Productive and reproductive traits of first-calf heifers of different origin under the conditions in LLC “Green lines – Kaluga”

Dairy cattle breeding have always occupied and will continue to occupy one of the leading places in the agro-industrial complex in our country. The most eff ective method of improving existing breeds according to opinion of a number of scientists is selection in line breeding. At the same time the evaluation of breeding sires by the quality of offspring is the cornerstone of breeding work. The purpose of the research was to analyze the influence of breeding sires, as well as their linear affiliation on the economically useful characteristics of first-calf heifers under specific conditions of maintenance and use. An analysis of the milk productivity and reproductive traits of first-calf heifers of different origin by sires and different line belonging has been presented in the article. The results of intra-linear selection and crosses of genealogical lines and their influence on the productive and reproductive traits of first-calf heifers have been evaluated. The research was carried out in LLC “Green Lines-Kaluga” of the Kaluga region. It has been established that for fixing in the genotype of the offspring of plentiful milk and fat milk in purebred breeding, it is necessary to use the following sires: Aragon 2102, Tabor 1292, Lira 2047, Phlox 1448, Chudny 1167, Yalik 397, Tabun 1277, as well as intra-linear selection in the line of Montwick Chieftain 9567929 and crosses of lines in combinations: Siling Traijun Rocket 252803 – Reflection Sovereign 198998 and Wes Ideal 933122 – Siling Traijun Rocket 252803. In order to reduce the age of the first insemination of maternal stock we recommend using a combination of lines: Wes Ideal 933122 – Montwick Chieftain 9567929, Wes Ideal 933122 – Reflection Sovereign 198998, Montwick Chieftain 9567929 – Wes Ideal 933122, Montwick Chieftain 9567929 – Reflection Sovereign 198998 and Siling Trijun Rocket 252803 – Wes Ideal 933122.

INTRA-LINEAR SELECTION AND CROSS-LINE SELECTION WHEN CREATING HIGHLY PRODUCTIVE DAIRY CATTLE HERDS

The aim of the research was to evaluate the compatibility of lines and improve on this basis the traditional selection methods for creating breeding herds in dairy cattle breeding. The results of the analysis showed that the best milk yield among the other lines were the first-born heifers (n=39) of the Holstein line Vis Back Idial (6441 kg of milk). The analysis of the results of the intra-linear selection showed that the best milk yield was also distinguished by the first-born heifers of the Vis Back Idial line – 6721 kg of milk. Analyzing the cross-line of the Vis Back Idial with other lines of the Holstein breed (MCH, RS, and PG), it should be noted that they are superior to their first-calf peers by 253-530 kg of milk. The first-calf cows, derived from the cross of the Montwick Miftaine line and the Reflection Sovering and Pabst Governer lines, also have some superiority over their peers. Thus, when improving breeding herds of dairy cattle, it is necessary to use both intra-linear selection and cross-lines, taking into account their compatibility.

A White Noise Approach to Evolutionary Ecology

Although the evolutionary response to random genetic drift is classically modelled as a sampling process for populations with fixed abundance, the abundances of populations in the wild fluctuate over time. Furthermore, since wild populations exhibit demographic stochasticity, it is reasonable to consider the evolutionary response to demographic stochasticity and its relation to random genetic drift. Here we close this gap in the context of quantitative genetics by deriving the dynamics of the distribution of a quantitative character and the abundance of a biological population from a stochastic partial differential equation driven by space-time white noise. In the process we develop a useful set of heuristics to operationalize the powerful, but abstract theory of white noise and measure-valued stochastic processes. This approach allows us to compute the full implications of demographic stochasticity on phenotypic distributions and abundances of populations. We demonstrate the utility of our approach by deriving a quantitative genetic model of diffuse coevolution mediated by exploitative competition for a continuum of resources. In addition to trait and abundance distributions, this model predicts interaction networks defined by rates of interactions, competition coefficients, or selection gradients. Analyzing the relationship between selection gradients and competition coefficients reveals independence between linear selection gradients and competition coefficients. In contrast, absolute values of linear selection gradients and quadratic selection gradients tend to be positively correlated with competition coefficients. That is, competing species that strongly affect each other’s abundance tend to also impose selection on one another, but the directionality is not predicted. This approach contributes to the development of a synthetic theory of evolutionary ecology by formalizing first principle derivations of stochastic models that underlie rigorous investigations of the relationship between feedbacks of biological processes and the patterns of diversity they produce.

Bite performance surfaces of three ecologically divergent Iguanidae lizards: relationships with lower jaw bones

Traits that interact to perform an ecologically relevant function are expected to be under multivariate non-linear selection. Using the lower jaw morphology as a biomechanical model, we test the hypothesis that lower jaw bones of lizards are subjected to stabilizing and correlational selection, associated with mechanical advantage and maximum bite force. We used three closely related tropidurine species that differ in size, head shape and microhabitat: Eurolophosaurus nanuzae, Tropidurus hispidus and Tropidurus semitaeniatus. We predicted a common pattern of correlational selection on bones that are part of in-levers or part of the out-lever of the lower jaw. The predicted pattern was found in E. nanuzae and T. hispidus, but this could not be shown to be statistically significant. For T. semitaeniatus, we found significant disruptive selection on a contrast involving the surangular, and also significant directional selection on linear combinations of traits in all species. The results indicate that the non-linear selection on lower jaw bones does not reflect an optimum to enhance mechanical advantage in all species. Divergent functional demands and specific ecological contexts of species seem relevant in shaping patterns of selection on morphology.