Dwarf chameleons in South Africa larger in urban environments than in the wild

Dwarf chameleons in South Africa larger in urban environments than in the wild

by Alex Negro Science

Dwarf chameleons of the genus Bradypodion from South Africa have long been known to adapt very well to urban habitats. Two scientists from Cape Town and Johannesburg have now investigated how different populations differ in body size, body weight and body condition score within urban and natural environments.

A total of 1107 individuals of five different dwarf chameleon species were studied over a period of four years. Bradypodion damaranum in George (Western Cape), Bradypodion melanocephalum in Durban (KwaZulu-Natal), Bradypodion setaroi in St Lucia (KwaZulu-Natal), Bradypodion thamnobates in Howick (KwaZulu-Natal) and Bradypodion ventrale in Jeffrey’s Bay (Eastern Cape) were each searched at night at three to eight locations. Forest fragments, grass savannahs or coastal bushland less than 15 km from the centre of the nearest town were classified as ‘natural sites’. All sites located within a city and consisting of both introduced and native flora regularly cut back by humans (gardens, public parks and green spaces, roadsides) were categorised as ‘urban’. The dwarf chameleons found were measured, weighed, sexed and marked with a felt-tip pen to avoid duplicate measurements on the same animals. Obviously pregnant females were not measured.

Statistical analyses and comparisons revealed that the chameleons at natural sites were always smaller and lighter on average than the populations of the same species at urban sites. Significantly larger and heavier in the city were both sexes in Bradypodion damaranum, the males in Bradypodion melanocephalum, ventrale and setaroi and the females in Bradypodion thamnobates. The body condition score was higher in urban areas for both sexes of Bradypodion damaranum and setaroi and males of Bradypodion melanocephalum than for the chameleons in natural habitats. In Bradypodion ventrale and thamnobates, there were no differences in body condition score between the different populations.

Research into exactly how these exciting differences come about is still pending.

Big cities, big bodies: urbanisation correlates with large body sizes and enhanced body condition in African dwarf chameleons (Genus: Bradypodion)
Jody M. Barends, Krystal A. Tolley
African Zoology 2024, 59(3)
DOI: 10.1080/15627020.2024.2402256

Photo: Bradypodion melanocephalum, photographed by suncana, licence Creative Commons Attribution 4.0 International

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

Chameleons at different altitudes of the Amber Mountain (Madagascar)

Chameleons at different altitudes of the Amber Mountain (Madagascar)

by Alex Negro Science

International scientists have intensively studied the different altitudes of the Amber Mountain and the amphibians and reptiles found there. The Amber Mountain (French Montagne d’Ambre) is a former volcanic massif in northern Madagascar. The mountain, which is up to 1475 m high, is mainly covered by rainforest, which belongs to the national park of the same name. To the north of the mountain is a dry forest that belongs to the Forêt d’Ambre Special Reserve. The north-western flank of the mountain has not yet been protected.

In the present work, amphibians and reptiles were observed and sampled over 12 km between 700 and 1470 metres altitude. The western slope of the Montagne d’Ambre at altitudes between 770 and 1290 m was also included in the study for the first time. In addition, animals were sampled in the Forêt d’Ambre from 470 m altitude. All animals found were measured. Cheek swabs, scales as well as live animals that had been euthanised were collected and genetically analysed. A total of 2631 observations of 34 species of amphibians and 48 species of reptiles were made. As expected, different animals occurred at different altitudes. The species richness of the Montagne d’Ambre was greatest at around 1000 m a.s.l. with 41 different species. Above 1100 m, about one third of the species found were locally endemic.

Two genetic clusters of the earth chameleon Brookesia tuberculata have been identified. Group 1 lives on the eastern flank of the Montagne d’Ambre at altitudes of 887 to 1170 m, group 2 at 1260 to 1455 m on the eastern flank and at 956 to 1150 m on the western slope of the Montagne d’Ambre. Group 1 showed a particularly high number of mitochondrial haplotypes, while group 2 had only one haplotype. The scientists assume that due to their small body size and high site fidelity, the species tends to form isolated groups rather than tree-inhabiting chameleons, which can overcome natural barriers more easily and thus move within a much larger environmental radius.

In Calumma linotum, the genetic differences between three groups at different altitudes were rather small. The measurement data of various body dimensions also showed no clear trend for this species at the different altitudes. Although Calumma linotum appeared to be slightly smaller at lower altitudes, this could have been due to subadult individuals misidentified as females. For Calumma amber and Calumma ambreense, body size decreased the higher the chameleons were found in the Montagne d’Ambre. This may be related to the cooler temperatures at higher altitudes, which contribute to slower growth. But it could also be that more younger animals were simply measured.

The study reveals interesting adaptations of different chameleon species to the altitudinal differences of the Montagne d’Ambre. It is possible that these are already the first indications of an early stage of speciation. The work also illustrates how important the different altitudinal levels are for species diversity.

