PARENT SESSION
Poster Session #14: Dispersal.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Hitching a ride in the warm deserts: Spatiotemporal dispersal of the devil`s claw.

Romero-Gutiérrez, Arturo^*,1, Minckley, Robert², Búrquez, Alberto¹, ¹ Instituto de Ecología, Universidad Nacional Autónoma de México, Unidad Hermosillo, Hermosillo, Sonora, MX² University of Utah, Salt Like City, Utah

ABSTRACT- There are few cases of North American plants dispersed by large vertebrates. Devil's claw (Proboscidea parviflora) is a disturbance specialist annual with a fruit pod sporting paired long spurs well adapted to clamp on vertebrates. The tough indurated fruits protect the dormant seeds during several seasons, releasing a few seeds each year. In this study, we tested the hypothesis that the functional significance of this unusual morphology is associated with vertebrate-aided seed dispersal by field trials and experimental manipulation on a natural population in the Chihuahuan Desert. Monthly fruit movement over one year was mapped in plots that differed in fruit density, in natural plots which were not manipulated, and trials with vertebrate dispersal were conducted. Fruit movement was strongly directional, evidently driven primarily by episodic sheet floods and prevailing wind. Vegetation structure in these plots influenced the distance of fruit movement but not average direction. In contrast, the direction of fruit movement in the presence of large vertebrates was haphazard, and of greater distance. This latter finding, coupled with the structural integrity of old fruits strongly suggest that these seeds pods take advantage of large vertebrates such as those of the diverse megafauna of the Holocene. The relatively fast movement of the fruits coupled with the slow seed release during several years, allow this species to distribute its regeneration probability by a conservative bet-hedging strategy through time and space.

KEY WORDS: dispersal, germination, Martyniaceae, arid ecosystem