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ABSTRACT Across the tree of life, many organisms are able to reproduce clonally, via vegetative spread, budding or parthenogenesis. In population genetic analyses of clonally reproducing organisms, it is common practice to retain only a single representative per multilocus genotype. Though this practice of clone correction is widespread, the theoretical justification behind it has been very little studied. Here, I use individual‐based simulations to study the effect of clone correction on the estimation of the genetic summary statistics HO, HS, FIS, FST, F′′ST and Dest. The simulations follow the standard finite island model, consisting of a set of populations connected by gene flow, but with a variable rate of sexual versus asexual reproduction. The results of the simulations show that by itself, the inclusion of replicated genotypes does not lead to a deviation in the values of the summary statistics, except when the rate of sexual reproduction is less than about one in thousand. However, clone correction can introduce a strong deviation in the values of most of the statistics, when compared to a scenario of full sexual reproduction. For HS and FIS, this deviation can be informative about the process of asexual reproduction, but for FST, F′′ST and Dest, clone correction can lead to incorrect conclusions. I therefore argue that clone correction is not strictly necessary, but can in some cases be insightful. However, when clone correction is applied, it is imperative that results for both the corrected and uncorrected data are presented. [ABSTRACT FROM AUTHOR]

Many sexual‐asexual complexes show a distinct pattern where the asexuals have larger and more northerly ranges than closely related sexuals. A prime candidate to explain this so‐called "geographical parthenogenesis" is ecological niche divergence between the sexuals and asexuals. Modern niche modelling techniques allow testing niche divergence by directly comparing the niches of sexuals and asexuals. In this study, I use such techniques to perform range‐wide tests of whether nine bioclimatic variables, including annual mean temperature and annual precipitation, contribute to geographical parthenogenesis in two dandelion taxa: Taraxacum section Ruderalia and Taraxacum section Erythrosperma, which are both comprised of sexual diploids and asexual triploids. For both sections, I found evidence of niche divergence, though the exact nature of this divergence was different for the two sections. In section Ruderalia, the sexuals preferred warmer and wetter conditions, whereas in section Erythrosperma, the sexuals preferred dryer conditions. Using Species Distribution Modelling, consistent differences between the sexuals and asexuals were found when looking at the niche determinants: the variables that are most important for modelling the distribution. Furthermore, and in contrast with theoretical expectations that predict that the sexuals should have a wider niche, in section Erythrosperma the asexuals were found to have a wider niche than the sexuals. In conclusion, differences in niche optima, niche determinants, and niche width all contribute to the pattern of geographical parthenogenesis of these two dandelion taxa. However, the results also indicate that the exact causation of geographical parthenogenesis is not uniform across taxa. [ABSTRACT FROM AUTHOR]

Abstract: Why and how sexual reproduction is maintained in natural populations, the so‐called “queen of problems,” is a key unanswered question in evolutionary biology. Recent efforts to solve the problem of sex have often emphasized results generated from laboratory settings. Here, we use a survey of representative “sex in the wild” literature to review and synthesize the outcomes of empirical studies focused on natural populations. Especially notable results included relatively strong support for mechanisms involving niche differentiation and a near absence of attention to adaptive evolution. Support for a major role of parasites is largely confined to a single study system, and only three systems contribute most of the support for mutation accumulation hypotheses. This evidence for taxon specificity suggests that outcomes of particular studies should not be more broadly extrapolated without extreme caution. We conclude by suggesting steps forward, highlighting tests of niche differentiation mechanisms in both laboratory and nature, and empirical evaluation of adaptive evolution‐focused hypotheses in the wild. We also emphasize the value of leveraging the growing body of genomic resources for nonmodel taxa to address whether the clearance of harmful mutations and spread of beneficial variants in natural populations proceeds as expected under various hypotheses for sex. [ABSTRACT FROM AUTHOR]