DISSERTATION RESEARCH: The relative contribution of pollen vs. seed dispersal to gene flow in a fragmented Neotropical landscape

Tulane University, New Orleans LA

Investigators

Abstract

Deforestation is one of the leading threats to biodiversity around the world. When large areas of forests are cut down, often to accommodate humans, the chance of extinction increases for plants and animals that remain in isolated fragments. For plants, the movement of pollen and seeds has the potential to connect these pieces of forest and increase long-term population health. This project will examine how pollen and seed movement among forest fragments influences genetic connectivity and diversity, thereby minimizing risk of extinction. This study is located in a rapidly developing region in northwest Ecuador where the local communities live alongside a high diversity of plants and animals. The results of this study will be shared directly with local owners of forest fragments, local schools and communities, as well as regional government agencies in charge of managing forests in the area. As part of this project, workshops will be given to local communities describing the biology and importance of forest fragments. US undergraduate volunteers will be recruited to participate in the proposed research and will receive training in field and laboratory techniques. This project will support the research and training of a doctoral student. The Neotropical palm Oenocarpus bataua is unusual in that seeds stay attached to established seedlings for several years. This characteristic affords the investigators the ability to separate the genetic contributions of pollen and seed dispersal within the same individuals by genotyping both seeds and leaves. Established seedlings throughout 5 additional forest fragments will be sampled for seed and leaf tissue. These samples will be combined with tissue samples already collected from 12 fragments. Microsatellite markers will be used to genotype these tissues and results will be used to estimate whether pollen or seed dispersal is contributing more to effective genetic diversity and genetic structure. The same data will be used to identify pollen and seed sources within and across fragments, as well as to compare genetic structure between fragments and continuous forest. The research will improve upon current approaches for studying gene flow of fragmented plant populations by unambiguously determining the separate and joint contributions of pollen and seed dispersal to realized patterns of genetic variation. This research is complemented by a simulation model that generates predictions of how restricting either or both pollen and seed dispersal will affect levels of genetic diversity and structure among forest fragments.