Olivier Marquis

• PhD
• Curator of reptiles, amphibians and invertebrates at Muséum National d'Histoire Naturelle

Solar ultraviolet-B (UV-B) radiation can be harmful for developing amphibians. As the UV-B dose increases with altitude, it has been suggested that high-altitude populations may have an increased tolerance to high levels of UV-B radiation as compared to lowland populations. We tested this hypothesis with the common frog (Rana temporaria) by compari...

Organic micropollutants are often damaging for aquatic organisms. Being usually hydrophobic compounds, they are often dissolved in an organic co-solvent which increases their solubility in water. The aim of this study was to study the toxicity of various solvents on embryos (protected or not by jelly coat) and on tadpoles of the common frog (Rana t...

This poster presents the preliminary results of chameleon inventory projects in the Vohimana reserve (Madagascar) and monitoring of Calumma parsonii by the Caméléon Center Conservation between 2023 and 2024.

The crocodylian dwarf species (i.e., Osteolaemus sp. and Paleosuchus sp.) that live in the equatorial forests all share the peculiarity to present an osteoderm shield which extends beyond the dorsal area that lies between the skull and the caudal crest symphysis. Here we study both the morphology and the microanatomy of the osteoderms in Paleosuchu...

Amphibian habitat preferences have ecological, evolutionary, and conservation implications, but information on habitat use is scarce for most species, especially at the microhabitat level. Considering ongoing widespread amphibian population declines, baseline estimates of abundance are increasingly important for informing conservation, yet most spe...

A summary of the recent EAZA Regional Collection Plan for Dendrobatinae and other neotropical frogs

Amphibian habitat preferences have ecological, evolutionary, and conservation implications, but for most species we have no information about habitat use, especially at the microhabitat level. Relatedly, considering ongoing widespread amphibian population declines, baseline estimates of abundance are increasingly important for informing conservatio...

Trace elements in the blood of crocodilians and the factors that influence their concentrations are overall poorly documented. However, determination of influencing factors is crucial to assess the relevance of caimans as bioindicators of environmental contamination, and potential toxicological impact of trace elements on these reptiles. In the pre...

In many animals, males engage in agonistic interactions. Color signals are commonly used to mitigate these potentially harmful interactions. Both pigment-based color and structural color, notably ultraviolet coloration, are used in this context to convey information, including an animal’s resource holding potential (RHP) or social status. Despite e...

To appropriately reflect the current breadth of population management activities, the needs of EAZA members, and the changes and opportunities within the conservation world at large, EAZA approved a new population management structure in April 2017. A detailed description on the working procedures used for the EAZA Amphibian TAG Dendrobatinae and o...

WHEN FORTY PER CENT OF A SPECIES IS THREATENED BY EXTINCTION, URGENT ACTION IS NEEDED – SO A NEW PLAN FOR THE WESTERN PALEARCTIC SALAMANDERS HOPES TO REVERSE THIS DECLINE.

EAZA Best Practice Guidelines (Striped) fire salamander, Salamandra salamandra (terrestris) is the first version of the EAZA Best Practice Guidelines for this species. This guideline has evolved out of the growing concern for extinction of local fire salamander populations due to the introduction of the invasive chytrid fungus Batrachochytrium sala...

Environmental contaminants affect ecosystems worldwide and have deleterious effects on biota. Non-essential mercury (Hg) and lead (Pb) concentrations are well documented in some taxa and are described to cause multiple detrimental effects on human and wildlife. Additionally, essential selenium (Se) is known to be toxic at high concentration but, at...

Mercury (Hg) is a global environmental contaminant that affects ecosystems. It is known to biomagnify through food webs, and to bioaccumulate especially in the tissues of top predators. Large scale comparisons between taxa and geographic areas are needed to reveal critical trends related to Hg contamination and its deleterious effects on wildlife....

The deleterious effects of mercury (Hg) contamination are well documented in humans and wildlife. Chronic exposure via diet and maternal transfer are two pathways which increase the toxicological risk for wild pop- ulations. However, few studies examined the physiological impact of Hg in crocodilians. We investigated the Hg contamination in neonate...

Considering that there are currently 8231 amphibians described, the TAG prioritised Western Palearctic caudata for this RCP. The TAG based this decision as a response to the threat of the fungal pathogen Batrochochyrium salamandrivorans (Bsal) and the fact that many Western Palearctic salamanders are highly susceptible to this pathogen. Furthermore...

Colour change is involved in various functions ranging from thermo- and hydroregulation to camouflage and communication. The role of colour change in communication has received increased attention over the past few decades, yet has been studied predominantly in the context of intrasexual competition. Here, we investigate the role of colour change i...

