NUCDIV - Nucleotide diversity in a population DNAsp : * Nucleotide diversity, Pi (p), the average number of nucleotide differences per site between two sequences (Nei 1987, equations 10.5 or 10.6), and its sampling variance (Nei 1987, equation 10.7). * Nucleotide diversity, Pi (p), the average number of nucleotide differences per site between two sequences (Nei 1987, equations 10.5 or 10.6; see also Nei and Miller 1990), and its sampling variance (Nei 1987, equation 10.7). The standard deviation (or standard error) is the square root of the variance.