Influence of Cytinus hypocistis parasitism on fruit and seed production in the mediterranean shrub Cistus albidus

Inter-individual variability in fruit and seed production are crucial factors influencing species distribution, community dynamics, and the effective conservation of ecosystems, which often are shaped by complex environmental interactions. We assessed inter-individual variability on fruit and seed production in the Mediterranean shrub Cistus albidus , and how it is influenced by parasitism in a natural population. A huge inter-individual variability was observed in fruit and seed production, as well as in seed viability, without any clear relationship between these parameters in C. albidus plants growing in a Mediterranean ecosystem. However, parasitism reduced both seed production per fruit and seed viability in C. albidus , highlighting the negative impact of C. hypocistis on host reproductive success. Furthermore, identification of plant parasitism in the field unmasked some biases in the effects of nutrients observed in correlative analyses between seed nutrient contents and seed viability loss. This study provides new insights into parasitism, specifically focusing on the detrimental effects of the holoparasitic plant Cytinus hypocistis on the reproductive fitness of its host C. albidus , and highlights the importance of identifying the effects of parasitism in the study of inter-individual variability in fruit and seed production in Mediterranean ecosystems. • Fruit and seed production showed a strong inter-individual variability in Cistus albidus . • Parasitism by Cytinus hypocistis reduced seed production per fruit and seed viability. • Plant parasitism has a strong negative impact on host reproductive success. • Identifying the effects of parasitism is essential in the study of inter-individual variability.