Limits Of Cold Tolerance Research Articles

The evolution of critical thermal limits of life on Earth

Understanding how species’ thermal limits have evolved across the tree of life is central to predicting species’ responses to climate change. Here, using experimentally-derived estimates of thermal tolerance limits for over 2000 terrestrial and aquatic species, we show that most of the variation in thermal tolerance can be attributed to a combination of adaptation to current climatic extremes, and the existence of evolutionary ‘attractors’ that reflect either boundaries or optima in thermal tolerance limits. Our results also reveal deep-time climate legacies in ectotherms, whereby orders that originated in cold paleoclimates have presently lower cold tolerance limits than those with warm thermal ancestry. Conversely, heat tolerance appears unrelated to climate ancestry. Cold tolerance has evolved more quickly than heat tolerance in endotherms and ectotherms. If the past tempo of evolution for upper thermal limits continues, adaptive responses in thermal limits will have limited potential to rescue the large majority of species given the unprecedented rate of contemporary climate change.

Sex-Dependent Cold Tolerance at the Northern Invasive Range Limit of Gambusia affinis on Cape Cod, Massachusetts

Many invasive species may be constrained in their ability to invade high latitude or elevation habitats due to limits of cold tolerance. However, isolated populations at the edge of these species' geographic ranges may face a combination of strong selection and lack of maladaptive gene flow that allows them to adapt to the cold and invade further. Here we show that an isolated population of Gambusia affinis (on Cape Cod, MA, USA), one of the most invasive fish in the world, can survive temperatures lower than any reported tolerances for other populations, with large, long-lived females showing more tolerance than males. Indeed, male acute cold tolerance appears insufficient, suggesting the population may persist through winters mainly via the ability of mated females to delay offspring production until spring. This combination of female cold tolerance and life history may open the door for further expansion of this invasive species into high latitude freshwater habitats.

Thermal tolerance patterns across latitude and elevation.

Linking variation in species' traits to large-scale environmental gradients can lend insight into the evolutionary processes that have shaped functional diversity and future responses to environmental change. Here, we ask how heat and cold tolerance vary as a function of latitude, elevation and climate extremes, using an extensive global dataset of ectotherm and endotherm thermal tolerance limits, while accounting for methodological variation in acclimation temperature, ramping rate and duration of exposure among studies. We show that previously reported relationships between thermal limits and latitude in ectotherms are robust to variation in methods. Heat tolerance of terrestrial ectotherms declined marginally towards higher latitudes and did not vary with elevation, whereas heat tolerance of freshwater and marine ectotherms declined more steeply with latitude. By contrast, cold tolerance limits declined steeply with latitude in marine, intertidal, freshwater and terrestrial ectotherms, and towards higher elevations on land. In all realms, both upper and lower thermal tolerance limits increased with extreme daily temperature, suggesting that different experienced climate extremes across realms explain the patterns, as predicted under the Climate Extremes Hypothesis. Statistically accounting for methodological variation in acclimation temperature, ramping rate and exposure duration improved model fits, and increased slopes with extreme ambient temperature. Our results suggest that fundamentally different patterns of thermal limits found among the earth's realms may be largely explained by differences in episodic thermal extremes among realms, updating global macrophysiological 'rules'. This article is part of the theme issue 'Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen'.

Physiological Limits along an Elevational Gradient in a Radiation of Montane Ground Beetles.

A central challenge in ecology and biogeography is to determine the extent to which physiological constraints govern the geographic ranges of species along environmental gradients. This study tests the hypothesis that temperature and desiccation tolerance are associated with the elevational ranges of 12 ground beetle species (genus Nebria) occurring on Mt. Rainier, Washington, U.S.A. Species from higher elevations did not have greater cold tolerance limits than lower-elevation species (all species ranged from -3.5 to -4.1°C), despite a steep decline in minimum temperature with elevation. Although heat tolerance limits varied among species (from 32.0 to 37.0°C), this variation was not generally associated with the relative elevational range of a species. Temperature gradients and acute thermal tolerance do not support the hypothesis that physiological constraints drive species turnover with elevation. Measurements of intraspecific variation in thermal tolerance limits were not significant for individuals taken at different elevations on Mt. Rainier, or from other mountains in Washington and Oregon. Desiccation resistance was also not associated with a species’ elevational distribution. Our combined results contrast with previously-detected latitudinal gradients in acute physiological limits among insects and suggest that other processes such as chronic thermal stress or biotic interactions might be more important in constraining elevational distributions in this system.

