Fruits of Yungas Andean forests as birds see them

BLENDINGER, PEDRO G.; MARIANO ORDANO; SILVIA B. LOMASCOLO; NATACHA P. CHACOFF; MARÍA G. NUÑEZ-MONTELLANO; JULIETA JIMENEZ; ROMÁN A. RUGGERA; MARIANA VALOY; MARIANO S. SANCHEZ; EDUARDO MARTIN

Drakensberg

Simposio; 6th International symposium-workshop on Frugivores and Seed Dispersal; 2015

In seed dispersal mutualisms, natural selection should promote strategies of fruit display that maximize disperser attraction. Plants might increase seed dispersal profitability by increasing fruit conspicuousness, understood as the ease with which fruits are detected by dispersers. Because strategies to maximize fruit conspicuousness are various, and most are costly, we would expect that individual plant species invest primarily in only one. We explored this prediction using fleshy-fruited species of subtropical Andean forests (Yungas) and a large dataset on frugivore diets. As mechanisms of advertising enhancement, we considered the chromatic contrast between diaspores and foliage, fruit size and architecture (exposure and aggregation) of fruit display. Towards this goal, we (1) characterized the tetrahedral colorspace of fruits and the variation in chromatic contrast (just noticeable difference (JND)) using avian vision models, (2) assessed the relationship between fruit traits determining conspicuousness, and (3) analyzed the importance of fruit conspicuousness on fruit consumption by birds. The colorspace of Yungas fruits was considerably larger than the average reported for tropical forests of South America. Fruit chromatic contrast did not covary with other traits determining conspicuousness (fruit size, exposure and aggregation), although it tended to decrease with fruit size. Fruit consumption was explained by chromatic contrast depending on fruit size, exposure and aggregation. Within the diversity of fruit displays observed in the Yungas, plant species might be using display strategies that combine chromatic contrast with morphological and architectural fruit traits.