Historical genetic demography and some insights into the systematics of Ateles (Atelidae, Primates) by means of diverse mitochondrial genes

We sampled 283 spider monkeys (Ateles) and sequenced three of their mitochondrial genes (Cyt-b, COI and COII). This was the largest molecular genetics sample set of Ateles ever analyzed and included all of the morphological taxa described for this genus. There were six main findings: 1. All the species, or main taxa studied, showed elevated mitochondrial gene diversity levels, with the exception of A. paniscus. The hybridus taxa, which showed considerably low gene diversity levels for nuclear DNA microsatellites (Ruiz-García et al., 2006), but also showed relatively elevated levels of mitochondrial gene diversity. 2. Changes in population size: The taxa chamek and belzebuth showed strong evidence of population expansions during the Pleistocene. Also, we detected population expansions in fusciceps and geoffroyi. The demographic history of marginatus was ambiguous with some of our analyses indicating population expansion while others suggesting a declination in females. This was probably due to small sample size. Similarly, paniscus didn't show clear evidence of demographic changes, but hybridus did show a declination trend in its female population. 3. Genetic heterogeneity: Taxa pairs with A. paniscus showed the highest values of genetic differentiation-suggesting A. paniscus is the most differentiated taxon within Ateles. Genetic heterogeneity values were only statistically significant when all taxa were analyzed together. 4. The Kimura 2P genetic distance model showed maximum values around 4% for the different taxa pairs. Many of these were around 2-3%, clearly lower than those of other Neotropical primate species within genera. This indicates that the number of Ateles species proposed by Groves (2001) is probably an overestimation (taxonomic inflation) caused by a very typological use of the Phylogenetic species concept. 5. Our molecular phylogenetic results support the existence of two (A. paniscus and A. belzebuth) or three (A. paniscus, A. belzebuth and A. geoffroyi) species. 6. We (both mitochondrial and microsatellites) detected a very strong phylogenetic relationship between hybridus and some fusciceps individuals. These results don't agree with the view of Collins and Dubach (2000a,b) and Nieves et al., (2005) that hybridus is a full and differentiated species.