Climate warming and ectotherm body size – from individual physiology to community ecology

Abstract

Summary1. Accumulating evidence suggests that the average body size of many organisms is declining in response to climate warming. This phenomenon has been suggested to represent a universal response to warming that may impose significant adverse effects on ecosystem functioning and services. 2. However, we do not have a thorough understanding of why body sizes are commonly declining, and why some organisms show the opposite response. Because ectotherms constitute the vast majority of organism biomass and about 99% of species worldwide, it is particularly important to understand how ectotherms respond to a warming climate. 3. This review discusses the underlying physiological mechanisms of changes in ectotherm body size and addresses observed responses within a broad ecological context at different levels of organization, from individuals to communities, particularly in aquatic systems. 4. Warming-induced responses in average body size are not only determined by changes in rates of individual growth and development, but also mediated through size-dependent feedbacks at the population level, as well as competitive and predatory interactions within the community. Emergent properties at higher organizational levels have already been observed in both experimental and natural systems. 5. Various approaches will be required for enhancing our knowledge about the importance of such processes in natural systems. These include controlled semi-natural experiments and phylogenetic comparisons as well as statistical models of time-series data and theoretical models linking climate effects at the individual, population and community levels. 6. Understanding causes of observed changes in organism body sizes and how these depend on the ecological context is essential for improving our predictions and the management of ecosystems in the face of a warming climate.

Effects of Climate Change on Trait-Based Dynamics of a Top Predator in Freshwater Ecosystems

“…Besides such direct physiological effects, temperature may also have indirect effects on the vital rates, through (i) changes in activity levels and behavior (Casselman 1996;Diana 1996); (ii) ecosystem changes, for instance, in the relative abundances of prey or competitor species (Winfield et al 2008;Ohlberger 2013);or (iii) correlations with other vital rates that are affected by temperature, reflecting trade-offs or constraints in the life history. Altered activity levels can affect survival through different exposures to predation and competitors and increased lev- .…”

Effects of environmental warming during early life history on libellulid odonates

“…Differential species responses to temperature could affect species interactions and therefore indirectly affect species abundances and community composition (Ohlberger 2013). By making direct comparisons of phenological responses to temperature, we can increase our ability to successfully make predictions about the winners and losers of climate change, and more broadly, how communities will be affected by warming climates (Ohlberger 2013). In our study, our results suggest that within libellulid dragonflies, the acceleration of egg development in response to temperature may be remarkably consistent.…”

“…Although we expected accelerated egg development, the consistency with which all species responded to warming was interesting given previous observations that species' phenological responses to warming are often idiosyncratic (Guo et al 2009;Diamond et al 2011;Caradonna et al 2014). Differential species responses to temperature could affect species interactions and therefore indirectly affect species abundances and community composition (Ohlberger 2013). By making direct comparisons of phenological responses to temperature, we can increase our ability to successfully make predictions about the winners and losers of climate change, and more broadly, how communities will be affected by warming climates (Ohlberger 2013).…”

Environmental and zooplankton parameter changes during the drying of a saline shallow temporary lake in central Argentina

“…Whereas in ectotherm vertebrates, individuals of small size are likely to occur at lower environmental temperatures (Gillooly et al 2002;Ohlberger, 2013), in zooplankton animals, such as cladocerans (Havens et al 2015) and copepods (Anufriieva & Shadrin, 2014), larger body sizes have been registered at lower temperatures. In the present study, the observed increase in body size for B. poopoensis and M. eugeniae is a likely consequence of the stress produced by increased salinity rather than that of low temperatures (Herbst, 2001).…”