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The morphological and ecological variation of Arctostaphylos (Ericaceae) fruit: a link between plant ecology and animal foraging behavior
  • Rebecca Crowe,
  • V. Parker
Rebecca Crowe
University of California Irvine

Corresponding Author:rebeccaecrowe@gmail.com

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V. Parker
San Francisco State University College of Science and Engineering
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Persistent soil seed banks are characteristic of Arctostaphylos (Ericaceae) species in the Mediterranean-climate California Floristic Province. While most species are obligate seeders, regeneration of stands of all Arctostaphylos species ultimately depends on post-fire seedling recruitment. Arctostaphylos seed banks are created, in large part, by scatter-hoarding rodents. Variation in fruit morphology, therefore, is expected to impact the Arctostaphylos-rodent interaction. Seeds produce sufficient rewards (nutritious mature embryo) to entice rodents to disperse and ultimately bury seeds in the soil. Hard seed coats increase the time required to extract the embryo, encouraging rodents to choose storage over immediate predation, and endocarps are frequently empty. We assessed the variation of fruit endocarp fusion and seed viability among species of Arctostaphylos. Factors such as latitude, elevation, life history, ploidy, and phylogenetic position were also analyzed. Generalized mixed effects models were used to determine the factors contributing to variation in fruit endocarp fusion and viability. Our results indicate that fruit volume and shape are the most important variables affecting endocarp fusion and seed viability. Additionally, other potential influences only show a weak correlation and are not predicted to significantly impact fruit endocarp fusion or viability. These findings provide insight into evolved strategies used by plants to increase reproductive success via scatter-hoarding rodents. Our study benefits the conservation and restoration of Arctostaphylos stands by emphasizing the importance of animal-mediated dispersal and providing estimates of seed viability for different species. With the anticipated effects of climate change, such as departures from historic fire regimes, the preservation of the relationship between plants and animal foragers is crucial for the continued survival of Arctostaphylos and California’s evergreen chaparral.