Petr Velensky

Chameleons are well-known lizards with unique morphology and physiology, but their sex determination has remained poorly studied. Madagascan chameleons of the genus Furcifer have cytogenetically distinct Z and W sex chromosomes and occasionally Z1Z1Z2Z2/Z1Z2W multiple neo-sex chromosomes. To identify the gene content of their sex chromosomes, we mi...

Chameleons are well-known lizards with unique morphology and physiology, but their sex determination has remained poorly studied. Madagascan chameleons of the genus Furcifer have cytogenetically distinct Z and W sex chromosomes and occasionally Z 1 Z 1 Z 2 Z 2 /Z 1 Z 2 W multiple neo-sex chromosomes. To identify the gene content of their sex chromo...

The European green lizard, Lacerta viridis (Laurenti, 1768), is a critically endangered species in the Czech Republic according to current legislation. Its distribution in the Czech Republic is limited to small isolated local populations, which are located here beyond the northern border of the continuous species range and depend on microclimatical...

For the needs of adequate management, we carried out an assessment of the Aldabrachelys gigantea (Schweigger, 1812) population in the institutions of the European Association of Zoos and Aquaria. This population was established a hundred years ago and is continuously growing. Today it is the largest ex situ population of all regional zoo associatio...

Starting in 2014, members of the European Association of Zoos and Aquariums (EAZA) began to acquire earless monitor lizards. In this paper, the focus is on the ex situ population of Lanthanotus borneensis in EAZA, its origin, current status, role and perspectives.

Populations of Johnstone's whistling frog Eleutherodactylus johnstonei Barbour, 1914 are reported in greenhouses in Prague for the first time. Currently, this non-native species is accidentally being transferred on plants between botanical and zoological greenhouses. Exceptionally, E. johnstonei can temporarily occupy habitats outside greenhouses a...

Life history traits are influenced by many factors, such as social structure, social displays and aggressive interactions. We investigated signalling and agonistic behavior in relation to body condition and lifespan in Trapelus sanguinolentus, a small, semi-arboreal, oviparous agamid lizard from the Central Asia. We individually examined basic morp...

Telomeres are nucleoprotein complexes protecting chromosome ends in most eukaryotic organisms. In addition to chromosome ends, telomeric-like motifs can be accumulated in centromeric, pericentromeric and intermediate (i.e., between centromeres and telomeres) positions as so-called interstitial telomeric repeats (ITRs). We mapped the distribution of...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Turtles demonstrate variability in sex determination and, hence, constitute an excellent model for the evolution of sex chromosomes. Notably, the sex determination of the freshwater turtles from the family Chelidae, a species-rich group with wide geographical distribution in the southern hemisphere, is still poorly explored. Here we documented the...

Squamate reptiles are considered to exhibit indeterminate growth. Nevertheless, current literature disputes the available definitions of this growth type, presents new theoretical models, and questions its universality in cold-blooded vertebrates. We have followed up on our previous research employing micro-CT to explore growth plate cartilage (GPC...

Chameleons are well-known, highly distinctive lizards characterized by unique morphological and physiological traits, but their karyotypes and sex determination system have remained poorly studied. We studied karyotypes in six species of Madagascan chameleons of the genus Furcifer by classical (conventional stain, C-banding) and molecular (comparat...

Monitor lizards are unique among ectothermic reptiles in that they have high aerobic capacity and distinctive cardiovascular physiology resembling that of endothermic mammals. Here, we sequence the genome of the Komodo dragon Varanus komodoensis, the largest extant monitor lizard, and generate a high-resolution de novo chromosome-assigned genome as...

We developed new tools to build a high-quality chromosomal map of the Komodo dragon ( Varanus komodoensis ) available for cross-species phylogenomic analyses. First, we isolated chromosomes by flow sorting and determined the chromosome content of each flow karyotype peak by FISH. We then isolated additional Komodo dragon chromosomes by microdissect...

Sex determination in varanids, Gila monsters, beaded lizards, and other anguimorphan lizards is still poorly understood. Sex chromosomes were reported only in a few species based solely on cytogenetics, which precluded assessment of their homology. We uncovered Z-chromosome-specific genes in varanids from their transcriptomes. Comparison of differe...

For a long time, turtles of the family Geoemydidae have been considered exceptional because representatives of this family were thought to possess a wide variety of sex determination systems. In the present study, we cytogenetically studied Geoemyda spengleri and G. japonica and re-examined the putative presence of sex chromosomes in Pangshura smit...

Despite their long history with the basal split dating back to the Eocene, all species of monitor lizards (family Varanidae) studied so far share the same chromosome number of 2n = 40. However, there are differences in the morphology of the macrochromosome pairs 5–8. Further, sex determination, which revealed ZZ/ZW sex microchromosomes, was studied...

The European green lizard, Lacerta viridis, is in the Czech Republic listed as a critically endangered species. Populations in the Bohemia region are located beyond the northern border of continuous range of the species and are closely related to the so-called river phenomenon of deeply engorged river valleys. This phenomenon describes specific mic...

