1
|
Bussy M, Destierdt W, Masnou P, Lazzari C, Goubault M, Pincebourde S. The lack of plasticity and interspecific variability in thermal limits produce a highly heat-tolerant tropical host-parasitoid system. J Therm Biol 2024; 123:103930. [PMID: 39116624 DOI: 10.1016/j.jtherbio.2024.103930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 07/19/2024] [Accepted: 07/21/2024] [Indexed: 08/10/2024]
Abstract
Thermal limits are often used as proxies to assess the vulnerability of ectotherms to environmental change. While meta-analyses point out a relatively low plasticity of heat limits and a large interspecific variability, only few studies have compared the heat tolerance of interacting species. The present study focuses on the thermal limits, and their plasticity (heat hardening), of three species co-occurring in Western Africa: two ectoparasitoid species, Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) and Eupelmus vuilleti (Crawford) (Hymenoptera: Eupelmidae), and their common host, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). The investigation delves into the Critical Thermal Maximum (CTmax), representing the upper tolerance limit, to understand how these species may cope with extreme thermal events. The CTmax of all three species appeared similarly high, hovering around 46.5 °C, exceeding the global mean CTmax observed in insects by 3.5 °C. Short-term exposure to moderate heat stress showed no impact on CTmax, suggesting a potential lack of heat hardening in these species. Therefore, we emphasized the similarity of heat tolerance in these interacting species, potentially stemming from both evolutionary adaptations to high temperatures during development and the stable and similar microclimate experienced by the three species over the years. While the high thermal tolerance should allow these species to endure extreme temperature events, the apparent lack of plasticity raises concerns about their ability to adapt to future climate change scenarios. Overall, this research provides valuable insights into the thermal physiology of these interacting species, providing a basis for understanding their responses to climate change and potential implications for the host-parasitoid system.
Collapse
Affiliation(s)
- Mathieu Bussy
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, University of Tours, Tours, France.
| | - Wendy Destierdt
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, University of Tours, Tours, France
| | - Pauline Masnou
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, University of Tours, Tours, France
| | - Claudio Lazzari
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, University of Tours, Tours, France
| | - Marlène Goubault
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, University of Tours, Tours, France
| | - Sylvain Pincebourde
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS, University of Tours, Tours, France
| |
Collapse
|
2
|
Powers SD, Grayson KL, Martinez E, Agosta SJ. Ontogenetic variation in metabolic rate-temperature relationships during larval development. J Exp Biol 2024; 227:jeb247912. [PMID: 38940758 DOI: 10.1242/jeb.247912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 06/18/2024] [Indexed: 06/29/2024]
Abstract
Predictive models of ectotherm responses to environmental change often rely on thermal performance data from the literature. For insects, the majority of these data focus on two traits, development rate and thermal tolerance limits. Data are also often limited to the adult stage. Consequently, predictions based on these data generally ignore other measures of thermal performance and do not account for the role of ontogenetic variation in thermal physiology across the complex insect life cycle. Theoretical syntheses for predicting metabolic rate also make similar assumptions despite the strong influence of body size as well as temperature on metabolic rate. The aim of this study was to understand the influence of ontogenetic variation on ectotherm physiology and its potential impact on predictive modeling. To do this, we examined metabolic rate-temperature (MR-T) relationships across the larval stage in a laboratory strain of the spongy moth (Lymantria dispar dispar). Routine metabolic rates (RMRs) of larvae were assayed at eight temperatures across the first five instars of the larval stage. After accounting for differences in body mass, larval instars showed significant variation in MR-T. Both the temperature sensitivity and allometry of RMR increased and peaked during the third instar, then declined in the fourth and fifth instar. Generally, these results show that insect thermal physiology does not remain static during larval ontogeny and suggest that ontogenetic variation should be an important consideration when modeling thermal performance.
