Naturally occurring triploids in contact zones between diploid/tetraploid Odontophrynus cordobae and O. americanus (Anura, Odontophrynidae)

GRENAT, PABLO R.; SALAS, NANCY E.; POLLO, FAVIO, E.; OTERO, MANUEL A.; BARAQUET, MARIANA; SINSCH, ULRICH; MARTINO, ADOLFO L.

AMPHIBIA-REPTILIA

BRILL ACADEMIC PUBLISHERS

Lugar: Leiden; Año: 2018 vol. 39 p. 1 - 10

0173-5373

Polyploidization plays an important role in speciation and evolution inanurans. However, a few stable triploid populations and some isolated triploidindividuals have been reported. Here, we report the discovery of naturally occurring triploids incontact zones between diploid Odontophrynuscordobae and tetraploid O. americanusfrom Central Argentina, and propose values of erythrocyte area for thedistinction of ploidy levels. A total of 101 individuals from three contactzones were studied and ploidy of each specimen was identified by mean chromosomecount and erythrocyte size. Twentythree adult triploidspecimens (males: n=21; females: n=2) from two contact sites wereidentified (percentage of individuals per ploidy level: site S2, 2n=40.6%, 3n=12.5%, 4n=46.9%;site S3: 2n=44.7%, 3n=40.4%, 4n=14.9%). The limit values of erythrocyte nuclear area usedto distinguish between different ploidy levels were 23.62 μm² (probability tobe assigned to a respective ploidy level =94.78%) for separating diploids andtriploids and 27.67 μm² (98.62%) for triploids and tetraploids. The high number of adult triploids occurringin more than one contact site between O. cordobae and O. americanusindicates that is not an isolated event. However, further studies are necessaryto provide a hypothesis on the origin and evaluatethe possible maintenance of triploids in syntopy with O. cordobae and O. americanus