Scale‐dependent thermal tolerance variation in Australian mountain grasshoppers

Physiological variation among and within species is thought to play a key role in determining distribution patterns across environmental gradients. We tested inter‐ and intraspecific variation in cold and heat tolerances for three grasshopper species (genus Kosciuscola) with overlapping elevation distributions, across their respective ranges in the Australian mountains. Of the three cold tolerance traits measured, the critical thermal minimum was the only trait to vary among species, with greater cold tolerance associated with a distribution extending to a higher elevation. Cold tolerance limits were regularly exceeded in exposed microhabitats, suggesting a role for cold adaptation in structuring species distribution patterns. In contrast to cold tolerance, heat tolerance variation was primarily partitioned within species. For two species, populations from treeless alpine habitat were more heat tolerant than their lower‐elevation counterparts, supporting recent models that suggest greater exposure to temperature extremes at higher elevations. These contrasting patterns of physiological variation among and within species emphasise the importance of considering variation within species when attempting to understand how species distributions are affected by thermal extremes.

C4 bioenergy crops for cool climates, with special emphasis on perennial C4 grasses.

There is much interest in cultivating C4 perennial plants in northern climates where there is an abundance of land and a potential large market for biofuels. C4 feedstocks can exhibit superior yields to C3 alternatives during the long warm days of summer at high latitude, but their summer success depends on an ability to tolerate deep winter cold, spring frosts, and early growth-season chill. Here, we review cold tolerance limits in C4 perennial grasses. Dozens of C4 species are known from high latitudes to 63 °N and elevations up to 5200 m, demonstrating that C4 plants can adapt to cold climates. Of the three leading C4 grasses being considered for bioenergy production in cold climates--Miscanthus spp., switchgrass (Panicum virgatum), and prairie cordgrass (Spartina pectinata)--all are tolerant of cool temperatures (10-15 °C), but only cordgrass tolerates hard spring frosts. All three species overwinter as dormant rhizomes. In the productive Miscanthus×giganteus hybrids, exposure to temperatures below -3 °C to -7 °C will kill overwintering rhizomes, while for upland switchgrass and cordgrass, rhizomes survive exposure to temperatures above -20 °C to -24 °C. Cordgrass emerges earlier than switchgrass and M. giganteus genotypes, but lacks the Miscanthus growth potential once warmer days of late spring arrive. To enable C4-based bioenergy production in colder climates, breeding priorities should emphasize improved cold tolerance of M.×giganteus, and enhanced productivity of switchgrass and cordgrass. This should be feasible in the near future, because wild populations of each species exhibit a diverse range of cold tolerance and growth capabilities.

Physiology of cold tolerance in the bark beetle, Pityogenes chalcographus and its overwintering in spruce stands

The seasonal development of physiological features underlying gradual acquisition of relatively high cold tolerance in overwintering adults of the bark beetles, Pityogenes chalcographus was described. Prior to overwintering, the beetles accumulated carbohydrate reserves in the form of glycogen and trehalose. These reserves were partially converted to glycerol during peaking winter so that glycerol concentration reached 1.4M in average, which corresponds to approximately one quarter of the beetle dry mass. Whole body supercooling points decreased from −12.8°C in average at the beginning of dormancy (August) to −26.3°C in average during peaking winter (January). More than 75% of January-collected beetles survived at −5°C for 30days, at −15°C for 60days and more than 40% of them survived at −26°C for 12h. High resistance against inoculation of body fluids with external ice crystals, and low mortality, was observed when January-collected beetles were encased in an ice block for 14days. Thus, the physiological limits of cold tolerance measured at individual level in laboratory were safely sufficient for survival of P. chalcographus at any conceivable cold spell that may occur in Central Europe. In contrast, the field experiment showed that winter survival fluctuated between 23.8% and 69.2% at a population level depending on microclimatic conditions in different altitudes and overwintering locations (standing tree trunk or ground level). The meaning of laboratory-assessed physiological limits of cold tolerance for predictions of population winter survival in the field is discussed.

Cold Storage of Adult <I>Gonatocerus ashmeadi</I> (Hymenoptera: Mymaridae) and Effects on Maternal and Progeny Fitness

Storage of Conatocerus ashmeadi Girault (Hymenoptera: Mymaridae) adults at 2, 5, and 10 degrees C showed that these parasitoids do not survive at 2 degrees C for 5 d, and exposure to 5 and 10 degrees C shortens their life span. The lethal time (LT) 50 (i.e., length of storage time for 50% wasp survival) at 5 degrees C was 14 d for males and approximately 29 d for females, whereas at 10 degrees C was 32 and 39 d, respectively. Effects of adult storage at 10 degrees C on other factors indicating fitness, such as fecundity, developmental time, parasitism, emergence, and sex ratio, were examined on female wasps and their progeny at 10-d intervals for up to 60 d. Glassy-winged sharpshooter, Homalodisca vitripennis (Germar), eggs were used as hosts for propagation of this wasp and for assessing its oviposition and fecundity. Increasing adult storage time decreased the length of the ovipositional period for the maternal generation, and oviposition was decreased by 90% after 60-d storage. A significant reduction in maternal lifetime fecundity occurred after 20-d storage and in the incidence of parasitism after 40 d. We also found a carryover effect caused by storage of the maternal generation that was expressed in the F1 generation. When cold storage of the adult parents was > or = 20 d, we observed delayed development, decreased fecundity, reduced longevity, and increased male production occurring in the F1 generation. Reduced fitness of the F1 generation was also expressed as a decrease in net reproductive rate (R(o)) and an increase in mean generation time (T(c)). However, none of these deleterious effects were evident in the F2 progeny that descended from grandparents that had experienced cold storage. Damage caused by indirect chilling injury and/or induced maternal aging occurring during storage can account for the decreased fitness of maternal and F1 generations. Providing that the limits of cold tolerance of G. ashmeadi as defined in this study are not exceeded, our results show that short-term cold storage of adults could be used in a mass-rearing program.

