Nestedness of Southern Ocean island biotas: ecological perspectives on a biogeographical conundrum

• Published in: Journal of Biogeography
• Main Authors: Greve, Michelle, Gremmen, Niek J. M., Gaston, Kevin J., Chown, Steven L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2004
• Subjects: Southern Ocean; Ocean Island; Single Island
• Online Access: http://dx.doi.org/10.1111/j.1365-2699.2004.01169.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2699.2004.01169.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2699.2004.01169.x

Abstract Aim To use patterns of nestedness in the indigenous and non‐indigenous biotas of the Southern Ocean islands to determine the influence of dispersal ability on biogeographical patterns, and the importance of accounting for variation in dispersal ability in their subsequent interpretation, especially in the context of the Insulantarctic and multi‐regional hypotheses proposed to explain the biogeography of these islands. Location Southern Ocean islands. Methods Nestedness was determined using a new metric, d1 (a modification of discrepancy), for the indigenous and introduced seabirds, land birds, insects and vascular plants of 26 Southern Ocean islands. To assess the possible confounding effects of spatial autocorrelation on the results, islands were assigned to 11 major island groups and each group was treated as a single island in a following analysis. In addition, nestedness of the six Southern Ocean islands comprising the South Pacific Province (New Zealand islands) was analysed. All analyses were conducted for species and genera, for each of the taxa on its own, and for the complete data sets. Results Statistically significant nestedness was found in all of the taxa examined, with nestedness declining in the order seabirds > land birds > vascular plants > insects for the indigenous species. Vagility had a marked influence on nestedness and the biogeographical patterns shown by the indigenous species. This influence was borne out by additional analyses of marine taxa and small‐sized terrestrial species, both of which were more nested than the most nested group examined here, the seabirds. Assemblages of non‐indigenous species also showed nestedness, and nestedness was generally more pronounced than in the indigenous species. Surprisingly, vagility had a significant effect on nestedness in these assemblages too. Main conclusions Nestedness analyses provide a quantitative means of comparing biogeographical patterns for groups differing in vagility. These comparisons revealed that vagility has a ...