Avian ecology and rapid morphological change in a novel plant-frugivore system
Novel ecosystems are increasingly common, and the stability and functioning of novel ecosystems depends on the ability of species to fulfil functional roles such as seed dispersal. The morphology and foraging behavior of non-native species can influence their ability to fulfil functional roles; however, the relationship between form and function may change as they experience morphological change. My research aimed to describe the rapid morphological change of the main frugivorous birds on the Hawaiian Island of Oʻahu where all native frugivores have gone extinct. To understand how the morphological changes may influence the species’ ecology, I then related their foraging and movement behavior to their morphology. Lastly, I used point counts conducted across the island to describe the spatial heterogeneity of the bird community and then related that heterogeneity and species’ abundances to habitat and environmental variables. I found that on the Hawaiian Island of Oʻahu, the primary avian frugivores (all non-native) have experienced morphological divergence from their native ranges with the general trend of smaller body measurements and more robust bills on Oʻahu. Further, I found significant relationships between morphology and ecology across the four main frugivores, suggesting a link between their form and ecological function. However, I found that ecomorphological relationships did not apparently explain patterns of community structure and that spatial heterogeneity in communities was driven primarily by elevation and invasion level. Still, two of the main frugivorous bird species, Zosterops japonicus and Pycnonotus cafer did show habitat associations that coincided with their morphology being the species with the larger wing in relation to their tarsi and occupying open habitats. My results indicate that species with more distinct ecologies and morphologies are more likely to establish (i.e. ecological filtering) during the introduction process which conserves the relationship between form and function in Oʻahu’s novel bird community. Thus, rapid morphological change potentially only further strengthens that relationship. Additionally, in combination, the presence of rapid morphological change and ecomorphological relationships suggests that rapid morphological change may influence the functional roles and ecosystem services of bird species on Oʻahu.
Rapid Evolution, Bird Ecology, Ecomorphology, Diversity Patterns, Oahu, Hawaii
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign