Abstract Detail

Biogeography

Kuznar, Shannon [1], Emery, Nancy [2].

Gone with the wind: geographic variation in seed dispersal traits in Lasthenia fremontii (Madieae, Asteraceae).

Dispersal is a fundamental driver of species distribution patterns: over ecological timescales, it determines the range of habitats that are colonized; over evolutionary timescales, it shapes patterns of gene flow among populations and the potential for niche evolution and range expansion. In turn, traits that influence dispersal ability are often heritable and can evolve rapidly in response to habitat quality, abundance, or variability. As a result, we expect dispersal traits to vary among populations within a species’ geographic range, and, conversely, to influence the evolution of local adaptation, ecological specialization and range limits. The goals of this study were to identify seed morphological traits that predict dispersal potential in the wind- and gravity-dispersed plant species Lasthenia fremontii (Madieae, Asteraceae), and to test if these traits vary among populations that occur at different geographic locations within the species’ range. We measured several morphometric traits on seeds that were collected from 10 populations that collectively span the entire geographic range of the species. Traits measured included: pappus size and shape; cypselae size, volume, and density; and wing loading. After morphometric traits were recorded, each seed was individually dropped three times into a wind tunnel at two different wind speeds (1.857m/s and 2.279m/s), and the distance they flew was measured for each trial. We used principal components analysis to collapse the morphometric measurements into independent trait axes, and tested for correlations between these axes and the distance that seeds flew under each wind speed. We found that the best predictor of wind dispersal distance was total seed weight and the density of the cypselae. Importantly, these traits varied significantly among populations, suggesting that populations vary in the distance that their seeds are likely to disperse by wind. These differences could be due to genetic differentiation among populations or differences in maternal allocation to seeds due to the conditions associated with each site. Future work will test between these two mechanisms and link dispersal trait variation to patterns of gene flow among populations.

1 - Purdue University, Biological Sciences, 915 West State Street, West Lafayette, IN, 47907-2054, United States
2 - Purdue University, Biological Sciences, and Botany & Plant Pathology, 915 West State Street, West Lafayette, IN, 47907-2054, United States

Keywords:
none specified

Presentation Type: Poster:Posters for Topics
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PBG003
Abstract ID:582
Candidate for Awards:None