Knysna dwarf chameleons: city vs. forest habitat

Knysna dwarf chameleons: city vs. forest habitat

by Alex Negro Science

How do chameleons change when their natural habitat has to make way for human settlements? International scientists recently got to the bottom of this question. They hypothesised that a chameleon living in a suburban area must differ from its forest-dwelling conspecifics in terms of injury frequency, external characteristics and bite force as an expression of changed living conditions.

Between 2020 and 2022, 276 Knysna dwarf chameleons (Bradypodion damaranum) were studied in South Africa. The locations chosen were George and Knysna, two towns located around 60 kilometres apart on the south coast of South Africa. George was founded in 1811 and now has over 220,000 inhabitants, while Knysna was founded in 1825 and currently has just under 76,000 inhabitants, although they live in much less space and are therefore much more densely populated. In both cities, Bradypodion damaranum were caught in urban environments (private gardens, public parks, roadsides), examined and then released. Chameleons were also studied 10 to 12 kilometres away in their natural habitat (temperate forest). The adult chameleons were measured and photographed. The data was analysed and compared using various methods. Wounds, scars and bone fractures visible to the naked eye were counted as injuries. To measure bite force, the animals were each encouraged to bite five times on a special piezoelectric measuring device.

The analysis showed that the dwarf chameleons in urban environments had significantly lower casques and shorter gulars. The males from the city, however, had larger and wider heads. The female dwarf chameleons from the forest had significantly larger casque spurs. The males in the city had significantly more injuries (88.1%) compared to the males in the forest (72.5%). In the city, the dwarf chameleons also bit harder than in the forest when casque height and parietal crest were included in the calculations. However, when snout-vent length was included instead, there was no difference in bite force.

Differences between urban and natural populations of dwarf chameleons (Bradypodion damaranum): a case of urban warfare?
Melissa A. Petford, Anthony Herrel, Graham J. Alexander, Krystal A. Tolley
Urban Ecosystems 2023
DOI: 0.1007/s11252-023-01474-1

Development of sexual characteristics in African chameleons

Development of sexual characteristics in African chameleons

by Alex Negro Science

Many chameleons show strong sexual dimorphism, meaning that the males look very different from the females of the same species. Bright colours, dorsal sails and bizarre rostral appendages are among the best-known sexual characteristics. However, exactly when the different characteristics developed in chameleons is largely unexplored. A publication by two US scientists now addresses this issue.

The two researchers collected morphological data from two standard works on African and Malagasy chameleons, which they then analysed together with phylogenetic trees. They identified eleven sexual characteristics that could be of interest for intraspecific behaviour: Casque, rostral appendages, supraorbital appendages, occipital lobes, dorsal crest, dorsal spines, gular crest, gular spines, ventral crest, tail crest and tail spines.

Surprisingly, there was no difference between the sexes in terms of the frequency with which traits were acquired or lost throughout evolution. Whether there is a connection to the habitat of the respective species is evaluated contradictorily. The oldest sexual characteristics include the rostral appendages and dorsal crest in males, which were acquired at least 65 million years ago. In contrast, the oldest sexual characteristics in females were the casque and dorsal crest. Six of the eleven features (rostral appendages, supraorbital appendages, dorsal crest/spines, caudal crest/spines) first appeared in males and only 15 million years later on average in females. In males, the number of sexual characteristics correlated significantly with snout-vent-length.

The genera Trioceros (up to 10 features in one species), Chamaeleo and Furcifer (up to seven features each in one species) showed a particularly high number of sexual characteristics at the same time. In contrast, there were particularly few sexual characteristics in the genera Brookesia, Calumma and Rieppeleon. None of the eleven sexual characteristics could be identified in the females of the genera Furcifer, Kinyongia, Nadzikambia and Rhampholeon; presumably they have lost these characteristics in the course of evolution.

Macroevolution of sexually selected weapons: weapon evolution in chameleons
Melissa Van Kleeck-Hann & John J. Wiens

Evolution 70 (10), 2023, pp. 2277-2290
DOI: 10.1093/evolut/qpad138

Panther chameleons looking for new homes

Panther chameleons looking for new homes

by Alex Negro Abzugeben General topics

A long-standing member of the AG Chameleons is looking for new owners for ten panther chameleons (Furcifer pardalis) at short notice. There are ten females, including animals between 10 months and three years old. Four females belong to the local form Ambilobe, five to the local form Sambava. The animals are available individually or in groups free of charge. If you are interested, please write to us at info@agchamaeleons.de for further information.

