Summary• Many plants combine sexual reproduction with vegetative propagation, but how trade-offs between these reproductive modes affect fitness is poorly understood. Although such trade-offs have been demonstrated at the level of individual shoots (ramets), there is little evidence that they scale up to affect genet fitness. For hermaphrodites, reproductive investment is further divided between female and male sexual functions. Female function should generally incur greater carbon costs than male function, which might involve greater nitrogen (N) costs.• Using a common garden experiment with diclinous, clonal Sagittaria latifolia we manipulated investment in reproduction through female and male sex functions of 412 plants from monoecious and dioecious populations.• We detected a 1 : 1 trade-off between biomass investment in female function and clonal reproduction. For male function, there was no apparent trade-off between clonal and sexual reproduction in terms of biomass investment. Instead, male function incurred a substantially higher N cost.• Our results indicate that: trade-offs between investment in clonal propagation and sexual reproduction occur at the genet level in S. latifolia; and sexual reproduction interferes with clonal expansion, with investment in female function limiting the quantity of clonal propagules produced, and investment in male function limiting the nutrient content of clonal propagules.

Clonality is a pervasive feature of sessile organisms, but this form of asexual reproduction is thought to interfere with sexual fitness via the movement of gametes among the modules that comprise the clone. This within-clone movement of gametes is expected to reduce sexual fitness via mate limitation of male reproductive success and, in some cases, via the production of highly inbred (i.e., self-fertilized) offspring. However, clonality also results in the spatial expansion of the genetic individual (i.e., genet), and this should decrease distances gametes and sexually produced offspring must travel to avoid competing with other gametes and offspring from the same clone. The extent to which any negative effects of clonality on mating success might be offset by the positive effects of spatial expansion is poorly understood. Here, we develop spatially explicit models in which fitness was determined by the success of genets through their male and female sex functions. Our results indicate that clonality serves to increase sexual fitness when it is associated with the outward expansion of the genet. Our models further reveal that the main fitness benefit of clonal expansion might occur through the dispersal of offspring over a wider area compared with nonclonal phenotypes. We conclude that, instead of interfering with sexual reproduction, clonal expansion should often serve to enhance sexual fitness.asexual reproduction | geitonogamy | genet | modularity | ramet M odular growth, clonality, and hermaphroditism are widespread features of sessile organisms. Sessile organisms might benefit from modularity and the spatial expansion of the individual via enhanced resource capture, and thereby improved growth and survival (1-3). However, growth and survival are only two of the key components of an organism's life history, and the third, reproduction, is the one that is most intimately linked to fitness. Indeed, during reproduction, the growth of a modular hermaphrodite might interfere with its success as a parent. In particular, it has been argued that the production of numerous partially or fully autonomous clonal modules (i.e., ramets) should interfere with mating success because there is a nonzero chance that sperm (or pollen) will encounter the receptive tissues associated with the female function of the same genetic individual (i.e., the genet). All else being equal, the larger the clone, the greater the chance that this kind of mating interference should occur (4, 5). The negative effects of such intraclonal mating is expected to occur through reductions in the number of offspring sired on other genets (i.e., outcross siring success, corresponding with the fitness of individuals via their male function) and, in self-compatible organisms, through inbreeding depression (i.e., a reduction in offspring fitness, with negative effects on the fitness of individuals through their female function; e.g., ref. 5). However, these forms of mating interference are simply by-products of attaining a larger size and are not exclusiv...

Clonal reproduction is thought to facilitate polyploid establishment in the angiosperms, but the evolutionary relationship between polyploidy and clonality has not been thoroughly tested. A perennial life history may confer many of the same advantages, and the relative importance of clonality versus perenniality is unknown.We used phylogenetic comparative analyses of 1751 species to examine associations between polyploidy, clonality, and life history. We test hypotheses of co-evolution by determining the sequence of trait development.Polyploidy is associated with both clonality and perenniality across species, and analyses show that clonality can be an important predictor of polyploidy beyond perenniality. Tests of directionality on our full dataset suggest that polyploidy is more likely to promote clonality or perenniality than vice versa, although there are significant differences in patterns of co-evolution among major angiosperm groups.Our results suggest that polyploidy and clonal reproduction are evolutionarily associated across the angiosperms, even when perenniality is considered, but we find little evidence at the whole-angiosperm level for the hypothesis that clonality promotes polyploidy. However, variation among different clades indicates that polyploidy and clonality are interacting in diverse ways, likely to be due to the variable roles of clonality in their evolutionary histories.

WGD immediately increases investment in asexual vs. sexual reproduction in C. angustifolium, potentially promoting within-cytotype mating and establishment for neopolyploids. However, evolutionary change after the polyploidization event negates the direct effects of WGD. Natural polyploids and diploids have similar root bud production and biomass allocation patterns, probably resulting from habitat- and ploidy-mediated selection on polyploids to become more like diploids. These results highlight the value of studying the effects of polyploidization in young vs. established polyploids.

Clonal reproduction is often associated with polyploidy and is expected to influence polyploid establishment success, but the immediate effects of whole-genome duplication (WGD) on clonal reproduction in autopolyploids are unknown. METHODS: We used synthesized neopolyploids to assess the direct effects of WGD on stolon and plantlet production in the wild strawberry Fragaria vesca by (1) comparing absolute clonal investment between diploids and neotetraploids under high and low resource conditions in the greenhouse and (2) determining realized clonal plantlet establishment and genet spatial structure using artificial field populations comprising both cytotypes. KEY RESULTS: Neotetraploids produced fewer stolons and plantlets than diploids at slower weekly rates in the greenhouse when resources were high, resulting in lower total investment in clonal reproduction. Low resources led to smaller reductions in clonal biomass for neotetraploids and less pronounced differences between cytotypes. Comparisons between neotetraploids representing 13 independent WGD events and close diploid relatives revealed considerable variation in the response to polyploidization for some clonal traits. Field populations corroborated greenhouse results; neotetraploid genets were smaller than diploid genets, containing 28% fewer stolons and 46% fewer rooted plantlets. CONCLUSIONS: WGD significantly decreases the clonal output of neotetraploid F. vesca, which is likely attributable to slower whole-plant growth of the neotetraploids than the diploids. In natural populations, smaller neotetraploid genets could decrease the probability of polyploid establishment in this species. However, variation between separate neopolyploid lines emphasizes that the response of clonal investment to WGD may not be uniform across polyploid origins.