Abstract
BackgroundPlants may adapt to alpine habitats by specialization in the reproductive strategy and functional aspects of their flowers and pollination systems. Alpine habitats reduce the opportunities for cross-pollination in a relatively high proportion of alpine plant species, and self-pollination may be favored in these adverse conditions. Here, we investigated the mating system and pollination of Incarvillea mairei, a perennial Himalayan herb typically found at altitudes between 3000 and 4500 m.ResultsAnalyses of floral morphology, observation of plant-pollinator interactions, and hand pollination experiments were conducted in three natural populations. Outcrossing rates and effective numbers of pollen donors were assessed in 45 open-pollinated families by using progeny analysis based on seven microsatellite markers. Incarvillea mairei displayed a set of apparently specialized floral traits, the stigma is sensitive to touch and close immediately and its reopening allows a second opportunity for the receipt of pollen. The species is fully self-compatible but employs a predominantly outcrossing mating system according to parentage analysis (tm > 0.9). Fruit set was low (26.3%), whereas seed set was high (67.2%), indicating that this species suffers pollinator limitation. Its main effective pollinator was Halictus sp., and visitation frequency was low.ConclusionsFloral features such as having a sensitive stigma and anther-prongs, in conjunction with pollinator behavior, function together contributing to a set of unique reproductive adaptations that enhance outcrossing success. The increased floral longevity and high pollination efficiency operated as compensatory mechanisms to counteract low pollinator visitation frequency.
Highlights
Plants may adapt to alpine habitats by specialization in the reproductive strategy and functional aspects of their flowers and pollination systems
Our study revealed that I. mairei is fully self-compatible, and this result is consistent with recent studies that have found two congeners (I. sinensis and I. arguta) to both be self-compatible [29,30]
Floral traits that promote outcrossing Incarvillea mairei employs a predominantly outcrossing mating system according to parentage analysis
Summary
Plants may adapt to alpine habitats by specialization in the reproductive strategy and functional aspects of their flowers and pollination systems. Alpine habitats reduce the opportunities for cross-pollination in a relatively high proportion of alpine plant species, and self-pollination may be favored in these adverse conditions. Pollinator limitation is a commonly encountered problem for outcrossing species in alpine habitats and is expected to increase at higher altitudes [14,15,16,17]. These species have evolved many reproductive strategies to cope with unfavourable pollination conditions [18]. Floral traits substantially influence pollination success; for instance, the herkogamous flower is expected to reduce self-fertilization allowing more opportunity for outcrossing [21,22]. Individual species may use complex variations of these strategies to ensure reproductive success [23,24,25,26]
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