Determinants of plant reproductive susceptibility to habitat fragmentation: a meta-analysis

AGUILAR R., ASHWORTH L., GALETTO L. & AIZEN M.A.

Oaxaca (Mexico)

Congreso; Diversitas: First Open Science Conference; 2005

Diversitas, International Programme of Biodiversity Science

Habitat fragmentation is one of the most pervasive changes in terrestrial ecosystems across the Earth and probably the main cause of current biodiversity loss. Fragmentation often reduces local population abundance, increases isolation between populations, and changes the surrounding environment, thus affecting many ecological processes. Sexual reproduction of animal-pollinated plants (~90% of extant Angiosperms) appears to be differentially susceptible to habitat fragmentation as evidenced from the great disparity of reproductive outcomes observed in the literature. Such responses may depend on certain ecological traits that typify the relationship with and the degree of dependence on their pollinators. Theory predicts that reproduction of self-incompatible (SI) plants will be more negatively affected than self-compatible (SC) ones. Similarly, pollination-specialist plants (S) should be more vulnerable than pollination-generalist (G). However, no study has yet formally tested these predictions. Here, we ask whether there is any ecological trait that may help to predict the reproductive response of plants to habitat fragmentation and therefore, their local extinction risk probability. By means of a meta-analysis we quantitatively reviewed the results from independent fragmentation studies throughout the world and from our own, and evaluated the reproductive output of 71 plant species with different compatibility and pollination systems and life forms. The overall magnitude of the effect size was strong and negative for all the species. Significant differences were found between SI and SC species. SI species were significantly more negatively affected than SC. Surprisingly, no differences were observed between S and G species; neither among different life forms. Our results only partially support theoretical concepts. We discuss possible explanations and stress the importance of these results for the conservation of both, pollination mutualisms and plant diversity.