# lynchD: Compute Lynch's Delta rate metric In paleoTS: Analyze Paleontological Time-Series

 lynchD R Documentation

## Compute Lynch's Delta rate metric

### Description

This function computes D, the rate metric proposed by Lynch (1990). This metric derives from the random walk model, with ```D = Vstep/(2Vp)```, where `Vstep` is the step variance of the unbiased random walk, and `Vp` is the within sample variance, pooled among samples. Under mutation - drift equilibrium, `D` is expected to range approximately between 5e-5 and 5e-3.

### Usage

```lynchD(y, gen.per.t = 1e+06, pool = TRUE, method = c("Joint", "AD"), ...)
```

### Arguments

 `y` a `paleoTS` object `gen.per.t` the number of generations per unit time `pool` logical, whether variances should be pooled over samples `method` parameterization to use: based on ancestor-descendant (AD) differences, or Joint consideration of all samples `...` further arguments, passed to `opt.URW` or `opt.joint.URW`

### Value

 `D` value of rate metric `pooled.var` value of pooled within-sample variance `gen.per.t` number of generations per unit time `vstep` computed `Vstep`, at the original time scale of `y` `drift.range` expected minimum and maximum values of `D` consistent with neutral evolution `result` conclusion reached about the plausibility of neutral evolution

### References

Lynch (1990). The rate of morphological evolution in mammals from the standpoint of the neutral expectation. The American Naturalist 136:727-741. Hunt, G. 2012. Fitting and comparing models of phyletic evolution: random walks and beyond. Paleobiology 38:351-373.

### Examples

```y <- sim.GRW(ns = 20, ms = 0, vs = 1e-4, tt=seq(0, 1e6, length.out=20))  # per-year simulation
lynchD(y, gen.per.t = 1)
```

paleoTS documentation built on Aug. 9, 2022, 1:06 a.m.