Variation in energy metabolism and water flux of free-ranging male lace monitors,Varanus varius (Squamata: Varanidae)

The energy and water used by Varanus varius correlated with changes in weather, activity, and possibly the availability of prey. In summer, CO(2) production and water influx rates were high (0.147 mL CO(2) g(-1) h(-1) and 23.6 mL H(2)O kg(-1) d(-1)) but substantially lower during autumn (0.053 mL CO(2) g(-1) h(-1) and 9.1 mL H(2)O kg(-1) d( -1)) and winter (0.016 mL CO(2) g(-1) h(-1) and 2.4 mL H(2)O kg(-1) d(-1)), increasing again in spring (0.052 mL CO(2) g(-1) h(-1) and 7.9 mL H(2)O kg(-1) d(-1)). The summer-winter difference represented more than a ninefold reduction in energy expenditure and water flux. However, individual V. varius could manipulate their energy and water requirements by up to sixfold during the summer period by regulating activity. Although we found no adaptive benefits of increased or decreased level of activity, we did find that larger animals moved more frequently and over greater distances than smaller animals. We hypothesise that V. varius regulates its activity on the basis of the trade-off between energy expenditure through activity and energy acquisition through foraging.     

Blood values in wild and captive Komodo dragons (Varanus komodoensis)

The Komodo dragon (Varanus komodoensis) is the largest living lizard and occupies a range smaller than that of any other large carnivore in the world. Samples from 33 free-ranging animals at five localities in Komodo National Park, Indonesia were evaluated to assess underlying health problems. To build a comparative database, samples from 44 Komodo dragons in both Indonesian and U.S. zoos were also analyzed. Tests performed included complete blood counts, clinical chemistry profiles, vitamin A, D(3), and E analyses, mineral levels, and screening for chlorinated pesticides or other toxins in wild specimens. Blood samples from wild dragons were positive for hemogregarines, whereas captive specimens were all negative. Total white blood cell counts were consistently higher in captive Komodo dragons than in wild specimens. Reference intervals were established for some chemistry analytes, and values obtained from different groups were compared. Vitamin A and E ranges were established. Vitamin D(3) levels were significantly different in Komodo dragons kept in captive, indoor exhibits versus those with daily ultraviolet-B exposure, whether captive or wild specimens. Corrective measures such as ultraviolet-permeable skylights, direct sunlight exposure, and self-ballasted mercury vapor ultraviolet lamps increased vitamin D(3) concentrations in four dragons to levels comparable with wild specimens. Toxicology results were negative except for background-level chlorinated pesticide residues. The results indicate no notable medical, nutritional, or toxic problems in the wild Komodo dragon population. Problems in captive specimens may relate to, and can be corrected by, husbandry measures such as regular ultraviolet-B exposure. Zoo Biol 19:495-509, 2000. Copyright 2000 Wiley-Liss, Inc.     

Functional analysis of the throat display in the sand goanna Varanus griseus (Reptilia: Squamata: Varanidae)

The threat behaviour in Varanus griseus was investigated with high-speed cinematography and X-ray films. Lizards exhibit threat display involving throat movements and associated throat, thorax and mouth movements. The functional anatomy of the bucco-pharyngeal region is described and threat displays are kinematically studied and functionally interpreted.     

Some behavioural observations on domestic fowl in the wild

Attempts to form a feral population of domestic fowl with artificially reared birds on an island nature reserve are described. The birds were subjected to predation by mink, but some hens produced broods and successfully reared their young, a few of which were more than 6 months old at the end of the study period. Factors leading to survival of the population in the face of certain selection pressures are discussed.     

Neurocranial osteology and systematic relationships of Varanus (Megalania) prisca Owen, 1859 (Squamata: Varanidae)

The neurocranial osteology of the giant monitor lizard Varanus (Megalania) prisca Owen, 1859 is described in detail for the first time. Optimization of neurocranial characters onto phylogenetic topologies for varanoids, including Lanthanotus, Heloderma, and Varanus species nests V. prisca within an Indo‐Australian clade of Varanus on the basis of characters of the otic capsule. A sister‐taxon relationship between V. prisca and Varanus komodoensis Ouwens, 1912 is proposed based on apomorphies of the crista prootica, fenestra vestibuli, occipital recess, and supraoccipital. These results support a monophyletic clade of giant monitors among Indo‐Australian species, and unambiguously synonymize Megalania with Varanus at both generic and subgeneric levels. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 445–457.     