This note reports a field observation of a breeding site of Paleosuchus trigonatus in the protected area “Réserve Naturelle Nationale des Nouragues” in French Guiana. It includes a description of its nest, hatchlings and habitat, with an emphasis on hatchlings’ vocal signal. It also reports the result of a playback experiment on an adult.

caiman (Paleosuchustrigonatus) is a forest crocodilian whose ecology remains largely unknown (Magnusson and Campos 2010). It is a discrete species that prefers dense forest, leading to rare exposure to direct UV radiation. Paleosuchus trigonatus lives in small streams and often uses terrestrial burrows or caves formed by rocky masses to retreat to...

The black caiman is one of the largest neotropical top predators, which means that it could play a structuring role within swamp ecosystems. However, because of the difficulties inherent to studying black caimans, data are sorely lacking on many aspects of their general biology, natural history, and ecology, especially in French Guiana. We conducte...

Schneider’s dwarf caiman, Paleosuchus trigonatus, is one of the least studied Alligatoridae species, whose cryptic behavior makes it difficult to observe. Our research focused on a population in the Nouragues Reserve, French Guiana, by capturing all observed specimens (N=16) and performing a radio-tracking survey, following adult animals (N= 4) on...

Amongst the 9 genera of existent crocodilians, two are known to display very different ecological habits compared to the others: Paleosuchus in South America and Osteolaemus in West and Central Africa (Merchant, Shirley et al. 2016). Both genera include species inhabiting mainly small streams or forest ponds in closed canopy rainforests (Magnusson...

The most commonly encountered ectoparasite in captive snakes is the hematophagous snake mite (Ophionyssus natricis). Infected snakes often exhibit lethargy, dysecdysis, pruritus, crusting dermatitis (sometimes progressing to abscesses), and behavioral changes (increased bathing time, rubbing against objects). Anemia and septicemia are occasional co...

Food availability is a major environmental factor that can influence life history within and across generations through direct effects on individual quality and indirect effects on the intensity of intra- and intercohort competition. Here, we investigated in yearling and adult common lizards (Zootoca vivipara) the immediate and delayed life-history...

1. Demographic theory and empirical studies indicate that cohort variation in demographic traits has substantial effects on population dynamics of long‐lived vertebrates but cohort effects have been poorly investigated in short‐lived species. 2. Cohort effects were quantified in the common lizard ( Zootoca vivipara Jacquin 1787), a short‐lived ecto...

Detailed studies of the mechanisms driving life history effects of food availability are of prime importance to understand the evolution of phenotypic plasticity and the capacity of organisms to produce better adapted phenotypes. Food availability may influence life history trajectories through three nonexclusive mechanisms: (i) immediate and long-...

Populations of widely distributed species can be subjected to unequal selection pressures, producing differences in rates of local adaptation. We report a laboratory experiment testing tolerance variation to UV-B and polycyclic aromatic hydrocarbons (PAHs) among common frog (Rana temporaria) populations according to their natural exposure level in...

An evaluation of the link between climate and population dynamics requires understanding of climate effects both within and across generations. In ectothermic vertebrates, demographic responses to climate changes should crucially depend on balancing needs for heat and water. Here, we studied how temperature and rainfall regimes experienced before a...

Solar ultraviolet radiation (UV) is harmful for developing amphibians. As UV increases with altitude and latitude, it is suggested that high altitude and latitude populations have evolved tolerance to high levels of UV. Using laboratory experiments, we tested the hypothesis that Rana temporaria populations from several altitudes (438–2,450m above s...

Several experiments have shown that ambient ultraviolet-B radiation (UV-B) has negative effects on the development of amphibians' embryos. We studied the effects of UV-B radiation on development, survival and frequency of deformity during egg development in the Natterjack toad (Bufo calamita) from a semiarid region of Lleida (Catalonia, Spain). Egg...

Polycyclic Aromatic Hydrocarbons (PAHs) are damaging for aquatic organisms such as amphibians. In this study, toxicity of a mixture of three PAHs (naphthalene (2 rings), phenanthrene (3 rings) and pyrene (4 rings)) was tested on Common frog (Rana temporaria) embryos. The protective role of the jelly coat surrounding the eggs was studied by exposing...

Behavioural observations were performed in an olfactometer to examine the effects of chemical stimuli from predators and conspecifics on the swimming activity of two larval anurans, the common frog, Rana temporaria, and the common toad, Bufo bufo. Both species of tadpoles showed a slight but non significant reduction in swimming behaviour when conf...