The Temperature‐Size Rule in Ectotherms: Simple Evolutionary Explanations May Not Be General

Abstract

In many organisms, individuals in colder environments grow more slowly but are larger as adults. This widespread pattern is embodied by two well-established rules: Bergmann's rule, which describes the association between temperature and body size in natural environments, and the temperature-size rule, which describes reaction norms relating temperature to body size in laboratory experiments. Theory predicts that organisms should grow to be larger in colder environments when growth efficiency decreases with increasing environmental temperature. Using data from 97 laboratory experiments, including 58 species of ectotherms, we found little evidence that growth efficiency is negatively related to environmental temperature within the thermal range that is relevant to the temperature-size rule. Instead, growth efficiency was either positively related or insensitive to environmental temperature in the majority of cases (73 of 89 cases for gross growth efficiency and 18 of 24 cases for net growth efficiency). Two possibilities merit consideration. First, high temperatures may impose constraints on growth that only arise late during ontogeny; this simple and potentially general explanation is supported by the fact that thermal optima for growth efficiency and growth rate decrease as individuals grow. Alternatively, the general explanation for relationships between temperature and body size may not be simple. If the latter view is correct, the best approach might be to generate and test theories that are tailored specifically to organisms with similar behavior and physiology.

Zooid size parallels contemporaneous oxygen isotopes in a large colony of Pentapora foliacea (Bryozoa)

“…Results thus far show a clear inverse relationship between temperature and zooid length, zooid width and zooid frontal area. These results mirror a response termed the temperature-size rule that occurs in a wide number of animal taxa (Atkinson 1994(Atkinson , 1995(Atkinson , 1996Atkinson and Sibly 1997;Angilletta and Dunham 2003). However, despite its ubiquity across taxa the mechanistic causes behind the temperature size-rule remain unknown (see Angilletta and Dunham 2003).…”

The effect of temperature and pH on the growth and physiological response of juvenile yellowtail kingfish Seriola lalandi in recirculating aquaculture systems

“…Although the R 2 value of that regression was fairly low (0.65), we believe the major contributing factor to the difference in temperature optima between the two studies was the difference in fish sizes. A decreasing ontogenetic shift in optimum temperature is common for most ectotherms (Angilletta and Dunham 2003) and has been described for a range of other marine fish including Atlantic cod (Gadus morhua; Lafrance et al, 2005;Bjornsson et al, 2001), turbot (Scophthalmus maximus; Imsland et al, 1996), Atlantic halibut (Hippoglossus hippoglossus; Hallaråker et al, 1995) and plaice (Pleuronectes platessa; Fonds et al, 1992). Further studies investigating temperature optima for various sizes of yellowtail kingfish will be of benefit for optimising fish performance in RAS where temperature can be easily manipulated to ensure fish always grow at their optimum rate.…”

Scaling of metabolism inHelix aspersasnails: changes through ontogeny and response to selection for increased size

“…We stress that future studies should reconcile the cellular and physiological (1-3) mechanisms associated with growth rate evolution, and should investigate their role in the origin of metabolic scaling variability on different levels of biological organization. Successful integration of these phenomena promises evolutionary explanations of different large-scale phenomena such as Bergmann's rule in ectotherms or patterns in interspecific body size distributions and life histories (Kozlowski and Weiner, 1997;Kindlemann et al, 1999;Kozlowski and Gawelczyk, 2002;Angilletta and Dunham, 2003;Kozlowski et al, 2003;Kozlowski et al, 2004).…”

“…Metabolic scaling is expected to affect optimal resource allocation to growth and reproduction, so it should substantially influence the life history of organisms (Kozlowski and Teriokhin, 1999;Czarnolę ski et al, 2003). Emerging evidence suggests that adaptive allocation responses to shifts in metabolic scaling can explain different ecological and evolutionary phenomena, such as the so-called 'temperature-size rule' in ectotherms (slower growth and larger final body size in colder environments) (Angilletta and Dunham, 2003;Kozlowski et al, 2004), or the interspecific patterns of body size distributions and life history allometries (Kozlowski and Weiner, 1997;Kindlemann et al, 1999;Kozlowski and Gawelczyk, 2002). In this work we examine the link between size-scaling of metabolism and growth rate in Helix aspersa snails.…”