August Weismann is famous for having argued against the inheritance of acquired characters. However, an analysis of his work indicates that Weismann always held that changes in external conditions, acting during development, were the necessary causes of variation in the hereditary material. For much of his career he held that acquired germ-plasm variation was inherited. An irony, which is in te...

The breeding system of Arabidopsis suecica was investigated through genetic analysis of microsatellite segregation patterns in five controlled crosses as well as in 16 single-mother families collected in the wild. Analysis of single and two-locus segregations in the F2 generation following a cross clearly shows that A. suecica is reproduces sexually. The single-mother families show a high level...

Several modes of reproduction were described in the genus Hypericum. Besides obligate sexuality, irregularities in meiosis, polyembryony and pseudogamous apomixis were noticed in various taxa of the genus. This review summarizes previous knowledge and also analyses evolutionary consequences of different breeding systems and possible employment of particular reproductive modes for breeding in th...

This report presents a model for simulating various reproduction modes and types restrictions from nature with the genetic algorithms. We consider three reproduction modes, which are self-fertilizing, hermaphrodite excluding self fertilization, and with two differentiated gender types (male and female). We start with a model in which the reproduction mode evolves along with the rest of the geno...

HE system of ciliary antigens of Paramecium aurelia has provided abundant T material for the study of the inheritance of diverse phenotypes by organisms of identical genotype. Each animal of any one stock of P. aurelia has the genetic potential for the expression of a series of serologically different alternative ciliary antigens (SONNEBORN 1948, 1950a; SONNEBORN and LESUER 1948; BEALE 1954). S...

Sex has many costs with respect to asexual reproduction, so its ubiquity is a puzzle. There has been a continuing effort to identify general circumstances in which aspects of sex generate an evolutionary advantage over asexual reproduction. Here we focus on the generality that individuals can experience good and bad "luck" at various stages of their life history regardless of genotype, and on t...

The prevalence of sexual reproduction remains one of the most perplexing phenomena in evolutionary biology. The deterministic mutation hypothesis postulates that sexual reproduction will be advantageous under synergistic epistasis, a condition in which mutations cause a greater reduction in fitness when combined than would be expected from their individual effects. The inverse condition, antago...

This study was performed to compare the efficiency of six microalgae namely Dunaliella tertiolecta, Tetraselmis suecica, Nannochloropsis oculata, Chaetoceros sp., Chlorella sp. and Spirolina sp. on the growth, survival rate and reproduction efficacy in Artemia urmiana in laboratory conditions. Artemia cysts were harvested from Urmia Lake and hatched according to the standard method. Live microa...