Chapter 6 Bootstrap sampling of cross trait covariance

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Figure 6.1 An example of genetic covariance estimated from offspring-parent data in the garter snake Thamnophis elegans (inland population). The genetic covariance of body and tail vertebral counts and be estimated from either of regressions shown in this animations or – better yet – from both. The average tail vertebral count of daughters as a function of mother’s body vertebral count (n = 154) is shown on the left; the average body vertebral count of daughters as a function of mother’s tail vertebral count (n = 117) is shown on the right. The animation shows 1,000 bootstrap samples from each data plot. The standard error of the point estimate for the covariance can be estimated from the histograms shown in the upper lefthand corners at the end of the run. The estimate of genetic covariance based on both sets of data is 3.78 ± 1.67 s.e. (Phillips & Arnold 1999)