Fluctuating selection across years and phenotypic variation in food-deceptive orchids

PeerJ

article

Giovanni Scopece¹  Nicolas Juillet²  Christian Lexer³  Salvatore Cozzolino¹ 

[1] Department of Biology, University of Naples Federico II;UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, Université de la Réunion;Department of Botany and Biodiversity Research, University of Vienna

关键词: Food-deceptive orchids;    Selection differentials;    Floral traits;    Fluctuating selection;    Orchis mascula;    Orchis pauciflora;    Phenotypic variation;   

DOI  :  10.7717/peerj.3704

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Nectarless flowers that deceive pollinators offer an opportunity to study asymmetric plant-insect interactions. Orchids are a widely used model for studying these interactions because they encompass several thousand species adopting deceptive pollination systems. High levels of intra-specific phenotypic variation have been reported in deceptive orchids, suggesting a reduced consistency of pollinator-mediated selection on their floral traits. Nevertheless, several studies report on widespread directional selection mediated by pollinators even in these deceptive orchids. In this study we test the hypothesis that the observed selection can fluctuate across years in strength and direction thus likely contributing to the phenotypic variability of this orchid group. We performed a three-year study estimating selection differentials and selection gradients for nine phenotypic traits involved in insect attraction in two Mediterranean orchid species, namely Orchis mascula and O. pauciflora, both relying on a well-described food-deceptive pollination strategy. We found weak directional selection and marginally significant selection gradients in the two investigated species with significant intra-specific differences in selection differentials across years. Our data do not link this variation with a specific environmental cause, but our results suggest that pollinator-mediated selection in food-deceptive orchids can change in strength and in direction over time. In perennial plants, such as orchids, different selection differentials in the same populations in different flowering seasons can contribute to the maintenance of phenotypic variation often reported in deceptive orchids.

【 授权许可】

CC BY