Status and distribution of reptiles and amphibians of the Mediterranean Basin
Reptile and amphibian diversity and endemism
The Mediterranean Basin has been designated as a biodiversity hotspot since it has very high levels of plant endemism (more than 10,000 species endemic) with a concomitant high level of threat (the mammal and bird faunas are largely derived from the Eurasian and African biogeographic zones and therefore exhibit relatively low levels of endemism). For the purposes of this study of reptiles and amphibians in the Mediterranean Basin, we have defined the region politically, rather than biogeographically (see section 2.2 below). Within the region of study, there are 355 species of reptile (excluding the marine turtles which we have not covered here), of which 170 (48%) are endemic, and 106 species of amphibian, of which 68 (64%) are endemic. Further details are given in Table 1.
Reptile diversity and endemism
Five orders of reptiles occur in the Mediterranean Basin: Amphisbaenidae (amphisbaenians); Crocodylia (crocodilians); Ophidia (snakes); Sauria (lizards); and Testudines (turtles and tortoises). However, the great majority of the species are snakes (30%) and lizards (67%). The largest reptile families in the region are the Colubridae (colubrid snakes – 67 species), the Viperidae (vipers and relatives – 25 species), the Gekkonidae (geckoes – 47 species), the Lacertidae (wall lizards and relatives – 112 species), and the Scincidae (skinks – 39 species). Some important evolutionary radiations in the region include the lizard genera Lacerta (20 species, 14 endemic), Podarcis (largely confined to the region – 18 species, 16 endemic), and Chalcides (also largely confined to the region – 21 species, 19 endemic). Almost half of the reptiles of the Mediterranean Basin are endemic to the region, but endemism is especially high in the amphisbaenians, the tortoises, and the two lizard families Lacertidae and Scincidae. Table 1 provides more detail.
|Table 1. Diversity and endemism in non-marine reptile and amphibian orders and families within the Mediterranean Basin|
|Order||Family||Number of species||Number of endemic species|
|Testudines (turtles and tortoises)||Bataguridae [Geoemydidae]||3||2 (67%)|
|Total – Turtles and Tortoises||12||6 (50%)|
|Sauria (lizards)||Agamidae||23||3 (13%)|
|Total – Lizards||238||123 (52%)|
|Ophidia (snakes)||Atractaspididae||2||1 (50%)|
|Total – Snakes||107||37 (35%)|
|Amphisbaenia (amphisbaenians)||Amphisbaenidae||4||3 (75%)|
|Total – Amphisbaenians||5||4 (80%)|
|Crocodylia (crocodilians)||Crocodylidae||1||0 (0%)|
|Total – Crocodilians||1||0 (0%)|
|Total – Reptiles||355||170 (48%)|
|Anura (frogs and toads)||Bombinatoridae||3||1 (33%)|
|Total – Frogs and Toads||64||37 (58%)|
|Caudata (newts and salamanders)||Plethodontidae||7||7 (100%)|
|Total – Newts and Salamanders||42||31(74%)|
|Total – Amphibians||106||68 (64%)|
Amphibian diversity and endemism
Amphibian diversity in the Mediterranean Basin is much lower than reptile diversity, this being largely a reflection of the extent to which arid and semi-arid habitats predominate in large parts of the region. However, at 64%, amphibian endemism is very high. One family, the Discoglossidae (painted frogs and midwife toads), is almost endemic to the region, and two of the three species of Pelodytidae (parsley frogs) are endemic. All four members of the Pelobatidae (Eurasian spadefoots) occur in the region, two of them being endemic. Among the newts and salamanders, 54% of the world’s Salamandridae species occur in the region, with five endemic genera (Chioglossa, Euproctus, Lyciasalamandra, Pleurodeles and Salamandrina). The region is also noteworthy for its seven endemic cave salamander species in the lungless salamander family Plethodontidae. Until the recent discovery of a species in Korea, these were thought to be the only Old World members of a family that has around 350 species in the Americas. The single Old World member of the Proteidae, Proteus anguinus, is endemic to the region; the other five members of the family occur in eastern North America.
