Identification of female heterogamety in a frog with undifferentiated sex chromosomes using 3RAD markers

GAMA JOANA DE MOURA; FERRO JM; LOURENÇO LB

Curitiba, Paraná

Congreso; VIIª Reunião Brasileira de Citogenética e Citogenômica; 2023

TheP. cuvieri-P. ephippifer species complex is composed of P. ephippiferand at least four other lineages genetically related to P. cuvieri.Physalaemus ephippifer has heteromorphic sex chromosomes Z and W,while its sister species (lineage L1) does not show differentiatedsex chromosomes. Chromosomal markers suggest the homeology between L1chromosomes 9 and P. ephippifer sex chromosomes, but the sexchromosome system (SCS) in L1 remains unknown. Restrictionsite-associated DNA sequencing (RAD-seq) has been increasingly usedto identify male or female heterogamy, especially in cases withundifferentiated sex chromosomes, as L1. Thus, to infer whether L1has a XX/XY or a ZZ/ZW SCS, sex-linked markers were identified fromcomparative analyses of 3RAD libraries constructed from 7 males and 3females of L1. For comparative purposes, we also analyzed 3RADlibraries from 5 males and 4 females of P. ephippifer. An averagenumber of 9 and 6 million reads were analysed for P. ephippifer andL1 individuals, respectively. A comparative analysis using theRADtools pipeline, was performed to recover candidate sex associatedloci for these species. First, tags for each individual weregenerated from forward reads through the RADtags module (clusterdistance = 10,quality threshold = 20, read threshold = 5). The locifrom each individual were compared across all individuals byRADmarkers module (mismatches = 2, tag count threshold = 4). Thefinal output was filtered to eliminate false positives, allowing theidentification of sex-specific markers. An abundance offemale-specific markers was found in both cases, suggesting thepresence of ZZ/ZW sex-determination systems. A total of 39female-specific markers and 6 male-specific markers were recognizedfor P. ephippifer, and 49 female-specific markers and 1 male-specificmarker were found for L1. The 3RAD analysis corroborates the P.ephippifer SCS and determine a similar system in L1, highlighting theoccurrence of two sister species with sex chromosomes in differentstages of differentiation.p { line-height: 115%; text-align: left; orphans: 2; widows: 2; margin-bottom: 0.1in; direction: ltr; background: transparent }a:link { color: #000080; text-decoration: underline }a:visited { color: #800000; text-decoration: underline }