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Invasive birds shed native seeds
When humans introduce exotic species into sensitive ecosystems, it often results in invasion and extinction of native species. The resulting ecological communities can develop unusual interactions between survivors and newcomers. Vizentin-Bugoni et al. analyzed the structure of seed dispersal networks in Hawaii, where native bird species were replaced by invaders. They discovered that native plants now depend on invasive birds for seed dispersal. The network of dispersion interactions is complex and stable, characteristic of native seed dispersal networks in other parts of the world. It appears that introduced species may, under certain circumstances, integrate with native ecosystems.
Science, this number p. 78
Abstract
The increase in the rates of invasion and extinction of species of human origin can reshape communities and change the structure, dynamics and stability of interactions between species. To investigate how such changes affect communities, we performed multi-scale analyzes of seed dispersal networks in O'ahu, Hawai'i. The networks consisted exclusively of new interactions, were largely dominated by introduced species and presented a modular and specialized structure at the local and regional scales, despite the great disparity of interactions between communities. In addition, the structure and stability of the new networks were similar to those of the predominantly Aboriginal communities around the world. Our results suggest that the history of shared evolution is not a necessary process in the emergence of a complex network structure and that interaction patterns can be highly conserved, regardless of the identity of the species and the environment. Introduced species can quickly become well integrated into new networks, making the restoration of native ecosystems more difficult than expected.
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