Local pollinator adaptation in deceptive Arum maculatum  

Barrierefreiheit: Kurzbeschreibung des BildesVisual and olfactory (scent) floral cues are means by which plants communicate with their animal pollinators and are thus essential in plant-pollinator interactions. The relative importance of these cues varies among systems, but specialized pollination systems are typically mediated by floral scents. Although several thousand scent compounds have been described so far, little is known about the individual compounds responsible for pollinator attraction. Floral scents are known to vary within species among populations, but there are still large gaps in our knowledge about the evolutionary forces driving this variability, which may be due to genetic drift and/or local selective adaptation in response to a geographically variable pollinator climate. © Eva Gfrerer

The deceptive Lords and Ladies, Arum maculatum, with its moth fly pollinators is our model system to identify the mechanisms of pollinator attraction and test whether variability in floral scent is adaptive. This plant attracts and lures specifically two psychodid moth flies (Psychoda phalaenoides and Psycha grisescens) that both oviposit on cow and horse dung, but have different olfactory preferences. In Europe, there is a strong geographical pattern of pollinator climate in that populations from north vs. south of the Alps are mainly pollinated by P. phalaenoides and P. grisescens, respectively, although both insect species occur in either region. Based on recent genetic reports, this north-south pattern matches a phylogeographic subdivision of A. maculatumin DNA fingerprints (AFLPs) but is not reflected in the mitochondrial DNA of the moth flies. Although the inflorescence scent of A. maculatum has been documented to vary intraspecifically, this has never been studied at a population level in relation to the north-south genetic/pollinator pattern. It is thus still unknown whether (1) local populations of A. maculatum from north vs. south of the Alps have adaptively diverged in scent traits to attract the most abundant and/or efficient regional pollinators; or (2) cis-trans Alpine variation in pollinator climate merely reflects local insect abundance rather than differences in scent traits.

We use a novel combination of ecological, chemical-ecological and genomic methods, and propose to study local adaptation in floral scents. For the first time, we take the opportunity to distinguish between different molecular signatures of neutral variation versus adaptive change in floral scents. Specifically, we will identify the compounds responsible for pollinator attraction in A. maculatum and study the evolutionary forces driving inter-population variability in floral scents. Obtained data will contribute to our understanding of the evolution of intraspecific variability in floral scents as a category of traits implicated in plant reproductive isolation and speciation.

Barrierefreiheit: Kurzbeschreibung des Bildes

PhD students: Mag.rer.nat. Eva Gfrerer, MSc Danae Laina In collaboration with Prof. Dr. Peter ComesDr. Anja Hörger,  Dr. Marc Gibernau Dr. Till Tolasch

Marotz-Clausen, G; Jürschik, S; Fuchs, R; Schäffler, I; Sulzer, P; Gibernau, M; Dötterl, S: Incomplete synchrony of inflorescence scent and temperature patterns in Arum maculatum L. (Araceae). Phytochemistry, 154, 77-84 (2018)