Revisiting the polyploidy in the genus Odontophrynus (Anura: Odontophrynidae)

From Firenze University Press Journal: Acta Herpetologica

University of Florence
3 min readFeb 13, 2024

André Luis de Souza, Departamento de Ciências Biológicas, Universidade Estadual do Paraná

Mayara Aparecida das Neves Micalichen, Departamento de Ciências Biológicas, Universidade Estadual do Paraná

Roger Alves da Rocha, Departamento de Ciências Biológicas, Universidade Estadual do Paraná

Rafael Bueno Noleto, Departamento de Ciências Biológicas, Universidade Estadual do Paraná

According to Frost (2023), the family Odontophrynidae currently contains 55 species distributed in three genera Macrogenioglottus Carvalho, 1946, OdontophrynusReinhardt and Lütken, 1862, and Proceratophrys Miranda-Ribeiro, 1920. Earlier phylogenies validate the monophyly of the family, as well as that Macrogenioglottus and Odontophrynus are sister taxa (Pyron and Wiens, 2011; Feng et al., 2017). The genus Odontophrynus is composed of eleven species widely distributed in southern and eastern South America. Odontophrynus americanus (Dumé-ril and Bibron, 1841), a small fossorial anuran with no apparent sexual dimorphism (Quiroga et al., 2015), has the greatest distribution, its range extends to central and southern Argentina, southern Paraguay, southern Brazil, and Uruguay (Frost, 2023).Odontophrynus americanus was the first case of natu-ral polyploidy found in vertebrates (Beçak et al., 1966). The Odontophrynus americanus species group is a com-plex of morphologically indistinguishable diploid and tetraploid species. It includes currently four diploid spe-cies: O. cordobae Martino and Sinsch, 2002, O. juquinha Rocha, Sena, Pezzuti, Leite, Svartman, Rosset, Baldo, and Garcia, 2017, O. lavillai Cei, 1985 and O. maisuma Rosset, 2008 with 2N = 2x = 22 chromosomes, and one widely distributed tetraploid species (O. americanus) with 2N = 4x = 44 chromosomes (Beçak et al., 1966; Ruiz et al., 1981; Martino and Sinsch, 2002; Rosset et al., 2006; Rosset, 2008). Martino et al. (2019) established the exist-ence of cryptic diversity and overestimation of species richness by combining molecular, morphological, and bioacoustic data. Populations known as O. americanuscomprise at least three species.Polyploidy plays an important role in speciation and evolution in anurans, with about 50 polyploid species described in several families (Bogart, 1980; Mable et al., 2011; Evans et al., 2012; Schmid et al., 2015). Polyploids originate by autopolyploidization (intraspecies whole-genome duplication) or allopolyploidization (associ-ated with interspecific hybridization). Thus, individuals with an autotetraploid genome can originate by fusion of unreduced (i.e., diploids) gametes, or by suppression of the first mitotic division in fertilized eggs (Schmid et al., 2015). In recently evolved autopolyploids, the homolo-gous chromosomes of a quartet are expected to exhibit identical chromosome banding patterns in somatic meta-phases, leading to the multivalent formation during the first meiotic division. On the other hand, in an allopoly-ploid genome, if there are differences among the karyo-types of the parental species, the banding techniques or the genomic in situ hybridization (GISH) allow chromo-somes from parental species to be distinguished (Schwar-zacher et al., 1989), which will form bivalent configura-tions in meiosis (Schmid et al., 2015).In this study, the structure of polyploid karyotype O. americanus from a southern Brazilian population is described and subjected to comparative analysis in order to add new data regarding the speculated species complex. Additionally, the data are placed in an evolutionary context, thus contributing to a better understanding of the evolutionary scenario concerning ploidy levels in this group.Cytogenetic analyses were carried out on six juveniles of O. americanus collected in União da Vitória, Paraná State, Brazil (26º13’48”S and 51º05’09”W). Chromosome preparations were performed directly from bone marrow, according to Baldissera et al. (1993). Briefly, the animals received intraperitoneal injection of aqueous solution of colchicine (0.01 ml/g body weight) 1% per 6 h, and then subjected to deep sedation euthanasia by dermal absorp-tion of Lidocaine 5% pomade, following the recommen-dations of the Ethical Committee in Animal Use from Universidade Estadual do Paraná.


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