Abstract Detail

Reproductive biology

Larson-Johnson, Kathryn [1].

Wind variability limits the influence of fruit morphology and descent rate on dispersal in the winged fruits of Carpinus (Betulaceae).

The wing is one of the most common adaptations in wind dispersed propagules, having independently evolved many times across seed plants. Accordingly, assessing the impact of winged propagule form on dispersal processes and patterns is an important component of understanding plant dispersal ecology. Many studies have identified wing loading (propagule mass divided by wing area) as the character most consistently important for descent rates of winged propagules, but the influence of this character on dispersal distances in natural environments over entire dispersal seasons remains unclear. A series of morphological measurements and experimental drops were performed on dispersed fruits from two species of Carpinus collected along highly resolved transects radiating from individual point-source trees. Carpinus is a primarily temperate group consisting of woody shrubs to trees with a wind dispersed fruit that has an attached involucre modified into an elongated wing that causes the propagule to autorotate as it falls. A significant relationship was found between wing loading and descent rate in still air, but the relationship between wing loading and actual dispersal distance in the field was random in all directions for both species. Results indicate that highly variable wind conditions over an entire dispersal season can erase any signal of form and descent rate on dispersal patterns. This randomization suggests that once enough of a wing evolves for the fruits to exhibit a consistently specialized aerodynamic behavior, further selection for forms that slow descent rates will not occur in environments with highly variable wind speeds. Consequently, randomization would impact evolutionary patterns by hampering selective potential for long distance dispersal. Additionally, results highlight the potential importance of incorporating aerodynamic behavior categories, as opposed to morphological measurements or descent rates, into studies and models of wind-dispersal patterns, especially in environments with variable wind conditions.

1 - Stanford University, School of Earth, Energy, and Environmental Sciences, 397 Panama Mall, Stanford, CA, 94305, USA

Keywords:
Fruit
winged propagule
seed dispersal
wind dispersal
morphology
Dispersal patterns.

Presentation Type: Oral Paper:Papers for Topics
Session: 2
Location: Salon 1/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 10:30 AM
Number: 2009
Abstract ID:1011
Candidate for Awards:None