Amphisbaenian Trogonophis Wiegmanni Research Articles

Satellite DNA supports the monophyly of Lacertibaenia (Amphisbaenia and Lacertidae) in squamate phylogeny

Lacertid and amphisbaenian lizards are two squamate reptile lineages very divergent morphologically. In fact, adaptation to burrowing deeply modified amphisbaenian worm-like body. Lacertids instead have a typical reptile morphology with a long tail and four well-developed limbs. Despite so different in appearance, they are evolutionarily very close as evidenced by molecular phylogenetic approaches. Consistently, a slow-evolving satellite DNA (IMO-TaqI) described in lacertid lizards was isolated from the genome of the amphisbaenian Trogonophis wiegmanni too. Comparison with lacertid repeats evidenced great similarity, highlighting that molecular characters appeared very suitable especially when morphology is subjected to strong selective pressures.

Coping with drought? The hidden microhabitat selection and underground movements of amphisbaenians under summer drought conditions.

Habitat selection is a dynamic process that depends on many environmental variables that can vary with weather conditions. This is important because, within a context of global change, extreme weather events, such as severe droughts, are predicted to become more frequent. We examined the patterns of microhabitat selection and underground movements (using PIT-tag telemetry) of a strictly fossorial reptile, the North African checkboard amphisbaenian Trogonophis wiegmanni, during the summer drought period. We aimed to test whether changes in strategies of habitat use and movements could allow this amphisbaenian to cope with unfavorable weather. We found that during the summer drought period, T. wiegmanni did not use the microhabitats in relationship to their availability, but particularly selected sites with high abundance of rocks but also areas under a high cover of bushes, where environmental conditions were more favorable. We also found, using PIT-tag telemetry, that the numbers of T. wiegmanni individuals located under rocks and their activity (number of days with movements) decreased largely in summer. However, the animals were not entirely inactive, but, especially males were active below the ground under bushes and made some relatively long underground hidden movements between favorable areas.

Intersexual and body size-related variation in chemical constituents from feces and cloacal products involved in intraspecific communication of a fossorial amphisbaenian.

Many animals rely on chemical cues for intraspecific communication. This is especially important in fossorial animals because visual restrictions of the underground environment limit the opportunities for visual communication. Previous experiments showed the ability of the amphisbaenian Trogonophis wiegmanni to discriminate between several categories of conspecifics based on chemical cues alone. However, in contrast with many other reptile species, T. wiegmanni does not have external secretory glands, but uses uncharacterized secretions from the cloaca in intraspecific chemosensory communication. Using gas chromatography-mass spectrometry (GC-MS), we analyzed the lipophilic compounds from feces and cloacal products freshly extracted from the cloaca of male and female T. wiegmanni. We identified and estimated relative proportions of the compounds found, and tested for intersexual and body-size related differences. We found a total of 103 compounds, being some steroids (mainly cholesterol and cholestanol), some alkanes and squalene the most abundant and frequent. Further, we found intersexual differences, with males, especially larger ones, having higher proportions of several alkanes between C13 and C24 and of squalene than females, which had higher proportions of several steroids and also of nonacosane and methylnonacosane than males. We compared these findings with secretions of other animals and discuss the potential role of these compounds and their variations in intraspecific communication of amphisbaenians.

Size-related changes and chemical basis of melanin-based body coloration in the amphisbaenian Trogonophis wiegmanni

Abstract Melanin is a fundamental pigment in animal coloration as it is involved in many different adaptive functions such as signaling or thermoregulation. Two forms of melanin are known to produce different colors (eumelanin: black; pheomelanin: yellow or brown). Here, we explored whether there were intersexual differences and/or size-related changes in melanization of the amphisbaenian Trogonophis wiegmanni, a fossorial species with a characteristic black and yellow color pattern of scales. We found a clear effect of body length, but not of sex, on the levels of melanization, which was also dependent on the body region; the proportion of melanin-dependent blackish coloration increased with body length in the dorsum, but decreased with body length in the ventral belly area. We also studied the chemical basis of this coloration using Raman spectroscopy and found that eumelanin was present in both black and yellow scales, but pheomelanin was not found in yellow scales, suggesting that this yellow coloration is caused by the reduction of eumelanin or dispersion of melanosomes and/or perhaps by other pigments.

Offspring and adult chemosensory recognition by an amphisbaenian reptile may allow maintaining familiar links in the fossorial environment.

