INGDIF - SIMPLE MEASURE BASED ON ANALYSIS OF GENETIC DIFFERENTIATION

Population differentiation based on genetic diversity was subject of many previous scientific studies. Consequently, various methods were suggested. The most widely used method was fixation index FST, as a part of FIS, FIT and FST parameters which were proposed by Wright (1943, 1951, 1965). The main objective is to hierarchically estimate genetic variation in populations. Nei (1973, 1987) suggested GST as more appropriate methods, with θ (Cockerham 1969, 1973; Weir et Cockerham 1984), and ΦST (Excoffier et al. 1992) introduced later on as more adequate methods for molecular markers. Wright’s FST has range between 0 and 1 where 0 indicates absence of differentiation, while 1 shows absolute divergence with no shared alleles. This method helps to quantify and compare level of genetic differentiation among populations. Since, in practice, when multialleles loci are applied, Fst value of 1 is almost never observed for fixation indices (Wright 1978; Hedrick 1999; Jost 2008). This fact reduces application of fixation indices when highly polymorphic markers (e.g microsatellites) are used (Hedrick 1999). However, certain literature suggests that Nei's GST and Wier and Cockerham's θ are flawed in the sense that 1 does not represent maximal differentiation. Arguing about practical applicability of standard genetic differentiation methods, Jost (2008) suggested allelic diversity (∆) to be base for measuring the genetic differentiation Dest as indicator of divergence (D). Jost considers that this approach corrects sampling bias, does not suffer the flaws of F-statistics and, being related to diversity, is more adequate. Nilsryman and Olofleimar (2009) concluded in their study that Dest suffers the same problems as other measures, and that GST is still more appropriate method.