth. Model parameter estimates for consumption differed among growth-groups in a manner similar to the growth models. 5,By combining the growth and consumption models, growth efficiencies were estimated. The maximum efficiencies were high, 42,58%, and higher in rivers offering hostile than benign feeding and growth opportunities. [source]


Genetic variation in thermal tolerance among natural populations of Drosophila buzzatii: down regulation of Hsp70 expression and variation in heat stress resistance traits

FUNCTIONAL ECOLOGY, Issue 3 2001
J. G. Srensen
Summary 1,Thermal adaptation was investigated in the fruitfly Drosophila buzzatii Patterson and Wheeler. Two natural populations originating from a high- and a low-temperature environment, respectively, were compared with respect to Hsp70 (heat shock protein) expression, knock-down resistance and heat shock resistance. 2,Three main hypotheses were tested: (i) The expression level of Hsp70 in flies from the high-temperature habitat should be down-regulated relative to flies from the colder habitat. (ii) Flies having higher Hsp70 expression levels should be weakened most by a hardening treatment and go faster into coma, as Hsp70 level reflects stress intensity, and therefore display reduced heat knock-down resistance. (iii) Heat shock resistance should be increased in the population with highest Hsp70 expression because the level of Hsp70 is positively associated with this trait. 3,The results generally matched the hypotheses. Hsp70 expression was reduced in the high-temperature population. Knock-down resistance was higher in the high-temperature population and survival after heat shock was lower in the high-temperature population. 4,This study showed genetic differences in thermal tolerance between populations, indicating that high temperature in nature may be an important selective factor. Moreover, knock-down resistance in this study seems to be a more relevant trait than standard heat shock resistance for identifying thermal adaptation in natural populations. [source]


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

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2006
M. SANTOS
Abstract 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 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 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 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. [source]


Temperature dependent larval resource allocation shaping adult body size in Drosophila melanogaster

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2003
Z. Bochdanovits
Abstract Geographical variation in Drosophila melanogaster body size is a long-standing problem of life-history evolution. Adaptation to a cold climate invariably produces large individuals, whereas evolution in tropical regions result in small individuals. The proximate mechanism was suggested to involve thermal evolution of resource processing by the developing larvae. In this study an attempt is made to merge proximate explanations, featuring temperature sensitivity of larval resource processing, and ultimate approaches focusing on adult and pre-adult life-history traits. To address the issue of temperature dependent resource allocation to adult size vs. larval survival, feeding was stopped at several stages during the larval development. Under these conditions of food deprivation, two temperate and two tropical populations reared at high and low temperatures produced different adult body sizes coinciding with different probabilities to reach the adult stage. In all cases a phenotypic trade-off between larval survival and adult size was observed. However, the underlying pattern of larval resource allocation differed between the geographical populations. In the temperate populations larval age but not weight predicted survival. Temperate larvae did not invest accumulated resources in survival, instead they preserved larval biomass to benefit adult weight. In other words, larvae from temperate populations failed to re-allocate accumulated resources to facilitate their survival. A low percentage of the larvae survived to adulthood but produced relatively large flies. Conversely, in tropical populations larval weight but not age determined the probability to reach adulthood. Tropical larvae did not invest in adult size, but facilitated their own survival. Most larvae succeeded in pupating but then produced small adults. The underlying physiological mechanism seemed to be an evolved difference in the accessibility of glycogen reserves as a result of thermal adaptation. At low rearing temperatures and in the temperate populations, glycogen levels tended to correlate positively with adult size but negatively with pupation probability. The data presented here offer an explanation of geographical variation in body size by showing that thermal evolution of resource allocation, specifically the ability to access glycogen storage, is the proximate mechanism responsible for the life-history trade-off between larval survival and adult size. [source]


Genetic response to rapid climate change: it's seasonal timing that matters

MOLECULAR ECOLOGY, Issue 1 2008
W. E. BRADSHAW
Abstract The primary nonbiological result of recent rapid climate change is warming winter temperatures, particularly at northern latitudes, leading to longer growing seasons and new seasonal exigencies and opportunities. Biological responses reflect selection due to the earlier arrival of spring, the later arrival of fall, or the increasing length of the growing season. Animals from rotifers to rodents use the high reliability of day length to time the seasonal transitions in their life histories that are crucial to fitness in temperate and polar environments: when to begin developing in the spring, when to reproduce, when to enter dormancy or when to migrate, thereby exploiting favourable temperatures and avoiding unfavourable temperatures. In documented cases of evolutionary (genetic) response to recent, rapid climate change, the role of day length (photoperiodism) ranges from causal to inhibitory; in no case has there been demonstrated a genetic shift in thermal optima or thermal tolerance. More effort should be made to explore the role of photoperiodism in genetic responses to climate change and to rule out the role of photoperiod in the timing of seasonal life histories before thermal adaptation is assumed to be the major evolutionary response to climate change. [source]


Geographies of embodied outdoor experience and the arrival of the patio heater

AREA, Issue 3 2007
Russell Hitchings
Machines that provide people with nearby sources of outdoor warmth have become increasingly popular in the UK as a crop of mushroom-shaped technologies has started to spring up outside many public houses and private homes in this country. Yet this development has also received considerable condemnation from advocates of sustainable consumption, who have seemingly been disgusted by the societal self-indulgence that they see in these devices. Moving away from these more immediate forms of outrage, this paper enriches our understanding of their arrival by considering these heaters in terms of cultural conventions of thermal adaptation and the changing geographies that can be attached to them. Through these means, it is argued that a more nuanced understanding of why these technologies have become prevalent is produced and that an existing disciplinary interest in embodied outdoor experience is taken towards some important new spaces for study. [source]


Structure of Bacillus amyloliquefaciens,-amylase at high resolution: implications for thermal stability

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2010
Jahan Alikhajeh
The crystal structure of Bacillus amyloliquefaciens,-amylase (BAA) at 1.4, resolution revealed ambiguities in the thermal adaptation of homologous proteins in this family. The final model of BAA is composed of two molecules in a back-to-back orientation, which is likely to be a consequence of crystal packing. Despite a high degree of identity, comparison of the structure of BAA with those of other liquefying-type ,-amylases indicated moderate discrepancies at the secondary-structural level. Moreover, a domain-displacement survey using anisotropic B -factor and domain-motion analyses implied a significant contribution of domain B to the total flexibility of BAA, while visual inspection of the structure superimposed with that of B. licheniformis,-amylase (BLA) indicated higher flexibility of the latter in the central domain A. Therefore, it is suggested that domain B may play an important role in liquefying ,-amylases, as its rigidity offers a substantial improvement in thermostability in BLA compared with BAA. [source]