Molecular phylogenetics of large‐bodied tamarins, Saguinus spp. (Primates, Platyrrhini)

Abstract

With 33 recognized taxa, the tamarins, Saguinus spp., constitute the most diverse genus of New World monkeys (Platyrrhini), and are found almost exclusively within the Amazon basin. This diversity can be subdivided into three main morphological groups, based primarily on pelage characteristics, although there is also an ecologically important division between the small‐ and large‐bodied forms (adult body weight ± 300 g vs. > 450 g, respectively). In the present study, the phylogenetic relationships among the large‐bodied forms were analysed using the sequences of a fragment of the mitochondrial rRNA16S gene, from which 58 informative sites were identified. The analysis revealed the existence of four main lineages, three of which coincided with geographical and/or morphological patterns. However, Saguinus leucopus formed a highly distinct clade, contradicting expectations based on its morphology and distribution, but corroborating a previous study of the NADH dehydrogenase subunit I (ND1) gene. Whereas genetic differences between some closely related species were relatively small ( S. imperator was twice higher (± 2%), indicating the possible presence of distinct species within this taxon. Previous molecular clock analysis suggested that the earliest radiation event of the large‐bodied tamarins occurred sometime in the lower Miocene, whereas the most recent events, such as the division of the closely related S. midas and S. niger would have occurred during the Pleistocene. Most of these events would thus have taken place before the formation of the present‐day river system, which now constitutes a considerable barrier to gene flow among many populations.

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