Mitogenomics phylogenetic relationships of the current sloth’s genera and species (Bradypodidae and Megalonychidae)

Abstract

We sequenced the complete mitogenome of 39 sloths (19 Bradypus variegatus, 4 B. tridactylus, 1 B. pygmaeus, 1 B. torquatus, 4 Choloepus didactylus, and 10 C. hoffmanni). A Bayesian tree (BI) indicated a temporal split between Bradypus and Choloepus around 31 million years ago (MYA, Oligocene) and the other major splits within each genera during the Miocene and Pliocene. A haplotype network (MJN) estimated a lower temporal split between the sloth genera (around 23.5 MYA). Both methods detected the ancestor of B. torquatus as the first to diverge within Bradypus (21 for BI and 19 MJN), followed by that of the ancestor of B. tridactylus. The split of B. pygmaeus from the common ancestor with B. variegatus was around 12 MYA (BI) or 4.3 MYA (MJN). The splits among the previous populations of B. variegatus began around 8 MYA (BI) or 3.6 MYA (MJN). The trans-Andean population was the first to diverge from the remaining cis-Andean populations of B. variegatus. The genetic differentiation of the trans-Andean B. variegatus population relative to the cis-Andean B. variegatus is similar to that found for different species of sloths. The mitogenomic analysis resolved the differentiation of C. hoffmanni from the C. didactylus individuals of the Guiana Shield. However, one C. didactylus from the Colombian Amazon specimen was inside the C. hoffmanni clade. This could be the first example of possible natural hybridization in the Amazon of both Choloepus taxa or the existence of un-differentiable phenotypes of these two species in some Amazonian areas.

Keywords:

• Bradypus
• Choloepus
• trans-Andean B. variegatus
• mitogenomics
• mt Cyt-b

Ackowledgements

Thanks to Dr Diana Alvarez, Pablo Escobar-Armel, Nicolás Lichilín, Luisa Castellanos-Mora, Kelly Luengas, and Alan Velarde for their respective help in obtaining sloth samples during the last 20 years. Thanks to the Instituto von Humboldt (Villa de Leyva in Colombia; Janeth Muñoz), the Peruvian Ministry of Environment, PRODUCE (Dirección Nacional de Extracción y Procesamiento Pesquero), Consejo Nacional del Ambiente and the Instituto Nacional de Recursos Naturales from Peru, to the Colección Boliviana de Fauna (Dr Julieta Vargas) and to CITES Bolivia. Also, thanks to the National Environmental authority from Panama, and the Brazilian IBAMA for their role in facilitating the obtainment of collection permits in Colombia, Peru, Bolivia, Panama, and Brazil. We also thank the many people of diverse Indian tribes in Peru (Bora, Shipigo-Comibo, Kishuarana, and Alamas), Bolivia (Sirionó, Canichana, and Chacobo), and Colombia (Tucano, Nonuya, Yuri, and Yucuna) and many people in Panama and Brazil for their support in obtaining samples of Bradypus and Choloepus.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.