scholarly journals Thermoregulatory behaviour explains countergradient variation in the upper thermal limit of a rainforest skink

Oikos ◽  
2016 ◽  
Vol 126 (5) ◽  
pp. 748-757 ◽  
Author(s):  
John Llewelyn ◽  
Stewart Macdonald ◽  
Amberlee Hatcher ◽  
Craig Moritz ◽  
Ben L. Phillips
Keyword(s):  
Thermal Limit ◽  
Countergradient Variation ◽  
Thermoregulatory Behaviour ◽  
Upper Thermal Limit

scholarly journals Neural dysfunction at the upper thermal limit in the zebrafish

2020 ◽  
Author(s):  
Anna H. Andreassen ◽  
Petter Hall ◽  
Pouya Khatibzadeh ◽  
Fredrik Jutfelt ◽  
Florence Kermen
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
High Temperatures ◽  
Neural Activity ◽  
Thermal Tolerance ◽  
Oxygen Availability ◽  
Adult Zebrafish ◽  
Thermal Limit ◽  
Larval Zebrafish ◽  
Upper Thermal Limit

ABSTRACTUnderstanding animal thermal tolerance is crucial to predict how animals will respond to increasingly warmer temperatures, and to mitigate the impact of the climate change on species survival. Yet, the physiological mechanisms underlying animal thermal tolerance are largely unknown. In this study, we developed a method for measuring upper thermal limit (CTmax) in larval zebrafish (Danio rerio) and found that it occurs at similar temperatures as in adult zebrafish. We discovered that CTmax precedes a transient, heat-induced brain-wide depolarization during heat ramping. By monitoring heart rate, we established that cardiac function is sub-optimal during the period where CTmax and brain depolarization occur. In addition, we found that oxygen availability affects both locomotor neural activity and CTmax during a heat stress. The findings of this study suggest that neural impairment due to limited oxygen availability at high temperatures can cause CTmax in zebrafish.HighlightsLarval zebrafish reach their critical thermal limit (CTmax) at similar temperature as adult zebrafishAcute heat stress causes a brain-wide spreading depolarization near the upper thermal limitCTmax precedes brain-wide depolarizationHeart rate declines at high temperatures but is maintained during CTmax and brain depolarizationNeural activity is impaired prior to CTmax and brain-wide depolarizationOxygen availability in the water affects both CTmax and neural activity

Limits to tolerance of temperature and salinity in the quagga mussel (Dreissena bugensis) and the zebra mussel (Dreissena polymorpha)

1995 ◽  
Vol 52 (10) ◽  
pp. 2108-2119 ◽  
Author(s):  
Adrian P. Spidle ◽  
Bernie May ◽  
Edward L. Mills
Keyword(s):  
Mortality Rate ◽  
Zebra Mussel ◽  
Dreissena Polymorpha ◽  
Temperature Limit ◽  
Acclimation Temperature ◽  
Quagga Mussel ◽  
Interspecific Difference ◽  
Thermal Limit ◽  
Dreissena Bugensis ◽  
Upper Thermal Limit

The quagga mussel (Dreissena bugensis) and the zebra mussel (Dreissena polymorpha) were exposed to varied levels of salinity and temperature in the laboratory to compare the tolerance of each species to environmental stress. The zebra mussel could tolerate 30 °C for extended periods and higher temperatures (< 39 °C) for a period of hours depending on the acclimation temperature and the rate of temperature change. The upper thermal limit of the quagga mussel may be as low as 25 °C. Mussels of both species acclimated to 5 °C were less able to survive at high temperatures (30–39 °C) than mussels acclimated to 15 or 20 °C. The reduced upper temperature limit of the quagga mussel implies that it will not be able to expand as far south in North America as has the zebra mussel. Both D. bugensis and D. polymorpha were exposed to three concentrations of NaCl (5, 10, and 20‰) to test salinity tolerance. No individuals of either species survived beyond 18 days in salinities of 5‰ or higher. No interspecific difference occurred in salinity-induced mortality rate.

scholarly journals Limited thermal acclimation capacity in cave beetles

2018 ◽  
Vol 1 ◽  
Author(s):  
Susana Pallarés ◽  
Ignacio Ribera ◽  
Aitor Montes ◽  
Andrés Millán ◽  
Valeria Rizzo ◽  
...  
Keyword(s):  
Thermal Tolerance ◽  
Video Recording ◽  
Thermal Acclimation ◽  
List Type ◽  
Thermal Limit ◽  
Control Temperature ◽  
Rate Of Increase ◽  
Subterranean Species ◽  
Upper Thermal Limit

