Community-wide effects of fruit and seed scaling in plants dispersed by vertebrates in subtropical Andean forests.

BLENDINGER PG; GIANNINI NP

Drakensberg

Simposio; Symposium: Patterns and processes in frugivore-plant interactions. 6th International Symposium-Workshop on Frugivores and Seed Dispersal; 2015

University of KwaZulu-Natal

An adaptive basis exists by which plants and their dispersers may commit to a continuing relationship over time, leaving traceable patterns of plant-animal coevolution. An adaptive explanation of the varying quantities that involve the whole fruit, pulp, and seeds would imply combinations of those values that help accomplish both the dispersal and nutrition functions of the interaction. However, an adaptive explanation of inter-specific patterns may emerge only after considering other options that may account for variation. With the aid of dimensional analysis, we dissected inter-specific effects of scaling in fleshy-fruited plants (121 species, 46 families) of subtropical Andean forests (Yungas). We contrast expected to empirically obtained relationships to test 15 specific predictions based on scaling, developmental, phylogenetic, and interactive hypotheses for quantitative relationships of the fruit, pulp and seed relevant to the plant-frugivore interaction. Phylogenetic relationships explained a minor fraction of the variability in fruit traits. We found strong support for most predicted relationships between fruit traits relevant for animal dispersal; community-level variation in dimensions, quantities and forms of fruits and seeds can be mostly explained by allometry, dimensionality, modularity and development, while adaptive explanations can account for deviations observed in individual species rather than for community-level responses. Additional aspects should be taken into account before judging whether the varying dimensions of the fruit, seeds, and pulp respond adaptively to forces shaping the plant-frugivore interaction. We conclude that adaptive responses to forces shaping the plant-disperser mutualism cannot explain the strong variability observed in the dimensions of fruits, seeds and pulp.