rr.test: Tajima Relative Rate Test of Molecular Clock

In pegas: Population and Evolutionary Genetics Analysis System

Tajima Relative Rate Test of Molecular Clock

Description

This function tests the hypothesis of a molecular evolutionary clock (i.e., a constant rate of molecular evolution) between two samples using an outgroup sample. It can be applied to both nucleotide and amino acid sequences.

Usage

rr.test(x, y, out)

Arguments

x, y	a single DNA sequence (object class "DNAbin").
out	a single DNA sequence to be used as outgroup.

Value

a list with two numeric values: Chi (Chi-squared statistic) and Pval (the P-value).

Author(s)

Alastair Potts [e-mail]

References

Tajima, F. (1993) Simple methods for testing molecular clock hypothesis. Genetics, 135, 599–607. (Equation 4)

Examples

require(ape)
data(woodmouse)
rr.test(x = woodmouse[2, ], y = woodmouse[3, ], out = woodmouse[1, ])

# Test all pairs in a sample:
outgroup <- woodmouse[1, ]
n <- nrow(woodmouse)
cc <- combn(2:n, 2)
FUN <- function(x)
    rr.test(woodmouse[x[1], ], woodmouse[x[2], ], outgroup)$Pval
OUT <- apply(cc, 2, FUN)
### two ways to arrange the output:
RES <- matrix(NA, n - 1, n - 1)
RES[row(RES) > col(RES)] <- OUT
RES <- t(RES)
RES[row(RES) > col(RES)] <- OUT
RES <- t(RES)
dimnames(RES) <- list(2:n, 2:n)
RES <- as.dist(RES)
### 2nd method:
class(OUT) <- "dist"
attr(OUT, "Labels") <- as.character(2:15)
attr(OUT, "Size") <- n - 1L
attr(OUT, "Diag") <- attr(OUT, "Upper") <- FALSE
### they are the same:
all(OUT == RES)

pegas documentation built on May 29, 2024, 2:27 a.m.