Abstract Detail

Biogeography

Oldfather, Meagan [1], Emery, Nancy [2].

Habitat Specialization, Landscape Heterogeneity, and the Fitness Consequences of Dispersal.

Plant dispersal strategies have important consequences for species distribution patterns, biotic interactions, and the range of environmental variation experienced by plant lineages over ecological and evolutionary timescales. Habitat specialization in patchy landscapes is hypothesized to select for seed and maternal plant traits that are associated with shorter dispersal distance. With habitat specialization there is an increased cost of dispersing into an unsuitable habitat, whereas less specialized species incur less of a cost when they disperse out their optimal habitat. However, the cost of longer-distance dispersal events is dynamic, and varies with the spatially and temporal heterogeneity of the landscape. Spatio-temporal variability in both abiotic and biotic conditions favors dispersal, especially for highly specialized species, due to an increased probability of a currently suitable habitat becoming unsuitable. This project empirically tests these proposed relationships between habitat specialization, landscape heterogeneity, and selection on dispersal strategies in three Lasthenia species (Asteraceae) that co-occur in vernal pool landscapes of the California Floristic Province. These three species have specialized on different microhabitats within these landscapes that vary in their abundance, patchiness, and predictability. Our project’s main objective is to quantify the consequences of dispersal distance across these three species. We addressed this objective with a seed-addition experiment at the University of California Davis Jepson Prairie Natural Reserve. We evaluated the strength and direction of selection on seed dispersal distance using a transplant experiment, in which seeds of each species are planted at varying distances away from maternal plants. We included a neighbor removal treatment to evaluate the direct effects of the competitive environment on shaping the costs and benefits of dispersing different distances. We examined the influence of dispersal distance from the maternal plant and neighborhood removal on the following fitness metrics: germination success, vegetation biomass, inflorescence weight, and number of viable seeds. Here we present preliminary results from the first year of this three-year experiment. We found no fitness consequences of dispersal distance, both with and without competition for all three species. However, release from competition increased the number of successful germinants, the inflorescence and vegetative biomass, and the number of viable seeds for subsets of the species across all dispersal distances. Overall, we found a large effect of competition on fitness, indicating that the spatial variation in competition may be a main driver of dispersal dynamics in this system.

1 - CU Boulder, Ecology and Evolutionary Biology, 1900 Pleasant Street, Boulder, CO, 80309, US
2 - University of Colorado Boulder, Ecology and Evolutionary Biology, 1900 Pleasant Street, Boulder, CO, 80309, United States

Keywords:
dispersal
habitat specialization
Lasthenia
vernal pools.

Presentation Type: Poster
Session: P, Biogeography Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PBG001
Abstract ID:180
Candidate for Awards:None