What influences colour patterns in chameleons

What influences colour patterns in chameleons

by Alex Negro Science

Chameleons are known for their ability to change colour. International scientists have now investigated what exactly influences different colour patterns in different populations. They want to know to what extent the habitat itself, the distance to other populations or social interactions influence the colour change.

The test subjects were European chameleons (Chamaeleo chamaeleon) caught in La Herradura and Sanlúcar in Spain. The two regions are around 230 kilometres apart. Other Chamaeleo chameleon were collected in the north-western Negev and on the Carmel coast in Israel (around 180 km apart). On the other hand, flap-necked chameleons (Chamaeleo dilepis) were captured in Simbithi, Zulu Falls and Maduma Boma in South Africa. The three locations are between 100 and 550 kilometres apart.

Each chameleon was subjected to two experiments. In the first, the scientists let the chameleon walk two metres on a horizontal stick, which was placed in the sun about one metre above the ground. In the second experiment, a second chameleon of the same species was placed on the same stick 50 cm away from the first. The colour patterns shown by the animal during the experiments and its behaviour were recorded for 20 minutes. The data was then analysed using computer programs. Blood was taken from a cut claw of all chameleons and genetically analysed. The habitats and soil conditions were also analysed in various ways and statistically evaluated. The captured animals were kept in ventilated plastic cages for a maximum of 12 hours and released after the analyses. Unfortunately, the study does not mention how many chameleons were caught and released in total.

As expected, it turned out that the individual populations of both the European and the flap-necked chameleon differed genetically from each other. The populations of Chamaeleo dilepis had significantly different haplotypes.

In the flap-necked chameleon, the females were significantly larger than the males in two locations, but not in Simbithi. The scientists also found that the colour patterns of the three populations studied could be clearly distinguished from each other. They concluded from the results that the colour patterns in Chamaeleo dilepis are primarily dependent on genetic isolation. The habitat itself and the size of the chameleons did not influence the colour patterns.

In the European chameleon, however, the situation was different: Body size and genetic distance to other populations predicted colour patterns in males very well. However, the colour patterns were independent of the location where the animals were found. Soil or vegetation colours only had a minor influence on the colour of females.

Genetic and behavioural factors affecting interpopulation colour pattern variation in two congeneric chameleon species
Tammy Keren-Rotem, Devon C. Main, Adi Barocas, David Donaire-Barroso, Michal Haddas-Sasson, Carles Vila, Tal Shaharabany, Lior Wolf, Krystal A. Tolley, Eli Geffen
Royal Society Open Science 11: 231554
DOI:  0.1098/rsos.231554

What influences the rediscovery of lost species?

What influences the rediscovery of lost species?

by Alex Negro Science

Throughout history, there have always been species that have been described once and then never seen again. There are also such cases among chameleons. Only a few years ago, the chameleon Furcifer voeltzkowi, which was thought to have been lost for almost 100 years, was rediscovered in western Madagascar. A recent publication by a large number of international authors now deals with the question of which factors influence rediscovery.

In 2023, the IUCN published a list of over 2,000 vertebrate species that had not been seen for more than ten years. Re:wild also published a list of 1008 lost species. Based on these lists and other literature, the scientists searched for species that had not been seen in the wild for more than ten years. In addition, there could not be any ex-situ populations (care in human hands outside the original occurrence). The result was a list of 1280 vertebrate species, which was then finalised with specialists in the respective fields. For example, species that are now considered extinct were excluded. This left 856 lost species, 42% of which were reptiles. The collected data was statistically analysed based on various factors.

Fewer reptiles were represented in the rediscoveries than mammals. Fewer reptile species were rediscovered than would have been statistically probable by chance. Reptiles also die out significantly faster than species are rediscovered. Overall, however, the rediscovery rate for reptiles is on the rise. Most rediscoveries have taken place in the tropics. Brazil and Ecuador are by far the countries with the most discoveries, closely followed by Australia, India and Madagascar. Surprisingly, a higher threat of habitat loss resulted in a higher rediscovery rate for reptiles.

Overall, there are several possible reasons why lost species have not yet been rediscovered. Firstly, there is a lack of data for several species – Brookesia lambertoni, which has not been seen in Madagascar since 1921, is mentioned here as an example. In the original description, its area of discovery is given as “Fito”. Fito is Malagasy for the number seven. Unfortunately, it is still not known what is meant by this name. There are many villages with the name, but it could also have meant a region, a river or a forest. It is also possible that the original description of the origin is due to a linguistic misunderstanding and that “Fito” does not exist as a place at all.

Furthermore, a lack of research capacity, especially in developing countries, also means a lower search intensity for lost species. In addition, many reptile species are rather inconspicuous and small. As a result, they are more difficult to advertise and attract little or no attention from potential sponsors. In addition, the habitat can also play a part in a species not being rediscovered. This is the case, for example, with very remote habitats or landscapes that are difficult to access, such as swamps.