Collapse
Affiliation(s)
- Sean D Powers
- Integrative Life Sciences Doctoral Program, Virginia Commonwealth University, Richmond, VA 2328, USA
| | | | - Eloy Martinez
- Department of Biological Sciences, Nova Southeastern University, Fort Lauderdale, FL 33328, USA
| | - Salvatore J Agosta
- Center for Environmental Studies, Virginia Commonwealth University, Richmond, VA 23284, USA
| |
Collapse
|
3
|
Weinstein AM, Bohman B, Linde CC, Phillips RD. Conservation assessment of the Drakaea livida (Orchidaceae) ecotypes and an evaluation of methods for their identification. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1004177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Morphologically cryptic taxa must be accounted for when quantifying biodiversity and implementing effective conservation measures. Some orchids pollinated by sexual deception of male insects contain morphologically cryptic ecotypes, such as the warty hammer orchid Drakaea livida (Orchidaceae). This species is comprised of three cryptic pollination ecotypes, which can be distinguished based on differences in pollinator species and floral volatiles. The present study aims were: (a) to investigate the geographic range of the three D. livida ecotypes, enabling assessment of their conservation status; and (b) to test the efficacy of different methods of identifying the D. livida ecotypes. Three methods of ecotype identification were assessed: morphometric analysis, genome size comparison, and analysis of chemical volatile composition of labellum extracts from pollinated flowers. MaxEnt species distribution models revealed that each ecotype has a different predicted geographic range, with small areas of overlap at the range margins. One ecotype is known from just ten populations over a limited geographic area, the majority of which has been cleared for agriculture, and urban development. While there was broad overlap between the ecotypes in individual morphological traits, multivariate analysis of morphological traits provided correct assignment to ecotype in 87% of individuals. Using the labellum of pollinated flowers, screening for volatile chemical compounds associated with particular ecotypes returned an even higher correct assignment rate, of 96.5%. As such, we advocate that the use of volatiles from the labellum of recently pollinated flowers is an effective way to determine the ecotype of unknown individuals of D. livida, with minimal impact on the flowering plant.
Collapse
|
4
|
Moffett ER, Fryxell DC, Benavente JN, Kinnison MT, Palkovacs EP, Symons CC, Simon KS. The effect of pregnancy on metabolic scaling and population energy demand in the viviparous fish Gambusia affinis. Integr Comp Biol 2022; 62:icac099. [PMID: 35767874 DOI: 10.1093/icb/icac099] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Metabolism is a fundamental attribute of all organisms that influences how species affect and are affected by their natural environment. Differences between sexes in ectothermic species may substantially alter metabolic scaling patterns, particularly in viviparous or live-bearing species where females must support their basal metabolic costs and that of their embryos. Indeed, if pregnancy is associated with marked increases in metabolic demand and alters scaling patterns between sexes, this could in turn interact with natural sex ratio variation in nature to affect population-level energy demand. Here, we aimed to understand how sex and pregnancy influence metabolic scaling and how differences between sexes affect energy demand in Gambusia affinis (Western mosquitofish). Using the same method, we measured routine metabolic rate in the field on reproductively active fish and in the laboratory on virgin fish. Our data suggest that changes in energy expenditure related to pregnancy may lead to steeper scaling coefficients in females (b = 0.750) compared to males (b = 0.595). In contrast, virgin females and males had similar scaling coefficients, suggesting negligible sex differences in metabolic costs in reproductively inactive fish. Further, our data suggest that incorporating sex differences in allometric scaling may alter population-level energy demand by as much as 20-28%, with the most pronounced changes apparent in male-biased populations due to the lower scaling coefficient of males. Overall, our data suggest that differences in energy investment in reproduction between sexes driven by pregnancy may alter allometric scaling and population-level energy demand.
