The Leptidea genus has always fascinated Roger Vila. In collaboration with a group of cytogenetic specialists from the Czech Republic, his research group has studied the sex determination system of these butterflies.

They observed significant differences in chromosome numbers and localization of genetic markers within the offspring of individual females. They also documented the presence of multiple chromosome fusions and/or fissions and other complex rearrangements. The analysis of female meiotic chromosomes revealed multiple sex chromosomes: W1W2W3Z1Z2Z3Z4 in L. juvernica, W1W2W3Z1Z2Z3 in L. sinapis and W1W2W3W4Z1Z2Z3Z4 in L. reali.

Multiple sex chromosome systems had been previously documented only in mammals (the Platypus case), fish and spiders. They also discuss the implications of such a dynamic karyotype for speciation in this complex of cryptic species.

Reference Article: Šíchová J, Voleníková A, Dincă V, Nguyen P, Vila R, Sahara K, and Marec F (2015). Dynamic karyotype evolution and unique sex determination systems in Leptidea wood white butterflies. BMC Evolutionary Biology.