Cranial allometry, phylogeography, and systematics of large-bodied papionins (primates: Cercopithecinae) inferred from geometric morphometric analysis of landmark data.
The cranial morphology of the African Old World monkeys Mandrillus, Papio, and Theropithecus (i.e., baboons) has been the subject of a number of studies investigating their systematic relationships, patterns of scaling, and growth. In this study, we use landmark-based geometric morphometrics and multivariate analysis to assess the effects of size, sex, taxonomy, and geographic location on cranial shape. Forty-five landmarks were digitized in three dimensions on 452 baboon crania and subjected to generalized Procrustes analysis (GPA), which standardizes geometric size but leaves scaling-based shape differences in the data. The resulting shape coordinates were submitted to regression analysis, principal components analysis (PCA), partial least-squares (PLS) analysis, and various clustering techniques. Scaling (shape differences correlated with size) was the largest single factor explaining cranial shape variation. For instance, most (but not all) of the shape differences between the sexes were explained by size dimorphism. However, central tendencies of shape clearly varied by taxon (both specific and subspecific) even after variations in size and sex were adjusted out. Within Papio, about 60% of the size- and sex-adjusted shape variations were explained by the geographic coordinates of the specimen's provenance, revealing a stepped cline in cranial morphology, with the greatest separation between northern and southern populations. Based on evidence from genetic studies, and the presence of at least two major hybrid/interbreeding zones, we interpret the phylogeographic pattern of cranial variation as indicating that these populations are best ranked as subspecies of a single species, rather than as two or more distinct biological species. This objective approach can be applied to other vertebrate species or species groups to help determine the taxonomic rank of problematic taxa. (+info)
Identification in gelada baboons (Theropithecus gelada) of a distinct simian T-cell lymphotropic virus type 3 with a broad range of Western blot reactivity.
Antibodies to simian T-cell lymphotropic virus (STLV) were found in serum or plasma from 12 of 23 (52.2 %) gelada baboons (Theropithecus gelada) captive in US zoos. A variety of Western blot (WB) profiles was seen in the 12 seroreactive samples, including human T-cell lymphotropic virus (HTLV)-1-like (n=5, 41.7 %), HTLV-2-like (n=1, 8.3 %), HTLV-untypable (n=4, 33.3 %) and indeterminate (n=2, 16.6 %) profiles. Phylogenetic analysis of tax or env sequences that had been PCR amplified from peripheral blood lymphocyte DNA available from nine seropositive geladas showed that four were infected with identical STLV-1s; these sequences clustered with STLV-1 from Celebes macaques and probably represent recent cross-species infections. The tax sequences from the five remaining geladas were also identical and clustered with STLV-3. Analysis of the complete STLV-3 genome (8917 bp) from one gelada, TGE-2117, revealed that it is unique, sharing only 62 % similarity with HTLV-1/ATK and HTLV-2/Mo. STLV-3/TGE-2117 was closest genetically to STLV-3 from an Eritrean baboon (STLV-3/PH969, 95.6 %) but more distant from STLV-3s from red-capped mangabeys from Cameroon and Nigeria (STLV-3/CTO-604, 87.7 %, and STLV-3/CTO-NG409, 87.2 %, respectively) and Senegalese baboons (STLV-3/PPA-F3, 88.4 %). The genetic relatedness of STLV-3/TGE-2117 to STLV-3 was confirmed by phylogenetic analysis of a concatenated gag-pol-env-tax sequence (6795 bp). An ancient origin of 73 628-109 809 years ago for STLV-3 was estimated by molecular clock analysis of third-codon positions of gag-pol-env-tax sequences. LTR sequences from five STLV-3-positive geladas were >99 % identical and clustered with that from a Papio anubisxP. hamadryas hybrid Ethiopian baboon, suggesting a common source of STLV-3 in these sympatric animals. LTR sequences obtained 20 years apart from a mother-infant pair were identical, providing evidence of both mother-to-offspring transmission and a high genetic stability of STLV-3. Since STLV-3-infected primates show a range of HTLV-like WB profiles and have an ancient origin, further studies using STLV-3-specific testing are required to determine whether STLV-3 infects humans, especially in regions of Africa where STLV-3 is endemic. (+info)