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We report on a phylogenetic analysis of correlations between the occurrence of dioecy and several ecological and life-history attributes: tropical distribution, woody growth form, abiotic pollination, small inconspicuous flowers and inflorescences, many-flowered inflorescences and fleshy fruits. Various hypotheses have been proposed to explain why(More)
■ Abstract Quantifying the extent to which seed production is limited by the availability of pollen has been an area of intensive empirical study over the past few decades. Whereas theory predicts that pollen augmentation should not increase seed production, numerous empirical studies report significant and strong pollen limitation. Here, we use a variety(More)
The number of ovules per flower varies over several orders of magnitude among angiosperms. Here we consider evidence that stochastic uncertainty in pollen receipt and ovule fertilization has been a selective factor in the evolution of ovule number per flower. We hypothesize that stochastic variation in floral mating success creates an advantage to producing(More)
Dioecious plants (with separate male and female individuals) more often have drab, inconspicuous flowers than related bisexual plants. Models indicate, however, that similar conditions favour the evolution of showy floral displays in dioecious and bisexual plants. One difference, however, is that dioecious plants may evolve floral displays that are sexually(More)
Understanding the evolution of specialization in host plant use by pollinators is often complicated by variability in the ecological context of specialization. Flowering communities offer their pollinators varying numbers and proportions of floral resources, and the uniformity observed in these floral resources is, to some degree, due to shared ancestry.(More)
Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining(More)
As pollinators decline globally, competition for their services is expected to intensify, and this antagonism may be most severe where the number of plant species is the greatest. Using meta-analysis and comparative phylogenetic analysis, we provide a global-scale test of whether reproduction becomes more limited by pollen receipt (pollen limitation) as the(More)
Ten years after DNA barcoding was initially suggested as a tool to identify species, millions of barcode sequences from more than 1100 species are available in public databases. While several studies have reviewed the methods and potential applications of DNA barcoding, most have focused on species identification and discovery, and relatively few have(More)
The vast majority of eukaryotic organisms reproduce sexually, yet the nature of the sexual system and the mechanism of sex determination often vary remarkably, even among closely related species. Some species of animals and plants change sex across their lifespan, some contain hermaphrodites as well as males and females, some determine sex with highly(More)