Revisiting the Karyotype Evolution of Neotropical Boid Snakes: A Puzzle Mediated by Chromosomal Fissions

Patrik F Viana,Ahmed Al-Rikabi,Eliana Feldberg,Thomas Liehr,Tariq Ezaz,Luiz Antônio Carlos Bertollo,Rodrigo Tavares-Pinheiro,Marcelo De Bello Cioffi

doi:10.3390/cells9102268

Abstract

The Boidae family is an ancient group of snakes widely distributed across the Neotropical region, where several biogeographic events contributed towards shaping their evolution and diversification. Most species of this family have a diploid number composed of 2n = 36; however, among Booidea families, the Boidae stands out by presenting the greatest chromosomal diversity, with 2n ranging between 36 and 44 chromosomes and an undifferentiated XY sex chromosome system. Here, we applied a comparative chromosome analysis using cross-species chromosome paintings in five species representing four Boidae genera, to decipher the evolutionary dynamics of some chromosomes in these Neotropical snakes. Our study included all diploid numbers (2n = 36, 40, and 44) known for this family and our comparative chromosomal mappings point to a strong evolutionary relationship among the genera Boa, Corallus, Eunectes, and Epicrates. The results also allowed us to propose the cytogenomic diversification that had occurred in this family: a process mediated by centric fissions, including fission events of the putative and undifferentiated XY sex chromosome system in the 2n = 44 karyotype, which is critical in solving the puzzle of the karyotype evolution of boid snakes.

Highlights

The modern boas (Booidea) and pythons (Pythonoidea) are an ancient group of snakes, often referred to as primitive snakes (Henophidia)
Boidae to the Neotropical region (Figure 1) [4,5,6,9]. This worldwide distribution is the result and Southern Asia, and Boidae to the Neotropical region (Figure 1) [4,5,6,9]. This worldwide distribution of numerous biogeographic events associated with the Gondwana fragmentation [10,11,12,13,14]
Adult snakes were collected from natural populations across the Amazon region under permission granted by Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio), number: 45275

Summary

Introduction

The modern boas (Booidea) and pythons (Pythonoidea) are an ancient group of snakes, often referred to as primitive snakes (Henophidia). The Booidea superfamily is a monophyletic group [5,6], including six families, Calabariidae, Candoiidae, Sanziniidae, Charinidae, Erycidae, and Boidae, with over 66 species that are distinct both morphologically and. Boidae to the Neotropical region (Figure 1) [4,5,6,9]. This worldwide distribution is the result and Southern Asia, and Boidae to the Neotropical region (Figure 1) [4,5,6,9] This worldwide distribution of numerous biogeographic events associated with the Gondwana fragmentation [10,11,12,13,14]

Methods

Results

Conclusion