Morphology and function of the tongue and hyoid apparatus in Varanus (Varanidae, Lacertilia)

The morphology and function of the tongue and hyoid apparatus in Varanus were examined by anatomical and experimental techniques. Morphological features unique to Varanus include a highly protrusible tongue that has lost a roughened dorsal surface, an exceptionally strong and mobile hyobranchial apparatus, a well-defined joint between the ceratohyal and anterior process, and a series of distinct muscles inserting at the anterior hyobranchial region. Varanus is also unusual among lizards in a number of feeding behaviors; it ingests prey entirely by inertial feeding, as the tongue does not participate in food transport. Further specializations include an increased reliance on hyobranchial movements in drinking and pharyngeal packing and compression. The long, narrow tongue is most likely related to the mechanics of tongue protrusion; the increased amount, strength, and complexity of hyobranchial movement is related to the fact that the hyobranchium in Varanus replaces the tongue in many functions. Previous hypotheses for the origin of these adaptations are discussed, and the difficulties of attributing these specializations to any specific scenario of adaptation or constraint are emphasized.     

Metabolic rate and endurance capacity in Australian varanid lizards (Squamata: Varanidae: Varanus)

In ecomorphological and ecophysiological studies, locomotor performance is often considered to be an intermediate step between the form of an organism and its environment. We examined this premise by measuring morphology, physiology and circular track endurance in the closely related group of Australian varanid lizards. Body size, body mass and relative body proportions were poor indicators of endurance. Body mass was not correlated with endurance and size-free lower forelimb length had only a weak relationship with endurance. Instead, maximal metabolic rate was positively correlated with endurance capacity in varanids. A comparison of varanids with other groups of lizards supported this result as varanids showed both elevated maximal metabolic rate and elevated endurance scores when compared with similar sized non-varanid lizards. There was support for a strong association between endurance with foraging mode and climate. Varanid species with higher endurance tended to be widely foraging and from xeric climates, while sit-and-wait and mesic species showed reduced endurance.   © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 664–676.     

Monitor lizards: a pan-African check-list of their zoogeography (Sauria: Varanidae: Polydaedalus)

Aim This goal of this paper is to present an up‐to‐date, accurate check‐list and distribution of the monitor lizards on the African continent. No such list of their distribution has been attempted since Robert F. Mertens' (1942) treatise (Abhandlungen Senckenbergischen Naturforschenden Gesellschaft, 462 , 465 , 466 ). Location The localities included herein are all countries on the African continent, and adjacent islands, with a list of Varanus known to Yemen and Saudi Arabian Republics included for clarity. One fossil Varanus rusingensis is included, as it is the first, and only described, fossil African Varanus known. Methods Locality records were reviewed from literature sources, museum voucher specimens, personal comments, field observations and photographic records. Results A summation of 3,268 locality records are included herein from the methods listed, with maps depicting these records. Main conclusions From the locality records listed herein, it is evident that the Nile monitor (V. niloticus) has the widest distribution, and that the Yemen monitor (V. yemenensis) has the most restricted distribution; paradoxically, both features may be indicative of their relic habitation on the African continent.     

Energy and Water Turnover Rates of a Free-living and Captive Goanna,Varanus caudolineatus (Lacertilia: Varanidae)

The small, arboreal goanna, Varanus caudolineatus, has a field metabolic rate of approximately 0.46 mL CO₂ g⁻¹ hr⁻¹ and a daily water intake requirement of approximately 31.6 mL kg⁻¹ day⁻¹ measured during the summer. V. caudolineatus held in a controlled-temperature environment of 35°C have lower metabolic (0.25 mL CO₂ g⁻¹ hr⁻¹) and water flux (24.9 mL H₂O kg⁻¹d⁻¹) rates than those in the field. Body water content was approximately 80% for V. caudolineatus.     

Behavioural observations on captive pairs of wild caught tamarins (Saguinus mystax)

Quantitative data are given on 12 categories of behaviour, including scent marking, allogrooming, huddling, and proximity for individual tamarins within 14 male, female pairs and the mated pair of one family group of four animlals. Time sample data were recorded at 30 sec intervals to a total of 260 hr. In addition, some data were collected from within time sample intervals. Individual and intergroup variation in behaviour was a main finding of the study. It was found, however, that females scent marked significantly more than males, at least on the basis of their total marking frequencies, that females tended to groom males more than vice versa, and that although the general proportions of activities were similar in two conditions of housing, their spatial distribution was different under the two conditions. There was very little overt aggression among the pairs.     

Niche construction and Dreaming logic: aboriginal patch mosaic burning and varanid lizards (Varanus gouldii) in Australia

Anthropogenic fire is a form of ecosystem engineering that creates greater landscape patchiness at small spatial scales: such rescaling of patch diversity through mosaic burning has been argued to be a form of niche construction, the loss of which may have precipitated the decline and extinction of many endemic species in the Western Desert of Australia. We find evidence to support this hypothesis relative to one keystone species, the sand monitor lizard (Varanus gouldii). Paradoxically, V. gouldii populations are higher where Aboriginal hunting is most intense. This effect is driven by an increase in V. gouldii densities near successional edges, which is higher in landscapes that experience extensive human burning. Over time, the positive effects of patch mosaic burning while hunting overwhelm the negative effects of predation in recently burned areas to produce overall positive impacts on lizard populations. These results offer critical insights into the maintenance of animal communities in the desert, supporting the hypothesis that the current high rate of endemic species decline among small animals may be linked to the interaction between invasive species and mid-century removal of Aboriginal niche construction through hunting and patch mosaic burning.     