Lecture for vets on prophylaxis for chameleons

Lecture for vets on prophylaxis for chameleons

by Alex Negro Tiermedizin Webinars

On 18 November 2023, the spokesperson of the AG Chameleons will give a lecture for veterinary colleagues on which prophylactic measures are possible and useful in veterinary practice. To a large extent, prophylaxis includes keeping the chameleons in the terrarium itself, so a large part of the lecture will deal with what needs to be considered when keeping chameleons and which common mistakes still lead to husbandry-related diseases or injuries in chameleons. She will also discuss the collection of the so-called minimum database during the annual check-up in the veterinary practice and show examples of diseases recognised early and late. A Q&A session directly after the respective presentations rounds off the short excursion into prophylaxis in chameleons.

Registration for the conference is also possible for non-DGHT members who are veterinarians – see the link below to the mVet conference platform.

Dr. Alexandra Laube Prophylaxis for chameleons – is it possible and if so, how?
59. Conference of DGHT working group amphibian and reptile diseases (AG ARK)
Online

Photo: Calumma amber in the Montagne d’Ambre, Madagascar, photographed by A. Laube

Lecture in Ulm about Spain

Lecture in Ulm about Spain

by Alex Negro Reiseberichte Live lectures

Heiko Werning, known as the editor of Reptilia and columnist for the taz, will be giving an illustrated lecture on 18 November 2023 in Neu-Ulm (Bavaria) about not only, but also chameleons in Spain.

On an exciting journey across Spain, he will show how many reptiles and amphibians the European country has to offer. And the diversity is impressive! Heiko’s journey begins in the Basque Country and then leads through Galicia to northern Castile with its beautiful salamanders. In the central Spanish mountain ranges, the herpetologist encounters the quaint mountain lizards. A few hours’ drive west of Madrid, in Extremadura, Heiko finds himself among vultures in the truest sense of the word. And on the southern Spanish Atlantic coast, he finally encounters the European chameleon and its habitat. Finally, Heiko takes his viewers to south-east Spain, where he has found, among other things, Moorish tortoises and the European fringed finger in the only desert in Europe. All in all, a colourful firework display of images and entertaining anecdotes – every reptile lover should get their money’s worth here!

Heiko Werning The Spanish mainland – A destination (also) for herpetological gourmets
DGHT City Group Ulm
Il Mio Ristorante
Europastraße 15
89231 Neu-Ulm
Meeting from 6.30 pm

Histology of the chameleon liver

Histology of the chameleon liver

by Alex Negro Tiermedizin Science

Histological examinations of organ tissue are part of every pathological examination in veterinary medicine. They are also frequently carried out in reptiles, but there are few studies on the histology of healthy organ tissue. An Arabic publication now deals with histological sections of chameleon livers.

Seven adult Yemen chameleons were captured in Abha City in the Aseer region and then killed with ether inhalation. The livers were placed in formalin and then poured into paraffin to make sections.

Morphologically, the liver was found to be a two-lobed, dark brown organ approximately 3.7 x 2 cm in size, which lies in the coelomic cavity in front of the stomach and surrounds the gall bladder. As in other animals, a capsule of connective tissue surrounds the liver.

Histologically, the liver of Yemen chameleons resembles that of other vertebrates in many respects. The liver capsule consists of closely spaced collagenous fibres and smooth muscle fibres. Normally, trabecular connective tissue divides the liver itself into many small lobules, but such a structure does not appear to be present in Yemen chameleons. In contrast to mammals, the liver cells (hepatocytes) are not arranged radially around a vein, but rather irregularly in follicles or alveoli. The hepatocytes are surrounded by capillary blood vessels. So-called melanoma macrophages, which are not found in birds and mammals, can be seen in the blood vessels. The hepatocytes in the Yemen chameleon are polyhedral or pyramid-shaped and usually contain several large, round cell nuclei in the periphery. The nuclei contain conspicuously dark nucleoli. Occasionally nuclei are central. Under haematoxylin-eosin (HE) staining, the hepatocytes appear very eosinophilic. In the connective tissue, branches of the portal vein, hepatic artery, small bile ducts and lymphatic vessels could be visualised. Haematopoietic tissue was found in the area directly under the liver capsule.

