Parthenogenesis in a Brazilian Rainbow Boa (Epicrates cenchria cenchria)

Abstract

A 22-year-old captive Brazilian rainbow boa (Epicrates cenchria cenchria) gave birth to four offspring after being housed with a vasectomized male. Sexual reproduction as a result of failed prior vasectomy, recanalization of the vas deferens, or prolonged sperm storage was ruled out using the clinical history, histopathology, and gross necropsy. Short tandem repeat (STR) DNA markers were genotyped in the male, female, and four offspring. None of the offspring possessed a diagnostic STR allele present in the potential sire. In addition, all offspring were homozygous at each STR locus evaluated, supporting parthenogenetic reproduction. This is the first report of parthenogenesis in a Brazilian rainbow boa and has implications for the conservation of reptiles maintained in captive breeding programs.

Um estudo de caso ligado ao sexo em Python regius (Serpentes: Boidae), com novas ideias sobre a determinação sexual em Henophidia

“…Although sex determination systems are subject to a high degree of evolutionary plasticity (Bachtrog et al 2014), Booth et al's (2011a) observation may be interpreted as evidence that the male is the heterogametic sex, because it demonstrates that the male has the genetic underpinnings necessary to express male and female gonads, whereas, there is no evidence to suggest that the female is capable of producing male gonads. Bergero and Charlesworth (2008) took note that some snakes may have an XX/XY sex chromosome system with only a small nonrecombining region, which has not yet been detected, and this hypothesis is consistent with the case study of CG presented herein, as well as with the cases of TFAP thus far documented in Henophidia (Booth et al 2011a, b, 2014, Kinney et al 2013. A few candidate sex chromosomes exist for Henophidia, based on genomic comparison to sex determining systems in other vertebrates.…”

“…Booth et al (2011aBooth et al ( , b, 2014 documented the occurrence of facultative parthenogenetic repro-duction in the Boa Constrictor, the Colombian Rainbow Boa (Epicrates maurus), the Ball Python, and the Reticulated Python (Malayopython reticulatus), and Kinney et al (2013) documented facultative parthenogenesis in the Brazilian Rainbow Boa (Epicrates cenchria). In these studies, Booth et al (2011aBooth et al ( , b, 2014 and Kinney et al (2013) genotyped multiple loci of the offspring and demonstrated that the offspring are homozygous throughout the majority of these loci, which the investigators interpreted as indicative of terminal fusion automictic parthenogenesis (TFAP). The parthenogens studied in these case studies were all females; Booth et al (2011a, b) and Kinney et al (2013) interpreted this to mean that these offspring were homozygous for a W sex chromosome.…”

“…In these studies, Booth et al (2011aBooth et al ( , b, 2014 and Kinney et al (2013) genotyped multiple loci of the offspring and demonstrated that the offspring are homozygous throughout the majority of these loci, which the investigators interpreted as indicative of terminal fusion automictic parthenogenesis (TFAP). The parthenogens studied in these case studies were all females; Booth et al (2011a, b) and Kinney et al (2013) interpreted this to mean that these offspring were homozygous for a W sex chromosome. Booth et al (2011a, b) hypothesized that only female parthenogens resulted (rather than 50% females, genotype WW, and 50% males, genotype ZZ, as would be expected from a ZW female displaying TFAP) because the mother is hemizygous, with genotype WØ (i.e.…”

“…However, neither Booth et al (2011a, b), nor Kinney et al presence or absence of any sex chromosomes, nor sex determining regions, in either the mothers, nor in the offspring. Therefore, the explanation given by Booth et al (2011a, b) and Kinney et al (2013) builds upon the assumption that the boas generally bear a ZZ/ZW sex determination system, and assumes that both WØ and WW individuals naturally occur, and are viable.…”

The emerging phylogenetic pattern of parthenogenesis in snakes

“…oviparity transitions, see Blackburn, 2015;Griffith et al, 2015). However, all boid species for which FP has been observed are viviparous (Booth et al, 2011a, b;Kinney et al, 2013;M. Oviparity has been documented in boid lineages; namely, a single species of sand boa (genus Eryx) and the African Calabaria reinhardtii.…”