Activity areas and daily movements of an arboreal monitor lizard,Varanus tristis (Squamata: Varanidae) during the breeding season

During the breeding season, in the western Great Victoria Desert, Western Australia, male Varanus tristis move greater daily distances (186.5 m) than females (99.7 m) and have larger activity areas (40.3 ha vs 3.7 ha). V. tristis retreat predominantly to live and dead upright Eucalyptus gongylocarpa (marble gum) trees that have hollows in their trunks and limbs. There is no observable difference between males and females in their preferred habitat, but females are found more frequently in a lesser number of preferred retreats during the breeding season.     

Hemiclitoris discovered: a fully differentiated erectile structure in female monitor lizards (Varanus spp.) (Reptilia: Varanidae)

In female monitor lizards ( Varanus spp.), the ubiquitous presence of paired evertible and erectile structures in the ventral portion of the tail root, which are miniaturized mirror images of the hemipenes of the males, was discovered. These organs contain all the structural elements (including a forked retractor muscle, supporting ossifications, epidermal flounces etc.) that are also characteristic for the hemipenes of the respective conspecific males. Consequently, it is proposed that the term hemiclitoris be used for this organ. A preliminary survey showed this organ to be present in several other squamate families, suggesting that it is ubiquitous in all female Squamata.

Zusammenfassung

Die Entdeckung der Hemiclitoris, eines differenzierten erektilen und ausstülpbaren Organs bei Waranweibchen (Reptilia: Varanidae)
In der Schwanzwurzel weiblicher Warane ( Varanus spp.) wurde das obligate Vorhandensein paariger, ausstülpbarer und erektiler Strukturen entdeckt, welche verkleinerte Spiegelbilder der Hemipenes der Männchen darstellen. Diese Organe enthalten sämtliche Strukturelemente (z.B. den gegabelten Rückziehmuskel, Stützknochen, epidermale Paryphasmen), die auch für die Hemipenes der betreffenden artgleichen Männchen charakteristisch sind. Ein erster Erfassungsansatz (mit ausführlicher Artenliste in einer demnächst zu publizierenden, derzeit erstellten Diplomarbeit) zeigt, daß dieses Organ auch bei diversen weiteren Squamatenfamilien nachweisbar ist. Dies legt nahe, daß es tatsächlich obligat bei alien weiblichen Squamata ausgebildet ist.     

Hemiclitoris discovered: a fully differentiated erectile structure in female monitor lizards (Varanus spp.) (Reptilia: Varanidae)

In female monitor lizards (Varanus spp.), the ubiquitous presence of paired evertible and erectile structures in the ventral portion of the tail root, which are miniaturized mirror images of the hemipenes of the males, was discovered. These organs contain all the structural elements (including a forked retractor muscle, supporting ossifications, epidermal flounces etc.) that are also characteristic for the hemipenes of the respective conspecific males. Consequently, it is proposed that the term hemiclitoris be used for this organ. A preliminary survey showed this organ to be present in several other squamate families, suggesting that it is ubiquitous in all female Squamata.     

Nuclear and mtDNA-based phylogeny of southern African sand lizards, Pedioplanis (Sauria: Lacertidae)

The diversity of lacertid lizards in Africa is highest in the southern African subcontinent, where over two-thirds of the species are endemic. With eleven currently recognized species, Pedioplanis is the most diverse among the southern African genera. In this study we use 2200 nucleotide positions derived from two mitochondrial markers (ND2 and 16S rRNA) and one nuclear gene (RAG-1) to (i) assess the phylogeny of Pedioplanis and (ii) estimate divergence time among lineages using the relaxed molecular clock method. Individual analyses of each gene separately supported different nodes in the phylogeny and the combined analysis yielded more well supported relationships. We present the first, well-resolved gene tree for the genus Pedioplanis and this is largely congruent with a phylogeny derived from morphology. Contrary to previous suggestions Heliobolus/Nucras are sister to Pedioplanis. The genus Pedioplanis is monophyletic, with P. burchelli/P. laticeps forming a clade that is sister to all the remaining congeners. Two distinct geographic lineages can be identified within the widespread P. namaquensis; one occurs in Namibia, while the other occurs in South Africa. The P. undata species complex is monophyletic, but one of its constituent species, P. inornata, is paraphyletic. Relationships among the subspecies of P. lineoocellata are much more complex than previously documented. An isolated population previously assigned to P. l. pulchella is paraphyletic and sister to the three named subspecies. The phylogeny identifies two biogeographical clades that probably diverged during the mid-Miocene, after the development of the Benguella Current. This probably led to habitat changes associated with climate and, in conjunction with physical barriers (Great Escarpment), contributed towards speciation within the genus Pedioplanis.