William R. Branch

Erosion of lizard diversity by climate change and altered thermal niches

Demise of the Lizards Despite pessimistic forecasts from recent studies examining the effects of global climate change on species, and observed extinctions in local geographic areas, there is little evidence so far of global-scale extinctions. Sinervo et al. (p. 894; see the Perspective by Huey et al.) find that extinctions resulting from climate change are currently reducing global lizard diversity. Climate records during the past century were synthesized with detailed surveys of Mexican species at 200 sites over the past 30 years. Temperature change has been so rapid in this region that rates of adaptation have not kept pace with climate change. The models were then extended to all families of lizards at >1000 sites across the globe, and suggest that climate change-induced extinctions are currently affecting worldwide lizard assemblages. A historical record of lizard populations in Mexico is used to parameterize models that predict global effects of climate change. It is predicted that climate change will cause species extinctions and distributional shifts in coming decades, but data to validate these predictions are relatively scarce. Here, we compare recent and historical surveys for 48 Mexican lizard species at 200 sites. Since 1975, 12% of local populations have gone extinct. We verified physiological models of extinction risk with observed local extinctions and extended projections worldwide. Since 1975, we estimate that 4% of local populations have gone extinct worldwide, but by 2080 local extinctions are projected to reach 39% worldwide, and species extinctions may reach 20%. Global extinction projections were validated with local extinctions observed from 1975 to 2009 for regional biotas on four other continents, suggesting that lizards have already crossed a threshold for extinctions caused by climate change.

Field guide to snakes and other reptiles of Southern Africa

This edition supplements the 397 South African reptiles originally represented in this field guide by 64 new species. Some of these are new discoveries in the region, others are reclassifications. Author Bill Branch has also adapted the original text, modifying distributions and biology to reflect the most up-to-date research on the subject. The book covers 133 species of snake, as well as many and varied lizard and gecko species, tortoises, turtles, terrapins and the crocodile. New species entries introduce 13 gecko species, eight skinks and three snakes, amongst others. Each species entry includes size range, a physical description of the creature and a discussion on biology and breeding, habitat and range. Where subspecies occur, these are described. Each account is accompanied by a distribution map, which has been updated where necessary. Explanatory notes and a comprehensive glossary make the subject accessible to even the beginner herpretologist.

Blindsnake evolutionary tree reveals long history on Gondwana.

Worm-like snakes (scolecophidians) are small, burrowing species with reduced vision. Although largely neglected in vertebrate research, knowledge of their biogeographical history is crucial for evaluating hypotheses of snake origins. We constructed a molecular dataset for scolecophidians with detailed sampling within the largest family, Typhlopidae (blindsnakes). Our results demonstrate that scolecophidians have had a long Gondwanan history, and that their initial diversification followed a vicariant event: the separation of East and West Gondwana approximately 150 Ma. We find that the earliest blindsnake lineages, representing two new families described here, were distributed on the palaeolandmass of India+Madagascar named here as Indigascar. Their later evolution out of Indigascar involved vicariance and several oceanic dispersal events, including a westward transatlantic one, unexpected for burrowing animals. The exceptional diversification of scolecophidians in the Cenozoic was probably linked to a parallel radiation of prey (ants and termites) as well as increased isolation of populations facilitated by their fossorial habits.

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.

Phylogenetics of the southern African dwarf chameleons, Bradypodion (Squamata: Chamaeleonidae)

The taxonomic relationships within the dwarf chameleons (Bradypodion) of southern Africa have long been controversial. Although informal phenotypic groups have been suggested, the evolutionary relationships among the 15 recognised species in southern Africa have not been previously investigated. To investigate the relationships among species within this genus, fragments of two mitochondrial genes (16S ribosomal RNA and ND2) were sequenced and analysed using maximum parsimony, maximum likelihood and Bayesian inference. All analyses showed congruent topologies, revealing at least 5 well-supported clades distributed across distinct geographic regions. The mtDNA gene tree indicated that in many instances, geographic location has played a role in shaping the evolution of this group, and that the previously suggested phenotypic groupings do not adequately reflect evolutionary relationships. Furthermore, it appears that some of the currently recognised species (described on morphology) are polyphyletic for mitochondrial sequences, most notably those occurring in the isolated forest patches of north-eastern South Africa, near the Drakensberg Escarpment.

