Authors: Jane E Carlson Kent E Holsinger
Publish Date: 2012/09/25
Volume: 171, Issue: 4, Pages: 905-919
Abstract
The coexistence of different color morphs is often attributed to variable selection pressures across space time morph frequencies or selection agents but the routes by which each morph is favored are rarely identified In this study we investigated factors that influence floral color polymorphisms on a local scale in Protea within which approximately 40 of species are polymorphic Previous work shows that seed predators and reproductive differences likely contribute to maintaining polymorphism in four Protea species We explored whether selection acts directly or indirectly on floral color in two populations of Protea aurea using path analysis of pollinator behavior nectar production seed predation color morphology and maternal fecundity fitness components We found that avian pollinators spent more time on white morphs likely due to nectar differences but that this had no apparent consequences for fecundity Instead the number of flowers per inflorescence underpinned many of the reproductively important differences between color morphs White morphs had more flowers per inflorescence which itself was positively correlated with nectar production seed predator occurrence and total longterm seed production The number of seeds per plant to survive predation in contrast was not directly associated with color or any other floral trait Thus although color differences may be associated with conflicting selection pressures the selection appears to be associated with the number of flowers per inflorescence and its unmeasured correlates rather than with inflorescence color itselfWe thank C Adams for assistance in the field and G Anderson for editorial comments T Rebelo and L Nurrish provided advice and logistical support in South Africa This work was funded by National Science Foundation Grants DEB0716622 and DEB1046328 Data were collected under Cape Nature permits AAA005001250028 and AAA005002140028 The experiments reported comply with the current laws of the country in which they were performed The authors declare that they have no conflict of interest
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