Could abiotic environment shape fleshy fruit traits? A field study of the desert shrub Ochradenus baccatus

In the reciprocal relations between fleshy-fruited plants and their seed dispersers, the pulp shape and content may have important consequences for the plant's fitness through their influence on frugivore's fruit choice and thus on seed dispersal success. It is completely unknown to what extent the variation of these fruit traits is affected by the abiotic environment. We tested the hypothesis that abiotic environment governs fruit morphology and chemistry. We studied fruit morphology and analyzed the chemical content of the pulp of the fleshy-fruited desert shrub Ochradenus baccatus in its natural habitat and related these fruit traits to water availability and soil nutrients using Redundancy Analysis (RDA). We found that soil abiotic conditions such as short and long-term water availability and nutrients concentration affected fruit and seed size, pulp:seed ratio and pulp nutritional content (carbohydrates, fat, protein and glucosinolates). These results demonstrated for the first time a linkage between fleshy fruit traits and abiotic conditions in the plants' microhabitat. We suggest that the abiotic environment plays a more important role in shaping fruit traits than has been proposed before. Thus, the abiotic environment may determine plant fitness through its effect on fruit traits and thereby on fruit choice by potential seed dispersers.

► We examined the hypothesis that abiotic conditions shape fleshy fruit chemistry and morphology.
► We measured these attributes in wild desert plant along an aridity gradient between two seasons.
► Increasing soil water and N increase fruit size, pulp:seed ratio and number of seeds.
►  Increasing soil water increases pulp water but decreases fats, carbohydrates, N and Mg.
► There were significant differences between seasons in morphological and chemical fruit traits.