Abstract
BackgroundGene flow in plants via pollen and seeds is asymmetrical at different geographic scales. Orchid seeds are adapted to long-distance wind dispersal but pollinium transfer is often influenced by pollinator behavior. We combined field studies with an analysis of genetic diversity among 155 physically mapped adults and 1105 F1 seedlings to evaluate the relative contribution of pollen and seed dispersal to overall gene flow among three sub-populations of the food-deceptive orchid Phalaenopsis pulcherrima on Hainan Island, China.ResultsPhalaenopsis pulcherrima is self-sterile and predominantly outcrossing, resulting in high population-level genetic diversity, but plants are clumped and exhibit fine-scale genetic structuring. Even so, we detected low differentiation among sub-populations, with polynomial regression analysis suggesting gene flow via seed to be more restricted than that via pollen. Paternity analysis confirmed capsules of P. pulcherrima to each be sired by a single pollen donor, probably in part facilitated by post-pollination stigma obfuscation, with a mean pollen flow distance of 272.7 m. Despite limited sampling, we detected no loss of genetic diversity from one generation to the next.ConclusionsOutcrossing mediated by deceptive pollination and self-sterility promote high genetic diversity in P. pulcherrima. Long-range pollinia transfer ensures connectivity among sub-populations, offsetting the risk of genetic erosion at local scales.
Highlights
Gene flow in plants via pollen and seeds is asymmetrical at different geographic scales
In vitro germination remains challenging for many orchid species [51], but the germination rates and resulting genetic data obtained in the present study suggest that recruitment is high and that there is no loss of genetic diversity from one generation to the
A predominantly outcrossing mating system based on deceptive pollination appears to contribute to high total genetic diversity and low genetic differentiation among sub-populations, as well as significant departure from Hardy-Weinberg equilibrium
Summary
Gene flow in plants via pollen and seeds is asymmetrical at different geographic scales. Orchid seeds are adapted to long-distance wind dispersal but pollinium transfer is often influenced by pollinator behavior. Pollen flow in orchids is usually limited by pollinator behavior, with insect foragerange being closely linked to pollen dispersal distances [6, 9]. This appears to make pollen-mediated gene flow dominant at short to intermediate distances typically of less than one hundred meters [9, 10]. Whitehead et al (2015) [15] used microsatellite markers to reveal that multiple pollen donors can fertilize ovules in a single ovary in Chiloglottis valida and C. aff. jeanesii, providing the first genetic confirmation of polyandry in orchids
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
