Seasonal body size reductions with warming covary with major body size gradients in arthropod species

Abstract

Major biological and biogeographical rules link body size variation with latitude or environmental temperature, and these rules are often studied in isolation. Within multivoltine species, seasonal temperature variation can cause substantial changes in adult body size, as subsequent generations experience different developmental conditions. Yet, unlike other size patterns, these common seasonal temperature-size gradients have never been collectively analysed. We undertake the largest analysis to date of seasonal temperature-size gradients in multivoltine arthropods, including 102 aquatic and terrestrial species from 71 global locations. Adult size declines in warmer seasons in 86% of the species examined. Aquatic species show approximately 2.5-fold greater reduction in size per °C of warming than terrestrial species, supporting the hypothesis that greater oxygen limitation in water than in air forces aquatic species to exhibit greater plasticity in body size with temperature. Total percentage change in size over the annual cycle appears relatively constant with annual temperature range but varies between environments, such that the overall size reduction in aquatic-developing species (approx. 31%) is almost threefold greater than in terrestrial species (approx. 11%). For the first time, we show that strong correlations exist between seasonal temperature-size gradients, laboratory responses and latitudinal-size clines, suggesting that these patterns share common drivers.

Genome size in arthropods; different roles of phylogeny, habitat and life history in insects and crustaceans

“…These differences may be exemplified by patterns of adaptation to cold environments: Crustaceans, especially marine species, will experience relatively long‐growth season (several months), but with constantly low temperatures (Fox & Czesak, 2000; Huntley & Lopez, 1992). The fact that they frequently possess Bergmann clines with large body size and also large genomes is consistent with arguments for general cold adaptation (Hessen et al., 2013; Horne, Hirst, & Atkinson, 2017; Leinaas et al., 2016). By contrast, a main challenge for insects in cold environments is to cope with time limitation due to shorter growth seasons and a more stochastic climate.…”

Rapid shifts in the thermal sensitivity of growth but not development rate causes temperature–size response variability during ontogeny in arthropods

“…Using these estimates, we determined the slopes of ordinary least‐squares (OLS) regressions of ln‐transformed body mass versus temperature for each life stage. This exponential (log‐linear) equation form has consistently been found to be the best for modelling temperature–size responses (Forster et al , Horne et al , ). These stage‐specific slopes were transformed into percentage change in mass per degree Celsius, using the formula (exp (slope) − 1) × 100 = % change in mass per °C (Forster et al ).…”

“…All four species are widely distributed, but particularly common in temperate coastal regions (Razouls et al –2018). Annual temperature variability is typically >10°C in these regions (Horne et al ). Thus, temperature treatments were chosen to reflect considerable but realistic seasonal variation in temperature, thereby also increasing the likelihood of detecting significant changes in body size with warming.…”

“…This intra‐specific, phenotypically plastic response, formalised as the temperature–size rule, has been observed in a diverse range of taxa including protists, rotifers, arthropods, cnidarians, tunicates, chaetognaths, fish, amphibians and plants (Atkinson , Forster et al , Horne et al ). Systematic differences in the magnitude and direction of adult temperature–size responses have been identified between taxa and environments, suggesting that the selective pressures driving body size change with warming differ between groups with different life histories (Forster et al , Horne et al , , ). Similarly, temperature–size responses can also vary between different life stages within a species, but relatively few studies have examined temperature–size responses over ontogeny at such high resolution (Gulbrandsen and Johnsen 1990, Leandro et al , Forster et al ).…”

Achteruitgang insectenpopulaties in Nederland: trends, oorzaken en kennislacunes

“…Echter, bij kleinere verschillen van slechts 3 graden Celsius boven de preferente temperatuur was deze trend ook waarneembaar bij steenvliegen (Sweeney, Vannote et al 1986). Een review van de effecten van temperatuurstijging gaf aan dat de grootte van adulte insecten afnam in 86% van de onderzochte soorten (Horne, Hirst et al 2017 Van der Plas et al 2015).…”