| Title: | Pollinator shifts between Ophrys sphegodes populations: might adaptation to different pollinators drive population divergence? |
| Author(s): | Breitkopf H; Schluter PM; Xu S; Schiestl FP; Cozzolino S; Scopece G; |
| Address: | "Department of Biology, University of Naples Federico II, Naples, Italy; Institute of Biochemistry and Biology, Biodiversity Research/Systematic Botany, University of Potsdam, Potsdam, Germany" |
| ISSN/ISBN: | 1420-9101 (Electronic) 1010-061X (Linking) |
| Abstract: | "Local adaptation to different pollinators is considered one of the possible initial stages of ecological speciation as reproductive isolation is a by-product of the divergence in pollination systems. However, pollinator-mediated divergent selection will not necessarily result in complete reproductive isolation, because incipient speciation is often overcome by gene flow. We investigated the potential of pollinator shift in the sexually deceptive orchids Ophrys sphegodes and Ophrys exaltata and compared the levels of floral isolation vs. genetic distance among populations with contrasting predominant pollinators. We analysed floral hydrocarbons as a proxy for floral divergence between populations. Floral adoption of pollinators and their fidelity was tested using pollinator choice experiments. Interpopulation gene flow and population differentiation levels were estimated using AFLP markers. The Tyrrhenian O. sphegodes population preferentially attracted the pollinator bee Andrena bimaculata, whereas the Adriatic O. sphegodes population exclusively attracted A. nigroaenea. Significant differences in scent component proportions were identified in O. sphegodes populations that attracted different preferred pollinators. High interpopulation gene flow was detected, but populations were genetically structured at species level. The high interpopulation gene flow levels independent of preferred pollinators suggest that local adaptation to different pollinators has not (yet) generated detectable genome-wide separation. Alternatively, despite extensive gene flow, few genes underlying floral isolation remain differentiated as a consequence of divergent selection. Different pollination ecotypes in O. sphegodes might represent a local selective response imposed by temporal variation in a geographical mosaic of pollinators as a consequence of the frequent disturbance regimes typical of Ophrys habitats" |
| Keywords: | "Amplified Fragment Length Polymorphism Analysis Animals Bees/physiology Female Flowers/chemistry Gene Flow Genome, Plant Hydrocarbons/analysis/chemistry Male Orchidaceae/*chemistry/genetics *Pollination Population Dynamics Reproductive Isolation Ophrys ad;" |
| Notes: | "MedlineBreitkopf, H Schluter, P M Xu, S Schiestl, F P Cozzolino, S Scopece, G eng Research Support, Non-U.S. Gov't Switzerland 2013/08/29 J Evol Biol. 2013 Oct; 26(10):2197-208. doi: 10.1111/jeb.12216. Epub 2013 Aug 28" |
