Chromosomal Evolution in the <b><i>Amolops mantzorum</i></b> Species Group (Ranidae; Anura) Narrated by Repetitive DNAs

Abstract

In an attempt to analyze the organization of repetitive DNAs in the amphibian genome, 7 microsatellite motifs and a 5S rDNA sequence were synthesized and mapped in the karyotypes of 5 Amolops species. The results revealed nonrandom distribution of the microsatellite repeats, usually in the heterochromatic regions, as found in other organisms. These microsatellite repeats showed rapid changes among Amolops species, documenting the recent evolutionary history within this lineage. In contrast, 5S rDNA was localized in chromosomes 5 of all species, suggesting that these chromosomes are homologous within the monophyletic clade. Furthermore, the heteromorphic X and Y sex chromosomes (chromosomes 5) of A.mantzorum, had identical patterns of 5S rDNA, indicating that the subtelocentric Y resulted from a pericentric inversion. Several microsatellite repeats were found in the heteromorphic sex chromosomes, verifying the association of repetitive DNAs with sex chromosome differentiation in A. mantzorum.

Assigning the Sex-Specific Markers via Genotyping-by-Sequencing onto the Y Chromosome for a Torrent Frog Amolops mantzorum

“…For A. mantzorum, the subtelocentric Y (chromosome 5) was formed with a large chromosome pericentric inversion [22,23], which could easily be identified with other chromosomes under light microscopy (Figure 1, Y chromosome microdissection). We completed Y chromosome isolation according to the protocol of Zimmer et al (1997) [24], and DNA amplification following the protocol of Yuan et al (2017) [25].…”

Heterogeneous Evolution of Sex Chromosomes in the Torrent Frog Genus Amolops

“…Finally, the sex-linked markers of eight of the nine Amolops species were successfully aligned to the genome of the sex chromosome (No. 5) of A. mantzorum , which was previously shown to be homologous among the A. mantzorum species group [ 40 , 41 ]. The results showed that, except for A. wuyiensis , of which only 13.8% of the sex-linked markers were successfully aligned, the majority of the sex-linked markers, ranging from 41.5% to 71.4%, were successfully mapped ( Figure S1; File S6 ).…”

Large X‐effects are absent in torrent frogs with nascent sex chromosomes

“…In which alleles show much lower F ST values between sexes in these frogs (Figure 3; Figures S6, S7 and S10a or Tables S5–S7), compared with those in animals with strongly degenerate sex chromosomes (Hooper et al, 2019; Moran et al, 2018; Schield et al, 2021; Van Belleghem et al, 2018). The previous cytogenetic investigations revealed that the similar sizes are maintained for X and Y homologues, although the pericentric inversion resulted in the subtelocentric Y compared with the metacentric X (Liu et al, 2019; Wu & Zhao, 1985). In fact, this heteromorphy is just involved in the centromere location changed but not concerning large‐scale structural differentiation or loss (Liu et al, 2017, 2019; Wu & Zhao, 1985; Zhang et al, 2015).…”

“…The previous cytogenetic investigations revealed that the similar sizes are maintained for X and Y homologues, although the pericentric inversion resulted in the subtelocentric Y compared with the metacentric X (Liu et al, 2019; Wu & Zhao, 1985). In fact, this heteromorphy is just involved in the centromere location changed but not concerning large‐scale structural differentiation or loss (Liu et al, 2017, 2019; Wu & Zhao, 1985; Zhang et al, 2015). In all four species investigated here, their Y chromosomes were evidenced to have continued to recombine within 1.94 million years, possibly leaving not enough time for Y chromosome degeneration (Ping et al, 2022).…”

“…In this study, we tested for a large X‐effect across hybrid zones between Amolops mantzorum species complex, a group of the torrent frog from Asian ranids in the Hengduan Mountain Region in southwestern China (Lu et al, 2014; Zeng et al, 2020). The sex of all these members investigated is determined by XY system with homomorphic sex chromosomes, except the species A. mantzorum which has heteromorphic ones, where the subtelocentric Y differs from the metacentric X by a pericentric inversion via cytogenetic investigations with fluorescence in situ hybridization (FISH) mapping of 5S rDNA (Liu et al, 2017, 2019; Ping et al, 2022). Here, we concentrate on patterns of introgression between four close relative species taxa, including A. jinjiangensis , A. xinduqiao , A. mantzorum , and A .…”