Genetics: Karyotype in the Veiled Chameleon

Genetics: Karyotype in the Veiled Chameleon

by Alex Laube Science

It has been known for some time that the sex of the Veiled chameleon (Chamaeleo calyptratus) is genetically determined. The species has an XX/XY system. Scientists from Russia, Great Britain, Italy, and Thailand have now studied the karyotype of the species, i.e. the characteristics of the chromosomes.

The probably most original karyotype of all chameleons is 2n= 36. This “primal chameleon” had six pairs of metacentric macrochromosomes and twelve pairs of microchromosomes, particularly small chromosomes. The Veiled chameleon, on the other hand, has a smaller number of chromosomes, namely only 2n=24. Using various genetic investigation methods, the researchers in the present study found that this karyotype probably arose through fusions. Microchromosomes apparently fused with each other twice, and micro- and macrochromosomes fused no less than four times. The latter, the so-called heterogeneous fusion between chromosomes of different sizes, is unusual for vertebrates. Normally, macro- and microchromosomes are located at different locations in the cell nucleus and are transcribed and replicated at different rates. However, this phenomenon is already known from alligators and turtles – for chameleons it is new.

Until now, it was also unclear which pair of chromosomes in the Veiled chameleon is actually responsible for the sex. In Chamaeleo chamaeleon, the second largest chromosome pair codes for sex. However, initial speculation suggests that in the Veiled chameleon the fifth chromosome pair (CCA5) may instead be the sex chromosome pair. The conjecture still needs to be validated by further research. It is also still up for discussion which gene is actually predominantly responsible for the development of the sex organs in the embryo – the researchers identified at least three possible genes on CCA5.

Identification of Iguania ancestral syntenic blocks and putative sex chromosomes in the Veiled Chameleon (Chamaeleo calyptratus, Chamaeleonidae, Iguania)
Katerina V. Tishakova, Dmitry Yu. Prokopov, Guzel I. Davletshina, Alexander V. Rumyantsev, Patricia C. M. O’Brien, Malcolm A. Ferguson-Smith, Massimo Giovannotti, Artem P. Lisachov, Vladimir A. Trifonov
International Journal of Molecular Sciences 23, December 2022
DOI: 10.3390/ijms232415838

Fossil finds of Chamaeleo chamaeleon in Morocco

Fossil finds of Chamaeleo chamaeleon in Morocco

by Alex Laube Science

There have only been a few fossil finds of reptiles from Morocco so far, especially concerning Agama bibronii and Chamaeleo chamaeleon. Archaeologists from the National Institute of Archaeology and Cultural Heritage (Institut National des Sciences de l’Archéologie et du Patrimoine, INSAP) in Rabat, Morocco, have now published an overview of Moroccan finds.

The rock cave of Ifri n’Ammar belongs to the Rif mountain range, which runs about 50 km away from the northeast coast of Morocco and is part of the Atlas Mountains. Ifri n’Ammar is located in a valley south of the town of Afso, on the border of two wadis. Since 1997, excavations have been led there by INSAP and the German Commission for Archaeology of Non-European Cultures (KAAK). Two Os prefrontale, two Os postorbitofrontale, three Os maxillare (upper jaw), six pieces of bone with acrodont teeth, and three vertebrae could be assigned to the family Chamaeleonidae so far. The distinction from fossil remains of agamas was quite clear: agamas have pleurodont teeth in the anterior region of the maxilla, whereas chameleons have only acrodont teeth. In addition, the shape and position of the nostrils differ. Agamas also do not have the bony tubercles and “crests” typical of chameleons. Since Chamaeleo chamaeleo is the only representative of the chameleons found in the Maghreb today, the fossils were attributed to this species.

The fossils were all found in a layer at a depth of three meters, which is assigned to the Middle Stone Age. The fossil remains are therefore between 83,000 and 171,000 years old, which is considerably older than the remains discovered so far for chameleons in Morocco (Tarofalt, Guenfouda) and Algeria (Gueldaman). The archaeologists assume that at that time the area around the site must have still been tree-covered.

It is partly questionable how the pieces of bone from Ifri n’Ammar arrived at the finding sites. Traces on some bones indicate digestion processes and thus that the associated chameleons were consumed as prey. So not all of the chameleons found there died a natural death. According to the traces, birds of prey and small carnivores such as the gundi (a North African rodent) or simply rats could be possible predators.