Life Underground: Food Habits and Reproductive Biology of Two Amphisbaenian Species from Southern Africa

Examination and dissection of 216 museum specimens of two species of amphisbaenians (the shovel-snouted Monopeltis anchietae and round-headed Zygaspis quadrifrons) from southern Africa provided data on morphology, sexual dimorphism, reproduction, and dietary habits. The two species differed considerably in absolute size, in body proportions (eg, head width relative to snout-vent length), and in the degree of sexual dimorphism in these traits. In the relatively heavy-bodied Monopeltis both sexes attained similar body lengths, but females had wider heads than conspecific males. Conversely, in the thin-bodied Zygaspis, females attained larger body sizes than conspecific males, and there was no sexual dimorphism in head size. Clutch sizes were small in both species (means of 2.4 neonates in Monapeltis, 3.3 eggs in Zygaspis) and were not correlated with maternal body size. Termites were the most common prey far both taxa, but a wide variety of other soft-bodied invertebrates (beetle larvae, caterpillars) was also consumed. The two species differed in dietary composition, mean prey size, and in the numbers of prey items per stomach. Stomachs of Monopeltis contained more prey items than stomachs of Zygaspis (means of 72.2 versus 13.0 prey items) and prey ingested by Monopeltis were larger than those of Zygaspis. In Monopeltis, there was a significant positive correlation between predator size and prey number, but larger lizards continued to feed on relatively small prey. The reverse pattern was found in Zygaspis. The substantial differences in trophic biology between these two taxa and other sympatric fossorial reptiles, suggest that adaptations to fossoriality do not constrain ecological diversity within burrowing squamates.

Reproductive Biology and Food Habits of Horned Adders, Bitis caudalis (Viperidae), from Southern Africa

Horned adders (Bitis caudalis) are small heavy-bodied viperid snakes widely distributed across a range of habitat types in southern Africa. Measurement and dissection of 580 preserved specimens in museum collections provided information on morphology, food habits, and reproductive biology of this species. In particular, it enabled us to assess the effects of sex and habitat type (arid to mesic) on adult body sizes and shapes, dietary composition, and reproductive output. Female horned adders mature at larger sizes than do males and grow much larger. At the same snout-vent length, females have larger heads and shorter tails than do males. Arid-zone snakes are longer and thinner than conspecifics from more mesic areas and have longer tails and larger heads. Horned adders feed primarily on lizards (especially lacertids, skinks, and geckos) but also take other small vertebrates. Dietary composition varies according to the snakes body size, sex, and geographic location: endothermic prey are taken mostly by larger snakes; by females rather than males; and by arid-zone rather than mesic-habitat snakes. Most prey are small relative to predator size, especially in large snakes. Litter sizes (3-19 offspring) increase with maternal body size, with no significant geographic differences in this relationship. However, reproductive frequency (as inferred from the proportion of adult females that were reproductive when collected) was significantly higher in mesichabitat snakes (> 50%) than in their arid-zone relatives (15%). Habitat-associated differences in resource availability may have affected traits such as body size and shape, degree of dietary specialization, growth rates and female reproductive frequencies.

Deep genealogical lineages in the widely distributed African helmeted terrapin: Evidence from mitochondrial and nuclear DNA (Testudines: Pelomedusidae: Pelomedusa subrufa)

We investigated the phylogeographic differentiation of the widely distributed African helmeted terrapin Pelomedusa subrufa based on 1503 base pairs of mitochondrial DNA (partial cyt b and ND4 genes with adjacent tRNAs) and 1937 bp of nuclear DNA (partial Rag1, Rag2, R35 genes). Congruent among different analyses, nine strongly divergent mitochondrial clades were found, representing three major geographical groupings: (1) A northern group which includes clades I from Cameroon, II from Ghana and Ivory Coast, III from Benin, Burkina Faso and Niger, IV from the Central African Republic, and V from Kenya, (2) a northeastern group consisting of clades VI from Somalia, and VII from Saudi Arabia and Yemen, and (3) a southern group comprising clade VIII from Botswana, the Democratic Republic of Congo, Madagascar and Malawi, and clade IX from South Africa. Malagasy and continental African populations were not clearly differentiated, indicating very recent arrival or introduction of Pelomedusa in Madagascar. The southern group was in some phylogenetic analyses sister to Pelusios, rendering Pelomedusa paraphyletic with respect to that genus. However, using partitioned Bayesian analyses and sequence data of the three nuclear genes, Pelomedusa was monophyletic, suggesting that its mitochondrial paraphyly is due to either ancient introgressive hybridization or phylogenetic noise. Otherwise, nuclear sequence data recovered a lower level of divergence, but corroborated the general differentiation pattern of Pelomedusa as revealed by mtDNA. This, and the depth of the divergences between clades, indicates ancient differentiation. The divergences observed fall within, and in part exceed considerably, the differentiation typically occurring among chelonian species. To test whether Pelomedusa is best considered a single species composed of deep genealogical lineages, or a complex of up to nine distinct species, we suggest a future taxonomic revision that should (1) extend the geographical sampling of molecular data, specifically focusing on contact zones and the possible sympatric occurrence of lineages without admixture, and (2) evaluate the morphology of the various genealogical lineages using the type specimens or topotypical material of the numerous junior synonyms of P. subrufa.

Life on the Lowest Branch: Sexual Dimorphism, Diet, and Reproductive Biology of an African Twig Snake, Thelotornis capensis (Serpentes, Colubridae)

Measurement and dissection of 144 twig snakes (Thelotornis capensis) from southern Africa provided data on morphology, sexual dimorphism, food habits, and reproductive biology of this species. Twig snakes are extremely elongate arboreal species that remain immobile for long periods and ambush passing vertebrates. Both sexes attain sexual maturity at about 60 cm snout-vent length, at around three years of age [based on growth rates from Jacobsens (1980) markrecapture study]. Maximum size is about 80 cm SVL in both sexes, and this lack of size dimorphism is consistent with published reports of male-male combat in this taxon. Males have longer tails, smaller heads, and thinner bodies (and hence, weigh less) than do females at the same body length. Reproductive cycles are highly seasonal in both sexes. Testes in adult males are turgid in spring (the mating season) but flaccid over most of the rest of the year. Females undergo vitellogenesis in spring, ovulate in late spring, and oviposit in summer. Clutch sizes ranged from 4-7 eggs, with a mode of 6. The diet of T. c. capensis is diverse: of 56 prey items, most were lizards (63%), frogs (27%), and snakes (8%). Only a single bird was recorded in a dissected twig snake. Approximately half of all prey items were arboreal taxa (e.g., chamaeleons, dwarf day geckos), with the rest being terrestrial in habit (e.g., brevicepid frogs). Thus, we infer that T. capensis often forages from a relatively low perch, which enables it to detect and seize terrestrial as well as arboreal prey. An ontogenetic increase in the proportion of terrestrial prey was evident, but even the largest snakes took many arboreal prey items. Larger snakes took larger prey, and the relationship between prey size and snake body length differed between the sexes, in concert with the observed sexual dimorphism in relative head size. Our results generally agree with those of previous studies on the biology of twig snakes; the most surprising result from our work is that a snake with extreme morphological and behavioral modifications for arboreal life nonetheless feeds to a large degree on terrestrial prey.

Molecular systematics of the African snake family Lamprophiidae Fitzinger, 1843 (Serpentes: Elapoidea), with particular focus on the genera Lamprophis Fitzinger 1843 and Mehelya Csiki 1903.

The snake family Lamprophiidae Fitzinger (Serpentes: Elapoidea) is a putatively Late Eocene radiation of nocturnal snakes endemic to the African continent. It incorporates many of the most characteristic and prolific of Africas non-venomous snake species, including the widespread type genus Lamprophis Fitzinger, 1843 (house snakes). We used approximately 2500 bases of mitochondrial and nuclear DNA sequence data from 28 (41%) of the approximately 68 recognised lamprophiid species in nine of the eleven genera to investigate phylogenetic structure in the family and to inform taxonomy at the generic level. Cytochrome b, ND4 and tRNA gene sequences (mitochondrial) and c-mos sequences (nuclear) were analysed using Maximum Likelihood, Bayesian Inference and Maximum Parsimony methods. The genus Mehelya Csiki, 1903 was paraphyletic with respect to Gonionotophis Boulenger, 1893. To address this, the concept of Gonionotophis is expanded to include all current Mehelya species. The genus Lamprophis emerged polyphyletic: the enigmatic Lamprophis swazicus was sister to Hormonotus modestus from West Africa, and not closely related to its nominal congeners. It is moved to a new monotypic genus (Inyoka gen. nov.). The remaining Lamprophis species occur in three early-diverging lineages. (1) Lamprophis virgatus and the widely distributed Lamprophis fuliginosus species complex (which also includes Lamprophis lineatus and Lamprophis olivaceus) formed a clade for which the generic name Boaedon Duméril, Bibron & Duméril, 1854 is resurrected. (2) The water snakes (Lycodonomorphus) were nested within Lamprophis (sensu lato), sister to Lamprophis inornatus. We transfer this species to the genus Lycodonomorphus Fitzinger, 1843. (3) We restrict Lamprophis (sensu strictissimo) to a small clade of four species endemic to southern Africa: the type species of Lamprophis Fitzinger, 1843 (Lamprophis aurora) plus Lamprophis fiskii, Lamprophis fuscus and Lamprophis guttatus.