Towards a more general species–area relationship: diversity on all islands, great and small
Article first published online: 21 DEC 2001
Journal of Biogeography
Volume 28, Issue 4, pages 431–445, April 2001
How to Cite
Lomolino and Weiser (2001), Towards a more general species–area relationship: diversity on all islands, great and small. Journal of Biogeography, 28: 431–445. doi: 10.1046/j.1365-2699.2001.00550.x
- Issue published online: 21 DEC 2001
- Article first published online: 21 DEC 2001
- insular biotas;
- small island effect;
- species richness;
To demonstrate a new and more general model of the species–area relationship that builds on traditional models, but includes the provision that richness may vary independently of island area on relatively small islands (the small island effect).
We analysed species–area patterns for a broad diversity of insular biotas from aquatic and terrestrial archipelagoes.
We used breakpoint or piecewise regression methods by adding an additional term (the breakpoint transformation) to traditional species–area models. The resultant, more general, species–area model has three readily interpretable, biologically relevant parameters: (1) the upper limit of the small island effect (SIE), (2) an estimate of richness for relatively small islands and (3) the slope of the species–area relationship (in semi-log or log–log space) for relatively large islands.
The SIE, albeit of varying magnitude depending on the biotas in question, appeared to be a relatively common feature of the data sets we studied. The upper limit of the SIE tended to be highest for species groups with relatively high resource requirements and low dispersal abilities, and for biotas of more isolated archipelagoes.
The breakpoint species–area model can be used to test for the significance, and to explore patterns of variation in small island effects, and to estimate slopes of the species–area (semi-log or log–log) relationship after adjusting for SIE. Moreover, the breakpoint species–area model can be expanded to investigate three fundamentally different realms of the species–area relationship: (1) small islands where species richness varies independent of area, but with idiosyncratic differences among islands and with catastrophic events such as hurricanes, (2) islands beyond the upper limit of SIE where richness varies in a more deterministic and predictable manner with island area and associated, ecological factors and (3) islands large enough to provide the internal geographical isolation (large rivers, mountains and other barriers within islands) necessary for in situ speciation.