Abstract
Many organisms overlap in their use of resources in space and time. Where and when resources are restricted, species must compete for them. Living space, often a critical resource controlling food and mate availability, is directly contested by organisms in most habitats. The ensuing animal interactions generally result in a winner gaining space and a loser, which may die. Contact matrices from studies of interference competition in encrusting marine Bryozoa (clonal and colonial animals), spanning at least 60 degrees latitude in both hemispheres, were analysed and subjected to a modern transitivity index. Only data for Bryozoa were used because (i) use of a single taxon with restricted ecology simplifies the scope for types of encounters, (and therefore) interpretation; and (ii) ecological bias is reduced because bryozoans are abundant at all latitudes. The analysis shows that assemblage competition is more hierarchical towards both poles. Thus, poorer competitors fail more frequently in interactions with increasing latitude. The cause of this trend is the simplification of overall outcomes between competitors, such as fewer ties, reversals in outcome or competitive loops (where low-ranking competitors beat those of higher ranking). The implication of such a trend is that the maintenance of biological diversity at high latitudes may principally be by physical rather than biological (competition) processes. Certainly, ocean surface energy increases with latitude through wind and wave action (and ice scour in polar regions).
Full Text
The Full Text of this article is available as a PDF (131.0 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Barnes D. K., Dick M. H. Overgrowth competition between clades: implications for interpretation of the fossil record and overgrowth indices. Biol Bull. 2000 Aug;199(1):85–94. doi: 10.2307/1542710. [DOI] [PubMed] [Google Scholar]
- Connell J. H. Diversity in tropical rain forests and coral reefs. Science. 1978 Mar 24;199(4335):1302–1310. doi: 10.1126/science.199.4335.1302. [DOI] [PubMed] [Google Scholar]
- Jackson J. B., Buss L. Alleopathy and spatial competition among coral reef invertebrates. Proc Natl Acad Sci U S A. 1975 Dec;72(12):5160–5163. doi: 10.1073/pnas.72.12.5160. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McKinney F. K., Lidgard S., Sepkoski J. J., Jr, Taylor P. D. Decoupled temporal patterns of evolution and ecology in two post-Paleozoic clades. Science. 1998 Aug 7;281(5378):807–809. doi: 10.1126/science.281.5378.807. [DOI] [PubMed] [Google Scholar]
- Roy K., Jablonski D., Valentine J. W., Rosenberg G. Marine latitudinal diversity gradients: tests of causal hypotheses. Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3699–3702. doi: 10.1073/pnas.95.7.3699. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wagnon K. A., Loy R. G., Rollins W. C., Carroll F. D. Social dominance in a herd of Angus, Hereford, and Shorthorn cows. Anim Behav. 1966 Oct;14(4):474–479. doi: 10.1016/s0003-3472(66)80048-9. [DOI] [PubMed] [Google Scholar]