[Population variability and biometric models of organism trait coordination]

Natural variability of individuals in a population can be considered as a result of experiments set up by nature. The coordinated (coadapted) changes of traits among individuals are consequences of the influence of causal factors in common. With a unique common cause, the coordination law can be expressed by means of the trajectory for joint trait changes due to causal influence. In the case of several variable common factors and fixed specific ones, the coordination law can be expressed by means of a surface in the trait space, the surface corresponds all possible values of the common factors. Considered in this paper, is a principle possibility to estimate the regularities of individual trait coordination (due to the common factors of individual variability) by biometric methods. Application of regression analysis for assessing the coordination does not correspond to the sense of the problem: under regression the joint trait changes are caused not only by the common coordinating factors, but also by the specific ones. The multivariate biometric models of trait variability determination by latent fundamental factors have no direct relation to the causal determination of traits. Under the same causal dependences, trait correlations and statistical factors can strongly vary. Without additional information (that is not contained in random sample), biometric methods do not allow to estimate the causal regularities hidden under uncontrolled intrapopulation variability.