Kin recognition is a phenomenon with an important function in maintaining cohesive social groups in animals. Several studies have examined parent–offspring recognition in species with direct parental care. Few studies have, however, explored parent–offspring recognition in animals that, at best, only show apparent indirect parental care, such as some reptiles. In this study, we investigated reciprocal parent–offspring recognition in the fossorial amphisbaenian Trogonophis wiegmanni, a viviparous species that shows potential stable ‘family groups’ in the form of parent-offspring long-term associations. We examined whether adult males and females could discriminate via chemical cues between familiar juveniles which associate with them within their family groups, and are potentially their offspring, to that of unfamiliar juveniles, and whether juveniles could discriminate between familiar adult males and females of their family group (probably their parents) and unfamiliar unrelated adults. We measured tongue flick behavior to study chemosensory responses to the scent of conspecifics. We found that adult female amphisbaenians, but not males, could discriminate between scents of familiar and unfamiliar juveniles. Juvenile amphisbaenians did not discriminate between familiar and unfamiliar adult females, but recognize familiar from unfamiliar males. We discuss our results of parent–offspring recognition according to its potential social function in an ecological fossorial context where visibility is limited and chemosensory kin recognition may contribute to the establishment of stable family groups.

How to maintain underground social relationships? Chemosensory sex, partner and self recognition in a fossorial amphisbaenian.

Maintaining social relationships depends on the ability to recognize partners or group members against other individuals. This is especially important in animals with relatively stable social groups. The amphisbaenian Trogonophis wiegmanni is a semi blind fossorial reptile that spends its entire life underground where it interacts with mates and social partners. In this environment, visual cues are limited. Chemosensory cues may rather allow conspecific social and partner recognition. We recorded the number of tongue-flick (TF) rates of T. wiegmanni amphisbaenians to scents of both sexes with different pairing social bonds (familiar vs. unfamiliar) presented on cotton swabs to test discrimination of social groups. As seen from a rise in the number of TFs, males discriminated unfamiliar females from unfamiliar males. This suggests that chemical cues may be used by males to locate new mates. In contrast, females detected scent of unfamiliar conspecifics, but did not show sex discrimination. Both males and females discriminated the scent of an individual with which they had formed a pair bond from an unfamiliar individual of the same sex as the partner. Also, males, but not females, were capable of self-recognition, suggesting that scent marks of males in home ranges may provide individual information in intrasexual relationships. We conclude that conspecific discrimination based on chemical cues may allow the maintenance of social relationships and relatively stable pairs in fossorial reptiles inhabiting visually restricted environments.

PIT-Tags as a technique for marking fossorial reptiles: insights from a long-term field study of the amphisbaenian Trogonophis wiegmanni

Many field studies of ecology or conservation require individual identification of the animals, and for this, several marking techniques have been developed. However, no specific labeling technique has been tested for fossorial reptiles, such as amphisbaenians. We describe the use of Passive Integrated Transponder (PIT) tags as a long-term labeling method of the amphisbaenian Trogonophis wiegmanni. We present the details of the marking procedure and examine the benefits and drawbacks of the technique considering the fossorial environment. After marking many individuals in a long-term field study, we can ensure that the marks were easily applicable and were not lost over a period of at least four years. Moreover, PIT tags did not negatively affect the body condition of amphisbaenians. We conclude that PIT tags are useful for doing field studies of this and similar fossorial species.

PIT-Tags as a technique for marking fossorial reptiles: insights from a long-term field study of the amphisbaenian Trogonophis wiegmanni

Many field studies of ecology or conservation require individual identification of the animals, and for this, several marking techniques have been developed. However, no specific labeling technique has been tested for fossorial reptiles, such as amphisbaenians. We describe the use of Passive Integrated Transponder (PIT) tags as a long-term labeling method of the amphisbaenian Trogonophis wiegmanni. We present the details of the marking procedure and examine the benefits and drawbacks of the technique considering the fossorial environment. After marking many individuals in a long-term field study, we can ensure that the marks were easily applicable and were not lost over a period of at least four years. Moreover, PIT tags did not negatively affect the body condition of amphisbaenians. We conclude that PIT tags are useful for doing field studies of this and similar fossorial species.

Underground cryptic speciation within the Maghreb: Multilocus phylogeography sheds light on the diversification of the checkerboard worm lizard Trogonophis wiegmanni

Biogeographic and evolutionary patterns in the North African portion of the Western Palaearctic are poorly known. A high fraction of undescribed diversity is expected in this region, especially in groups such as reptiles. Here we used mitochondrial (12S, 16S, cytb) and nuclear (pomc, rag2, cmos) markers and morphological data to investigate phyletic diversification and phylogeographical structure in the amphisbaenian Trogonophis wiegmanni endemic to the Maghreb. Phylogenetic and molecular dating analyses based on gene trees and species trees support three deeply divergent lineages of Pliocene origin, two in Morocco and one in central Algeria and Tunisia. Parapatry, reciprocal monophyly, high genetic divergence and limited morphological differentiation between them suggest that these lineages represent independent cryptic taxonomic units. Emerging lines of evidence from this study and from available literature on Maghreb taxa support (i) a major biogeographic break between western and eastern Maghreb and (ii) a role of the Atlas as a biogeographic divide within the western Maghreb (Morocco). The origin of these biogeographic units is probably associated with the evolutionary events prompted by the Late Miocene palaeogeographic setting and later by Plio-Pleistocene climatic changes and their interplay with prominent orographic barriers within North Africa.

