Herping the African Continent: Alien Amphibians and Reptiles in the sub-Saharan Africa

Introduction of species consists today one of the most important problem of nature conservation. Special attention is paid to alien vascular plants and vertebrates. In the Afrotropical Region (sub-Saharan Africa), avian and mammalian introductions have attracted the attention of many re-searchers and was recently reviewed, but there is a lack of such comprehensive review of alien amphibians and reptiles. The presented paper constitutes an attempt to overview the status, distribution, threats introduced herp species to sub-Saharan Africa since he second half of the 18^th century. This review includes 21 amphibian (including 10 established) and 57 reptile (including 19 established) species introduced to sub-Saharan. The introduced amphibians are representatives of Urodela (n=4 spp., none established) and Anura (n=17 species, incl. 10 established). Introduced reptiles species belonged to the following orders: Testudines (n=11 species, incl. 6 established), Sauria (n=32 spp., incl. 29 established), Serpentes (n=13 spp., incl. 2 established) and Crocolylia (1 sp. not established). Most species introduced to sub-Saharan Africa which subsequently developed viable populations originated from the Afrotropical (35%), Malagasy (27%) and Oriental (27%) regions. However, the proportions of introduced species which failed to establish viable populations were quite different: Nearctics (25%), Afrotropics (22%), and Neotropics (17%); Malagasy 11%, Oriental Region only 6%. First introduction of alien herp species, i.e. Gehyra mutilate and Ptachadena mascareniensis, in Africa took place in 18^th century. By the end of 19^th century, four other species have been introduced and in the two last decades of that century – 5 species. Similarly, in 20^th century, most introduction were made in the last two decades, when an exponential growth of introduction begun and lasts till present. This growth has been caused by an increase in international trade and herp pet industry, especially in South Africa. Stowaway and pet trade are the most common pathways of introductions. Few factors determine the successful establishment of introduced alien herp species in sub-Saharan Africa, viz.: the behavioural and morphological traits, propagula pressure, climate and habitat overlap, and presence of potentially competing species. The impact of alien herps in sub-Saharan Africa on the local biodiversity is not well-investigated. Negative effects have been, however, evidenced for species such as Sclerophrys gutturalis, Agama agama, Hemidactylus frenatus, Trachemys scripta (competition); Xenopus laevis, Sclerophrys gutturalis, Rhinella marina, Lycodon aulica (predation); Xenopus laevis, Python sabae (hybridization); Xenopus laevis, Palea steindachneri (diseases and parasites). In comparison with other continents (Europe and North America) the number of introduced and established herp species in sub-Saharan Africa is relatively low, possibly because the Afrotropical region is saturated with herps which can potentially compete and prey on the alien species, preventing their successful establishment. Madagascar, the Mascarenes and other small islands in the Malagasy Region have the highest number of introduced herp species in sub-Saharan Africa. However these numbers are still much lower than those recorded for instance in the Greater Caribbean, probably for the same reasons as in the mainland.