Collapse
Affiliation(s)
- Emma R Moffett
- Ecology and Evolutionary Biology, University of California, Irvine, USA
| | - David C Fryxell
- School of Environment, The University of Auckland, New Zealand
- Ecology and Evolutionary Biology, The University of California, Santa Cruz, USA
| | - J N Benavente
- School of Environment, The University of Auckland, New Zealand
| | - M T Kinnison
- School of Biology and Ecology,The University of Maine, USA
| | - E P Palkovacs
- Ecology and Evolutionary Biology, The University of California, Santa Cruz, USA
| | - C C Symons
- Ecology and Evolutionary Biology, University of California, Irvine, USA
| | - K S Simon
- School of Environment, The University of Auckland, New Zealand
| |
Collapse
|
5
|
Bawa SA, Gregg PC, Del Soccoro AP, Miller C, Andrew NR. Estimating the differences in critical thermal maximum and metabolic rate of Helicoverpa punctigera (Wallengren) (Lepidoptera: Noctuidae) across life stages. PeerJ 2021; 9:e12479. [PMID: 34820201 PMCID: PMC8605760 DOI: 10.7717/peerj.12479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 10/21/2021] [Indexed: 11/22/2022] Open
Abstract
Temperature is a crucial driver of insect activity and physiological processes throughout their life-history, and heat stress may impact life stages (larvae, pupae and adult) in different ways. Using thermolimit respirometry, we assessed the critical thermal maxima (CTmax-temperature at which an organism loses neuromuscular control), CO2 emission rate (V́CO2) and Q10 (a measure of V́CO2 temperature sensitivity) of three different life stages of Helicoverpa punctigera (Wallengren) by increasing their temperature exposure from 25 °C to 55 °C at a rate of 0.25 °C min−1. We found that the CTmax of larvae (49.1 °C ± 0.3 °C) was higher than pupae (47.4 °C ± 0.2 °C) and adults (46.9 °C ± 0.2 °C). The mean mass-specific CO2 emission rate (ml V́CO2 h−1) of larvae (0.26 ± 0.03 ml V́CO2 h−1) was also higher than adults (0.24 ± 0.04 ml V́CO2 h−1) and pupae (0.06 ± 0.02 ml V́CO2 h−1). The Q10: 25–35 °C for adults (2.01 ± 0.22) was significantly higher compared to larvae (1.40 ± 0.06) and Q10: 35–45 °C for adults (3.42 ± 0.24) was significantly higher compared to larvae (1.95 ± 0.08) and pupae (1.42 ± 0.98) respectively. We have established the upper thermal tolerance of H. punctigera, which will lead to a better understanding of the thermal physiology of this species both in its native range, and as a pest species in agricultural systems.
Collapse
Affiliation(s)
- Samuel A Bawa
- Zoology, Insect Ecology Laboratory, University of New England, Armidale, NSW, Australia.,Asuansi Agric. Station, Cape Coast, Central Region, Ghana
| | - Peter C Gregg
- Agronomy and Soil Science, University of New England, Armidale, NSW, Australia
| | - Alice P Del Soccoro
- Agronomy and Soil Science, University of New England, Armidale, NSW, Australia
| | - Cara Miller
- Science and Technology, University of New England, Armidale, NSW, Australia
| | - Nigel R Andrew
- Zoology, Insect Ecology Laboratory, University of New England, Armidale, NSW, Australia
| |
Collapse
|
6
|
Videlier M, Rundle HD, Careau V. Sex-specific genetic (co)variances of standard metabolic rate, body mass and locomotor activity in Drosophila melanogaster. J Evol Biol 2021; 34:1279-1289. [PMID: 34107129 DOI: 10.1111/jeb.13887] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/14/2021] [Accepted: 06/01/2021] [Indexed: 11/27/2022]
Abstract
A longstanding focus in evolutionary physiology concerns the causes and consequences of variation in maintenance metabolism. Insight into this can be gained by estimating the sex-specific genetic architecture of maintenance metabolism alongside other, potentially correlated traits on which selection may also act, such as body mass and locomotor activity. This may reveal potential genetic constraints affecting the evolution of maintenance metabolism. Here, we used a half-sibling breeding design to quantify the sex-specific patterns of genetic (co)variance in standard metabolic rate (SMR), body mass and daily locomotor activity in Drosophila melanogaster. There was detectable additive genetic variance for all traits in both sexes. As expected, SMR and body mass were strongly and positively correlated, with genetic allometry exponents (bA ± SE) that were close to 2/3 in females (0.66 ± 0.16) and males (0.58 ± 0.32). There was a significant and positive genetic correlation between SMR and locomotor activity in males, suggesting that alleles that increase locomotion have pleiotropic effects on SMR. Sexual differences in the genetic architecture were largely driven by a difference in genetic variance in locomotor activity between the sexes. Overall, genetic variation was mostly shared between males and females, setting the stage for a potential intralocus sexual conflict in the face of sexually antagonistic selection.
