Molecular phylogenetics and phylogeography of all the Saimiri taxa (Cebidae, Primates) inferred from mt COI and COII gene sequences

Abstract

Some previous genetic studies have been performed to resolve the molecular phylogenetics of the squirrel monkeys (Saimiri). However, these studies did not show consensus in how many taxa are within this genus and what the relationships among them are. For this reason, we sequenced 2,237 base pairs of the mt COI and COII genes in 218 Saimiri individuals. All, less 12 S. sciureus sciureus from French Guyana, were sampled in the wild. These samples represented all the living Saimiri taxa recognized. There were four main findings of this study. (1) Our analysis detected 17 different Saimiri groups: albigena, cassiquiarensis, five polyphyletic macrodon groups, three polyphyletic ustus groups, sciureus, collinsi, boliviensis, peruviensis, vanzolinii, oerstedii and citrinellus. Four different phylogenetic trees showed the Central American squirrel monkey (S. oerstedii) as the most differentiated taxon. In contrast, albigena was indicated to be the most recent taxon. (2) There was extensive hybridization and/or historical introgression among albigena, different macrodon groups, peruviensis, sciureus and collinsi. (3) Different tests showed that our maximum likelihood tree was consistent with two species of Saimiri: S. oerstedii and S. sciureus. If no cases of hybridization were detected implicating S. vanzolinii, this could be a third recognized species. (4) We also estimated that the first temporal splits within this genus occurred around 1.4-1.6 million years ago, which indicates that the temporal split events within Saimiri were correlated with Pleistocene climatic changes. If the biological species concept is applied because, in this case, it is operative due to observed hybridization in the wild, the number of species within this genus is probably more limited than recently proposed by other authors. The Pleistocene was the fundamental epoch when the mitochondrial Saimiri diversification process occurred.

Continuous Miocene, Pliocene and Pleistocene Influences on Mitochondrial Diversification of the Capybara (Hydrochoerus Hydrochoeris; Hydrochoeridae, Rodentia): Incapacity to Determine Exclusive Hypotheses on the Origins of the Amazon and Orinoco Diversity for This Species

“…It is interesting to note the discrepancy between the BI (fossil-calibrated DNA phylogeny) and borrowed molecular clock (MNJ). We found this to be true in many of our other research projects involving a variety of Neotropical mammalian species [107][108][109][110][156][157][158][159][160][161]. If these last temporal splits are accurate, the PH and RLH could be excluded as main hypotheses in the generation of genetic capybara diversity.…”

Molecular data highlight hybridization in squirrel monkeys (Saimiri, Cebidae)

“…Lau and Arrighi (1976) using chromosomal banding analyses detected two nonhomologous pericentric inversions in the telocentric group of chromosomes of a squirrel monkey, Saimiri sciureus, suggesting that this individual was an intersubspecific hybrid whose parents originated from different geographical locations. Recently, Ruiz-García et al (2015) also found evidence of hybridization between Saimiri species based on mitochondrial markers (Cox1 and Cytb), emphasizing the importance of this process in the species-level diversification of this genus. In fact, these authors concluded that this genus comprises only three species, S. oerstedi , S. sciureus , and Saimiri vanzolinii , which diversified during the Pleistocene.…”

“…Based on the 14 clades identified in the analysis of the mitochondrial DNA (D-loop and cytb), these authors suggested a provisional taxonomy consisting of S. sciureus , S. oerstedii ( S. o. oerstedii and S. o. citronellus ), S. collinsi , S. ustus (A, B, and C lineages), S. boliviensis, S. cassiquiarensis ( S. c. cassiquiarensis, S. c. albigena, S. c. macrodon A, S. c. macrodon B, and S. c. macrodon C), and S. vanzolinii . Analyzing mitochondrial DNA (CoxI and CoxII), Ruiz-García et al (2015) proposed the following classification: S. oerstedii , with two subspecies ( S. o. oerstedii and S. o. citrinellus ), S. vanzolinii and S. sciureus , with two subspecies, S. s. boliviensis [with two lineages: 1 ( boliviensis ) and 2 ( peruviensis )] and S. s. sciureus [with 12 lineages: 1 ( sciureus ), 2( cassiquiarensis ), 3( ustus I=A), 4( ustus II = B), 5( ustus III = C), 6 ( macrodon I=D),7( macrodon II = E), 8 ( macrodon III = F), 9 ( macrodon IV = G), 10 ( macrodon V = H), 11 ( collinsi ) and 12 ( albigena )].…”

Terminal 13p deletion in squirrel monkey (Saimiri sciureus) with differentiated phenotype

“…While previous molecular studies have shown insights into the taxonomy and phylogeny of the genus, the phylogenetic relationships and divergence date estimates among major squirrel monkey clades still remain unclear. [1][2][3][4][5][6][7][8][9][10] All squirrel monkeys were once considered to be a single species (S. sciureus) defined by phenotypic characteristics with several geographically separated subspecies. 2 It is now considered that there are five species: S. ustus, S. boliviensis, S. vanzolinii, S. sciureus, and S. oerstedii, 11 although molecular phylogenetics and phylogeography study considers that due to observed hybridizations, the number of species could be smaller 9 or greater.…”

“…There is a great disagreement about their taxonomy. While previous molecular studies have shown insights into the taxonomy and phylogeny of the genus, the phylogenetic relationships and divergence date estimates among major squirrel monkey clades still remain unclear . All squirrel monkeys were once considered to be a single species ( S. sciureus ) defined by phenotypic characteristics with several geographically separated subspecies .…”