نتایج جستجو برای: asexual propagation
تعداد نتایج: 111548 فیلتر نتایج به سال:
Apomixis is a natural form of asexual reproduction through seeds that leads to viable offspring genetically identical to the mother plant. New evidence from sexual model species indicates that the regulation of female gametogenesis and seed formation is also directed by epigenetic mechanisms that are crucial to control events that distinguish sexuality from apomixis, with important implications...
As the pioneering research cited in the previous chapter demonstrates, the kinds and concentrations of nutrients affect the development of the asexual apparatus of watermolds. The beginning efforts to study the relationship between nutrition and morphogenesis, not only of the sporangia but of the sexual apparatus as well, were severely hampered by lack of attention to precise chemical definitio...
It is necessary to understand how environmental changes affect plant fitness to predict survival of a species, but this knowledge is scarce for lichens and complicated by their formation of sexual and asexual reproductive structures. Are the presence and number of reproductive structures in Lobaria pulmonaria, a threatened lichen, dependent on thallus size, and is their formation sequential? Do...
Theory suggests that occasional or conditional sex involving facultative switching between sexual and asexual reproduction is the optimal reproductive strategy. Therefore, the true 'paradox of sex' is the prevalence of obligate sex. This points to the existence of powerful, general impediments to the invasion of obligately sexual populations by facultative mutants, and recent studies raise the ...
At present there is no consensus theory explaining the evolutionary stability of mutualistic interactions. However, the question is whether there are general 'rules', or whether each particular mutualism needs a unique explanation. Here, I address the ultimate evolutionary stability of the 'agricultural' mutualism between fungus-growing termites and Termitomyces fungi, and provide a proximate m...
Pseudostellaria heterophylla has been used in traditional Chinese medicine for hundreds of years (Xiao, 2002). The primary medicinal components of the herb include alkaloids, which are located mostly in the root tubers (Wu et al., 2004; Cai et al., 2005). P. heterophylla seeds are difficult to germinate because the seed coat is too thick (Wen, 2003). Its root tubers are generally used for propa...
Anemonefishes and their host sea anemones form an iconic symbiotic association in reef environments, and are highly sought after in the marine aquarium trade. This study examines asexual propagation as a method for culturing a geographically widespread and commonly traded species of host sea anemone, Entacmaea quadricolor. Two experiments were done: the first to establish whether size or colour...
Aspergillus fumigatus, a ubiquitous human fungal pathogen, produces asexual spores (conidia), which are the main mode of propagation, survival and infection of this human pathogen. In this study, we present the molecular characterization of a novel regulator of conidiogenesis and conidial survival called MybA because the predicted protein contains a Myb DNA binding motif. Cellular localization ...
BACKGROUND AND AIMS Expected life history trade-offs associated with sex differences in reproductive investment are often undetected in seed plants, with the difficulty arising from logistical issues of conducting controlled experiments. By controlling genotype, age and resource status of individuals, a bryophyte was assessed for sex-specific and location-specific patterns of vegetative, asexua...
The twofold cost of sex implies that sexual and asexual reproduction do not coexist easily. Asexual forms tend to outcompete sexuals but may eventually suffer higher extinction rates, creating tension between short- and long-term advantages of different reproductive modes. The 'short-sightedness' of asexual reproduction takes a particularly intriguing form in gynogenetic species complexes, in w...
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