Interestingly, the 800-year-old sample from Troy (Turkey) falls within contemporary genetic diversity
S. saprophyticus, by contrast, appears to be a generalist that colonizes a range of environments.
The length of the branch leading to S. saprophyticus Troy is similar to those leading to the other tips (Figure 4A), suggesting there is little temporal signal in the phylogeny.
Calibrated phylogenetic analyses (Appendix) confirmed the absence of temporal signal, which precludes reliable estimation of the rate of substitution or divergence times for S. saprophyticus.
The 800 year interval between S. saprophyticus Troy and the other tips may simply be too short relative to the overall depth of the tree to allow reliable rate inference.
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