TY  - JOUR
A1  - Breitkopf, Hendrik
A1  - Schlüter, P. M.
A1  - Xu, S.
A1  - Schiestl, Florian P.
A1  - Cozzolino, S.
A1  - Scopece, G.
T1  - Pollinator shifts between Ophrys sphegodes populations: might adaptation to different pollinators drive population divergence?
JF  - Journal of evolutionary biology
N2  - 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.
KW  - adaptation
KW  - ecotypes
KW  - floral scent
KW  - gene flow
KW  - Ophrys
KW  - orchids
KW  - pollinator shift
KW  - sexual deception
KW  - speciation
Y1  - 2013
U6  - https://doi.org/10.1111/jeb.12216
SN  - 1010-061X
SN  - 1420-9101
VL  - 26
IS  - 10
SP  - 2197
EP  - 2208
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -