P. le Fras N. Mouton

Between a rock and a hard polytomy: Rapid radiation in the rupicolous girdled lizards (Squamata: Cordylidae)

Girdled lizards (Cordylidae) are sub-Saharan Africas only endemic squamate family and contain 80 nominal taxa, traditionally divided into four genera: Cordylus, Pseudocordylus, Chamaesaura and Platysaurus. Previous phylogenetic analysis revealed Chamaesaura and Pseudocordylus to be nested within Cordylus, and the former genera were sunk into the later. This taxonomic revision has received limited support due to the studys poor taxon sampling, weakly supported results and possible temporary nomenclatural instability. Our study analyzes three nuclear and three mitochondrial genes from 111 specimens, representing 51 in-group taxa. Parsimony, likelihood and Bayesian analyses of concatenated and partitioned datasets consistently recovered a comb-like tree with 10, well-supported, monophyletic lineages. Our taxonomic reassessment divides the family into 10 genera, corresponding to these well-supported lineages. Short internodes and low support between the non-platysaur lineages are consistent with a rapid radiation event at the base of the viviparous cordylids.

The effect of body armature on escape behaviour in cordylid lizards

Abstract The possession of armour may affect escape behaviour in two ways. On one hand, by decreasing vulnerability to predators, armour may permit individuals to use habitats and behaviours that are too risky for unarmoured individuals. Alternatively, the possession of armour may have negative trade-offs on other traits involved in antipredator behaviour, such as sprint speed, thus constraining antipredator options relative to those available to unarmoured individuals. To examine these contrasting predictions, we examined species in the lizard family Cordylidae, which contains remarkable morphological diversity, ranging from completely unarmoured to heavily defended species. Moreover, phylogenetic analysis indicates that armour has been an evolutionarily labile trait. We found support for the second prediction. Degree of body armature was inversely correlated with distance run from a predator: heavily armoured species always entered refuges after short distances, whereas many unarmoured lizards continued to flee and could not be induced to enter a refuge. Possession of armour was also negatively related to use of vertical surfaces during escape behavour. These results were unchanged when analysed in a phylogenetic context. Thus, we conclude that the morphological requirements for active flight and armoured defence are incompatible. Heavily armoured species are bulky, have short legs and run more slowly than less armoured species. Rather than constituting an alternative to behavioural antipredator tactics, we conclude that the possession of armour is part of an antipredator syndrome that includes habitat use and behaviour as well as morphology. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .

Molecular data suggest that melanistic ectotherms at the south-western tip of Africa are the products of Miocene climatic events: Evidence from cordylid lizards

In the present study the evolutionary relationships among Cordylus niger–oelofseni–cordylus are investigated using molecular sequence data to: (1) estimate the divergence within this group; (2) date the origin of melanism in the clade and to evaluate possible palaeoecological events responsible for its evolution; (3) examine the systematic relationships among the three isolated populations of C. oelofseni that were previously shown to be polyphyletic using allozyme data. The recovered topology for the combined sequence data (16S and NADH dehydrogenase component 2 (ND2)) among C . niger–oelofseni–cordylus suggests that melanism evolved only once in the clade. The application of a molecular clock to the data demonstrates that melanism evolved during the Miocene epoch, 17–15 million years ago. We believe that the development of a cold-water current and upwelling system along the south-west coast of Africa during this epoch was instrumental in the evolution of melanism in this lizard clade and possibly also in other ectotherm clades with melanistic forms occurring in the area. The results show that C. oelofseni , as presently construed, is composed of three distinct evolutionary lineages, with no shared haplotypes present and marked sequence divergence. Two of the three lineages represent undescribed species. Cordylus cordylus is composed of two distinct clades, a montane clade and a coastal lowland clade. Cladogenic activity in mountain areas of the Western Cape in South Africa has been particularly pronounced and the systematic diversity of many taxa may have been underestimated.

Adaptive radiation in cordyliform lizards: An overview

MOUTON, P. LE F.N., and J. H. VAN WYK. 1997. Adaptive radiation in cordyliform lizards: An overview. Afr. J. Herpetol. 46(2): 78–88. Ecophysiological and behavioral character evolution in the Cordyliformes is discussed. Arguments are based on Langs generic-level phylogenetic tree for the Cordyliformes, but with Platysaurus taken as the most basal genus in the Cordylidae. Ancestral values for reproductive mode, foraging mode, prey chemical discrimination ability and preferred substrate are evaluated using parsimony criteria and the Scincidae and Lacertoidea as outgroups. The available data suggest that, within Cordyliformes, sit-and-wait foraging, lack of prey chemical discrimination, and a rupicolous lifestyle co-evolved in the immediate ancestor of the Cordylidae, while viviparity evolved in the immediate ancestor of the Cordylus-Chamaesaura-Pseudocordylus clade. The highland distribution and viviparous reproductive mode of the latter clade suggest that the ancestor became adapted to cool regimes, in ot...

Pheromonal Detection and Sex Discrimination of Conspecific Substrate Deposits by the Rock-Dwelling Cordylid Lizard Cordylus cordylus

The cordylid lizard Cordylus cordylus, a member of a family in which pheromonal communication was previously unreported, detects conspecific pheromones and responds differently to male and female pheromones. In an arena containing a clean ceramic tile or one marked by a male or female conspecific, males tongue flicked male-labeled and female-labeled tiles more frequently than clean tiles, indicating detection of conspecific stimuli. Females detected female pheromones and tongue flicked at a higher rate in response to female than male pheromones, but tongue flicks elicited by male stimuli were not significantly greater than those elicited by clean tiles. Both sexes are territorial, and each sex is more aggressive to consexuals. Both sexes performed more tongue flicks in response to same-sex than to opposite-sex pheromones. The most likely sources of pheromones detected are secretions of femoral and possibly generation glands. Both occur on the ventral femur where transfer to hard surfaces is facilitated

Taxonomie status of the melanistic forms of the Cordylus cordylus complex (Reptilia: Cordylidae) in the south-western Cape, South Africa

The taxonomie status of the two melanistic morphotypes belonging to the Cordylus cordylus complex in the south-western Cape, South Africa, is considered. It is proposed that the coastal melanistic form, previously described as subspecies of C. cordylus, be considered a separate species, while the previously unknown montane melanistic form is also described as a new species. Areas of uncertainty, which may affect the status of the two melanistic species in the future, are discussed.

