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Oxygen hypothesis of polar gigantism not supported by performance of Antarctic pycnogonids in hypoxia
- Publication Year :
- 2008
- Publisher :
- The Royal Society, 2008.
-
Abstract
- Compared to temperate and tropical relatives, some high-latitude marine species are large-bodied, a phenomenon known as polar gigantism. A leading hypothesis on the physiological basis of gigantism posits that, in polar water, high oxygen availability coupled to low metabolic rates relieves constraints on oxygen transport and allows the evolution of large body size. Here, we test the oxygen hypothesis using Antarctic pycnogonids, which have been evolving in very cold conditions (−1.8–0°C) for several million years and contain spectacular examples of gigantism. Pycnogonids from 12 species, spanning three orders of magnitude in body mass, were collected from McMurdo Sound, Antarctica. Individual sea spiders were forced into activity and their performance was measured at different experimental levels of dissolved oxygen (DO). The oxygen hypothesis predicts that, all else being equal, large pycnogonids should perform disproportionately poorly in hypoxia, an outcome that would appear as a statistically significant interaction between body size and oxygen level. In fact, although we found large effects of DO on performance, and substantial interspecific variability in oxygen sensitivity, there was no evidence for size×DO interactions. These data do not support the oxygen hypothesis of Antarctic pycnogonid gigantism and suggest that explanations must be sought in other ecological or evolutionary processes.
- Subjects :
- Oceans and Seas
chemistry.chemical_element
Antarctic Regions
Oxygen
General Biochemistry, Genetics and Molecular Biology
Oxygen Consumption
medicine
Temperate climate
Animals
Ecosystem
Sea spider
Arthropods
General Environmental Science
General Immunology and Microbiology
biology
Ecology
Body Weight
Oxygen transport
Hypoxia (environmental)
General Medicine
Interspecific competition
medicine.disease
biology.organism_classification
Gigantism
chemistry
General Agricultural and Biological Sciences
Research Article
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....4421c41391bfa7c727d40e87d5c91f6c