Forest Fragmentation Influences on the Genetic Structure and Diversity of Understory tree Symphonia globulifera: an Interdisciplinary Approach
Thesis (Ph.D., Environmental Science) -- University of Idaho, 2016 | Tropical wet forests are unique ecosystems with complex vertical structure and species with unique adaptations and species interactions. Human development and land cover change dynamics are important factors contributing to the loss, fragmentation and modifications of tropical wet forest landscape across the globe. This dissertation evaluated the impacts of forest fragmentation and land use intensification in the northeastern Caribbean lowlands of Costa Rica. I describe the social and economic implications of pineapple expansion, specifically the concentration of land, labor and financial resources, quantifying pineapple cultivation’s spatial characteristics, and assessing the effects of pineapple expansion on surrounding forest ecosystems, on the agricultural matrix and on biodiversity conservation. Also within this fragmented landscape we identified the potential pollinators for Symphonia globulifera an understory tree species. In addition we compare genetic diversity and genetic structure across three life stages (adults, saplings, seedlings) using 324 S. globulifera samples per cohort and 9 nuclear DNA microsatellite loci. Our results indicate that pineapple production concentrates land, labor, and financial resources, which has a homogenizing effect on the agricultural economy in the study region. This constrains farm-based livelihoods, with larger implications for food security and agricultural diversity. Landscape ecology analyses further reveal how pineapple production simplifies and homogenizes the agricultural matrix between forest patches, which is likely to have a negative effect on biodiversity. In this study the species of flower visitors with more interactions with flowers and which display a behavior of potential pollinators for S. globulifera are the stingless bee Tetragonisca angustula and the hummingbird Phaethornis longirostris, during visits they come in contact with anther and stigma which can allow pollen transfer between conspecific adults resulting in effective pollination. This study provides evidence that forest fragmentation and land use change have significantly reduced genetic diversity, increased inbreeding and reduced gene flow for S. globulifera understory populations.