Pre-dispersal seed predation and abortion in species of Callisthene and Qualea (Vochysiaceae) in a Neotropical savanna

Abstract

The ability of plants to generate fertile offspring is influenced by morpho-physiological and ecological factors. Hence, reproductive success is directly linked to factors affecting quantity and quality of their progeny. In the Cerrado (savanna) of Brazil, the Vochysiaceae is a widely distributed and ecologically important family. Factors affecting pre-dispersal seed predation and abortion were studied for populations of Callisthene fasciculata, C. major, Qualea multiflora and Q. parviflora. To characterize differences between genera, as well as among species, study areas, and individuals, we quantified pre-dispersal seed predation and abortion. Differences of seed abortion among the species were related to intrinsic reproductive features and not to area or other factors. In contrast, seed predation varied not only among species but also among areas and among individuals. Only C. fasciculata showed no seed predation. In Qualea species, insect predators were found inside the seeds; whereas predators of Callisthene species were outside seeds. In both genera, seed abortion correlated negatively with area size, as did pre-dispersal seed predation, which suggest seed abortion may be a counter-measure to avoid predation. Although seed abortion and predation reduced the progenies of the studied species, seed production did not differ from other Cerrado species.

Crop size influences pre-dispersal seed predation in the Brazilian Cerrado

“…There was also substantial within-species variation among years (e.g. 8.2 % and 15.9 % of seed predation in two years for Copaifera langsdorffii) (Souza & Fagundes 2017) and sites (0 % and 51.3 % seed predation in two different sites for Callisthene major) (Custódio et al 2014) (Tab. 1).…”

“…The literature review indicated great among-species variation in the amount of seed predation, from 0 % in Callisthene fasciculate (Custódio et al 2014) up to 100 % in Eriotheca grassilipes (Francisco et al 2008) (Tab. 1).…”

“…Indeed, Xylopia and Erythroxylum produce much larger annual crops than those plants affected by positive density-dependence seed predation, although other traits such as growth form and seed mass may also be under these differences (see Moles & Westoby 2006). Variable relationships between crop size and the likelihood of predispersal seed predation are also reported in other systems (Augspurger 1981;Jordano 1987;Brody & Mitchell 1997;Kelly & Sork 2002;Bogdziewicz et al 2017), including great among and within species variation in pre-dispersal seed predation for other tropical savannas (Ernst et al 1990;Custódio et al 2014).…”

“…For instance, in tropical dry forests of Mexico, Erythroxylym havanense shows density-dependent seed predation in some years, while in other years seed predation fluctuate at random (Boege & Domínguez 2008). There is also the possibility that plants aborted reproductive structures and the infested seeds before maturation due to herbivore attack Custódio et al 2014), what may produce underestimates of seed losses measured latter during fruit maturation. Although I cannot eliminate this possibility, a visual inspection of aborted seeds sampled in traps showed no evidence of damage by seed predators, suggesting that Xylopia and Erythroxylum do not selectively aborted infested fruits (see also Boege & Domínguez 2008 for Erythroxylum havanense).…”

Temporal variation in the spider assemblage (Arachnida, Araneae) in canopies of Callisthene fasciculata (Vochysiaceae) in the Brazilian Pantanal biome

“…Callisthene fasciculata reaches between 4 and 15 m in height, and has a thick, dark, and highly rough bark (Pott & Pott, 1994). The flowering period takes place between September and October, together with the dispersion of seeds generated in the previous year (Custódio et al, 2014). It is a deciduous species with absent leaf fall during the periods of high water and receding water up to the beginning of dry season, followed by partial and total deciduousness that begins in the dry season and lasts until the beginning of the rising water period (Corsini & Guarim-Neto, 2000).…”