Reproductive and genetic consequences of habitat fragmentation in plant populations: What do we know after two decades of research?

AGUILAR, A.; QUESADA, M.; ASHWORTH, L.; HERRERIAS-DIEGO, Y.

Ciudad del Cabo, Sudafrica

Congreso; DIVERSITAS - Open Science Conference II - Biodiversity & Society; 2009

DIVERSITAS

<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } --> The loss and fragmentation of natural habitats by human activities are pervasive phenomena in terrestrial ecosystems across the Earth and the main current driving forces behind biodiversity loss. Fragmentation studies in plant populations have mostly focused on sexual plant reproductive dynamics. More recently, plant population genetic parameters have also been thoroughly investigated in fragmented habitats. By means of meta-analyses we reviewed the results of 20 years of fragmentation studies around the world and tested whether reproductive output and genetic diversity decreases in fragmented habitats, and whether fragmentation has differential effects depending on certain life history and ecological traits of plants. We also tested whether certain methodological approaches used by authors influence the ability to detect fragmentation effects. Overall, fragmentation has large and negative effects on pollination, plant reproduction, genetic diversity and outcrossing rates but no effects on inbreeding coefficients. The mating system of plants, which reflects both the degree of dependence on pollinator mutualism and also the distribution of genetic diversity within and among populations, explained most of the variation among the species’ effect sizes. Outcrossing, self-incompatible plants showed strong negative fragmentation effects on reproduction and allelic richness. The rarity status of plants also determined differential susceptibility to genetic erosion, where common and recently rare plants were more negatively affected. Higher inbreeding coefficients in fragmented habitats were only observed in studies analyzing progenies. The time elapsed in fragmentation conditions significantly influenced the results. Our results suggest that fragmentation is shifting mating patterns towards increased selfing. We conclude that animal-pollinated self-incompatible plants are exceptionally vulnerable to fragmentation as a consequence of both, ecological and genetic mechanisms.