Plant/Pollinator Interactions in Fragmented Landscapes
Quesada, Mauricio , Rosas, Fernando , Rosas-Guerrero, Victor .
Effects of forest fragmentation on pollination, reproduction and gene flow of tropical dry forest plants.
Fragmentation of natural habitats is predicted to disrupt animal pollination and negatively affect sexual reproduction in tropical plants. Consequently, it is of functional and conservation interest to understand how fragmentation alter a) pollination systems and b) pollen mediated gene flow in animal pollinated plants, to assess the reproductive and genetic susceptibility of plants to habitat degradation. These two topics were analyzed in two contrasting plant systems in a tropical dry forest of Jalisco, Mexico. First we describe the pollination system and the variation in the composition, richness, and abundance of the Ipomoea species on forest fragments of different successional stages. We also evaluated the variation in the pollinator’s assemblage of the tree Ipomoea wolcottiana using the same design. Contrary to our prediction, neither pollination nor breeding systems explain the Ipomoea composition in the different successional stages. However, as expected we found greater species richness of floral visitors and more specialized pollination systems in late successional stages. More functional groups and species of pollinators were found in I. wolcottiana in late successional stages. Pollinator’s assemblages of Ipomea are more susceptible in early stages of succession. Second, we examined the effect of forest fragmentation on gene flow via pollen in the insect pollinated tropical tree Swietenia humilis (Meliaceae), using 7 microsatellite loci, from progeny of 30 seed maternal parents, from two conserved forests (CF) and four fragmented forests (FF). The pollen pool structure is greater in FFs (Φst = 0.29, P < 0.001) than in CFs (Φst = 0.17, P < 0.001 ), and there is a reduction of effective pollen donors (Nep) in FF (Nep = 1.72) when compared with CF (Nep = 2.94). We estimated a mean pollen dispersal distance of 55 m in CF and 41 m in FF. Therefore, reductions of seed parents in populations negatively affect the number seed sires and pollen movement mediated by pollinators, reducing the genetic diversity in Swietenia humilis.
The evaluation of the consequences of the accelerated rates of habitat loss and forest fragmentation on pollination, plant mating patterns and gene flow of tropical plant populations is critical to understand the degree of cohesion and disruption of remnant and threatened populations in tropical forests
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1 - University of California, Los Angeles, Ecology and evolutionary biology, 621 Charles E. Young DR S, Los Angeles, CA, 90095, USA
2 - Universidad Nacional Autónoma de México, Centro de Investigaciones en Ecosistemas, Apartado Postal 27-3, (Xangari), Morelia, Michoacán, 58089, Mexico
tropical dry forest
Presentation Type: Symposium or Colloquium Presentation
Location: 552B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 4:45 PM