In addition to the histological examination, several pieces of liver were also examined using transmission electron microscopy. Images of both examination methods can be found in the publication.

Histomorphological, histochemical and ultrastructural studies on the healthy liver of Yemen Veiled Chameleon (Chamaeleo calyptratus) in Southern Saudi Arabia
Amin A. Al-Doaiss, Mohammed A. Alshehri, Ali A. Shati, Mohammad Y. Alfaifi, Mohammed A. Al-Kahtani, Ahmed Ezzat Ahmed, Refaat A. Eid, Laila A. Al-Shuraym, Fahd A. Al-Mekhlafi, Mohammed Al Zahrani, Mohammed Mubarak
International Journal of Morphology 41(5), 2023: pp. 1513-1526.
DOI: none

Image: Histological section of the liver of a Yemen chameleon from the above-mentioned publication

Presentation in Bern about Samos (Greece)

Presentation in Bern about Samos (Greece)

by Alex Negro Live lectures

Markus Grimm, long-time member of AG Chamäleons and entrusted for many years in Switzerland with conducting expert courses for chameleon keeping, will show a detailed lecture on the island of Samos (Greece) on 08 November 2023 in Bern (Switzerland).

The Greek island of Samos is located in the Eastern Aegean Sea and is only 1.2 km away from the Turkish mainland. It is precisely this geographical location that makes the island with its flora and fauna extremely diverse and exciting. A pinch of culture, integrated into the nature of the plants, with a bouquet of orchids, surrounded by countless animals such as birds, insects, spiders, scorpions, amphibians and reptiles make up the recipe for this lecture. Markus Grimm has been visiting the island of Samos for more than 25 years, always discovering something new. His first visit to Samos was to see the European Chameleon. But it didn’t stop there and so the fauna and flora of this unique island became a part of his life.

Markus Grimm Samos – Die griechische Natur hautnah
SIGS Sektion Bern
Restaurant Kreuz
Jegenstorf (Schweiz)
Vortragsbeginn 20.00 Uhr

Foto: Markus Grimm

Genome of South African dwarf chameleons decoded

Genome of South African dwarf chameleons decoded

by Alex Negro Science

After a reference genome for the panther chameleon (Furcifer pardalis) was recently published for the first time in China, scientists from South Africa have now followed with the genome of two dwarf chameleon species.

For the analyses, a male Bradypodion pumilum from Cape Town and a male Bradypodion ventrale from an introduced population in Johannesburg were taken. Muscle and liver tissue was used for long sequencing (HiC). The genome size of Bradypodion pumilum is 2.43 gigabase pairs (Gb), that of Bradypodion ventrale 2.40 Gb. The BUSCO analysis demonstrated a high completeness with about 97% of all existing coding genes in vertebrates. Furthermore, the current publication confirms the six macrochromosomes already found from the karyotype in Bradypodion thamnobates 2017. Various comparisons with Anolis sagrei were made. It remains open which chromosomes in Bradypodion are sex chromosomes.

The genomes can be viewed in the NCBI BioProject under the number PRJNA9861319 and under the BioSample numbers SAMN35825189 and SAMN35825190 respectively.

De novo whole genome assemblies for two Southern African Dwarf Chameleons (Bradypodion, Chamaeleonidae)
Jody M. Taft, Krystal A. Tolley, Graham J. Alexander, Anthony J. Geneva
Genome Biology and Evolution 15 (10), 2023, pp. 1-8
DOI: 10.1093/gbe/evad182

Presentation in Mönchengladbach about South Africa

Presentation in Mönchengladbach about South Africa

by Alex Negro Reiseberichte Live lectures

On Friday, 3 November 2023, Reinhard Münzer will give a lecture on a trip to South Africa that is not just about herpetology. The country, which is 3.4 times the size of Germany and has a diverse natural environment, offers the best conditions for exciting and varied discoveries. The lecture will not only show reptiles, but of course also the Big Five.

Reinhard Münzer Travel impressions South Africa
DGHT regional group Mönchengladbach/Krefeld
Vereinsheim SC 08 Schiefbahn
Siedlerallee 27
47877 Willich-Schiefbahn
Meeting from 7.30 pm, presentation starts at 8.00 pm

Picture: Reinhard Münzer