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Inherited biotic protection in a neotropical pioneer plant

Déjean A., Corbara B., Leroy C., Delabie J.H.C., Rossi V., Céréghino R.. 2011. PloS One, 6 (3) : e18071 (11p.).

Chelonanthus alatus is a bat-pollinated, pioneer Gentianaceae that clusters in patches where still-standing, dried-out stemsare interspersed among live individuals. Flowers bear circum-floral nectaries (CFNs) that are attractive to ants, and seeddispersal is both barochorous and anemochorous. Although, in this study, live individuals never sheltered ant colonies,dried-out hollow stems - that can remain standing for 2 years - did. Workers from species nesting in dried-out stems as wellas from ground-nesting species exploited the CFNs of live C. alatus individuals in the same patches during the daytime, butwere absent at night (when bat pollination occurs) on 60.5% of the plants. By visiting the CFNs, the ants indirectly protectthe flowers - but not the plant foliage - from herbivorous insects. We show that this protection is provided mostly by speciesnesting in dried-out stems, predominantly Pseudomyrmex gracilis. That dried-out stems remain standing for years and areregularly replaced results in an opportunistic, but stable association where colonies are sheltered by one generation of deadC. alatus while the live individuals nearby, belonging to the next generation, provide them with nectar; in turn, the antsprotect their flowers from herbivores. We suggest that the investment in wood by C. alatus individuals permitting stillstanding,dried-out stems to shelter ant colonies constitutes an extended phenotype because foraging workers protect theflowers of live individuals in the same patch. Also, through this process these dried-out stems indirectly favor thereproduction (and so the fitness) of the next generation including both their own offspring and that of their siblings, alladding up to a potential case of inclusive fitness in plants. (Résumé d'auteur)

Mots-clés : formicidae; gentianaceae; chelonanthus alatus

Thématique : Ecologie végétale; Ecologie animale

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