The effects of dispersal mode on the spatial distribution patterns of intertidal molluscs
Article first published online: 20 DEC 2001
Journal of Animal Ecology
Volume 70, Issue 4, pages 641–649, July 2001
How to Cite
Johnson, M. P., Allcock, A. L., Pye, S. E., Chambers, S. J. and Fitton, D. M. (2001), The effects of dispersal mode on the spatial distribution patterns of intertidal molluscs. Journal of Animal Ecology, 70: 641–649. doi: 10.1046/j.1365-2656.2001.00519.x
- Issue published online: 20 DEC 2001
- Article first published online: 20 DEC 2001
- direct development;
- larval dispersal;
- spatial distribution
- 1As many species of marine benthic invertebrates have a limited capacity for movement as adults, dispersal mode is often considered as a determinant of geographical ranges, genetic structure and evolutionary history. Species that reproduce without a larval stage can only disperse by floating or rafting. It is proposed that the colonization processes associated with such direct developing species result in spatial distributions that show relatively greater fine scale patchiness than the distributions of species with a larval dispersal stage. This hypothesis was tested by collecting molluscs at different spatial scales in the Isle of Man.
- 2Spatial distribution patterns supported the predictions based on dispersal mode. Estimated variance components for species with larval dispersal suggested that the majority of the spatial variation was associated with variation between shores. In comparison, there was relatively more variability within shores for abundance counts of species with direct development.
- 3Multivariate analyses reflected the univariate results. An assemblage of direct developers provided a better discrimination between sites (100 m separation) but the group of species with larval dispersal gave a clearer separation of shores (separated by several km).
- 4The fine scale spatial structure of direct developing species was reflected in higher average species diversity within quadrats. Species richness also reflected dispersal mode, with a higher fraction of the regional species pool present for direct developers in comparison to species with larval dispersal. This may reflect the improved local persistence of taxa that avoid the larval dispersal stage.