Present address: Laboratorio de Interacciones Ecológicas, IADIZA, CRICYT, 5500 Mendoza, Argentina.
Signal convergence in fruits: a result of selection by frugivores?
Article first published online: 25 JAN 2010
© 2010 The Authors. Journal Compilation © 2010 European Society For Evolutionary Biology
Journal of Evolutionary Biology
Volume 23, Issue 3, pages 614–624, March 2010
How to Cite
LOMÁSCOLO, S. B. and SCHAEFER, H. M. (2010), Signal convergence in fruits: a result of selection by frugivores?. Journal of Evolutionary Biology, 23: 614–624. doi: 10.1111/j.1420-9101.2010.01931.x
- Issue published online: 25 JAN 2010
- Article first published online: 25 JAN 2010
- Received 30 March 2009; revised 7 December 2009; accepted 10 December 2009
- colour vision model;
- Dispersal syndromes;
- plant–animal communication;
- signal evolution
The Dispersal Syndrome hypothesis remains contentious, stating that apparently nonrandom associations of fruit characteristics result from selection by seed dispersers. We examine a key assumption under this hypothesis, i.e. that fruit traits can be used as reliable signals by frugivores. We first test this assumption by looking at whether fruit colour allows birds and primates to distinguish between fruits commonly dispersed by birds or primates. Second, we test whether the colours of fruits dispersed by primates are more contrasting to primates than the colours of bird-dispersed fruits, expected if fruit colour is an adaptation to facilitate the detection by seed dispersers. Third, we test whether fruit colour has converged in unrelated plant species dispersed by similar frugivores. We use vision models based on peak sensitivities of birds’ and primates’ cone cells. We base our analyses on the visual systems of two types of birds (violet and ultraviolet based) and three types of primates (trichromatic primates from the Old and the New Worlds, and a dichromatic New World monkey). Using a Discriminant Function Analysis, we find that all frugivore groups can reliably discriminate between bird- and primate-dispersed fruits. Fruit colour can be a reliable signal to different seed dispersers. However, the colours of primate-dispersed fruits are less contrasting to primates than those of bird-dispersed fruits. Fruit colour convergence in unrelated plants is independent of phylogeny and can be better explained by disperser type, which supports the hypothesis that frugivores are important in fruit evolution. We discuss adaptive and nonadaptive hypotheses that can potentially explain the pattern we found.