Unraveling signatures of chicken genetic diversity and divergent selection in breed-specific patterns of early myogenesis, nitric oxide metabolism and post-hatch growth.

Due to long-term domestication, breeding and divergent selection, a vast genetic diversity in poultry currently exists, with various breeds being characterized by unique phenotypic and genetic features. Assuming that differences between chicken breeds divergently selected for economically and culturally important traits manifest as early as possible in development and growth stages, we aimed to explore breed-specific patterns and interrelations of embryo myogenesis, nitric oxide (NO) metabolism and post-hatch growth rate (GR). These characteristics were explored in eight breeds of different utility types (meat-type, dual purpose, egg-type, game, and fancy) by incubating 70 fertile eggs per breed.

Simulation of evolution implemented in the mutualistic symbioses towards enhancing their ecological efficiency, functional integrity and genotypic specificity.

We created the mathematical model for the evolution of the Efficiency of Mutualistic Symbioses (EMS) which was estimated as the microsymbiont impacts on the host's reproductive potential. Using the example of rhizobia-legume interaction, the relationships were studied between EMS and Functional Integrity of Symbiosis (FIS) which is represented as a measure for concordance of changes in the partners' genotypic frequencies under the environmental fluctuations represented by the minor deviations of the systemic model parameters. The FIS indices correlate positively with EMS values suggesting an enhancement of FIS via the natural selection operating in the partners' populations in favor of high EMS.

Equilibrium between the "genuine mutualists" and "symbiotic cheaters" in the bacterial population co-evolving with plants in a facultative symbiosis.

The mathematical model for evolution of the plant-microbe facultative mutualistic interactions based on the partners' symbiotic feedbacks is constructed. Using the example of rhizobia-legume symbiosis, we addressed these feedbacks in terms of the metabolic (C<-->N) exchange resulting in the parallel improvements of the partners' fitness (positive feedbacks). These improvements are correlated to the symbiotic efficiency dependent on the ratio of N(2)-fixing bacterial strains ("genuine mutualists") to the non- N(2)-fixing strains ("symbiotic cheaters") in the root nodules.

Interplay of Darwinian and frequency-dependent selection in the host-associated microbial populations.

In order to analyze the microevolutionary processes in host-associated microorganisms, we simulated the dynamics of rhizobia populations composed of a parental strain and its mutants possessing the altered fitness within "plant-soil" system. The population dynamics was presented as a series of cycles (each one involves "soil-->rhizosphere-->nodules-->soil" succession) described using recurrent equations. For representing the selection and mutation pressures, we used a universal approach based on calculating the shifts in the genetic ratios of competing bacterial genotypes within the particular habitats and across several habitats.