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.

Critical thermal maximum in mice

1976 ◽  
Vol 40 (5) ◽  
pp. 683-687 ◽  
Author(s):  
G. L. Wright
Keyword(s):  
Heat Stress ◽  
Cooling Capacity ◽  
Heating Time ◽  
Critical Thermal Maximum ◽  
Thermal Limit ◽  
Ambient Temperatures ◽  
Thermal Maximum ◽  
Righting Reflex ◽  
Colonic Temperature ◽  
Extended Exposure

The critical thermal maximum (the colonic temperature of heat-induced convulsion and righting reflex loss) and thermoregulatory response of male mice were examined following I, exposure to colonic temperature (Tco) 42 degrees C; II, a single exposure to the critical thermal maximum (Tco 44 degrees C); AND III, acclimation at ambient temperatures of 15 or 30 degrees C for 14 days. The critical thermal maximum (CTM) was greater in 30 degrees C acclimated mice than 15 degrees C acclimated mice but was unchanged in mice surviving exposure to Tco 42 degrees C or the CTM. The heating time to apparent breakdown of thermoregulation coincident with an explosive rise in the Tco during exposure to ambient temperature 40.8 degrees C was increased (100%) during the 48-h period following exposure to Tco 42 degrees. It appeared that mice exposed to severe, short-term heat stress (Tco 42 degrees) undergo a compensatory increase in their thermoregulatory cooling capacity with little or no change in the upper temperature tolerated. The animals did, however, exhibit the capability for adaptive adjustments of the upper thermal limit during extended exposure to the more prolonged and less severe environmental heat stress of acclimation at 30 degrees C.

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 Water temperature affects aggressive interactions in a Neotropical cichlid fish

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Manuela L. Brandão ◽  
Gisele Colognesi ◽  
Marcela C. Bolognesi ◽  
Roselene S. Costa-Ferreira ◽  
Thaís B. Carvalho ◽  
...  
Keyword(s):  
Aggressive Behavior ◽  
Water Temperature ◽  
Elevated Temperatures ◽  
Cichlid Fish ◽  
Aquatic Organisms ◽  
Swimming Activity ◽  
Critical Thermal Maximum ◽  
Physiological Mechanisms ◽  
Aggressive Interactions ◽  
Thermal Maximum

ABSTRACT Changes in water temperature may affect the aggressive behavior of aquatic organisms, such as fish, either by changing some physiological mechanisms or by increasing the probability of encounters between individuals as a result of variation in their swimming activity. In our study, we evaluated the influence of increasing and decreasing temperature on the aggressive behavior of the Neotropical cichlid fish Cichlasoma paranaense. Firstly, we tested the critical thermal maximum (CTMax) tolerated by this species. Then, we tested the effect of decreasing or increasing the water temperature in 6o C (starting at 27° C) on the aggressive interactions of fish under isolation or housed in groups. We found a CTMax value of 39° C for C. paranaense. We also observe that a 6° C decrease in water temperature lowers swimming activity and aggressive interactions in both isolated and group-housed fish, as expected. On the other hand, the increase in temperature had no effect on the fish’s aggressive behavior, neither for isolated nor for grouped fish. We concluded that C. paranaense shows high tolerance to elevated temperatures and, in turn, it does not affect aggressive behavior. Nevertheless, we cannot dismiss possible effects of elevated temperatures on aggressive interactions over longer periods.

scholarly journals Bovine tuberculosis disturbs parasite functional trait composition in African buffalo

2019 ◽  
Vol 116 (29) ◽  
pp. 14645-14650 ◽  
Author(s):  
Brianna R. Beechler ◽  
Kate S. Boersma ◽  
Peter E. Buss ◽  
Courtney A. C. Coon ◽  
Erin E. Gorsich ◽  
...  
Keyword(s):  
Community Composition ◽  
Bovine Tuberculosis ◽  
Community Dynamics ◽  
Parasite Community ◽  
Functional Trait ◽  
Taxonomic Composition ◽  
African Buffalo ◽  
Emerging Infections ◽  
Parasite Communities ◽  
Parasite Richness

Novel parasites can have wide-ranging impacts, not only on host populations, but also on the resident parasite community. Historically, impacts of novel parasites have been assessed by examining pairwise interactions between parasite species. However, parasite communities are complex networks of interacting species. Here we used multivariate taxonomic and trait-based approaches to determine how parasite community composition changed when African buffalo (Syncerus caffer) acquired an emerging disease, bovine tuberculosis (BTB). Both taxonomic and functional parasite richness increased significantly in animals that acquired BTB than in those that did not. Thus, the presence of BTB seems to catalyze extraordinary shifts in community composition. There were no differences in overall parasite taxonomic composition between infected and uninfected individuals, however. The trait-based analysis revealed an increase in direct-transmitted, quickly replicating parasites following BTB infection. This study demonstrates that trait-based approaches provide insight into parasite community dynamics in the context of emerging infections.

