FIG. 2.

Subspecies origin of captive chimpanzees. Chimpanzees were classified as members of the central (P. t. troglodytes) or the Nigerian (P. t. vellerosus) subspecies by mtDNA analysis (7). Representative sequences from newly characterized P. t. troglodytes and P. t. vellerosus apes (GenBank accession no. AY126678 through AY126696) are highlighted in red and magenta, respectively (previously reported mtDNA sequences are shown in black); the SIVcpz-infected ape CAM13 is boxed. A 498-bp (D loop) fragment was amplified from fecal DNA. Nucleotide sequences were aligned by using CLUSTAL W (28); the gap-stripped alignment contained 391 sites. The tree was obtained by the Bayesian method (implemented in MRBAYES) (12) by using the general reversible model of evolution with a gamma distribution of rates across sites. The scale bar indicates 0.02 substitutions per site. Asterisks denote branches with estimated posterior probabilities of 95% or higher. The tree was rooted with human sequences.