Repeated divergence of amphibians and reptiles across an elevational gradient in northern Madagascar
Mark D. Scherz, Robin Schmidt, Jason L. Brown, Julian Glos, Ella Z. Lattenkamp, Zafimahery Rakotomalala, Andolalao Rakotoarison, Ricky T. Rakotonindrina, Onja Randriamalala, Achille P. Raselimanana, Safidy M. Rasolonjatovo, Fanomezana M. Ratsoavina, Jary H. Razafindraibe, Frank Glaw, Miguel Vences
Ecology and Evolution 13 (3)
DOI: 10.1002/ece3.9914

Chamaeleo chamaeleon in Turkey

Chamaeleo chamaeleon in Turkey

by Alex Negro 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

Factors in the geographical dispersal of chameleons

Factors in the geographical dispersal of chameleons

by Alex Negro Science

For a long time, people have been trying to find out how and why chameleons have spread across the African continent, to islands and as far as Europe and Asia. French scientists, in collaboration with international colleagues, have now used phylogenetics and various computational models to investigate how the factors of body size, coastal habitat and extreme lifestyles may have affected the distribution of different chameleon species. The study examined 181 species divided into nine main biogeographical regions: North Africa and Arabia, Central Africa, Southeast Africa, Southwest Africa, India, Socotra, Madagascar, Comoros and Seychelles.

Chameleon species that occurred more than 10 km from the sea historically spread significantly less than the 74 coastal chameleon species. A similar phenomenon is known from skinks and crocodiles. Dispersal probably took place mainly along the coasts, mostly on the same continent and only rarely across the water to other continents or islands.

The size of the different chameleons also seems to have influenced their dispersal throughout history: Large chameleons spread further and more frequently than small chameleons. This could be related to the fact that larger chameleons have a lower metabolic rate – so they need less energy overall relative to smaller competitors. In addition, larger chameleons lay clutches with significantly more eggs, which simply gives them an advantage in numbers.

A somewhat unexpected result came from the study of different life cycles. One would initially assume that short life cycles are associated with faster dispersal. In fact, the calculations showed that especially chameleon species with extreme life cycles spread further. Thus, those that reproduced particularly slowly or particularly quickly were historically more successful among chameleons than the species “in the middle”. In this regard, the authors consider whether particularly slow life cycles with late sexual maturity and long gestation might be more successful on the same continent, while faster reproductive strategies with large clutches are more favourable for dispersal across the sea to islands and other continents. In line with this, Furcifer polleni and Furcifer cephalolepis in Comoros and Chamaeleo zeylanicus in India, all three examples of aquatic dispersal, have a very fast life cycle.

The 34 chameleon species with the combination of living close to the coast, large size and extreme life cycle had a 98% higher dispersal rate than species without these characteristics.  All in all, this is certainly a very theoretical study, but it nevertheless provides exciting insights into the historical distribution and dispersal of chameleons.

Chameleon biogeographic dispersal is associated with extreme life history strategies
Sarah-Sophie Weil, Laurie Gallien, Sébastien Lavergne, Luca Börger, Gabriel W. Hassler, Michaël P.J. Nicolaï & William L. Allen
Ecography
DOI: 10.1111/ecog.06323

New research on the Labord’s chameleon in Kirindy, Madagascar

New research on the Labord’s chameleon in Kirindy, Madagascar

by Alex Negro Science

Furcifer labordi is known as the world’s shortest-lived chameleon. Within three months, these animals grow from hatchling to adult chameleons, mate, lay eggs and mostly die immediately afterwards. Scientists at the University of Göttingen researched whether the short lifespan has an influence on the mating strategy of Furcifer labordi.

The study site was the dry forest of Kirindy in western Madagascar. Kirindy is located about 60 km north of the coastal town of Morondava and about 20 km from the sea in the Menabe region. During the rainy season in early 2020, 39 Furcifer labordi of both sexes were fitted with radio transmitters there. Weight and body length at the time of discovery as well as some other values were measured, and the sleeping height of the animals found at night was noted. The animals were released at the site where they were found. The researchers then tracked the chameleons twice during the day and once at night for several weeks using telemetry to record GPS data and establish movement and behaviour patterns.

The results of the study show that female Furcifer labordi in Kirindy are very site-faithful. They only cover short distances. In contrast, male Furcifer labordi move much more and over longer distances, so that seven to fourteen times more males than females could be observed in a forest section. The observed females mated with up to six different males – however, the researchers repeatedly found unmarked males among the observed females. This suggests that Furcifer labordi could actually have a significantly higher number of different reproductive partners. The individually very different body sizes of the males as well as differently pronounced nasal processes had no connection to movement patterns. Furthermore, it could be shown that Furcifer labordi does not occupy and defend territories. This means that presumably the short lifespan actually leads to competition for the few available females being more intense – and as observations show also more aggressive – than in other chameleon species. This study is the first investigation of the mating system of a Malagasy chameleon.

Sex-specific movement ecology of the shortest-lived tetrapod during the mating season
Lennart Hudel & Peter M. Kappeler

Published in Scientific Reports 12
Open Access (free download possible)
DOI https://doi.org/10.1038/s41598-022-14156-3