Evaluation of biodiversity metrics through environmental DNA metabarcoding compared with visual and capture surveys in river fish community

2019 ◽  
Author(s):  
Hideyuki Doi ◽  
Ryutei Inui ◽  
Shunsuke Matsuoka ◽  
Yoshihisa Akamatsu ◽  
Masuji Goto ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Species Turnover ◽  
Environmental Dna ◽  
List Type ◽  
Visual Capture ◽  
Gamma Diversity ◽  
Community Patterns ◽  
Community Assemblages ◽  
Study Sites ◽  
River Fish

AbstractInformation on alpha (local), beta (between habitats), and gamma (regional) diversity is fundamental to understanding biodiversity as well as the function and stability of community dynamics. The methods like environmental DNA (eDNA) metabarcoding are currently considered useful to investigate biodiversity.We compared the performance of eDNA metabarcoding with visual and capture surveys in estimating alpha/gamma diversity and the variation of the community assemblages of river fish communities, particularly considering community nestedness and turnover.In five rivers across west Japan, with comparing to visual/capture surveys, eDNA metabarcoding detected more species in the study sites, consequently the overall number of species in the region (i.e., gamma diversity) was higher. In particular, the species found by visual/capture surveys were encompassed by those by eDNA metabarcoding.With analyzing the community assemblages between the rivers, we showed the different results between the both methods. While, in the same river, the nestedness and species turnover changing from upstream to downstream did not significantly differ between the both methods. Our results suggest that eDNA metabarcoding may be suitable method, especially for understanding regional community patterns, for fish monitoring in rivers.

scholarly journals Effects of warming rate, acclimation temperature and ontogeny on the critical thermal maximum of temperate marine fish larvae

PLoS ONE ◽  
2017 ◽  
Vol 12 (7) ◽  
pp. e0179928 ◽  
Author(s):  
Marta Moyano ◽  
Caroline Candebat ◽  
Yannick Ruhbaum ◽  
Santiago Álvarez-Fernández ◽  
Guy Claireaux ◽  
...  
Keyword(s):  
Marine Fish ◽  
Fish Larvae ◽  
Acclimation Temperature ◽  
Critical Thermal Maximum ◽  
Marine Fish Larvae ◽  
Thermal Maximum ◽  
Warming Rate

Critical Thermal Maximum Temperatures in Australian Scincid Lizards: Their Ecological and Evolutionary Significance.

1980 ◽  
Vol 28 (1) ◽  
pp. 91 ◽  
Author(s):  
AE Greer
Keyword(s):  
Maximum Temperature ◽  
Evolutionary Significance ◽  
Thermal Barrier ◽  
Critical Thermal Maximum ◽  
Thermal Maximum ◽  
Surface Dwelling ◽  
Maximum Temperatures

The critical thermal maximum temperature (CTMAX) has now been determined for representatives of 16 of the 21 genera of scincid lizards in Australia. Taxa from the warm interior of the country generally have a mean CTMAX greater than 39.5�C regardless of their behaviour or habitat. Taxa from the cooler periphery of the continent fall into two groups based on their behaviour and habitat: diurnal, surface- dwelling forms generally have a mean CTMAX above 39.5�C whereas crepuscular to nocturnal. or cryptozoic to fossorial forms, have a mean CTMAX below 39.5�C. The skinks of the interior probably evolved from ancestors occupying habitats most similar to ones now occurring on the periphery. In these more equable habitats. diurnal surface-dwelling forms, with their high CTMAX, would have been preadapted to invade the habitats of the interior, whereas crepuscular to nocturnal. or cryptozoic to fossorial forms, with their low CTMAX, may have had to overcome a thermal barrier to enter these habitats. This may account in part for the paucity of crepuscular to nocturnal or cryptozoic to fossorial skink lineages in the interior. Unlike most other lizard families, most skinks do not pant when heat stressed. The reasons for this are unknown.

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