Article

Biological Invasions

, Volume 8, Issue 3, pp 449-457

Life in a Double-Hotspot: The Transformation of Hawaiian Passerine Bird Diversity following Invasion and Extinction

  • Julie L. LockwoodAffiliated withEcology, Evolution and Natural Resources, Rutgers University Email author 

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Abstract

Although recent research has shown that non-indigenous species often increase local-scale species richness, few have documented how such increases translate into compositional changes across biological scales. In particular, transformations of biodiversity patterns may be acute within regions that are simultaneously extinction and invasion hotspots (i.e. double-hotspots), such as the Hawaiian Islands. Nevertheless, modification of diversity relationships in such places are rarely quantified. Here, I utilize passerine non-indigenous species introductions and native species extinctions on Hawaii to quantitatively explore the changing relationship between within- (alpha), between- (beta), and across-island (gamma) diversity. My results indicate that, even after incorporating the enrichment effects of non-indigenous species invasions, across-island passerine diversity has dropped substantially. Nevertheless, within-island diversity has remained largely unchanged, or in some cases increased. Perhaps the more profound changes in diversity have come from the loss of between-island diversity. Because nearly all native Hawaiian passerines are extinct or near extinction, the current diversity relationships are inordinately influenced by patterns in the transportation and establishment of non-indigenous birds. These human-induced ‘dispersal’ patterns are markedly different from natural ones. In addition, these dispersal patterns may be unique to vagile species such as birds, thus indicating that transformations of diversity within other groups (e.g. plants or freshwater fishes) currently inhabiting Hawaii may differ. These results suggest the need to explore how alteration of diversity relationships translate into the loss of ecosystem services, or other valued components of biodiversity.

Keywords

diversity extinction Hawaii homogenization hotspot invasion non-indigenous passerine