Squirrel monkeys, Saimiri, are commonly found in zoological parks and used in biomedical research. S. boliviensis is the most common species for research; however, there is little information about genome evolution within this primate lineage. Here, we reconstruct the Alu element sequence amplification and evolution in the genus Saimiri at the time of divergence within the family Cebidae lineage. Alu elements are the most successful SINE (Short Interspersed Element) in primates. Here, we report 46 Saimiri lineage specific Alu subfamilies. Retrotransposition activity involved subfamilies related to AluS, AluTa10, and AluTa15. Many subfamilies are simultaneously active within the Saimiri lineage, a finding which supports the stealth model of Alu amplification. We also report a high resolution analysis of Alu subfamilies within the S. boliviensis genome [saiBol1].

Platy-1 elements are Platyrrhine-specific, short interspersed elements originally discovered in the Callithrix jacchus (common marmoset) genome. To date, only the marmoset genome has been analyzed for Platy-1 repeat content. Here, we report full-length Platy-1 insertions in other New World monkey (NWM) genomes ( Saimiri boliviensis , squirrel monkey; Cebus imitator , capuchin monkey; and Aotus nancymaae , owl monkey) and analyze the amplification dynamics of lineage-specific Platy-1 insertions. A relatively small number of full-length and lineage-specific Platy-1 elements were found in the squirrel, capuchin, and owl monkey genomes compared with the marmoset genome. In addition, only a few older Platy-1 subfamilies were recovered in this study, with no Platy-1 subfamilies younger than Platy-1-6. By contrast, 62 Platy-1 subfamilies were discovered in the marmoset genome. All of the lineage-specific insertions found in the squirrel and capuchin monkeys were fixed present. However, ∼15% of the lineage-specific Platy-1 loci in Aotus were polymorphic for insertion presence/absence. In addition, two new Platy-1 subfamilies were identified in the owl monkey genome with low nucleotide divergences compared with their respective consensus sequences, suggesting minimal ongoing retrotransposition in the Aotus genus and no current activity in the Saimiri , Cebus , and Sapajus genera. These comparative analyses highlight the finding that the high number of Platy-1 elements discovered in the marmoset genome is an exception among NWM analyzed thus far, rather than the rule. Future studies are needed to expand upon our knowledge of Platy-1 amplification in other NWM genomes.