Seed rescue in rattlesnakes: testing germination viability of Foothill Palo Verde seeds up to one year following snake gut-transit

Acevedo, Mariana

acevedom1815@gmail.com

Salywon, Andrew M.

Blackwell, Steven A.

Hodgson, Wendy C.

Desert Botanical Garden

Phoenix, Arizona USA

Davis, Mark A.

Illinois Natural History Survey-Prairie Research InstituteUniversity of Illinois Urbana-ChampaignChampaign, Illinois USA

Hughes, Zachary S.

Chiricahua Desert Museum

Rodeo, New Mexico USA

Schuett, Gordon W.

Department of Biology | Neuroscience Institute

Georgia State University

Atlanta, Georgia USA

Chiricahua Desert Museum

Rodeo, New Mexico USA

Persistent defaunation across numerous ecosystems at a global level is a leading factor contributing to an emerging seed dispersal crisis. Large knowledge gaps regarding types of dispersers and their conservation status, moreover, serve only to exacerbate this growing problem. One category of seed dispersal in particular—diploendozoochory—remains severely understudied with respect to relationships of dispersers and plant species. Here, using live plant and snake subjects of the Sonoran Desert, we broaden our previous laboratory research on diploendozoochory. Foothill Palo Verde (Parkinsonia microphylla) seeds and captive-held Western Diamondback Rattlesnakes (Crotalus atrox) were used to test germination viability of excreted seeds up to one year post gut-transit. Specifically, rattlesnake excrement (feces and urates) laden with P. microphylla seeds were generated experimentally in late summer and fall (2023), and stored cool (10-15.5°C), dark, and dry during winter and spring (2024). These seeds were tested for germination viability during the summer monsoon (June-September, 2024) under natural conditions (wild-collected soil, outdoor environment, direct exposure to sun and rain). Based on the diversified germination behavior (dormant vs. non-dormant seeds) of Foothill Palo Verde, we predicted 50% germination. The post-gut seeds were placed in one of two treatments: treatment-1 (seeds planted with excrement) or treatment-2 (seeds planted without excrement). Control seeds had no snake exposure. Seeds successfully germinated in treatment-1 (40.07%), treatment-2 (28.95%), and the control (28.2%), but none achieved 50% germination. Treatment-1 was statistically significant from treatment-2, suggesting a role for excrement in promoting germination. Importantly, we contend that under the threat of a global seed dispersal crisis, investment in field-based studies on the role of diploendozoochory in snakes in deserts and other understudied ecosystems is clearly warranted.