A comparative study of mitotic and meiotic chromosomes of the Montandon's newt,Triturus montandoni (Urodela: Salamandridae) from Poland and Rumania

Abstract

A karyological analysis was carried out on two populations of Triturus montandoni, one from Poland and another from Rumania. For both samples, morphometric characteristics and C-banding pattern of mitotic chromosomes are provided. Only slight differences between specimens from two geographic localities were found.Data on chiasma frequency and distribution are presented for male meiosis. No sex-related heteromorphism was found and for none of the chromosomal arms was a consistent absence of chiasmata recorded. There was a relatively high proportion of spermatocyte metaphases I with chiasmata on both arms of all chromosomes in all specimens studied. It is concluded that there are no well-defined sex chromosomes in the chromosomal complement of the male T. montandoni.The findings are compared with previous studies on chromosome morphology, C-banding pattern, and meiosis in closely related species, T. vulgaris and T. helveticus.

Linkage Map ofLissotritonNewts Provides Insight into the Genetic Basis of Reproductive Isolation

“…The former explanation is supported by ample cytogenetic evidence. All Lissotriton species have 12 chromosome pairs and ∼1 chiasma per chromosomal arm in meiosis ( Wickbom 1945 ; Watson and Callan 1963 ; Barsacchi et al 1970 ; Herrero and López-Fernández 1986 ; Zbożeń and Rafiński 1993 ), which predicts a map length of ∼1200 cM, slightly shorter than reported here. However, the number of chiasmata in Lissotriton is at the lower end of the scale observed in salamanders ( Table 3 ), which typically have more than one chiasma per chromosome arm ( Wickbom 1945 ; Callan and Spurway 1951 ), even in excess of four in A. mexicanum ( Callan 1966 ).…”

“…Strong reduction of recombination in L. montandoni × L. vulgaris hybrids is unlikely for two reasons. First, the karyotypes of the parental species are very similar indicating a lack of major chromosomal rearrangements ( Zbożeń and Rafiński 1993 ; Zbożeń 1997 ). Second, in hybrid males, meiotic recombination assessed by cytogenetic methods is similar to males of pure parental species ( Zbożeń 1997 ).…”

“…Because salamanders exhibit genomic gigantism ( Gregory 2015 ), a causal relationship between the genome size and map length was suggested ( Smith et al 2005 ). However, although salamanders share large genome size and most families have similar numbers of chromosomes ( Sessions 2008 ), the number of chiasmata per chromosomal arm varies considerably between taxa ( Callan 1966 ; Herrero and López-Fernández 1986 ; Zbożeń and Rafiński 1993 ). Lissotriton newts are at the lower end of this continuum, with ∼1 chiasma per chromosomal arm.…”

Differential introgression across newt hybrid zones: Evidence from replicated transects

“…Most notably, more extensive introgression was inferred on LG4. Lissotriton newts have poorly differentiated, recombining sex chromosomes (Zbożeń & Rafiński, ) so we were not able to test for reduced introgression of X‐linked genes, a phenomenon observed in multiple studies (reviewed by Payseur & Rieseberg, ). Overall, we did not find much evidence for systematic differences in reproductive isolation between Lm and the two lineages of Lv involved in hybridization in the IN and OUT zones.…”