A new diploid species arises through interspecies hybridisation.


Interbreeding between species is more widespread than scientists could imagine – up until recently have they discovered that hybridisation can trigger a new species formation, a process by which a new reproductively isolated species arises combining parts of the parental genomes with a different karyotype, namely the number and appearance of chromosomes in the complete set.

The new diploid genome is like a transformer: hybridisation of chromosomally divergent parental species results in the fixation of a novel combination of chromosome in hybrid descendants, drastically rearranged in terms of chromosome number, but without a lack or surplus in ploidy. Hybridisation resulted in the origin of reproductive isolation between hybrid and parental forms, which, in turn, leads to the formation of a new diploid genome. Interestingly, the new diploid genome has the same set of chromosomes as humans do, namely the diploid set of chromosomes. – The genome is generally characterised in terms of the content, e.g. a set of genes that encode genetic information, and form, e.g. the number and appearance of the chromosomes. The discovery proves a creative role of hybridisation in the origin of a species formation without change in terms of the content, but different karyotipic number, which ensures the formation of a new species, — accounted for the research results Vladimir A. Lukhtanov, Professor of SPbU.

The research sample was represented by three species of Agrodiaetus butterflies.  As far as 30 years ago, Vladimir A. Lukhtanov and his colleagues delved into the investigation of this group of insects, including research on karyotype. Among all the complex animals, Lycaenidae appeared to have the largest number of chromosomes, ranging from 20 to 268.  Besides, the genus comprises a number of evolutionally new forms (new species, subspecies and populations which remain of uncertain status), in their genomes there can be traced signs of recent evolution. Based on the molecular phylogenetic techniques, the analysis of the evolutionary relationships promotes advances in evolutionary biology.

The research results have been published in Proceedings of the Royal Society B, a world`s leading academic journal, published by the Royal Society in London.