Thermal tolerance is a key vulnerability factor for species that cannot cope with changing conditions by behavioural adjustments or dispersal, such as subterranean species. Previous studies of thermal tolerance in cave beetles suggest that these species may have lost some of the thermoregulatory mechanisms common in temperate insects, and appear to have a very limited thermal acclimation ability. However, it might be expected that both thermal tolerance and acclimation ability should be related with the degree of specialization to deep subterranean environments, being more limited in highly specialized species. To test this hypothesis, we use an experimental approach to determine the acclimation capacity of cave beetles within the tribe Leptodirini (family Leiodidae) with different degrees of specialization to the deep subterranean environment. For this, we acclimate groups of individuals at a temperature close to their upper thermal limit (20ºC) or a control temperature (approximately that of the cave in which they were found) for 2 or 10 days (short- vs. long-term acclimation). a temperature close to their upper thermal limit (20ºC) or a control temperature (approximately that of the cave in which they were found) for 2 or 10 days (short- vs. long-term acclimation). Upper thermal limits (heat coma temperature, HC) are then measured for each individual using a ramping protocol (rate of increase of 1ºC/min) combined with infrared thermography and video recording. Preliminary results in a deep subterranean species (Speonomidius crotchi, with an intermediate degree of specialization) showed no significant effect of acclimation temperature in HC at any of the exposure times. Such reduced thermal plasticity could be also expected for other highly specialized subterranean species. The potential implications of these findings for subterranean biodiversity in a climate change context are discussed.

scholarly journals Critical Thermal maximum measurements and its biological relevance: the case of ants

2020 ◽  
Author(s):  
Chi-Man Leong ◽  
Toby P. N. Tsang ◽  
Benoit Guénard
Keyword(s):  
Community Dynamics ◽  
Phylogenetic Signal ◽  
Methodological Approach ◽  
Functional Trait ◽  
List Type ◽  
Critical Thermal Maximum ◽  
Thermal Limit ◽  
Thermal Maximum ◽  
Multiple Species ◽  
Upper Thermal Limit

ABSTRACTUpper thermal limit (UTL) is a key trait in evaluating ectotherm fitness. Critical Thermal maximum CTmax, often used to characterize the UTL of an organism in laboratory setting, needs to be accurate to characterize this significant and field-relevant threshold. The lack of standardization in CTmax assays has, however, introduce methodological problems in its measurement and incorrect estimation of species upper thermal limit; with potential major implications on the use of CTmax in forecasting community dynamics under climate change. In this study we ask if a satisfactory ramping rate can be identified to produce accurate measures of CTmax for multiple species.We first identified the most commonly used ramping rates (i.e. 0.2, 0.5 and 1.0 °Cmin−1) based on a literature review, and determined the ramping rate effects on CTmax value measurements in 27 ant species (7 arboreal, 16 ground, 4 subterranean species) from eight subfamilies using both dynamic and static assays. In addition, we used field observations on multiple species foraging activity in function of ground temperatures to identify the most biologically relevant CTmax value to ultimately develop a standardized methodological approach.Integrating dynamic and static assays provided a powerful approach to identify a suitable ramping rate for the measurements of CTmax values in ants. Our results also showed that among the values tested the ramping rate of 1 °Cmin−1 is optimal, with convergent evidences from CTmax values measured in laboratory and from foraging thermal maximum measured in the field. Finally, we illustrate how methodological bias in terms of physiological trait measurements can also affect the detection of phylogenetic signal (Pagel’s λ and Bloomberg’s K) in subsequent analyses.Overall, this study presents a methodological framework allowing the identification of suitable and standardized ramping rates for the measurement of ant CTmax, which may be used for other ectotherms. Particular attention should be given to CTmax values retrieved from less suitable ramping rate, and the potential biases that functional trait based research may induce on topics such as global warming, habitat conversion or their impacts on analytical interpretations on phylogenetic conservatism.

Evolutionary Adaptation to Temperature. VII. Extension of the Upper Thermal Limit of Escherichia coli

Evolution ◽  
1999 ◽  
Vol 53 (2) ◽  
pp. 386 ◽  
Author(s):  
Judith A. Mongold ◽  
Albert F. Bennett ◽  
Richard E. Lenski
Keyword(s):  
Escherichia Coli ◽  
Evolutionary Adaptation ◽  
Thermal Limit ◽  
Upper Thermal Limit

scholarly journals EVOLUTIONARY ADAPTATION TO TEMPERATURE. VII. EXTENSION OF THE UPPER THERMAL LIMIT OFESCHERICHIA COLI

Evolution ◽  
1999 ◽  
Vol 53 (2) ◽  
pp. 386-394 ◽  
Author(s):  
Judith A. Mongold ◽  
Albert F. Bennett ◽  
Richard E. Lenski
Keyword(s):  
Ofescherichia Coli ◽  
Evolutionary Adaptation ◽  
Thermal Limit ◽  
Upper Thermal Limit

EFFECT OF CELLULAR MEMBRANE RESISTIVITY INHOMOGENEITY ON THE THERMAL NOISE-LIMIT

2015 ◽  
Vol 11 (3) ◽  
pp. 3171-3183
Author(s):  
Gyula Vincze
Keyword(s):  
Field Strength ◽  
Thermal Noise ◽  
Cellular Membrane ◽  
Thermal Limit ◽  
Low Frequencies ◽  
Membrane Resistivity ◽  
Noise Limit ◽  
The Asymmetry ◽  
Characteristic Field

Our objective is to generalize the Weaver-Astumian (WA) and Kaune (KA) models of thermal noise limit to the case ofcellular membrane resistivity asymmetry. The asymmetry of resistivity causes different effects in the two models. In the KAmodel, asymmetry decreases the characteristic field strength of the thermal limit over and increases it below the breakingfrequency (10  m), while asymmetry decreases the spectral field strength of the thermal noise limit at all frequencies.We show that asymmetry does not change the character of the models, showing the absence of thermal noise limit at highand low frequencies in WA and KA models, respectively.

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