Ultrastructural comparison between the tongue of two reptilian species endemic in Egyptian fauna; Bosc's fringe‐toed lizard Acanthodactylus boskianus and Sinai fan‐fingered gecko Ptyodactylus guttatus

2021 ◽  
Author(s):  
Doaa I. Gewily ◽  
Fatma A. Mahmoud ◽  
Samy A. Saber ◽  
Boshra A. ElSalkh ◽  
Asmaa A. El‐Dahshan ◽  
...  
Keyword(s):  
Reptilian Species

scholarly journals Discovery of a phylogenetically distinct poxvirus in diseased Crocodilurus amazonicus (family Teiidae)

2021 ◽  
Author(s):  
Kerstin Seitz ◽  
Anna Kübber-Heiss ◽  
Angelika Auer ◽  
Nora Dinhopl ◽  
Annika Posautz ◽  
...  
Keyword(s):  
Phylogenetic Relationship ◽  
Genome Sequence ◽  
Skin Disease ◽  
Reptilian Species

AbstractA novel poxvirus was discovered in Crocodilurus amazonicus (Teiidae) presenting with a debilitating skin disease. The generated first genome sequence of a reptilian poxvirus revealed the closest phylogenetic relationship to avipoxviruses, highlighting potential virus exchanges between avian and reptilian species.

scholarly journals Molecular and Cellular Mechanisms Underlying Temperature-Dependent Sex Determination in Turtles

2021 ◽  
pp. 1-9
Author(s):  
Horacio Merchant-Larios ◽  
Verónica Díaz-Hernández ◽  
Diego Cortez
Keyword(s):  
Animal Models ◽  
Sex Determination ◽  
Incubation Temperature ◽  
State Of The Art ◽  
Current Understanding ◽  
Temperature Dependent ◽  
Cellular Mechanisms ◽  
Male Phenotype ◽  
History Of ◽  
Reptilian Species

The discovery in mammals that fetal testes are required in order to develop the male phenotype inspired research efforts to elucidate the mechanisms underlying gonadal sex determination and differentiation in vertebrates. A pioneer work in 1966 that demonstrated the influence of incubation temperature on sexual phenotype in some reptilian species triggered great interest in the environment’s role as a modulator of plasticity in sex determination. Several chelonian species have been used as animal models to test hypotheses concerning the mechanisms involved in temperature-dependent sex determination (TSD). This brief review intends to outline the history of scientific efforts that corroborate our current understanding of the state-of-the-art in TSD using chelonian species as a reference.

Thermal sensitivity of reptilian melatonin rhythms: "cold" tuatara vs. "warm" skink

1989 ◽  
Vol 256 (5) ◽  
pp. R1160-R1163 ◽  
Author(s):  
B. T. Firth ◽  
M. B. Thompson ◽  
D. J. Kennaway ◽  
I. Belan
Keyword(s):  
Environmental Conditions ◽  
Thermal Sensitivity ◽  
Cold Temperature ◽  
Daily Rhythm ◽  
Threshold Temperature ◽  
Daily Rhythms ◽  
Thermoregulatory Behavior ◽  
Lower Amplitude ◽  
Sphenodon Punctatus ◽  
Reptilian Species

Daily rhythms in plasma melatonin levels were compared in two ecologically diverse reptilian species under natural environmental conditions in autumn. The nocturnal, cold temperature-adapted tuatara (Sphenodon punctatus) had a melatonin rhythm of much lower amplitude than did the diurnal desert-adapted sleepy lizard (Tiliqua rugosa). Experiments in controlled laboratory environments showed that, although both species are capable of attaining a comparable melatonin peak (approximately 750 pmol/l), the threshold temperature at which a significant daily rhythm occurs is approximately 15 degrees C in S. punctatus compared with approximately 25 degrees C in T. rugosa. This difference probably reflects the disparate thermoregulatory adaptations of the two species, S. punctatus favoring mean activity temperatures of 11.5 degrees C and T. rugosa, 32.5 degrees C. In ectotherms such as reptiles, therefore, species-typical thermoregulatory behavior may provide thermal cues that interact with photoperiod to provide the appropriate melatonin signal for the regulation of annual physiological cycles.

