Discovery of facultative parthenogenesis in a new world crocodile

Abstract

Over the past two decades, there has been an astounding growth in the documentation of vertebrate facultative parthenogenesis (FP). This unusual reproductive mode has been documented in birds, non-avian reptiles—specifically lizards and snakes—and elasmobranch fishes. Part of this growth among vertebrate taxa is attributable to awareness of the phenomenon itself and advances in molecular genetics/genomics and bioinformatics, and as such our understanding has developed considerably. Nonetheless, questions remain as to its occurrence outside of these vertebrate lineages, most notably in Chelonia (turtles) and Crocodylia (crocodiles, alligators and gharials). The latter group is particularly interesting because unlike all previously documented cases of FP in vertebrates, crocodilians lack sex chromosomes and sex determination is controlled by temperature. Here, using whole-genome sequencing data, we provide, to our knowledge, the first evidence of FP in a crocodilian, the American crocodile, Crocodylus acutus . The data support terminal fusion automixis as the reproductive mechanism; a finding which suggests a common evolutionary origin of FP across reptiles, crocodilians and birds. With FP now documented in the two main branches of extant archosaurs, this discovery offers tantalizing insights into the possible reproductive capabilities of the extinct archosaurian relatives of crocodilians and birds, notably members of Pterosauria and Dinosauria.

GenAPoPop 1.0: A user‐friendly software to analyse genetic diversity and structure from partially clonal and selfed autopolyploid organisms

“…Eukaryotes with more than two sets of homologous chromosomes (autopolyploids) or duplicated genomic segments are very common in ferns, flowering plant and fungi species (Albertin & Marullo, 2012; Barker et al., 2016; Wood et al., 2009). Polyploidy seems less frequent in animals albeit significant in a handful of clades such as in fishes, cnidarians, amphibians and reptiles (Booth et al., 2023; Gregory & Mable, 2005; Mable et al., 2011). It also occurs in some species only for some chromosomes (aneuploidy), like commonly observed in partially clonal parasitic protozoa (Rougeron et al., 2015; Tibayrenc & Ayala, 2013).…”

The mystery of distribution of Smittia brevipennis (Diptera, Chironomidae, Orthocladiinae)

“…,Ross et al, 1997, Korenko et al, 2009, Schut et al, 2009, Booth et al, 2023). Among insects three main types can be distinguished: arrhenotoky (the birth of only haploid males from unfertilized eggs and diploid females from fertilized eggs), thelytoky (birth of only diploid females from unfertilized eggs) and deuterotoky (birth of males and females from unfertilized eggs)(Lynch, 1984, Amiri Bandaniet, 2021.…”