Back to Search Start Over

Post-meiotic mechanism of facultative parthenogenesis in gonochoristic whiptail lizard species

Authors :
David V Ho
Duncan Tormey
Aaron Odell
Aracely A Newton
Robert R Schnittker
Diana P Baumann
William B Neaves
Morgan R Schroeder
Rutendo F Sigauke
Anthony J Barley
Peter Baumann
Source :
eLife, Vol 13 (2024)
Publication Year :
2024
Publisher :
eLife Sciences Publications Ltd, 2024.

Abstract

Facultative parthenogenesis (FP) has historically been regarded as rare in vertebrates, but in recent years incidences have been reported in a growing list of fish, reptile, and bird species. Despite the increasing interest in the phenomenon, the underlying mechanism and evolutionary implications have remained unclear. A common finding across many incidences of FP is either a high degree of homozygosity at microsatellite loci or low levels of heterozygosity detected in next-generation sequencing data. This has led to the proposal that second polar body fusion following the meiotic divisions restores diploidy and thereby mimics fertilization. Here, we show that FP occurring in the gonochoristic Aspidoscelis species A. marmoratus and A. arizonae results in genome-wide homozygosity, an observation inconsistent with polar body fusion as the underlying mechanism of restoration. Instead, a high-quality reference genome for A. marmoratus and analysis of whole-genome sequencing from multiple FP and control animals reveals that a post-meiotic mechanism gives rise to homozygous animals from haploid, unfertilized oocytes. Contrary to the widely held belief that females need to be isolated from males to undergo FP, females housed with conspecific and heterospecific males produced unfertilized eggs that underwent spontaneous development. In addition, offspring arising from both fertilized eggs and parthenogenetic development were observed to arise from a single clutch. Strikingly, our data support a mechanism for facultative parthenogenesis that removes all heterozygosity in a single generation. Complete homozygosity exposes the genetic load and explains the high rate of congenital malformations and embryonic mortality associated with FP in many species. Conversely, for animals that develop normally, FP could potentially exert strong purifying selection as all lethal recessive alleles are purged in a single generation.

Details

Language :
English
ISSN :
2050084X
Volume :
13
Database :
Directory of Open Access Journals
Journal :
eLife
Publication Type :
Academic Journal
Accession number :
edsdoj.7edbd2f11d01455196310a6666645c25
Document Type :
article
Full Text :
https://doi.org/10.7554/eLife.97035