Collapse
Affiliation(s)
| | - Howard D Rundle
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Vincent Careau
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| |
Collapse
|
7
|
Ducret V, Videlier M, Moureaux C, Bonneaud C, Herrel A. Do female frogs have higher resting metabolic rates than males? A case study with
Xenopus allofraseri. J Zool (1987) 2020. [DOI: 10.1111/jzo.12820] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- V. Ducret
- Département Adaptations du Vivant UMR 7179 C.N.R.S/M.N.H.N. Paris France
| | - M. Videlier
- Functional Ecology Laboratory Department of Biology University of Ottawa Ottawa ON Canada
| | - C. Moureaux
- Département Adaptations du Vivant UMR 7179 C.N.R.S/M.N.H.N. Paris France
| | - C. Bonneaud
- Centre for Ecology & Conservation College of Life and Environmental Sciences University of Exeter Penryn UK
| | - A. Herrel
- Département Adaptations du Vivant UMR 7179 C.N.R.S/M.N.H.N. Paris France
| |
Collapse
|
8
|
Tomlinson S. The construction of small‐scale, quasi‐mechanistic spatial models of insect energetics in habitat restoration: A case study of beetles in Western Australia. DIVERS DISTRIB 2020. [DOI: 10.1111/ddi.13074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Sean Tomlinson
- School of Molecular and Life Sciences Curtin University of Technology Perth WA Australia
- Department of Biodiversity, Conservation an Attractions Kings Park Science Kings Park WA Australia
| |
Collapse
|
9
|
Videlier M, Rundle HD, Careau V. Sex-Specific Among-Individual Covariation in Locomotor Activity and Resting Metabolic Rate in Drosophila melanogaster. Am Nat 2019; 194:E164-E176. [PMID: 31738101 DOI: 10.1086/705678] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A key endeavor in evolutionary physiology is to identify sources of among- and within-individual variation in resting metabolic rate (RMR). Although males and females often differ in whole-organism RMR due to sexual size dimorphism, sex differences in RMR sometimes persist after conditioning on body mass, suggesting phenotypic differences between males and females in energy-expensive activities contributing to RMR. One potential difference is locomotor activity, yet its relationship with RMR is unclear and different energy budget models predict different associations. We quantified locomotor activity (walking) over 24 h and RMR (overnight) in 232 male and 245 female Drosophila melanogaster that were either mated or maintained as virgins between two sets of measurements. Accounting for body mass, sex, and reproductive status, RMR and activity were significantly and moderately repeatable (RMR: R=0.33±0.06; activity: R=0.58±0.03). RMR and activity were positively correlated among (rind=0.26±0.09) but not within (re=0.05±0.06) individuals. Moreover, activity varied throughout the day and between the sexes. Partitioning our analysis by sex and activity by time of day revealed that all among-individual correlations were positive and significant in males but nonsignificant or even significantly negative in females. Such differences in the RMR-activity covariance suggest fundamental differences in how the sexes manage their energy budget.
Collapse
|
10
|
Wang W, Liu GM, Zhang DX. Intraspecific variation in metabolic rate and its correlation with local environment in the Chinese scorpion Mesobuthus martensii. Biol Open 2019; 8:bio.041533. [PMID: 31164338 PMCID: PMC6602336 DOI: 10.1242/bio.041533] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Scorpions are well known for their reduced resting metabolic rate (RMR) in comparison to typical arthropods. Since RMR is a key physiological trait linked with evolutionary fitness, it is expected that there may exist intraspecific RMR variation given the ecological and geographical heterogeneities across the distributional range of a species. Nevertheless, it is unclear whether RMR variation exists among scorpion populations. Here, we compared the RMR (VCO2) of 21 populations of the Chinese scorpion Mesobuthus martensii (Scorpiones: Buthidae) at 25°C after at least 3 months of laboratory acclimation. The following results were obtained. First, there was significant difference in RMR between sexes when body-weight effects were factored out. Second, significant local variation in RMR was detected by analyses of both variance and covariance, with one population showing significantly reduced RMR and another significantly increased RMR. Third, regression analysis indicated that the local mean temperature and mean annual days of rainfall were the two significant factors associated with the aforementioned inter-population difference in RMR. The implication of such an association was discussed. Summary: Metabolic rate variation is observed between the two sexes and among populations in the Chinese scorpion, with the latter being correlated negatively with local mean temperature and positively with annual days of rainfall.