Distribution patterns of decapod crustaceans in polar areas: a result of magnesium regulation?

Nearly all decapod crustaceans found in Antarctic waters south of the Antarctic Convergence are caridean shrimps (Natantia) while the group of Reptantia is largely absent in this area. Progress in the development of a physiological hypothesis is reported, which explains this distribution pattern based on differences in the regulation of magnesium levels in the haemolymph ([Mg2 +]HL) and on the Mg2 + dependence of threshold temperatures below which cold-induced failure of cardiac and ventilatory performance occurs. Previous studies had shown that an increase in oxygen consumption and activity levels in the cold can be induced by experimental reduction of [Mg2 +]HL in different reptant decapod species. In the present study, we tested the potential of these experimental findings for predicting the effect of low [Mg2+]HL in nature, and investigated temperature-induced changes in oxygen consumption in two species with low but different [Mg2+]HL from southern Chile, Halicarcinus planatus and Acanthocyclus albatrossis ([Mg2+]HL = 10.7 and 21.6 mmol 1-1, respectively). In accordance with previous findings, low [Mg2+]HL levels were associated with a reduction of thermal sensitivity and a higher metabolic rate in the cold. A model is developed which de-scribes how [Mg2+]HL reduction caused a threshold temperature (pejus temperature, Tp) to fall, which characterises the onset of cold-induced failure in oxygen supply to tissues. This threshold temperature is interpreted, not only to indicate the limits of cold tolerance, but also of geographical distribution. Tp is shifted towards lower temperatures in Natantia, which are efficient [Mg2+]HL regulators. In contrast, Reptantia, which are poor [Mg2+]HL regulators, appear unable to colonise the permanently cold water of the Antarctic due to insufficient capacity of cardiac performance and, therefore, largely reduced scope for activity at high [Mg2+]HL.

New Zealand timberlines. 2. A study of forest limits in the Crow Valley near Arthur's Pass, Canterbury

Abstract The Crow is typical of many mountain valleys in that the Nothofagus forest clothing the valJey sides narrows to a mid-slope wedge in the glacially broadened upper reaches. In a study of this phenomenon, temperatures near the ground were measured, and observations on winter death of shoots, seed fall, and distribution and growth of mountain beech (N. solandri var. cliffortioides) seedlings were made. On clear, calm nights, temperatures in the open close to the ground above the upper forest limits, or below an inverted timberline, are lower than those measured in openings within the forest, and can be lower than the experimentally determined limits of cold tolerance of beech seedlings. Other factors influencing the position of the alpine timberline are a tendency for growth rates of seedlings to decrease with increasing altitude, winter die-back of exposed shoots (especially where snow drifts into the forest margin), and poor seed dispersal beyond the forest margin. Below the inverted timberline, s...

New Zealand timberlines. 3. A synthesis

Abstract An experimental comparison of the native mountain beech (Nothofagus solandri var. cliffortioides) with exotic timberline species, and a study of the configuration of timberline in an alpine valley in relation to topography and microclimate are synthesised with the results of other timberline studies to develop general hypotheses about New Zealand timberlines. Although assimilation and growth in mountain beech decrease with increasing altitude, the abrupt nature and local altitudinal variations of beech timberlines mainly reflect the cold-tolerance limits of its seedlings. Winter death of beech twigs, that can lead to a krummholz form, is aligned with downslope winds, but sensitivity to low temperatures may also be involved. At least some of the tall shrubs that replace beech forest in cirque-form valley heads possess greater cold-tolerance. These shrubs also have endotrophic mycorrhizal associations, in contrast to the ectotrophic mycorrhizas of beech, which may have bearing on their lower stature and slower growth. On a regional scale, maximum tree limit, whether of beech or tall shrubs, is related to the regular altitudinal decrease in atmospheric temperatures, and not to microclimates as influenced by aspect and topography; and it is more likely related to how long temperatures lie within a range conducive to maturation and winter-hardening of shoots, than to annual carbon gain. Above tree limit, however, summer growth may not compensate for winter dieback. Low shrubs ascend far above tree limit, because the genetic restriction on their height growth protects them from repeated die-back. Species of northern hemisphere timberlines generally achieve far greater winter-hardiness than native trees, but many are limited in New Zealand because they are damaged by summer frosts. Pinus contorta, however, seems capable of forming trees 200 m above the natural tree limit. and krummholz at still higher altitudes.