What factors influence the rediscovery of lost tetrapod species?
Tim Lindken, Christopher V. Anderson, Daniel Ariano-Sánchez, Goni Barki, Christina Biggs, Philip Bowles, Ramamoorthi Chaitanya, Drew T. Cronin, Sonja C. Jähnig, Jonathan M. Jeschke, Rosalind J. Kennerley, Thomas E. Lacher Jr., Jennifer A. Luedtke, Chunlong Liu, Barney Long, David Mallon, Gabriel M. Martin, Shai Meiri, Stesha A.. Pasachnik, Victor Hugo Reynoso, Craig B. Stanford, P. J. Stephenson, Krystal A. Tolley, Omar Torres-Carvajal, David L. Waldien, John C.Z. Woinarksi, Thomas Evans
Global Change Biology 30, 2024, pp. 1-18.
DOI:  10.1111/gcb.17107

Photo: Furcifer voeltzkowi in Mahajanga, photographed by Alex Laube

Chameleons in Bobaomby (Madagascar)

Chameleons in Bobaomby (Madagascar)

by Alex Negro Verbreitung Science

The Bobaomby complex is located at the northernmost tip of Madagascar, north and west of the largest coastal town in the north, Antsiranana (Diego Suarez in French). It consists of dry forest at sea level up to a maximum of 200 metres above sea level as well as extensive savannahs on karst rock and various rock formations. The area has not been protected to date.

Scientists from Madagascar conducted reptile counts in the Bobaomby complex in 2018. The counts were carried out in February and March, i.e. during the rainy season. Five different locations were analysed: Beantely, Antsisikala and Ambanililabe as examples of varying degrees of degraded dry forest, Anjiabe for its intact dry forest and Ampombofofo with relatively intact forest. To find animals, the visual survey was used on 25 days during the day and at night in selected transects, sometimes specifically in suitable habitats such as leaf axils or under dead tree trunks, and pitfall traps along erected fences were also used.

A total of 42 reptile species have been recorded. All of them, except one gecko species, originally only occur on Madagascar, while two other gecko species are now also found on neighbouring islands. There is a small novelty among the chameleons: the leaf chameleon Brookesia ebenaui was recorded for the first time in Bobaomby, more precisely in Beantely. Brookesia stumpffi and Furcifer petteri were found in Beantely, Anjiabe and Ampombofofo. Furcifer pardalis and Furcifer oustaleti occurred as expected throughout the whole Bobaomby complex.

The authors suggest that the Bobaomby complex – especially the three forests where most of the reptiles were found – should be protected to preserve the local herpetofauna.

Overview of reptile diversity from Bobaomby complex, northern tip of Madagascar
Randriamialisoa, Raphali R. Andriantsimanarilafy, Alain J. Rakotondrina, Josué A. Rakotoarisoa, Nasaina T. Ranaivoson, Jeanneney Rabearivony, Achille P. Raselimanana
Animals 13: 3396, 2023
DOI:  10.3390/ani13213396

Photo: Furcifer petteri, male, in the north of Madagascar, photographed by Alex Laube

The Indian Chameleon in Solapur (India)

The Indian Chameleon in Solapur (India)

by Alex Negro Verbreitung Science

It has long been known that the Indian chameleon occurs in Maharashtra. A recently published survey study has even found evidence of it in an area near Solapur that is covered only with grass and bushes.

The area studied is a 15 km² area of semi-arid grassland around a site earmarked for an airport at an altitude of 450 to 500 metres. The nearest village is Boramani, a small town just outside the city of Solapur in the state of Maharashtra in western India. For one year, about half of the grassland was surveyed four times a month for the presence of reptiles. Squares of 50 metres x 50 metres were laid out, each at least 300 metres apart. Each observation period consisted of five hours and only observations with the naked eye.

During the study period, 888 individuals of 14 different reptile species were recorded. Of these, more than 300 were Sitana laticeps, a fan-throated lizard. Among the species found were two Chamaeleo zeylanicus. The activity of the lizards increased from March, stabilised during the monsoon season in June-July and then declined again from August.

The authors argue in favour of protecting the grassland area due to the existing biodiversity. This should prevent the construction of the airport and thus the disappearance of the habitat.

Ecology of lizards in an ecologically significant semi-arid grassland patch near Solapur, Maharashtra, India
Mahindrakar Yogesh Y., Waghmare Akshay M., Hippargi Rajshekhar V.
International Journal of Zoological Investigations 9 (2) 2023, pp. 210-223
DOI: 10.33745/ijzi.2023.v09i02.022

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

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

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

Findings on the synonyms of Trioceros ituriensis

Findings on the synonyms of Trioceros ituriensis

by Alex Negro Verbreitung Science

Synonyms for the Congolese Ituri chameleon (Trioceros ituriensis) have existed for several decades. A recent publication by the herpetologist Wolfgang Böhme questions whether two of them could be separate species.

