Convergent evolution of floral signals underlies the success of Neotropical orchids

Abstract

The great majority of plant species in the tropics require animals to achieve pollination, but the exact role of floral signals in attraction of animal pollinators is often debated. Many plants provide a floral reward to attract a guild of pollinators, and it has been proposed that floral signals of non-rewarding species may converge on those of rewarding species to exploit the relationship of the latter with their pollinators. In the orchid family (Orchidaceae), pollination is almost universally animal-mediated, but a third of species provide no floral reward, which suggests that deceptive pollination mechanisms are prevalent. Here, we examine floral colour and shape convergence in Neotropical plant communities, focusing on certain food-deceptive Oncidiinae orchids (e.g. Trichocentrum ascendens and Oncidium nebulosum) and rewarding species of Malpighiaceae. We show that the species from these two distantly related families are often more similar in floral colour and shape than expected by chance and propose that a system of multifarious floral mimicry—a form of Batesian mimicry that involves multiple models and is more complex than a simple one model–one mimic system—operates in these orchids. The same mimetic pollination system has evolved at least 14 times within the species-rich Oncidiinae throughout the Neotropics. These results help explain the extraordinary diversification of Neotropical orchids and highlight the complexity of plant–animal interactions.

<em>Zygostates alleniana</em> (Orchidaceae: Epidendroideae: Cymbidieae: Oncidiinae): estructura floral relacionada con la polinización

“…Dentro de Oncidiinae hay especies que poseen flores miméticas a las de Malpighiaceae (Powell & et al, 2003;Vale & al., 2011;Papadopulos & al., 2013), las cuales carecen de elaióforos y atraen a los visitantes por engaño. Otras especies, cuyas flores también son semejantes a las Malpighiaceae, poseen elaióforos y ofrecen recompensa a sus polinizadores.…”

Higher seed number compensates for lower fruit set in deceptive orchids

“…Within orchids, deceptive pollination evolved multiple times independently, which might have played a key role in their extraordinary diversification (Papadopulos et al . ). Possible reasons for the disproportionate frequency of deception in the orchid family compared to other angiosperm families have been assessed by Jersáková, Johnson & Kindlmann ().…”

Disentangling visual and olfactory signals in mushroom‐mimicking Dracula orchids using realistic three‐dimensional printed flowers

“…Flowers evolve in response to the perceptual biases of pollinators for traits such as scent, color and pattern (Schaefer & Ruxton, 2009;Schiestl & D€ otterl, 2012;Papadopulos et al, 2013). Small differences in perceptual acuity and bias can be exploited by selection if they impart an increase in fitness (Chittka et al, 2001).…”