Class
Article
College
S.J. & Jessie E. Quinney College of Natural Resources
Department
Wildland Resources Department
Presentation Type
Oral Presentation
Abstract
Dioecious plants can exhibit sex-specific physiological traits that manifest as distinct landscape-scale distributions, putatively due to the energetic burden associated with seed production in females. In aspen (Populus tremuloides), when distribution is patchy and clones are large, a strong distributional sex bias may limit successful seed fertilization and production. Variation in aspen sex distribution has only been described in limited, local-scale studies, with the ratio skewing higher towards males at higher elevations. Aspen sex ratios have not been assessed at a large spatial scale. We hypothesize that if seed production and physiological constraints limit female success in harsher habitats, the overall sex ratio of aspen genets on the landscape will be male-biased both at higher elevations and at sites with a greater heat load index. We sampled leaves from approximately fifty individual trees from each of thirty-three, 30 x 30 km sites across the Intermountain West. Tree sampling was intentionally distributed across elevational and moisture gradients within sites. Sex was determined using a genetic marker. Elevation and heat load index for sampling locations were determined by transforming and extracting values from USGS 10m DEMs. A Bayesian model was used to analyze effects at both the local and landscape-scale distributions. Results at the landscape-scale indicate an increase in the male-to-female ratio of aspen as elevation and heat load increase separately, but no interaction between them. Site-level associations between sex ratios and elevation and/or heat load were highly variable and may have more to do with local variation than an overarching trend on the landscape.
Location
Room 155
Start Date
4-11-2019 10:30 AM
End Date
4-11-2019 11:45 AM
Included in
Effects of Elevation and Heat Load on the Landscape-Scale Distribution of Male and Female Trees in Aspen (Populus tremuloides)
Room 155
Dioecious plants can exhibit sex-specific physiological traits that manifest as distinct landscape-scale distributions, putatively due to the energetic burden associated with seed production in females. In aspen (Populus tremuloides), when distribution is patchy and clones are large, a strong distributional sex bias may limit successful seed fertilization and production. Variation in aspen sex distribution has only been described in limited, local-scale studies, with the ratio skewing higher towards males at higher elevations. Aspen sex ratios have not been assessed at a large spatial scale. We hypothesize that if seed production and physiological constraints limit female success in harsher habitats, the overall sex ratio of aspen genets on the landscape will be male-biased both at higher elevations and at sites with a greater heat load index. We sampled leaves from approximately fifty individual trees from each of thirty-three, 30 x 30 km sites across the Intermountain West. Tree sampling was intentionally distributed across elevational and moisture gradients within sites. Sex was determined using a genetic marker. Elevation and heat load index for sampling locations were determined by transforming and extracting values from USGS 10m DEMs. A Bayesian model was used to analyze effects at both the local and landscape-scale distributions. Results at the landscape-scale indicate an increase in the male-to-female ratio of aspen as elevation and heat load increase separately, but no interaction between them. Site-level associations between sex ratios and elevation and/or heat load were highly variable and may have more to do with local variation than an overarching trend on the landscape.