Snakes as agents of seed rescue and secondary seed dispersal: a novel germination test using Foothill Palo Verde seeds and Western Diamond-backed Rattlesnakes

Snakes as agents of seed rescue and secondary seed dispersal: a novel germination test using Foothill Palo Verde seeds and Western Diamond-backed Rattlesnakes 

Acevedo, Mariana

acevedom1815@gmail.com

Salywon, Andrew M.

Blackwell, Steven

Hodgson, Wendy C.

Desert Botanical Garden

Phoenix, Arizona USA

Davis, Mark A.

Illinois Natural History Survey-Prairie Research Institute

University of Illinois Urbana-Champaign

Champaign, Illinois USA

Hughes, Zachary S.

Chiricahua Desert Museum

Rodeo, New Mexico USA

Schuett, Gordon W.

Department of Biology

Georgia State University

Atlanta, Georgia USA

Chiricahua Desert Museum

Rodeo, New Mexico USA

Snakes have a near worldwide distribution and are important predators in diverse ecological communities, but only recently have they been studied as potential agents for seed rescue and secondary seed dispersal (diploendozoochory). Recently, a museum study documented that seeds can both imbibe and germinate within snakes’ digestive tracts (DT), and a subsequent laboratory study confirmed that Foothill Palo Verde (FPV - Parkinsonia microphylla) seeds that have freshly passed through snakes’ DT can germinate in laboratory petri dishes. We build on these previous findings to test more “natural” conditions to determine 1) whether FPV seeds that have passed through Western Diamond-backed Rattlesnakes (Crotalus atrox) and then dried and stored for 4-10 months will germinate, and 2) whether the presence of the snake excrement influences germination. Germination tests were conducted outdoors in the summer months in Phoenix, Arizona using 2-gallon pots with native Sonoran Desert soils and supplemental water. Specifically,  we found that the experimental FPV seeds that were dried and stored after being passed showed a high germination rate. Experimental seeds had a statistically significant higher percent germination than control seeds. Length of storage did not significantly affect germination rate. Germination of experimental seeds was not affected by the presence of snake fecal matter when compared to experimental seeds that were washed of fecal matter and sown. Our study provides further support for the role of snakes as non-traditional agents of seed rescue and dispersal in nature and their potential as ecosystem engineers.