Polymorphism of a satDNA in a zone of secondary contact of lineages with distinct sex chromosomes

BONFIM LHS; GATTO KP; FERRO JM; DE SÁ FP; LOURENÇO LB

Praga

Congreso; ESEB-Congress of the European Society for Evolutionary Biology; 2022

The species complex Physalaemus cuvieri–Physalaemus ephippifer consists of fivemajor lineages and presents a wide karyotype diversity. Curiously, only P. ephippifer hasheteromorphic Z and W chromosomes. Incongruences between mitochondrial DNA and3RAD datasets suggested the existence of a secondary contact zone (CZ) between P.ephippifer and Lineage 1 of “P. cuvieri” (L1). However, previous cytogenetic analyses ofthis CZ failed to identify F1 hybrids and showed heteromorphic Z and W resembling P.ephippifer, although they were not identical, suggesting no current hybridization. Tobetter characterize this CZ, we analyzed the distribution of clusters of PcP190 satDNA,which is known to vary considerably between the parental lineages, being mapped to 3p,Zq and Wq of P. ephippifer and to centromere/pericentromere of all chromosomes of L1.We mapped PcP190 satDNA to karyotypes of specimens from three Brazilian localities ina transect, including a CZ between P. ephippifer and L1. We found a clinal variation inthe number of PcP190 clusters and several PcP190 sites were present in aheterozygous condition. The lowest number of chromosomes carrying PcP190 clusters(4 to 9) were found in a site near P. ephippifer occurrence areas, whereas the highestnumbers (13 to 17) were found in specimens from a locality close to L1 areas.Additionally, PcP190 mapping differed the sex chromosomes found in CZ from thoseof P. ephippifer. Our findings reinforce the hypothesis of ancient hybridization between P.ephippifer and L1, which may have driven a fast sex chromosome evolution in this group.