Mosquito populations give a new insight into the role of Caucasus in evolution

We know that the Caucasus is a relatively large mountainous region, situated between Black and the Caspian seas. In its turn, it is divided into three subregions: Ciscaucasia, Greater Caucasus and Transcaucasia, also known as South Caucasus.

A closer look into the chromosome structure of mosquito larvae of a curious group of species (Chironomus “annularius” sensu Strenzke (1959)), collected from the three localities, has allowed Dr Mukhamed Karmokov of the Tembotov Institute of Ecology of Mountain territories at the Russian Academy of Science to figure out how the specificity of the Caucasian region has simultaneously unified its fauna geographically, yet has divided it evolutionarily. His paper is published in the open access journal Comparative Cytogenetics.

Having collected a sufficient amount of mosquito larvae, the researcher managed to study the chromosome structure, rearrangements and possible peculiarities of the separate Caucasian populations, in order to compare them.

Additionally, he analysed their relations to earlier known populations from Europe, Siberia, Kazakhstan and North America.

Amongst the curious peculiarities Karmokov identified in the chromosome structure of the studied larvae were some rearrangements which appear unique to Caucasus. Furthermore, he found that despite the close geographic proximity, the genetic distance between the Caucasian populations is quite significant, even While not enough to determine them as separate species, it could prove them as separate subspecies.

In conclusion, the scientist notes that the obtained data confirm that the Caucasian populations of the studied species have complex genetic structure and provide evidence for microevolution processes in the region.

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Original source:

Karmokov MKh (2018) Karyotype characteristics and chromosomal polymorphism of Chironomus “annularius” sensu Strenzke (1959) (Diptera, Chironomidae) from the Caucasus region. Comparative Cytogenetics 12(3): 267-284. https://doi.org/10.3897/CompCytogen.v12i3.25832

New butterfly species discovered in Russia with an unusual set of 46 chromosomes

What looked like a population of a common butterfly species turned out to be a whole new organism, and, moreover – one with a very peculiar genome organisation.

Discovered by Vladimir Lukhtanov, entomologist and evolutionary biologist at the Zoological Institute in St. Petersburg, Russia, and Alexander Dantchenko, entomologist and chemist at the Moscow State University, the startling discovery was named South-Russian blue (Polyommatus australorossicus). It was found flying over the northern slopes of the Caucasus mountains in southern Russia. The study is published in the open access journal Comparative Cytogenetics.

“This publication is the long-awaited completion of a twenty-year history,” says Vladimir Lukhtanov.

In the mid-nineties, Vladimir Lukhtanov, together with his students and collaborators, started an exhaustive study of Russian butterflies using an array of modern and traditional research techniques. In 1997, Alexander Dantchenko who was mostly focused on butterfly ecology, sampled a few blue butterfly specimens from northern slopes of the Caucasus mountains. These blues looked typical at first glance and were identified as Azerbaijani blue (Polyommatus aserbeidschanus).

However, when the scientists looked at them under a microscope, it became clear that they had 46 chromosomes – a very unusual number for this group of the blue butterflies and exactly the same count as in humans.

Having spent twenty years studying the chromosomes of more than a hundred blue butterfly species and sequencing DNA from all closely related species, the researchers were ready to ascertain the uniqueness of the discovered butterfly and its chromosome set.

Throughout the years of investigation, it has become clear that caterpillars of genetically related species in the studied butterfly group feed on different, but similar plants. This discovery enables entomologists to not only discover new butterfly species with the help of botanic information, but also protect them.

“We are proud of our research,” says Vladimir Lukhtanov. “It contributes greatly to both the study of biodiversity and understanding the mechanisms of biological evolution.”

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Original source:

Lukhtanov VA, Dantchenko AV (2017) A new butterfly species from south Russia revealed through chromosomal and molecular analysis of the Polyommatus (Agrodiaetus) damonides complex (Lepidoptera, Lycaenidae). Comparative Cytogenetics 11(4): 769-795. https://doi.org/10.3897/CompCytogen.v11i4.20072

New butterfly species discovered in Israel for the first time in 109 years

Vladimir Lukhtanov, entomologist and evolutionary biologist at the Zoological Institute in St. Petersburg, Russia, made a startling discovery: what people had thought was a population of a common species, turned out to be a whole new organism and, moreover – one with an interesting evolutionary history. This new species is named Acentria’s fritillary (Melitaea acentria) and was found flying right over the slopes of the popular Mount Hermon ski resort in northern Israel. It is described in the open access journal Comparative Cytogenetics.

“To me, it was a surprise that no one had already discovered it,” says Vladimir Lukhtanov.

“Thousands of people had observed and many had even photographed this beautifully coloured butterfly, yet no one recognised it as a separate species. The lepidopterists (experts in butterflies and moths) had been sure that the Hermon samples belonged to the common species called Persian fritillary (Melitaea persea), because of their similar appearance, but nobody made the effort to study their internal anatomy and DNA”.

In 2012, Vladimir Lukhtanov, together with his students, initiated an exhaustive study of Israeli butterflies using an array of modern and traditional research techniques. In 2013, Asya Novikova (until 2012, a master’s student at St. Petersburg University and, from 2013, a PhD student at the Hebrew University, Jerusalem) sampled a few fritillaries from Mt. Hermon.

It was at that time when the researchers noticed that the specimens “didn’t look right” – their genitalia appeared different from those of the typical Persian fritillary. Over the next few years, Lukhtanov and his students studied this population in-depth. They carried out sequencing DNA from the specimens and found that they had a unique molecular signature – very different from the DNA of any other fritillary.

The Acentria’s fritillary seems to be endemic in northern Israel and the neighbouring territories of Syria and Lebanon. Its evolutionary history is likely to prove interesting.

“The species is probably one of a handful of butterflies known to have arisen through hybridisation between two other species in the past,” says Lukhtanov. “This process is known to be common in plants, but scientists have only recently realised it might also be present in butterflies.”

This is the first new butterfly species discovered and described from the territory of Israel in 109 years.

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Original source:

Lukhtanov VA (2017) A new species of Melitaea from Israel, with notes on taxonomy, cytogenetics, phylogeography and interspecific hybridization in the Melitaea persea complex (Lepidoptera, Nymphalidae). Comparative Cytogenetics 11(2): 325-357. https://doi.org/10.3897/CompCytogen.v11i2.12370