Absence of haemoparasite infection in the fossorial amphisbaenian Trogonophis wiegmanni.

Blood parasites such as haemogregarines and haemosporidians have been identified in almost all groups of vertebrates. However, very little is known about biodiversity of these parasites and their effects on some major groups of reptiles such as amphisbaenians, a distinctive group with many morphological and ecological adaptations to fossorial life. Conditions of the fossorial environment might also affect host-parasite relationships. We investigated the presence and the potential prevalence of three genera of haemoparasitic aplicomplexan blood parasites (Hepatozoon, Plasmodium and Haemoproteus) in the amphisbaenian Trogonophis wiegmanni, a fossorial worm lizard species from North West Africa. Blood parasite infection was not detected in T. wiegmanni, both in visual surveys of blood smears and using molecular methods to detect DNA of such parasites in the blood of the potential amphisbaenian hosts. We discuss how conditions of the fossorial environment might affect blood parasitaemias in amphisbaenians as well as in other fossorial reptiles.

Chemosensory Prey Detection by the AmphisbaenianTrogonophis wiegmanni

Foraging underground poses a number of important challenges for fossorial animals, such as amphisbaenians. For instance, visual detection and identification of prey is often hampered by low light conditions and poor eye sight. In response, many fossorial animals have switched to other sensory systems, such as chemoreception. We tested the ability of the amphisbaenian Trogonophis wiegmanni to detect and discriminate between different prey types based on chemical cues alone. Results of a laboratory experiment showed that amphisbaenians were able to detect prey using chemoreception, as indicated by an increase in chemosensory tongue-flick responses to swabs bearing chemicals from prey in comparison with blank controls. Also, differential tongue-flick rates to chemicals from different prey types indicated that at least some prey types may be discriminated from others based on chemosensory cues. These results suggest that T. wiegmanni amphisbaenians use chemoreception when foraging.

Sexual Dimorphism in the North African AmphisbaenianTrogonophis wiegmanni

Abstract Sexual dimorphism in size or shape is common in many reptile species. Amphisbaenians are morphologically specialized for a fossorial life, which might constrain the evolution of sexual dimorphism. This might explain why some amphisbaenian species, but not others, show some type of sexual dimorphism. To understand the differential occurrence of sexual dimorphism in amphisbaenians, studies on a wide number of species belonging to different families and inhabiting different ecological conditions are needed. We measured several morphological variables in a population of the amphisbaenian Trogonophis wiegmanni, a representative of the little-studied family Trogonophidae from North Africa. Results show that males and females have similar body size; but for individuals of similar size, males are heavier, have longer tails, and have larger heads than do females. These differences might be explained by sexual selection, if males with larger heads had advantages in intrasexual contests, or by sexual diet d...

Social aggregation behaviour in the North African amphisbaenian Trogonophis wiegmanni

The ecology and behaviour of Amphisbaenians is poorly known due to their fossorial habits. However, amphisbaenians are often found under rocks where they thermoregulate, and probably engage in social interactions. We describe aggregations under rocks in a North African population of the little studied amphisbaenian Trogonophis wiegmanni. These observations could be used to make initial inferences about the social behaviour of this amphisbaenian. Results showed that amphisbaenians were sometimes found in pairs under the same rock. However, these aggregations were not random. Adult males were only found together with adult females, but we did not find pairs of adult males or adult females. This might suggest that there is intra-sexual intolerance, and that adult individuals of the same sex do not occupy the same rock space. Pairs of adults were more frequently found in spring than in autumn, coinciding with the mating season. Also, juvenile individuals were often found together with an adult, but juveniles tended to be more often with an adult female than with an adult male. This might indicate that juveniles are allowed to remain with their parents until they are older, which might enhance offspring fitness by providing access to high-quality habitats.

Aerobic and Anaerobic Activity Metabolism of Limbless and Fossorial Reptiles

We studied oxygen consumption and lactate accumulation during intense, short-term exercise at 25 C by four species of limbless reptiles: the fossorial lizards Anniella pulchra and Ophisaurus ventralis, the fossorial amphisbaenian Trogonophis wiegmanni, and the snake Thamnophis butleri. The three fossorial reptiles had standard metabolic rates 34%-67% below average for reptiles of their mass, which may be beneficial in their subterranean habitats. During a 2-min burst of activity;, oxygen consumption rose 7-15-fold in Anniella, Trogonophis and Thamnophis, and 33-fold in Ophisaurus. Anniella, Trogonophis, and Thamnophis had active metabolic rates, mass-specific aerobic scopes, anaerobic scopes, and total metabolic scopes similar to those of other reptiles of their body size, whereas Ophisaurus had exceptionally high values. Ophisaurus is thus unusual in having both a very high aerobic scope and a large anaerobic scope. Our data lead us to conclude that limblessness is not associated with a marked divergence...