Collapse
Affiliation(s)
- Wei Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing 100101, China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Gao-Ming Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing 100101, China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - De-Xing Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing 100101, China .,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.,Beijing Institute of Genomics, Chinese Academy of Sciences, 1 Beichen West Road, Beijing 100101, China
| |
Collapse
|
11
|
Tomlinson S. The mathematics of thermal sub-optimality: Nonlinear regression characterization of thermal performance of reptile metabolic rates. J Therm Biol 2019; 81:49-58. [PMID: 30975423 DOI: 10.1016/j.jtherbio.2019.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 01/22/2019] [Accepted: 02/02/2019] [Indexed: 11/20/2022]
Affiliation(s)
- Sean Tomlinson
- School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley 6102, Western Australia, Australia; Kings Park Science, Department of Biodiversity, Conservation and Attractions, Kattidj Close, Kings Park 6005, Western Australia, Australia.
| |
Collapse
|
12
|
Tomlinson S, Webber BL, Bradshaw SD, Dixon KW, Renton M. Incorporating biophysical ecology into high‐resolution restoration targets: insect pollinator habitat suitability models. Restor Ecol 2017. [DOI: 10.1111/rec.12561] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Sean Tomlinson
- School of Biological Sciences The University of Western Australia 35 Stirling Highway, Crawley WA 6009 Australia
- Kings Park Botanic Gardens Fraser Avenue, Kings Park, Perth WA 6005 Australia
| | - Bruce Lloyd Webber
- School of Biological Sciences The University of Western Australia 35 Stirling Highway, Crawley WA 6009 Australia
- CSIRO Land and Water 147 Underwood Avenue, Floreat WA 6016 Australia
| | - Sidney Don Bradshaw
- School of Biological Sciences The University of Western Australia 35 Stirling Highway, Crawley WA 6009 Australia
| | - Kingsley Wayne Dixon
- Department of Environment and Agriculture Curtin University Kent Street, Bentley WA 6102 Australia
| | - Michael Renton
- School of Biological Sciences The University of Western Australia 35 Stirling Highway, Crawley WA 6009 Australia
- School of Agriculture and Environment The University of Western Australia 35 Stirling Highway, Crawley WA 6009 Australia
| |
Collapse
|
13
|
Kovac H, Käfer H, Petrocelli I, Stabentheiner A. Comparison of thermal traits of Polistes dominula and Polistes gallicus, two European paper wasps with strongly differing distribution ranges. J Comp Physiol B 2016; 187:277-290. [PMID: 27744515 PMCID: PMC5253161 DOI: 10.1007/s00360-016-1041-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 09/26/2016] [Accepted: 10/06/2016] [Indexed: 11/27/2022]
Abstract
The two paper wasps, Polistes dominula and Polistes gallicus, are related species with strongly differing distribution ranges. We investigated thermal tolerance traits (critical thermal limits and metabolic response to temperature) to gain knowledge about physiological adaptations to their local climate conditions and to get evidence for the reasons of P. dominula’s successful dispersion. Body and ambient temperature measurements at the nests revealed behavioural adaptations to microclimate. The species differed clearly in critical thermal minimum (P. dominula −1.4 °C, P. gallicus −0.4 °C), but not significantly in critical thermal maximum of activity (P. dominula 47.1 °C, P. gallicus 47.6 °C). The metabolic response did not reveal clear adaptations to climate conditions. At low and high temperatures, the metabolic rate of P. dominula was higher, and at intermediate temperatures, we determined higher values in P. gallicus. However, the species exhibited remarkably differing thermoregulatory behaviour at the nest. On average, P. gallicus tolerated a thoracic temperature up to ~41 °C, whereas P. dominula already tried at ~37 °C to keep the thorax below ambient temperature. We suggest this to be an adaptation to the higher mean ambient temperature we measured at the nest during a breeding season. Although we determined for P. dominula a 0.5 °C larger thermal tolerance range, we do not presume this parameter to be solely responsible for the successful distribution of P. dominula. Additional factors, such as the thermal tolerance of the queens could limit the overwintering success of P. gallicus in a harsher climate.
Collapse
Affiliation(s)
- Helmut Kovac
- Institut für Zoologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, 8010, Graz, Austria.
| | - Helmut Käfer
- Institut für Zoologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, 8010, Graz, Austria
| | - Iacopo Petrocelli
- Dipartimento di Biologia, Università degli Studi di Firenze, Via Madonna del Piano 6, 50019, Sesto Fiorentino, Italy
| | - Anton Stabentheiner
- Institut für Zoologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, 8010, Graz, Austria.