The reconstruction of the evolutionary dynamics of karyotypes and sex determining systems in squamate reptiles is precluded by the lack of data in many groups including most chameleons (Squamata: Acrodonta: Chamaeleonidae). We performed cytogenetic analysis in 16 species of chameleons from 8 genera covering the phylogenetic diversity of the family...

Growth plate cartilage (GPC) is responsible for the growth of long bones due to endochondral ossification, which is the main mechanism of longitudinal skeletal growth in tetrapods. Degradation of GPC is a sign of determinate growth as it arrests the growth irreversibly. By contrast, indeterminate growth requires the persistence of GPC throughout th...

The evolution of male-biased sexual size dimorphism is often explained by sexual selection providing competitive advantage to the larger males. The aggressive interactions are often dangerous and energy consuming; thus, it is advantageous to reduce the risks by adjusting behavior to correspond with body size as a predictor of fighting success. Orga...

The Komodo dragon (Varanus komodoensis) is the largest lizard in the world. Surprisingly, it has not yet been cytogenetically examined. Here, we present the very first description of its karyotype and sex chromosomes. The karyotype consists of 2n = 40 chromosomes, 16 macrochromosomes and 24 microchromosomes. Although the chromosome number is consta...

The critically endangered Annam leaf turtle Mauremys annamensis faces extinction in nature. Because of that, the conservation value of the population kept in European zoos becomes substantial for reintroduction programmes. We sampled 39 specimens of M. annamensis from European zoos and other collections (mainly founders, imports and putatively unre...

In male-larger species of animals, males typically continue to grow after the age of female sexual maturation has been reached. Consequently, a switch of energy allocation occurs as the female investment from growth is shifted into egg production. We focus on the transitional period when both sexes heavily invest into anabolic processes; males inve...

Blood cell morphology and count are not uniform across species. Recently, between-species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa, and this finding was interpreted in the context of the metabolic theory. In the present study, we examined the numbers and the size of blood cells in 2 spec...

Describing the stages of normal development of Varanus indicus, the present paper provides the first developmental data on Varanidae. The incubation period is relatively long (180 days at 28°C) and without any diapause. The development is rather slow during the first 50 days, after which a considerable acceleration can be observed. The stage of acc...

Most lizards feed on a variety of food items that may differ dramatically in their physical and behavioral characteristics. Several lizard families are known to feed upon hard-shelled prey (durophagy). Yet, specializations toward true molluscivory have been documented for only a few species. As snails are hard and brittle food items, it has been su...

The Malaysian Giant Turtle (Orlitia borneensis) is a poorly known turtle with rapidly decreasing numbers in nature in spite of its strong protection on paper. Most individuals of this species kept in European zoos and included in captive breeding programs are confiscates from the illegal trade for food consumption and their geographic provenance is...

In monitor lizards, males are typically larger than conspecific females, but body shape is usually quite similar in both sexes. This not only represents a puzzle worthy of evolutionary explanation, but also makes field sex determination of monitor lizards difficult. We asked whether subtle differences in body shape follow the same pattern as in oth...

New and published accounts of artificial and natural hybrids between Natrix tessellata and the other two Natrix-species is briefly summarized. Hybrids exist for both interspecific pairings, but viability of offspring seems to be reduced, at least under natural conditions.

The dice snake, Natrix tessellata, is classified as a highly endangered species in the Czech Republic. The Prague Zoo, supervised by the Agency for Nature Conservation and Landscape Protection (AOPK), promoted the study of its isolated population of dice snakes along the Vltava River in order to contribute to the rehabilitation of the nationally en...

Monitor lizards belong to the largest and the most sexually dimorphic lizards in terms of size, making this group an ideal model for studies analyzing ontogenetic causes of sexual dimorphism. Understanding of these ontogenetic factors is essential to the current discussion concerning patterns of sexual dimorphism in animals. We examined the ontogen...

Ex situ conservation strategies may be substantially informed by genetic data, and yet only recently have such approaches been used to facilitate captive population management of endangered species. The Galápagos tortoise Geochelone nigra is an endangered species that has benefited greatly from the application of molecular and population genetic da...

Within the broader context of taxonomy, ecology, zoogeography and conservation of iguanas of the genus Cyclura, a summary of knowledge about biology of the Cuban ground iguana, Cyclura nubila, studied in human care is given. Emphasis is focused on their husbandry, eco-ethology, reproductive biology and social life, which is very complex and more di...

The Cuban iguanas imported from Cuba were successfully reproduced at Prague Zoo in 1993. All five juvenile iguanas of the F1-generation had been reared at Prague Zoo, and consequently, in 1996, they reproduced. So, the F2-generation of Cuban iguanas born at Prague Zoo is now reared here. F1-generation consists of one male and four females born on 5...

We present our knowledge about the biology and husbandry of varanids Varanus prasinus, Varanus rudicollis and Varanus salvadorii based on our observations in human care.