Bayesian inference of species diffusion in the West African Agama agama species group (Reptilia,Agamidae)

The savannah and tropical forest biomes of Africa have a long history of expansion and contraction, and the recent and rapid spread of dry savannah habitats has influenced the spatial and temporal diversification of vertebrate taxa across this region. We used a combination of species tree and phylogeographic methods to describe the spatio-temporal changes through time and across space (= species diffusion) in a clade of seven West African lizard species in the Agama agama species group. A Bayesian species tree diffusion approach was used to compare the relative rates at which species ranges changed across the landscape. We found that some species have high diffusion rates characterized by significant movement in their range location and minor changes to their overall range size, whereas other species show little movement in their range centre with an exponential increase in range size. This discrepancy between the rates that range locations shift versus change in their relative area could be linked to populations tracking their preferred habitats through time. A continuous Bayesian phylogeography approach using a relaxed random walk model was used to estimate the timing and rate of population size change and geographic diffusion in A. picticauda, the single species in the group with an extensive African distribution from Mauritania to Ethiopia. The mean dispersal rate of A. picticauda increased dramatically throughout the Pleistocene, and a Bayesian skyride analysis supports exponential population growth over this same time period. A comparison of genetic diversity across different loci and species suggests that A. lebretoni experienced a mitochondrial selective sweep that has caused a deficit of variation at this locus in relation to nuclear loci.     

Genetic variation and climatic selection in the lizard Agama stellio in Israel and Sinai

Summary Allozymic variation in proteins encoded by 25 loci was analyzed electrophoretically in 242 adult specimens representing nine populations of the Levantine lizard, Agama stellio, comprising two subspecies: the Mediterranean A. stellio subsp., and the desert-inhabiting A. stellio brachydactyla from the Negev and Sinai. Likewise, four body traits were measured in the same populations. The nine populations were sampled along a general southward transect of increasing aridity. Agama stellio is above average in both polymorphism, P, and heterozygosity, H, as compared to other reptiles and vertebrates in general, displaying levels of genetic variation characterizing habitat generalist vertebrates. In the populations studied no fixation of alternative alleles was found in any of the 25 loci: rather the commonest allele was either fixed or predominated in 23 of 25 loci examined. Eleven loci (44%) were monomorphic in all nine populations. However, of the remaining 14 polymorphic loci, eight were strongly polymorphic displaying distinct genetic differentiation between populations. Genetic diversity (indexed by P and H) displayed geographic variation and was slightly higher in A.s. brachydactyla than in A. stellio subsp. Nevertheless, genic similarity between populations was high. A statistically significant amount of morphological variation between localities was found for all body characters. In general, body size increased southwards and eastwards with aridity.Selection at some loci is suggested by significant deviation from Hardy-Weinberg expectations and possibly by excess heterogeneity of effective inbreeding coefficients, F_e. Furthermore, allozymic variation at seven loci (Ldh-1, Idh-1, 6-Pgd-1, Aat-1, Pgm-2, Pept-1, and Trf) and geographic variation in body size and weight were significantly correlated with, and predictable by, climatic variables, primarily by water availability and secondarily by temperature. Finally, allozymic and morphological variations were partly correlated.The spatial patterns and ecological correlates of genic and morphological variations in Agama stellio in Israel and Sinai suggest that at least some proteins and body size differentiate geographically and appear to be adaptive, presumably with respect to factors affecting the availability of water.     