Aggregation behaviour of lizards in the arid western regions of South Africa

Abstract Investigations of aggregation behaviour in five lizard species (three diurnal rock-dwelling species, one nocturnal rock-dwelling species, and one diurnal terrestrial species) occurring in the arid western regions of South Africa revealed that there is no single set of causal factors explaining this behaviour. Aggregating behaviour in Cordylus macropholis is simply the result of environmental constraints, namely a shortage of preferred shelter sites. Individuals of Ouroborus cataphractus aggregate to benefit from the early predator detection effect. In Platysaurus broadleyi and Chondrodactylus bibronii aggregation behaviour appears to be the result of environmental constraints as well as possible benefits from the dilution effect. At present there is no conclusive information on the reasons for aggregation in Namazonurus peersi. In the rock-dwelling species investigated, the extent of adaptation to counter the effects of intra-group competition appears to be correlated with the proportion of activity time spent at the communal shelter. The proportion of time spent at the shelter, in turn, appears to be determined by the morphology of the species and whether it is diurnal or nocturnal.

Electrophoretic analysis of the Cordylus cordylus species group in the southwestern Cape, South Africa

Allozyme frequencies were used to test a proposed hypothesis on the evolution and biogeography of the taxa in the Cordylus cordylus species group in the southwestern Cape. The population structures of the three species were also analysed. Low levels of heterozygosity were found in C.oelofseni and C.niger which have small distribution ranges, and intermediate levels in C.cordylus which has an extensive distribution range. Genetic distances were calculated among species and approximate times of divergence were estimated. These divergence times do not agree with the times suggested by other authors. Both phenetic and cladistic approaches were used to assess relationships among the three species. The results suggest that C.niger is monophyletic, but that C.oelofseni is polyphyletic, the population at Landdroskop in the Hottentots Holland Mountains being closer to C.cordylus than to the remaining C.oelofseni populations. It is demonstrated that average genetic distance is not a reliable aid in decisions regarding the taxonomic status of C.oelofseni. Proposed relationships within, as well as monophyly of this group, remain unconfirmed as conflicting results were obtained.

What doesn't kill you might make you stronger: functional basis for variation in body armour

1. Predation has been proposed to be a selective agent in the evolution of morphological antipredator strategies in prey. Among vertebrates, one of the morphological traits that evolved multiple times is body armour, including carapaces, thickened keratinized scales and plates of dermal bone. 2. It has been generally assumed that body armour provides protection against a predatory attack; yet, few explicit tests of the hypothesis exist. Cordylidae, a relatively small family of southern African lizards, show considerable variation in the degree of body armour. Hence, this family provides an opportunity to test the hypothesis that body armour serves as protection against predators. 3. Experiments were conducted to test whether the bite forces of four species of mammalian predators were high enough to penetrate the skins of Karusasaurus polyzonus, Namazonurus peersi, Cordylus cordylus and Cordylus macropholis, as well as those of Ouroborus cataphractus individuals originating from three localities that differed in their predator diversity. Furthermore, histological techniques were used to test whether variation in skin toughness was associated with concomitant changes in the degree of epidermal (i.e. β-keratin) and dermal (i.e. osteoderm) armour. 4. The skin toughness values for four out of five cordylid lizards tested in this study were well below the bite forces of the mammalian predators. In contrast, the thick osteoderms in the dermis of O. cataphractus can withstand bites from several mongoose species. However, the significant variation in body armour that is present between the three populations of O. cataphractus does not seem to be related to predator diversity. 5. It is concluded that body armour can serve as protection against predation in O. cataphractus, but that alternative selection pressures, such as thermoregulation or predation by snakes, presumably underlie variation in defensive morphology in the other cordylid lizards.

ACTIVE GENERATION GLANDS PRESENT IN NEONATES OF SOME CORDYLID LIZARDS : A CASE STUDY OF CORDYLUS MACROPHOLIS (SAURIA: CORDYLIDAE)

Generation glands are holocrine epidermal glands occurring on the ventral aspect of the thigh of cordylid lizards. In most species these glands seemingly start to differentiate with the onset of sexual maturity, but macroscopic signs of generation gland activity were noted in neonates of the large‐scaled girdled lizard, Cordylus macropholis. The glands of neonatal, subadult, and adult individuals were examined microscopically using standard histological techniques. The glands of the five neonatal specimens examined, including both males and females, all had the same basic structure and displayed two layers of mature glandular material. In subadult and adult specimens, the number of layers varied from seven to nine. The structure of the generation glands of C. macropholis is similar to that of the few other Cordylus species that have been described to date. They are of the protruding kind with multiple mature glandular generations. Juveniles of an additional 12 cordylid species have been examined for the presence of active generation glands. Active glands were found to be present in neonates of C. tasmani and C. tropidosternum, both of which are, like C. macropholis, terrestrial species. In C. cordylus and C. coeruleopunctatus, active generation glands are absent in neonates, but differentiate soon after birth. In other cordylid species, generation glands apparently differentiate only with the onset of sexual maturity. J. Morphol. 235:177–182, 1998.