Agama bibronii (Sauria: Agamidae) et Chamaeleo chamaeleon (Sauria: Chamaeleonidae) d’Ifri n’Ammar (Rif oriental, Maroc)
Touria Moushine, Fethi Amani, Abdeslam Mikdad
Quaternaire 33 (03), 2022
DOI: 10.4000/quaternaire.16948

Chamaeleo chamaeleon in Turkey

Chamaeleo chamaeleon in Turkey

by Alex Laube Science

The European chameleon Chamaeleo chamaeleon inhabits a range that extends from North Africa through southern Portugal and Spain as well as Cyprus and Malta to Lebanon, Syria and Turkey. So far, however, very little is known about the populations in Turkey.

Turkish biologists have recently undertaken the first small study to change this state. They examined 29 European chameleons for their snout-vent-length and, using skeletochronology, for their age. 15 of them were males, 14 females. The animals studied were museum specimens from Dokuz Eylül University. They were collected in the surroundings of the Akyatan lagoon at earlier times. Akyatan is located in the south of Turkey directly on the Mediterranean Sea, about 200 km from the Syrian border. The nearest major Turkish cities are Mersin and Adana.

The average head-torso length of Chamaeleo chamaeleon from Akyatan was 85.34 mm, with females slightly larger than males. The smallest chamaeleon measured 59.71 mm, and the largest 106.84 mm. Thus, the studied population in Akyatan seems to be possibly somewhat smaller than the comparative populations in Spain and Egypt. However, the numbers of animals examined are too small to be able to make reliable statements about this. The age of the animals was between two and four years. The males reached sexual maturity after the first hibernation, while the females did not reach sexual maturity until the second year of life.

Age and body size of the Mediterranean Chameleon, Chamaeleo chamaeleon (Linnaeus 1758) (Lacertilia: Chamaeleonidae) specimens collected from Adana, Türkiye
Elif Yildirim, Nurettin Beşer, Can Yilmaz, Kamil Candan, Yusuf Kumlutaş, Çetin Ilgaz, Elnaz Najafi Majd
Commagene Journal of Biology
DOI: 10.31594/commagene.1104020

New publication: A book about the European Chameleon

New publication: A book about the European Chameleon

by Alex Laube Book publications

“The common chameleon – Chamaeleo chamaeleon” fills a small gap in the reptile book market, because until now there was no comparable book dealing only with this species. The authors are Jürg Meier, professor emeritus of zoology at the University of Basel in Switzerland and member of the AG Chamäleons, Juan Pablo González de la Vega, herpetologist from Andalusia and Joaquín Santaolalla, head of the Biodiversity Control Centre at the Málaga Veterinary Office.

At the beginning of the book, the species Chamaeleo chamaeleon is introduced, its habitat and the differences to Chamaeleo africanus, the second chameleon species native to Europe. The rest of the first half of the book then deals mainly with basic knowledge about chameleons in general. The body structure, the modified hands and feet, the highly specialised eye, the ability to change colour and the famous tongue shot are discussed among other things. Again and again, results from scientific studies are incorporated into the text. The second half of the book deals with the life cycle and occurrence of Chamaeleo chamaeleon. Predators are introduced, and mating and reproduction, as well as the different colour dresses of the animals, are explained. Photos of nest-building, egg-laying and hatching of the small chameleons complete the presentation of the species. Finally, the endangerment of the European chameleon and current conservation efforts in Spain are discussed. Many photos and graphics illustrate the text.

The book is aimed at laymen – people who do not know much about chameleons and would like to learn more. It is easy to read and easy to understand, only a few sections get a little lost in scientific terms. A bit of a pity is some pixelated and altogether very colourful graphics in the book, which detract from the valuable overall impression. Ultimately, however, this does not detract from the purpose of the book. It awakens enthusiasm for chameleons, especially among interested nature lovers who have had nothing to do with these fascinating reptiles until now. And that is exactly what it was designed for. The book is currently being used in Málaga as a small textbook in environmental lessons at school and as a purchasable read for curious travellers and locals.

The book is available in German and Spanish. It is self-published and can currently be obtained from the author (see below) or from the Chameleon Centre of the Veterinary Office of Málaga, Spain.

The common chameleon – Chamaeleo chamaeleon
Jürg Meier, Juan Pablo Gonzalez de la Vega, Joaquín Santaolalla
128 pages, Jumeba Sachbuch Verlag
ISBN 978-3-907338-00-1

20 € including shipping
Order under https://jumeba.ch/shop/ or directly via the first author j.meier@jumeba.ch