CONICET | Buscador de Institutos y Recursos Humanos

Background and Aims. Floral integration is thought to be an adaptation to promote cross-fertilization, and it is often assumed that it increases morphological matching between ﬂowers and pollinators, increasing the efﬁciency of pollen transfer. However, the evidence for this role of ﬂoral integration is limited, and recent studies have suggested a possible positive association between ﬂoral integration and selﬁng. Although a number of explanations exist to account for this inconsistency, to date there has been no attempt to examine the existence of an association between ﬂoral integration and mating system. This study hypothesized that if pollinator-mediated pollen movement among plants (outcrossing) is the main factor promoting ﬂoral integration, species with a predominantly outcrossing mating system should present higher levels of ﬂoral integration than those with a predominantly selﬁng mating system.Methods. A phylogenetically informed meta-analysis of published data was performed in order to evaluate whether mating system (outcrossing vs. selﬁng) accounts for the variation in ﬂoral integration among 64 species of ﬂowering plants. Morphometric ﬂoral information was used to compare intra-ﬂoral integration among traits describing sexual organs (androecium and gynoecium) and those corresponding to the perianth (calix and corolla).Key Results. The analysis showed that outcrossing species have lower ﬂoral integration than selﬁng species. This pattern was caused by signiﬁcantly higher integration of sexual traits than perianth traits, as integration of the latter group remained unchanged across mating categories.Conclusions. The results suggest that the evolution of selﬁng is associated with concomitant changes in intra-ﬂoral integration. Thus, ﬂoral integration of sexual traits should be considered as a critical component of the selﬁng syndrome.

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