ENDEL discovered that genes segregate, rather than blend during the process M of germ cell formation in heterozygotes. This makes sexual and asexual reproduction profoundly different in their genetic consequences. Asexual reproduction yields a progeny which, barring mutation, is genotypically uniform and identical with the mother. Sexual reproduction engenders genetic variability in the offspri...

Although herbivory can affect plant fitness, few studies have investigated the effects of herbivory on the fitness of plants that reproduce vegetatively via fragmentation. Plants that reproduce in this manner are common in tropical wet forest understories, where they are subject to damage from falling branches and other debris. For these species, the ability to reproduce via fragmentation may b...

Asexuality confers demographic advantages to invasive taxa, but generally limits adaptive potential for colonizing of new habitats. Therefore, pre-existing adaptations and habitat tolerance are essential in the success of asexual invaders. We investigated these key factors of invasiveness by assessing reproductive modes and host-plant adaptations in the pea aphid, Acyrthosiphon pisum, a pest re...

We model direct fitness benefits of genetic mosaicism for a long-lived tree in coevolution with a short-lived herbivore to test four hypotheses: that mosaicism reduces selection on the herbivore for resistance to plant defenses; that module-level selection allows the individual tree to adapt to its herbivore; and that this benefits the tree population, increasing average tree fitness and reduci...

Clonality is a common phenomenon in plants, allowing genets to persist asexually for much longer periods of time than ramets. The relative frequency of sexual vs. asexual reproduction determines long-term dominance and persistence of clonal plants at the landscape scale. One of the most familiar and valued clonal plants in North America is aspen (Populus tremuloides). Previous researchers have ...

In dioecious species with both sexual and asexual reproduction, the spatial distribution of individual clones affects the potential for sexual reproduction and local adaptation. The seaweed Fucus radicans, endemic to the Baltic Sea, has separate sexes, but new attached thalli may also form asexually. We mapped the spatial distribution of clones (multilocus genotypes, MLGs) over macrogeographic ...

Despite the severe fitness costs associated with sexual reproduction, its persistence and pervasiveness among multicellular organisms testifies to its intrinsic, short-term advantages. However, the reproductive assurance hypothesis predicts selection favoring asexual reproduction in sparse populations and when mate finding is difficult. Difficulties in finding mates is especially common in para...

Transitions to obligate asexuality have been documented in almost all metazoan taxa, yet the conditions favoring such transitions remained largely unexplored. We address this problem in the rotifer Brachionus calyciflorus. In this species, a polymorphism at a single locus, op, can result in transitions to obligate parthenogenesis. Homozygotes for the op allele reproduce strictly by asexual repr...

Self-fertilization and admixture of genotypes from different populations can have major fitness consequences in native species. However, few studies have addressed their potential roles in invasive species. Here, we used plants of Mimulus guttatus from seven native North American, three invasive Scottish and four invasive New Zealand populations to address this. We created seeds from self-ferti...

One of the major potential disadvantages to asexual reproduction is believed to be a reduction in phenotypic variability. This study represents an empirical test for such a reduction in the variance of physiological traits in parthenogenetic species of the lizard genus Cnemidophorus. Five performance traits (burst speed, endurance, maximal exertion, standard metabolic rate and evaporative water...