Fissions, fusions, and translocations shaped the karyotype and multiple sex chromosome constitution of the northeast-Asian wood white butterfly,Leptidea amurensis

Abstract

Previous studies have shown a dynamic karyotype evolution and the presence of complex sex chromosome systems in three cryptic Leptidea species from the Western Palearctic. To further explore the chromosomal particularities of Leptidea butterflies, we examined the karyotype of an Eastern Palearctic species, Leptidea amurensis. We found a high number of chromosomes that differed between the sexes and slightly varied in females (i.e. 2n = 118–119 in females and 2n = 122 in males). The analysis of female meiotic chromosomes revealed multiple sex chromosomes with three W and six Z chromosomes. The curious sex chromosome constitution [i.e. W1–3/Z1–6 (females) and Z1–6/Z1–6 (males)] and the observed heterozygotes for a chromosomal fusion are together responsible for the sex‐specific and intraspecific variability in chromosome numbers. However, in contrast to the Western Palearctic Leptidea species, the single chromosomal fusion and static distribution of cytogenetic markers (18S rDNA and H3 histone genes) suggest that the karyotype of L. amurensis is stable. The data obtained for four Leptidea species suggest that the multiple sex chromosome system, although different among species, is a common feature of the genus Leptidea. Furthermore, inter‐ and intraspecific variations in chromosome numbers and the complex meiotic pairing of these multiple sex chromosomes indicate the role of chromosomal fissions, fusions, and translocations in the karyotype evolution of Leptidea butterflies.

A new butterfly species from south Russia revealed through chromosomal and molecular analysis of the Polyommatus (Agrodiaetus) damonides complex (Lepidoptera, Lycaenidae)

“…Previously, the low or no underdominance of chromosomal fusions/fissions was demonstrated for butterflies of the genus Leptidea Billberg, 1820 (Lukhtanov et al 2011, Šíchová et al 2015, 2016). In the Agrodiaetus subgenus the low underdominance of chromosomal fusions/fissions was indirectly demonstrated through analysis of homoploid hybrid speciation in P. karindus-P. morgani-P. peilei species complex (Lukhtanov et al 2015b).…”

“…1) COI differentiation. Fusions and fissions of chromosomes are the most probable rearrangements driving the chromosome number change in the P. damonides complex as well as in other butterfly species (Lukhtanov et al 2011, Šíchová et al 2015, 2016). In P. ninae , P. damonides gilanensis , P. arasbarani and P. lukhtanovi some of these fusions/fissions are found in heterozygous conditions resulting in trivalent formation at the MI stage.…”

Lack of gene flow: Narrow and dispersed differentiation islands in a triplet of Leptidea butterfly species

“…Moreover, both L. sinapis and L. juvernica are further subdivided into multiple geographically distinct ecotypes with complex habitat utilization preferences and life history characteristics, potentially reflecting variation in environmental conditions across the distribution ranges (Friberg, Leimar, & Wiklund, ; Friberg, Olofsson, et al, ; Friberg & Wiklund, , ). Leptidea sinapis also shows striking intraspecific chromosome number variation present in a cline with a gradual increase from 2 n ≈ 56–58 in the northern and eastern parts (Scandinavia–Kazakhstan) to 2 n ≈ 106–108 in the southwestern parts (Iberia) of the distribution range (Dincă et al, , ; Šíchová et al, , ). The exact mechanism behind this karyotype variation is unknown, but both visual inspection of metaphase spreads (Lukhtanov et al, ) and genome size analysis (Talla, Suh, et al, ) strongly suggest that this is a result of a large number of chromosome fissions/fusions rather than whole or partial genome duplications.…”

Flow cytometry may allow microscope-independent detection of holocentric chromosomes in plants

“…These features, and the absence of a centromere, substantially affect genome and karyotype evolution10111213141516 and make holocentric lineages useful model systems for studying various evolutionary phenomena, such as recombination rates and adaptability17, meiotic drive1819, sex-chromosome evolution202122 and homoploid hybridization232425.…”