| Title: | "Are tetraploids more successful? Floral signals, reproductive success and floral isolation in mixed-ploidy populations of a terrestrial orchid" |
| Address: | "Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland. Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland florian.schiestl@systbot.uzh.ch" |
| ISSN/ISBN: | 1095-8290 (Electronic) 0305-7364 (Print) 0305-7364 (Linking) |
| Abstract: | "BACKGROUND AND AIMS: Polyploidization, the doubling of chromosome sets, is common in angiosperms and has a range of evolutionary consequences. Newly formed polyploid lineages are reproductively isolated from their diploid progenitors due to triploid sterility, but also prone to extinction because compatible mating partners are rare. Models have suggested that assortative mating and increased reproductive fitness play a key role in the successful establishment and persistence of polyploids. However, little is known about these factors in natural mixed-ploidy populations. This study investigated floral traits that can affect pollinator attraction and efficiency, as well as reproductive success in diploid and tetraploid Gymnadenia conopsea (Orchidaceae) plants in two natural, mixed-ploidy populations. METHODS: Ploidy levels were determined using flow cytometry, and flowering phenology and herbivory were also assessed. Reproductive success was determined by counting fruits and viable seeds of marked plants. Pollinator-mediated floral isolation was measured using experimental arrays, with pollen flow tracked by means of staining pollinia with histological dye. KEY RESULTS: Tetraploids had larger floral displays and different floral scent bouquets than diploids, but cytotypes differed only slightly in floral colour. Significant floral isolation was found between the two cytotypes. Flowering phenology of the two cytotypes greatly overlapped, and herbivory did not differ between cytotypes or was lower in tetraploids. In addition, tetraploids had higher reproductive success compared with diploids. CONCLUSIONS: The results suggest that floral isolation and increased reproductive success of polyploids may help to explain their successful persistence in mixed-ploidy populations. These factors might even initiate transformation of populations from pure diploid to pure tetraploid" |
| Keywords: | Orchidaceae/genetics/*physiology *Pollination *Polyploidy Switzerland *Sympatry Floral signals Gymnadenia conopsea Orchidaceae diploid floral colour floral isolation floral morphology floral scent mixed-ploidy populations orchid pollination polyploidizati; |
| Notes: | "MedlineGross, Karin Schiestl, Florian P eng Research Support, Non-U.S. Gov't England 2015/02/06 Ann Bot. 2015 Feb; 115(2):263-73. doi: 10.1093/aob/mcu244" |
