Table 2. Parametric estimates (with 95% confidence intervals) under the piecewise expansion model for the three genealogies.

Parameter	env	pol	gag
Substitution rate	4.20 × 10-3	2.46 × 10-3	1.22 × 10-3
Transition time	1960 (1955-1963)	1967 (1962-1970)	1951 (NA-1957)
Growth rate, yr-1	0.201 (0.167-0.236)	0.243 (0.197-0.286)	0.198 (0.164-0.240)
Current population	10,109 (5,138-21,218)	6,183 (3,166-11,896)	31,636 (13,829-888,070)

The estimates for the population parameters under the piecewise expansion model are based on the evolutionary rate calibrated by the 1940 date for the MRCA of HIV-2 subtype A. NA, not applicable.