The US herpetologist Karl Patterson Schmidt described the chameleon as Chamaeleon ituriensis in 1919. At that time, Schmidt gave Medje, Ituri Forest, in the Democratic Republic of Congo as the type locality. He already noticed the external similarity to Chamaeleon johnstoni affinis, which is why he gave exactly that as a synonym of his Chamaeleon ituriensis. At the same time, Chamaeleon johnstoni affinis must not be confused with today’s Trioceros affinis, a separate species from Ethiopia that had already been described in 1845. In the course of the 20th century, Chamaeleo johnstoni affinis was placed in the genus Trioceros, sometimes thought to be a subspecies of its own, sometimes not. Böhme states that Trioceros johnstoni affinis is definitely a synonym of Trioceros ituriensis. Differences between Trioceros johnstoni and Trioceros ituriensis are the body size, the “reversed” sexual dimorphism (in T. ituriensis the females are larger than the males), a white line along the belly, several rows of enlarged scales along the side of the body, conical scales on the sides of the throat and the absence of rostral and preocular horns in male T. ituriensis.

However, the author is not sure about the species status of Chamaeleo laevigularis. The species was originally described from South Africa in 1926, then considered a synonym of Trioceros johnstoni and last identified as T. ituriensis by Tilbury in 2010. Böhme considers, because of different scaling of the throat, whether either a wrong locality was noted in the first description or it is a separate species, but could be extinct or lost.

Böhme also comes to the conclusion that Trioceros tremperi, which was described by Neĉas in 1994, could possibly also represent an already extinct species or a lost species and that the locality simply corresponded to incorrect information. Trioceros tremperi was last given as a synonym of Trioceros ituriensis by Tilbury 2010 and Spawls 2018. The chameleons had not been found in the type locality in Kenya before.

Documenting synonymies in Trioceros ituriensis (Schmidt, 1929) with remarks on sexual dimorphism in chameleons (Squamata: Chamaeleonidae)
Wolfgang Böhme
Revue Suisse de Zoologie 130(2), 2023: pp. 521-264
Correction from 2024
DOI: 10.35929/RSZ.0099

Photo: Trioceros ituriensis in the Budongo forest, Uganda, photographed by Katja Rembold

Effect of human chorionic gonadotropin in chameleons

Effect of human chorionic gonadotropin in chameleons

by Alex Negro Tiermedizin Science

After a study on sperm collection in chameleons was already published this year, further results from the largely same team of authors now follow. The aim is to further research the basics of assisted reproduction, i.e. medical assistance in reproduction, in chameleons.

At Louisiana State University, 24 Veiled Chameleons were kept under standardised conditions for over a year. All animals came from a dealer who had taken them from the population of wild Veiled Chameleons in Florida. All were kept individually in ReptiBreeze, equipped with automatic sprinklers and artificial plants. Temperatures were around 28-29°C during the day with spots to seek higher values. 12 h UV-B irradiation per day was offered. Crickets and zophobas were fed. Before the start of the study, all 24 chameleons were clinically examined and several parasite treatments were carried out. Only after a month of acclimatisation did the actual study begin.

The first experiment tested what dose of human choriogonadotropin (hCG) is needed to increase the hormone levels of testosterone in the blood by 50%. Eleven Veiled Chameleons were randomly assigned to one of three groups. The three groups received injections of 100, 200 or 300 IU hCG under the skin at two-week intervals. Blood samples were taken before the first hormone injection and at 30 minutes, one hour, two hours, four hours, eight hours, 12 hours and 24 hours afterwards.

The second experiment tested the effect of hCG treatment on sperm production. 13 Veiled Chameleons were randomly assigned to a treatment or a control group. Once a week for one month, the animals in the first group were treated with 100 IU of hCG, while the second group was only injected with the same volume of isotonic saline. After a four-week break, the groups were switched and the experiment repeated. Blood samples to measure testosterone levels were taken before treatment and on day 15 and 30 afterwards. Semen was collected by electroejaculation under anaesthesia on the day before treatment and 30 days after.

The results showed that the testosterone level in male Veiled Chameleons increased significantly directly after the administration of hCG and remained elevated for about 24 hours. However, it did not matter which dose of hCG had been given beforehand. It could also be shown that the testosterone level increased significantly after the administration of hCG compared to the control group, which only received saline solution. The number of successful electroejaculations could be increased under hCG.

Effects of exogenous human chorionic gonadotropin administration on plasma testosterone and semen production in the Veiled Chameleon (Chamaeleo calyptratus)
Sean M. Perry, Sarah R. Camlic, Michael Lierz, Mark A. Mitchell
Journal of Herpetological Medicine and Surgery 33 (3), 2023, pp. 180-191
DOI: 10.5818/JHMS-D-22-00038