Table 2.

The estimated substitution rates and the dates of most recent common ancestor by four different models

Molecular clock	Demographic model	Substitution ratea, ×10−3 (95% HPD)	tMRCA, D9 (95% HPD)	tMRCA, G3 (95% HPD)
Strict	Constant	2.54 (0.96–4.35)	2005 September 20 (2002 May to 2007 Nov)	2008 May 18 (2007 Oct to 2008 Aug)
Strict	Exponential growth	2.71 (1.10–4.47)	2006 January 12 (2003 Mar to 2007 Nov)	2008 May 29 (2007 Nov to 2008 Aug)
Lognormal relaxed	Constant	2.78 (0.72–4.96)	2005 August 3 (2001 Sept to 2007 Nov)	2008 May 15 (2007 Sept to 2008 Aug)
Lognormal relaxed	Exponential growth	3.37 (0.92–6.23)	2006 January 20 (2003 Jan to 2007 Nov)	2008 May 24 (2007 Oct to 2008 Aug)

tMRCA time to the most recent common ancestor, HPD highest posterior density interval.

^aSubstitutions/site/year.