In utero exposure to the oestrogen mimic diethylstilbestrol disrupts gonadal development in a viviparous reptile

2015 ◽  
Vol 27 (7) ◽  
pp. 1106 ◽  
Author(s):  
Laura M. Parsley ◽  
Erik Wapstra ◽  
Susan M. Jones
Keyword(s):  
Endocrine Disrupting Chemicals ◽  
Gonadal Development ◽  
Seminiferous Tubules ◽  
Endocrine Disrupting ◽  
Multiple Routes ◽  
Ovarian Structure ◽  
Advanced Knowledge ◽  
Dose Response Effect ◽  
Ubiquitous Presence ◽  
Reptilian Species

The ubiquitous presence of endocrine-disrupting chemicals (EDCs) in the environment is of major concern. Studies on oviparous reptiles have significantly advanced knowledge in this field; however, 30% of reptilian species are viviparous (live-bearing), a parity mode in which both yolk and a placenta support embryonic development, thus exposure to EDCs may occur via multiple routes. In this first study of endocrine disruption in a viviparous lizard (Niveoscincus metallicus), we aimed to identify effects of the oestrogen mimic diethylstilbestrol (DES) on gonadal development. At the initiation of sexual differentiation, pregnant N. metallicus were treated with a single dose of DES at 100 or 10 µg kg­–1, a vehicle solvent or received no treatment. There was no dose-response effect, but the testes of male neonates born to DES-exposed mothers showed reduced organisation of seminiferous tubules and a lack of germ cells compared with those from control groups. The ovaries of female neonates born to DES-exposed mothers exhibited phenotypic abnormalities of ovarian structure, oocytes and follicles compared with controls. The results indicate that, in viviparous lizards, maternal exposure to oestrogenic EDCs during gestation may have profound consequences for offspring reproductive fitness.

Sex and ontogenetic dietary shift in Pogona barbata, the Australian eastern bearded dragon

2016 ◽  
Vol 64 (1) ◽  
pp. 14 ◽  
Author(s):  
Danny Wotherspoon ◽  
Shelley Burgin
Keyword(s):  
Dietary Habits ◽  
High Protein Diet ◽  
Reproductive Season ◽  
Museum Specimens ◽  
Adult Males ◽  
Dietary Shift ◽  
Bearded Dragon ◽  
Males And Females ◽  
Optimum Foraging ◽  
Reptilian Species

Differences may occur in the carnivore–omnivore–herbivore spectrum over the lifespan of a reptilian species, but it seldom occurs between adult males and females. Information regarding the dietary habits of Australian eastern bearded dragon (Pogona barbata) is also limited. We dissected museum specimens and road kills of the Australian eastern bearded dragon to compare ontogenetic shift in diet. Juveniles were insectivorous. They typically consumed larger, more active, arthropod prey than mature individuals – they are active predators. Adults were omnivorous and typically consumed small arthropod prey, and tended to be sit-and-wait predators. Mature males, particularly larger males, were primarily herbivorous. Such divergence in adult reptilian diet has rarely been reported. We suggest that the dietary switches observed are consistent with the Optimum Foraging Model. Juveniles require a high protein diet to maximise growth from juvenile to maturity. Beyond maturity females continue to require higher levels of protein for reproduction than males. At least in part, this is because males rely on sham aggression to defend territory during the reproductive season rather than resorting to aggressive behaviour. This results in a lesser requirement for protein for adult males than is required for juveniles and adult females. Males have the advantage of not being as dependent on protein, and thus are able to rely more heavily on vegetation.

scholarly journals The Contribution of Kurī (Polynesian Dog) to the Ecological Impacts of the Human Settlement of Aotearoa New Zealand

