Effects of pollen load, parasitoids and the environment on pre-dispersal seed predation in the cleistogamous Ruellia nudiflora

• Published in: Oecologia Vol. 173; no. 3; pp. 871 - 880
• Main Authors: Munguía-Rosas, Miguel A., Abdala-Roberts, Luis, Parra-Tabla, Víctor
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer 01.11.2013; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Abiotic factors; Acanthaceae - parasitology; Acanthaceae - physiology; Analysis; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomass; Biomedical and Life Sciences; Ecological genetics; Ecology; Ecosystem; Ecosystem components; Experimental design; Flowers; Fruit; Fruit - anatomy & histology; Fruit - parasitology; Fruit - physiology; Fruits; Fundamental and applied biological sciences. Psychology; General aspects; Hydrology/Water Resources; Insect ecology; Life Sciences; Linear Models; Mexico; Parasitoids; Plant Sciences; PLANT-ANIMAL INTERACTIONS; Plant-animal interactions - Original research; Plants; Pollen; Pollination - physiology; Pollinators; Predation (Biology); Predators; Reproduction; Ruellia nudiflora; Seed Dispersal; Seed predation; Seeds; Seeds - cytology; Water availability; Mexico; Watering; Cleistogamy; Seed predation; Fruit dimorphism; Shade; Load; Seeds; Fruit; Dimorphism; Dispersion; Parasitoid; Entomophagous; Environment; Pollen; Predation
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-013-2649-0

Few studies have simultaneously addressed the effects of biotic and abiotic factors on pre-dispersal seed predation (PSP). Plant–seed predator interactions may be influenced by natural enemies and pollinators (the latter through changes in fruit or seed traits), and the activity of pre-dispersal seed predators and their natural enemies may both be affected by the abiotic environment. Additionally, in the case of cleistogamous plants with fruit dimorphism, PSP may be biased towards larger and more seeded chasmogamous (CH) fruits [relative to the smaller cleistogamous (CL) fruits], and the effects of biotic and abiotic factors may be contingent upon this fruit dimorphism. We studied PSP in the cleistogamous Ruellia nudiflora using a split-plot experimental design and asked the following: (1) is PSP biased towards CH fruits and is there an effect of pollen load on PSP? (2) Do parasitoids influence PSP and is their effect influenced by pollen load or fruit type? And (3) do light and water availability modify PSP and parasitoid effects? PSP was higher for CH relative to CL fruits, and under low water availability it was lower for pollen-supplemented CH fruits relative to open-pollinated CH fruits. Parasitoids were not influenced by abiotic conditions, but their negative effect on PSP was stronger for pollen-supplemented CH fruits. Overall, we show that fruit dimorphism, abiotic factors and natural enemies affect PSP, and that these effects can be non-additive.