Genetic Differentiation and Similarity Degree Quantified by Statistical Parameters in the Romanian Sheep Breeds

The paper proposes some procedures for quantifying the biological relations among the four main indigenous sheep breed types from Romanian (Merino, Tsigai, Tsurcana and Karakul) depending on their genetic endowment. The investigational support of these interrelations was represented by the allelic configuration within the five biochemical-genetic systems (haemoglobin, transferrin, albumin, amylase and blood potassium), six immunogenetic systems (A, B, C, D, M and R-O) and two molecular-genetic systems (β-lactoglobulin and calpastatin). The measurability of these interrelations is feasible by means of a mathematical (classical) parameter - the genetic distance (D) – which estimates the genetic differentiation degree among the breeds and an informational statistics concept - the informational correlation (Cx,y) - which reveals the genetic similarity degree among these taxonomic entities by calculating the informational correlation coefficient (Rx,y). At the same time, the paper tries to discriminate which of these two statistical indicators is more eloquent to characterize the biological relations among these sheep breeds. On the basis of values of these statistical parameters, the genetic similarity or differentiation degree among the autochthonous sheep breeds from Romania has been interpreted also by numerical classification methods of biological systems: cluster analysis (CA), multidimensional scaling (MDS) and discriminatory analysis (DA). The paper describes the usefulness of these statistical parameters in the selection, improvement and breeding field in the ovine species.