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Herpetological research in Somalia dates from 1881 (G. Revoil`s Expedition) and progressively spread over most of the Somali territory thanks above all to the scientific missions conducted by R.H.R. Taylor (1929–34), G. Scortecci (1931, 1953, 1957) and, since 1959, by the University of Florence and the « Centro di Studio per la Faunistica ed Ecologia Tropicali » of the Consiglio Nazionale delle Ricerche (Florence, Italy). According to this list of the amphibians and reptiles reported to date for the Somali Democratic Republic, there are 27 species of amphibians, four of which (= 14.8%) are endemic; all these species belong strictly to the Ethiopian subregion sensu Darlington (1957). A monotypic genus, Lanzarana, is endemic. The reptiles are represented by at least 200 species. Excluding the marine species (six turtles and one snake), there are 194 species, of which 75 (= 38.6%) ar endemic to Somalia. Four genera are endemic: Xenagama (Agamidae), Haackgreerius gen. n. (Scincidae), Aeluroglena and Brachyophis (Colubridae). The majority of the Somali reptilian fauna is composed of species belonging strictly to the Ethiopian subregion sensu Darlington (1957): 164 species (= 84.5%). The remaining 30 species (= 15.5%) have a different, prevalently south-Mediterranean geonemy. Some reptiles inhabiting both Somalia and south-west Arabia confirm the well-known close biogeographic relationship existing between the two countries.

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Aim To map and assess the richness patterns of reptiles (and included groups: amphisbaenians, crocodiles, lizards, snakes and turtles) in Africa, quantify the overlap in species richness of reptiles (and included groups) with the other terrestrial vertebrate classes, investigate the environmental correlates underlying these patterns, and evaluate the role of range size on richness patterns. Location Africa. Methods We assembled a data set of distributions of all African reptile species. We tested the spatial congruence of reptile richness with that of amphibians, birds and mammals. We further tested the relative importance of temperature, precipitation, elevation range and net primary productivity for species richness over two spatial scales (ecoregions and 1° grids). We arranged reptile and vertebrate groups into range-size quartiles in order to evaluate the role of range size in producing richness patterns. Results Reptile, amphibian, bird and mammal richness are largely congruent (r = 0.79–0.86) and respond similarly to environmental variables (mainly productivity and precipitation). Ecoregion size accounts for more variation in the richness of reptiles than in that of other groups. Lizard distributions are distinct with several areas of high species richness where other vertebrate groups (including snakes) are species-poor, especially in arid ecoregions. Habitat heterogeneity is the best predictor of narrow-ranging species, but remains relatively important in explaining lizard richness even for species with large range sizes. Main conclusions Reptile richness varies with similar environmental variables as the other vertebrates in Africa, reflecting the disproportionate influence of snakes on reptile richness, a result of their large ranges. Richness gradients of narrow-ranged vertebrates differ from those of widespread taxa, which may demonstrate different centres of endemism for reptile subclades in Africa. Lizard richness varies mostly with habitat heterogeneity independent of range size, which suggests that the difference in response of lizards is due to their ecological characteristics. These results, over two spatial scales and multiple range-size quartiles, allow us to reliably interpret the influence of environmental variables on patterns of reptile richness and congruency.

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Aim Body size is instrumental in influencing animal physiology, morphology, ecology and evolution, as well as extinction risk. I examine several hypotheses regarding the influence of body size on lizard evolution and extinction risk, assessing whether body size influences, or is influenced by, species richness, herbivory, island dwelling and extinction risk. Location World-wide. Methods I used literature data and measurements of museum and live specimens to estimate lizard body size distributions. Results I obtained body size data for 99% of the world`s lizard species. The body size–frequency distribution is highly modal and right skewed and similar distributions characterize most lizard families and lizard assemblages across biogeographical realms. There is a strong negative correlation between mean body size within families and species richness. Herbivorous lizards are larger than omnivorous and carnivorous ones, and aquatic lizards are larger than non-aquatic species. Diurnal activity is associated with small body size. Insular lizards tend towards both extremes of the size spectrum. Extinction risk increases with body size of species for which risk has been assessed. Main conclusions Small size seems to promote fast diversification of disparate body plans. The absence of mammalian predators allows insular lizards to attain larger body sizes by means of release from predation and allows them to evolve into the top predator niche. Island living also promotes a high frequency of herbivory, which is also associated with large size. Aquatic and nocturnal lizards probably evolve large size because of thermal constraints. The association between large size and high extinction risk, however, probably reflects a bias in the species in which risk has been studied.