| |
Collapse
|
14
|
Ayton S, Tomlinson S, Phillips RD, Dixon KW, Withers PC. Phenophysiological variation of a bee that regulates hive humidity, but not hive temperature. ACTA ACUST UNITED AC 2016; 219:1552-62. [PMID: 26994173 DOI: 10.1242/jeb.137588] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 03/04/2016] [Indexed: 11/20/2022]
Abstract
Seasonal acclimatisation of thermal tolerance, evaporative water loss and metabolic rate, along with regulation of the hive environment, are key ways whereby hive-based social insects mediate climatic challenges throughout the year, but the relative importance of these traits remains poorly understood. Here, we examined seasonal variation in metabolic rate and evaporative water loss of worker bees, and seasonal variation of hive temperature and relative humidity (RH), for the stingless bee Austroplebeia essingtoni (Apidae: Meliponini) in arid tropical Australia. Both water loss and metabolic rate were lower in the cooler, dry winter than in the hot, wet summer at most ambient temperatures between 20°C and 45°C. Contrary to expectation, thermal tolerance thresholds were higher in the winter than in the summer. Hives were cooler in the cooler, dry winter than in the hot, wet summer, linked to an apparent lack of hive thermoregulation. The RH of hives was regulated at approximately 65% in both seasons, which is higher than unoccupied control hives in the dry season, but less than unoccupied control hives in the wet season. Although adaptations to promote water balance appear more important for survival of A. essingtoni than traits related to temperature regulation, their capacity for water conservation is coincident with increased thermal tolerance. For these small, eusocial stingless bees in the arid tropics, where air temperatures are relatively high and stable compared with temperate areas, regulation of hive humidity appears to be of more importance than temperature for maintaining hive health.
Collapse
Affiliation(s)
- Sasha Ayton
- School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia Science Directorate, Kings Park and Botanic Gardens, West Perth, Western Australia 6009, Australia
| | - Sean Tomlinson
- Science Directorate, Kings Park and Botanic Gardens, West Perth, Western Australia 6009, Australia
| | - Ryan D Phillips
- Science Directorate, Kings Park and Botanic Gardens, West Perth, Western Australia 6009, Australia Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Kingsley W Dixon
- Science Directorate, Kings Park and Botanic Gardens, West Perth, Western Australia 6009, Australia Department of Environment and Agriculture, Curtin University, Bentley, Western Australia 6847, Australia
| | - Philip C Withers
- School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia Department of Environment and Agriculture, Curtin University, Bentley, Western Australia 6847, Australia
| |
Collapse
|
15
|
Tomlinson S. Novel approaches to the calculation and comparison of thermoregulatory parameters: Non-linear regression of metabolic rate and evaporative water loss in Australian rodents. J Therm Biol 2016; 57:54-65. [DOI: 10.1016/j.jtherbio.2016.01.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 01/26/2016] [Accepted: 01/26/2016] [Indexed: 11/29/2022]
|
16
|
Does metabolic rate and evaporative water loss reflect differences in migratory strategy in sexually dimorphic hoverflies? Comp Biochem Physiol A Mol Integr Physiol 2015; 190:61-7. [PMID: 26384457 DOI: 10.1016/j.cbpa.2015.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 11/21/2022]
Abstract
A typical explanation for ecologically stable strategies that apply to only a proportion of a population, is bet hedging, where increased reproductive success offsets reduced reproductive rate. One such is partial migration, where only a proportion of a population moves seasonally to avoid inclement climatic conditions. Bet hedging may overlook unseen costs to maintain broad physiological resilience, implied by encountering a breadth of environmental conditions. We investigated the physiological correlates of partial migration by measuring standard metabolic rates, and rates of evaporative water loss, and then estimating upper and lower thermal tolerance in males and females of two hoverfly species, Episyrphus balteatus and Eristalis tenax. In central Europe, females of these species may either migrate or overwinter, whereas males may migrate south to the Mediterranean, but have not been found overwintering. Both species were sexually dimorphic; female Ep. balteatus were lighter than males, but female Er. tenax were heavier than males. While allometrically- corrected metabolic rate in both species increased with temperature, the most parsimonious models included no sex-specific differences in metabolic rate for either species. Evaporative water loss of both species also increased with temperature, but was higher for females of both species than males. Assuming that resting metabolism is congruent with the activity requirements of migration, highly consistent thermal tolerance and metabolic rate suggests that any given fly could migrate, although water loss patterns suggest that females may be less well-adapted to Mediterranean climates. We infer that partial migration probably results from the imperatives of their reproductive strategies.
Collapse
|