Long-term study on sperm collection in chameleons

Long-term study on sperm collection in chameleons

by Alex Negro Tiermedizin Science

Assisted reproduction has become increasingly common in the conservation of extremely rare animals such as the Spix’s macaw or northern white rhinoceros in recent years. In reptiles, on the other hand, there have only been a few studies on assisted reproduction, and only a few on chameleons in particular. Scientists from the USA have now conducted a study on male Veiled and Panther Chameleons (Chamaeleo calyptratus and Furcifer pardalis).

At Louisiana State University, 16 males of each species were kept under standardised conditions for over a year. The panther chameleons were purchased from a US breeder, the Yemen chameleons from a dealer who had taken them from the introduced wild chameleon population in Florida. All males were kept individually in ZooMed screen cages, 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. They were fed with crickets and zophobas.

Before the start of the study, all 32 chameleons were clinically examined and parasites were treated. Only after a month of acclimatisation did the actual study begin. During the study year, all chameleons were put under anaesthesia twice a month. Each time, blood was taken from the ventral tail vein or the jugular vein to determine the testosterone concentration. Ultrasound was used to measure the size of the testicles. In addition, each time an attempt was made to obtain sperm by electroejaculation. Electroejaculation involved inserting a small metal probe into the cleaned cloaca. Each chameleon was then treated up to three times in succession with up to 15 electric shocks of 0.1/0.2/0.3 mAs. The semen collection experiments were stopped as soon as the animal ejaculated. The sperm collected was preserved and examined for ejaculate volume, presence of sperm, sperm motility, concentration, and morphology.

The results suggest that Veiled Chameleons follow a so-called prenuptial reproductive strategy under constant husbandry conditions. The testosterone concentration in the blood already increased before the sperm volume of the males had reached its maximum. The months of May, April, and June brought the best sperm volumes, the most sperm was produced by electroejaculations in the third attempt. Testicle sizes also varied throughout the year, with the largest measurements from August to December.

Panther chameleons, on the other hand, seem to follow a postnuptial reproductive strategy. In them, most sperm could only be obtained well after the highest point of testosterone concentration. The electroejaculations worked best in March, April, May and June. Much more often than in Yemen chameleons, electroejaculation in panther chameleons worked already in the first attempt. The size of the testicles also varied throughout the year, but most were largest in the months mentioned above. Together with the factors mentioned above, the volume of ejaculate, sperm concentration, sperm motility and sperm morphology also changed during the year.

The authors recommend that electroejaculation in chameleons should generally only be performed under anaesthesia. The success rate for spermatozoa in the two highest cases was 82 and 88%, which is similar to the success in other reptiles during their reproductive season. The mortality rate among the 32 animals was only 0.12% over the whole year. One panther chameleon died after 10 months during the 20th anaesthesia, after death kidney damage was detected. From the low mortality rate, the authors conclude that electroejaculation rather does not play a role in the development of kidney disease, as was suspected in other studies. However, an examination of the blood for kidney values was not carried out on any of the surviving chameleons after the study. It also remains unclear what role the lack of imitation of rainy and dry seasons during the year plays for both species and their reproductive cycle.

Characterizing the annual reproductive cycles of captive male veiled chameleons (Chamaeleo calyptratus) and panther chameleons (Furcifer pardalis)
Sean M. Perry, Sarah R. Camlic, Ian Konsker, Michael Lierz, Mark A. Mitchell
Journal of Herpetological Medicine and Surgery 33 (1), 2023, pp. 45-60
DOI: 10.5818/JHMS-D-22-00037

Introduced chameleons in Florida

Introduced chameleons in Florida

by Alex Negro Science

The “Sunshine State” Florida in the southeast of the USA has long been known for a variety of introduced reptiles. Students at the University of Florida recently published a small brochure on the current status of chameleon species introduced there.

As early as the late 1800s, a non-native reptile was documented to have found its way to Florida by ship: an anole. Since then, some 150 introduced species have been documented in the US state, including eight species of chameleons. Three of them are now spread over the entire southern half of the peninsula and even reproduce: the Yemen chameleon Chamaeleo calyptratus, the Malagasy Giant chameleon Furcifer oustaleti, and the panther chameleon Furcifer pardalis.

Current known distribution of Panther, Veiled, and Malagasy Giant Chameleons in Florida.

All three species are thought to have come into the country with increasing pet trade and private keeping of chameleons. Furcifer oustaleti has been in Florida since at least the year 2000. At that time, the first findings became known in an avocado plantation located in the immediate vicinity of the buildings of a former importer in Miami – Dade County. Chamaeleo calyptratus was first recorded in Fort Myers on a vacant lot only a little later, in 2002. Furcifer pardalis followed in 2008.

The question of whether any of the three species mentioned should be considered invasive is difficult to answer so far due to a lack of data. A species is considered invasive if it is non-native, has been introduced by humans, and has been proven to cause damage to native flora and fauna. The last point, however, is debatable. While Jackson’s chameleons in Hawaii have been shown to consume endangered native snail species, among others, the same is not yet known from Florida. There, the animals are currently considered more of a nuisance, but with the potential to threaten the native invertebrate fauna.

The problem is that chameleons are still being released – sometimes they escape unintentionally, but sometimes they are deliberately released in order to collect and sell the offspring later. For the latter, you need a permit in Florida. Interesting to note: Anyone is allowed to kill introduced chameleons on their own property “in a humane way”. In some places, chameleons are already being collected to be sold to private owners.

The students call for observations of chameleons in Florida to be reported on the internet via IveGot1.org or via the app of the same name. So far, not all populations are known, as much information is only passed on by hand. Furthermore, they ask that chameleons that have become a nuisance should not be abandoned, but handed into the Exotic Pet Amnesty Program of the Florida Fish and Wildlife Conservation Commission. The surrender there is free of charge, and the EPAP is ultimately looking for new keepers for the animals.

Florida’s introduced reptiles: Veiled Chameleon (Chamaeleo calyptratus), Oustalet’s chameleon (Furcifer oustaleti), and panther chameleon (Furcifer pardalis)
Max Maddox, Karissa Beloyan, Natalie M. Claunch, Steve A. Johnson
Veröffentlichung des Wildlife Ecology and Conservation Department, Universität of Florida
DOI: 10.32473/edis-UW501-2022