Purification and kinetic properties of skeletal muscle lactate dehydrogenase from the lizard Agama stellio stellio

Lactate dehydrogenase isoenzyme LDH-5 (M4) was purified to homogeneity from the skeletal muscle of lizard Agama stellio stellio as a poikilothermic animal, using colchicine-Sepharose chromatography and heat inactivation. The purified enzyme showed a single band after SDS-PAGE, corresponding to a molecular weight of 36 kD. The K _m values for pyruvate, NADH, lactate, and NAD⁺ were 0.020, 0.040, 8.1, and 0.02 mM, respectively. Pyruvate showed maximum activity at about 180 M, with a decline at higher concentrations. The enzyme was stable at 70°C for 30 min, but was rapidly inactivated at 90°C. The optimum pH for the forward reaction (pyruvate to lactate) was 7.5, and for the reverse reaction (lactate to pyruvate) was 9.2. Oxalate, glutamate, Cu²⁺, Co²⁺, Mn²⁺, and Mg²⁺ were inhibitory in both forward and reverse reactions.     

On the distribution of four species of agama (Agamidae) in Turkey

Abstract

The distribution of the Hardun, Agama stellio, the Caucasian Agama, Agama caucasia, the Syrian Agama, Agama ruderata, and Phrynocephalus helioscopus, in Turkey is presented with dot maps A. stellio and A. caucasia are sharply separated both horizontally and vertically. The area of A. stellio is defined by the March isotherm of 8°C and the July and August isotherms of 24°C. A. ruderata occurs in the large steppe areas of Inner and South-east Anatolia, but not in those of Eastern Anatolia.     

A positive fever response in Agama agama and Sceloporus orcutti (Reptilia: Agamidae and iguanidae)

Summary Three species of lizards (Agama agama, Mabuya perrotetii, and Sceloporus orcutti) were tested for a possible increase in mean selected body temperature (MSBT) in response to intraperitoneal injection of alcohol-killed Aeromonas sobria, a gram-negative bacterium known to be pathogenic to reptiles. A paired experimental design was utilized in which each animal was given an injection of sterile saline and 1 · 10¹⁰ A. sobria. Body temperatures were monitored via indwelling cloacal thermocouples at 4-min intervals for one 12-h light period under saline injection and for two consecutive 12-h light periods under bacteria injection. Agama agama demonstrated a significant increase in MSBT on both day 1 and day 2 of bacteria injection with increases of 2.7 and 2.3°C, respectively. The latency period on day 1 averaged 6.4 h. Sceloporus orcutti demonstrated a significant decrease in MSBT on day 1 of bacteria injection and a significant increase in MSBT of 1.0°C on day 2 of bacteria injection. No fever was evident in S. orcutti until the beginning of day 2. Mabuya perrotetii did not exhibit a significant change in MSBT on either day 1 or day 2 of bacteria injection. Agama agama (family Agamidae) is the first Old World reptile to exhibit a fever response to bacteria injection, and with these results fever has now been demonstrated in the lizard families Agamidae, Iguanidae, and Teiidae.Abbreviations MSBT mean selected body temperature - T _b body temperature     

Identity and distribution of Agama stellio picea Parker (Sauria: Agamidae), endemic to the volcanic desert of Jordan

Abstract

Agama stellio picea Parker, 1935, was clearly defined as a black lizard, with the female dotted with orange, from the Transjordan lava desert. Three later collections confirmed this. While the subspecies appears to be endemic to Jordan, its name has been erroneously applied to other A. stellio populations in adjacent countries.     

Reproduction,predation, sexual dimorphism and diet in Agama anchietae (Reptilia: Agamidae) from Namibia

Agama anchietae is one of eight species of agama found in Namibia, its distribution range in the upper half of the country covers desert, Karoo and savannah type biomes and overlaps with that of some of its congeners. Here, we describe its sexual dimorphism, reproductive traits, predation, diet and nematode infection, and compare and contrast each aspect among the three biomes as well as to published findings for three other Namibian congenerics, Agama etoshae, Agama aculeata aculeata and Agama planiceps planiceps. Interesting similarities and differences were found among the biomes as well as with the three congenerics. Our hypothesis that the aspects studied in A. anchietae would be more in line with those of A. a. aculeata and A. etoshae, with which it shares similarities in body colouration, social organisation and microhabitat utilisation, was only partially confirmed. This cautions against using morphological and ecological similarities between agamas as proxies for making life-history strategy inferences.