the objective of this study was to determine the best time for artificial insemination in taleshi ewes. one hundred and fifty ewes were randomly allotted to three groups (n=50/per group). estrus was synchronized with intravaginal insertion of controlled internal drug release (cidr) for 14 days. at the time of cidr removal pmsg (300iu) was injected to the ewes. the first (ai28), second (ai40) an...

Both chemical pollution and human reproduction are complex topics. Inquiry into chemical-related damage to human reproduction is hampered by this complexity. In general, the whole area of environmental chemicals versus human reproduction is one of great concern but. at this time, there are few hard data. The following provides an analytic framework for discussion of these topics, and also provi...

Sexual reproduction and dispersal are often coupled in organisms mixing sexual and asexual reproduction, such as fungi. The aim of this study is to evaluate the impact of mate limitation on the spreading speed of fungal plant parasites. Starting from a simple model with two coupled partial differential equations, we take advantage of the fact that we are interested in the dynamics over large sp...

The study of alternative genetic systems and mixed modes of reproduction, whereby sexual and asexual reproduction is combined within the same lifecycle, is of fundamental importance as they may shed light on classical evolutionary issues, such as the paradox of sex. Recently, several such cases were discovered in social insects. A closer examination of these systems has revealed many amazing fa...

Five successive generations of asexually derived populations of D. tigrina and their sexually derived parental population were reared under each of six combinations of 20, 23 and 26 °C with 12 and 16 h of daylight. Asexual and sexual reproduction were recorded for each population. Peaks of asexual reproduction occurred increasingly earlier in consecutive generations to finally disappear or occu...

Organisms ranging from bacteria and corals to plants and vertebrates can form intransitive competitive networks, in which coexistence can be maintained because no one species or genotype is superior to all others. However, in the simplest case with three competing types, the long-term outcome may not be so clear if two of the three represent the ends of a continuous heritable trait distribution...

ABSTRACT We find that the maximum likelihood method proposed by J. K. M. Brown has deficiencies that limit its usefulness for actual data sets. We propose two alternative statistical methods based on maximum likelihood that could be used to quantify rates of recombination and immigration in fungal populations. We also show that minor modification of our original method, which was based upon pos...

Climate warming can shift the reproductive phenology of plant, and hence dramatically reduced the reproductive capacity both of density-dependent and -independent plant species. But it is still unclear how climate warming affects flowering phenology and reproductive allocation of plant under different planting densities. Here, we assessed the impact of simulated warming on flowering phenology a...

The maintenance of sexual reproduction in natural populations is a pressing question for evolutionary biologists. Under the "Red Queen" hypothesis, coevolving parasites reduce the reproductive advantage of asexual reproduction by adapting to infect clonal genotypes after they become locally common. In addition, the "geographic mosaic" theory of coevolution proposes that structured populations o...