2021 ◽  
Vol 9 ◽  
Author(s):  
Karen Greig ◽  
Nicolas J. Rawlence
Keyword(s):  
New Zealand ◽  
Human Impact ◽  
Marine Mammal ◽  
Ecological Impacts ◽  
Human Settlement ◽  
Sea Lions ◽  
Aotearoa New Zealand ◽  
Top Predators ◽  
Mammalian Predators ◽  
Reptilian Species

The pre-human Aotearoa New Zealand fauna was dominated by avian and reptilian species. Prior to first human settlement by East Polynesian colonists, the top predators were two giant raptorial birds. Aside from humans themselves, colonisation also resulted in the simultaneous introduction of two novel mammalian predators into this naive ecosystem, the kiore (Pacific rat) and kurī (Polynesian dog). While the ecological impacts of kiore are relatively well understood, those of kurī are difficult to assess, and as such kurī have frequently been disregarded as having any meaningful impact on New Zealand’s biodiversity. Here we use the archaeological and palaeoecological record to reassess the potential impacts of kurī on this ecosystem. We argue that far from being confined to villages, kurī could have had a significant widespread but relatively localised impact on New Zealand’s avian, reptilian and marine mammal (seals and sea lions) fauna as a novel predator of medium-sized species. In this way, kurī potentially amplified the already significant impacts of Polynesian colonists and their descendants on New Zealand’s ecosystem, prior to European arrival. As such, kurī should be included in models of human impact in addition to over-hunting, environmental modification and predation by kiore.

scholarly journals Sex determination without sex chromosomes

2021 ◽  
Vol 376 (1832) ◽  
pp. 20200109 ◽  
Author(s):  
Ceri Weber ◽  
Blanche Capel
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Metabolic Pathways ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Alternative Pathway ◽  
Cellular Processes ◽  
Molecular Events ◽  
Effects Of Temperature ◽  
Reptilian Species

With or without sex chromosomes, sex determination is a synthesis of many molecular events that drives a community of cells towards a coordinated tissue fate. In this review, we will consider how a sex determination pathway can be engaged and stabilized without an inherited genetic determinant. In many reptilian species, no sex chromosomes have been identified, yet a conserved network of gene expression is initiated. Recent studies propose that epigenetic regulation mediates the effects of temperature on these genes through dynamic post-transcriptional, post-translational and metabolic pathways. It is likely that there is no singular regulator of sex determination, but rather an accumulation of molecular events that shift the scales towards one fate over another until a threshold is reached sufficient to maintain and stabilize one pathway and repress the alternative pathway. Investigations into the mechanism underlying sex determination without sex chromosomes should focus on cellular processes that are frequently activated by multiple stimuli or can synthesize multiple inputs and drive a coordinated response. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part I)’.

scholarly journals Biogeography, inventory and new data on reptiles of M’sila region, Algeria

2021 ◽  
Author(s):  
Hadj Aissa Benelkadi ◽  
Adel Mammeri ◽  
Mansour Amroun
Keyword(s):  
Statistical Analysis ◽  
Small Area ◽  
Near Threatened ◽  
Reptilian Species

This study is the first contribution to the evaluation of reptile diversity in different habitats of M’sila region, Algeria. We carried out 94 trips between 2016 and 2018 across three sites: Mergueb (six stations), L’mhazem (three stations) and Kaf Afoul (two stations), on average, accompanied by prospectors. Our aims were to make an inventory of reptilian species in this region, as well as to study their diversity, distribution, ecology and abundance. Altogether, we recorded 193 specimens belonging to 22 species: two turtles, one amphisbaenian, twelve lizards and seven snakes. Two species classified as Near Threatened by the IUCN were recorded: Uromastyx acanthinurus (Bell, 1825) and Daboia mauritanica (Duméril & Bibron, 1848). Statistical analysis revealed that the type of habitat directly influences the distribution of reptiles in the study area. Although this small area is rich in reptilian species, their abundance remains low and worrying

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