Sex is a paradoxical phenomenon because it is less efficient compared with asexual reproduction. To resolve this paradox we need a direct comparison between sexual and asexual forms. In many organisms, however, sexual and asexual forms do not occur in the same habitat, or at the same time. In a few cases where sexual and asexual forms are found in a single population, some (though rare) genetic...

Many asexual animal species are of hybrid origin, with consequent high levels of heterozygosity. Data from some studies suggest that increased heterozygosity may be functionally correlated with superior performance in a variety of fitness-related traits. Thus, hybrid asexual species could be expected to exhibit some degree of heterosis. This spontaneous heterosis hypothesis is tested in a compa...

Human asexuality has been described as a lack of sexual attraction toward anyone or anything. One percent of the adult population is thought to be asexual, and research suggests that asexuality is best conceptualized as a sexual orientation. A serious limitation in past research on asexuality has been the complete lack of a validated tool to measure asexuality. Due to limitations in recruiting ...

According to the repair hypothesis, sex originated as a cooperative interaction-the benefit being damage repair. As with all cooperative strategies, cooperative sex may be vulnerable to selfish mutants. The purpose of the present paper is to understand what implications such selfish mutants may have both for the origin of sex, especially in competition with asexual diploidy, and for the elabora...

DNA methylation is an epigenetic mechanism that has the potential to affect plant phenotypes and that is responsive to environmental and genomic stresses such as hybridization and polyploidization. We explored de novo methylation variation that arises during the formation of triploid asexual dandelions from diploid sexual mother plants using methylation-sensitive amplified fragment length polym...

Coral reefs are the most diverse and productive marine ecosystems on earth. The National Museum of Marine Biology Aquarium has cultured more than 35 species corals for research. When we conducted asexual propagation corals, octocoral Sinularia flexibilis released a black pigment that stained operator’s hands black. This is first reported case skin being dyed while propagating corals. We quantif...

The biostimulant segment is becoming increasingly important worldwide. One of the reasons for this that fewer plant protection products are placed on market in European Union, and environmental sustainability also plays an role their use. Biostimulants often used several horticultural sectors, including ornamentals, to strengthen plants, achieve commercial standards, produce quality goods, incr...

The micronucleus of Paramecium plays an essential role in the development of the oral apparatus in both asexual and sexual cycles. The present study analyses this somatic function of the micronucleus by interspecific transplantation of the micronucleus between two species, P. jenningsi and P. tetraurelia. The two species are similar in nucleogenesis in the sexual cycle, in the dependence of sto...

1 We used isozyme variation to examine the genet structure of Uvularia perfoliata patches in gap and closed canopy habitats in a temperate deciduous forest in Maryland, USA. 2 A large patch in a gap habitat was composed of a small number of widely spread genets with many ramets, and a large number of genets with more restricted distribution and few ramets. Genets with many ramets were patchily ...