The majority of ectotherms mature at a larger size at lower rearing temperatures. Although this temperature-size rule is well established, a general explanation for this phenomenon has remained elusive. In this article, we address the problem by exploring the proximate and ultimate reasons for why a temperate grasshopper, Chorthippus brunneus, is an exception to the temperature-size rule. Using a complete set of life-history data to parameterize an established life-history model, we show that it is optimal for this species to mature at a larger size at higher temperatures. We also show that plasticity in adult size is determined by the relative difference between the minimum temperature thresholds for growth and development rates. The mechanism relates to aspects of the biophysical model of van der Have and de Jong. Ectotherms that obey the temperature-size rule are identified as having a higher temperature threshold for development rate than for growth rate; exceptions are identified as having a lower temperature threshold for development rate than for growth rate. The latter scenario may arise broadly in two ways. These are discussed in reference to the thermal biology of temperate grasshoppers and ectotherms in general.
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http://dx.doi.org/10.1086/501029 | DOI Listing |
Ecol Lett
November 2024
Department of Ecosystems Biology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
Mol Ecol
January 2025
U.S. Fish and Wildlife Service, San Juan River Basin Recovery Implementation Program, Albuquerque, New Mexico, USA.
Environmental temperature shapes the ontogeny of ectotherms by influencing rates of growth and development which can be key determinants of survival. Whereas the escalating impacts of water management on freshwater ecosystems is well documented, the effects of cold-water releases from dams-which can alter downstream temperatures-remains relatively underexplored but may present novel challenges to endemic ectotherms. Specifically, little is known about how thermal depressions reshape phenotypic and genetic patterns during larval metamorphosis for fishes that evolved in warmwater systems.
View Article and Find Full Text PDFJ Therm Biol
August 2024
Graduate School of Environmental Life, Natural and Technology, Okayama University, Okayama, Japan.
Adult size in numerous insects is strongly dependent on temperature. In several cases, a temperature-size rule is observed in which developmental temperature and adult size tradeoff. Although several previous studies have demonstrated the temperature-size rule, only a few have explored the relationship between developmental temperature and weapon traits or sexual size dimorphism.
View Article and Find Full Text PDFProc Biol Sci
August 2024
Laboratory of Evolutionary Stress Ecology and Ecotoxicology, University of Leuven, Debériotstraat 32 , Leuven 3000, Belgium.
Body size reduction is a universal response to warming, but its ecological consequences across biological levels, from individuals to ecosystems, remain poorly understood. Most biological processes scale with body size, and warming-induced changes in body size can therefore have important ecological consequences. To understand these consequences, we propose a unifying, hierarchical framework for the ecological impacts of intraspecific body size reductions due to thermal plasticity that explicitly builds on three key pathways: morphological constraints, bioenergetic constraints and surface-to-volume ratio.
View Article and Find Full Text PDFSci Rep
August 2024
Fisheries Behavioral Ecology Program, Resource Assessment and Conservation Engineering Division, Alaska Fisheries Science Center, Hatfield Marine Science Center, National Marine Fisheries Service, NOAA, Newport, OR, 97365, USA.
Marine heatwaves (MHWs) are often associated with physiological changes throughout biological communities but can also result in biomass declines that correspond with shifts in phenology. We examined the response of larval Pacific cod (Gadus macrocephalus) to MHWs in the Gulf of Alaska across seven years to evaluate the effects of MHWs on hatch phenology, size-at-age, and daily growth and identify potential regulatory mechanisms. Hatch dates were, on average, 19 days earlier since the onset of MHWs, shifting a mean of 15 days earlier per 1 ℃ increase.
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