Understanding the relationships between functional traits and environment is increasingly important for assessing ecosystem health and forecasting biotic responses to future environmental change. Taxon-free analyses of functional traits (ecometrics) allow for testing the performance of such traits through time, utilizing both the fossil record and paleoenvironmental proxies. Here, we test the role of body size as a functional trait with respect to climate, using turtles as a model system. We examine the influence of mass-specific metabolic rate as a functional factor in the sorting of body size with environmental temperature and investigate the utility of community body size composition as an ecometric correlated to climate variables. We then apply our results to the fossil record of the Plio-Pleistocene Shungura Formation in Ethiopia. Results show that turtle body sizes scale with mass-specific metabolic rate for larger taxa, but not for the majority of species, indicating that metabolism is not a primary driver of size. Body size ecometrics have stronger predictive power at continental than at global scales, but without a single, dominant predictive functional relationship. Application of ecometrics to the Shungura fossil record suggests that turtle paleocommunity ecometrics coarsely track independent paleoclimate estimates at local scales. We hypothesize that both human disruption and biotic interactions limit the ecometric fit of size to climate in this clade. Nonetheless, examination of the consistency of trait–environment relationships through deep and shallow time provides a means for testing anthropogenic influences on ecosystems.
1. Metabolism is the fundamental process that powers life. Understanding what drives metabolism is therefore critical to our understanding of the ecology and behaviour of organisms in nature.
2. Metabolic rate generally scales with body size according to a power law. However, considerable unexplained variation in metabolic rate remains after accounting for body mass with scaling functions.
3. We measured resting metabolic rates (oxygen consumption) of 227 field‐caught wolf spiders. Then, we tested for effects of body mass, species, and body condition on metabolic rate.
4. Metabolic rate scales with body mass to the 0.85 power in these wolf spiders, and there are metabolic rate differences between species. After accounting for these factors, residual variation in metabolic rate is related to spider body condition (abdomen:cephalothorax ratio). Spiders with better body condition consume more oxygen.
5. These results indicate that recent foraging history is an important determinant of metabolic rate, suggesting that although body mass and taxonomic identity are important, other factors can provide helpful insights into metabolic rate variation in ecological communities.
more » « less- NSF-PAR ID:
- 10460710
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ecological Entomology
- Volume:
- 44
- Issue:
- 5
- ISSN:
- 0307-6946
- Page Range / eLocation ID:
- p. 659-664
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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