The potential role of synzoochory in the naturalization of almond tree

Abstract

Domesticated plants can occasionally naturalize, becoming feral elements of natural communities. This is only possible if crops overcome the abiotic and biotic barriers that restrict their dispersal and recruitment. The naturalization of almond trees (Prunus dulcis, (Mill.) D.A. Webb) was recently reported in SE Spain, but the mechanisms driving it remain to be established. In this study, we begin to elucidate how almonds overcome dispersal and initial establishment limitations, the first steps in feralization. We characterized seed removal and demographic structure in feral Prunus dulcis populations. Additionally, we investigated whether seed burial facilitated germination of almonds under greenhouse conditions. Our results indicate that dispersal by rodents (Apodemus and Rattus) might be an important mechanism favouring almond naturalization in SE Spain. Germination experiments showed that seed burial promotes germination and seedling emergence, suggesting that seed caching might play a beneficial role in recruitment. Lastly, our demographic surveys revealed that recruitment does not seem to be influenced by proximity to the maternal plant. We propose that rodents have a synzoochorous relationship with almonds, promoting their feralization and facilitating their establishment in natural communities.