Results for reptiles
|Table 2. Summary of the global Red List status for all the non-marine reptiles of the Mediterranean Basin|
|IUCN Red List categories||No. species|
|Extinct in the Wild (EW)||0|
|Threatened categories||Critically Endangered (CR)||13|
|Near Threatened (NT)||36|
|Least Concern (LC)||253|
|Data Deficient (DD)||19|
|Total number of reptiles assessed||355|
The number of species in the different IUCN Red List Categories is shown in Table 2 and Figure 1. To summarize, 13% of Mediterranean reptile species are globally threatened, with 3.7% Critically Endangered, 6.2% Endangered and 3.1% Vulnerable. A total of 71% (252 species) are assessed as Least Concern and 19 (5.4%) species were considered to be Data Deficient. One species is listed as Extinct, the giant lizard from La Palma in the Canary Islands, Gallotia auaritae.
The conservation status varies between the reptile orders. No threatened species occur in the region among the amphisbeanians or the crocodilians. Snakes have a relatively low level of threat, with only six species (5.6%) being threatened. Among the lizards, the percentage of threatened species is higher – 15.5% (37 species). Three species of non-marine turtle (25%) are threatened. Within these orders, it appears that certain groups are more vulnerable to threats. For example, five of the seven species of the lizard genus Iberolacerta, centered on Spain, are globally threatened. Three species of giant lizard from the Canary Islands in the genus Gallotia are Critically Endangered (in addition to the one already Extinct), and two of the five tortoise species (genus Testudo) are also Critically Endangered. Among the wall lizard genus Podarcis, there is a tendency for species endemic to small islands to be at elevated risk, and three such species are threatened.
Several reptile species only marginally occur in the Mediterranean Basin. Many of these species may be considered to be Least Concern globally, but their Mediterranean populations are sometimes very threatened. Examples include the Nile crocodile Crocodylus niloticus, several species of snake including Gongylophis colubrinus, Dasypeltis scabra, Lamprophis fuliginosus, Lycophidion capense (possibly extinct in the Mediterranean Basin), Platyceps elegantissimus, Psammophis punctulatus, Psammophis rukwae, Naja haje, Leptotyphlops nursii (possibly extinct in the Mediterranean Basin), Bitis arietans, Cerastes gasperettii, Echis leucogaster, a number of lizards such as Chamaeleo africanus, Hemidactylus sinaitus, Pristurus flavipunctatus, Stenodactylus doriae, Tarentola ephippiata, Ophisops elbaensis, Pseuderemias mucronata, and the African softshell turtle Trionyx triunguis. The sand boa Eryx jaculus occurs widely in the Mediterranean Basin, where it is generally in decline, although it is Least Concern globally.
Patterns of species richness
Species richness of reptiles
Information on the species richness of reptiles within orders and families has already been given in section 1.2.1 and Table 1. The geographic distribution of reptile species richness in the Mediterranean Basin is presented in Figure 2. Diversity is highest in the eastern part of the region, notably in southern Turkey, Lebanon, southwestern Syria, Israel / Palestine, Jordan and parts of northern Egypt. In the western Mediterranean, diversity is much higher in North Africa than in western Europe, with a peak of concentration in northeastern Algeria. In North Africa, diversity appears to be highest in the mountainous area, in semi-arid regions along the northern margins of the Sahara, and in the Nile Valley. The Sahara itself is relatively species poor, although there are concentrations of species in mountainous areas, such as the Hoggar in southern Algeria. In Europe, species diversity is much higher in the Balkans than elsewhere. North of the Mediterranean Basin in Europe, the diversity of reptiles is very low. In Turkey, diversity appears to be higher in the south, but this should be treated with caution, because the species occurring only in the northeastern part of the country were excluded from this analysis, and are not mapped in Figure 2. There are 28 reptile species known from northeastern Turkey, that do not occur in the Mediterranean part.
The species richness of reptiles in the countries of the Mediterranean Basin is given in Table 3. As expected, higher species totals occur in countries on the eastern and southern sides of the basin. Countries larger in area will inevitably tend to have more species, so small countries with large numbers, such as Israel / Palestine and Lebanon, indicate high diversity. The relatively high number of species for Spain is a sum of the different faunas on the Spanish mainland, the Balearic Islands, the Canary Islands, and the Spanish territories of Ceuta and Melilla in North Africa.
Species richness of threatened reptiles
|Table 3. The number of non-marine reptiles in the countries of the Mediterranean Basin.|
|Bosnia and Herzegovina||29||1||0||0||0||0|
|Israel / Palestine||80||1||2||0||1||0|
|Libyan Arab Jamahiriya||58||9||0||0||0||0|
|Serbia and Montenegro||37||0||0||0||0||0|
|Syrian Arab Republic||80||10||0||0||0||0|
|* Note that the total number of reptile species in Turkey is higher than is shown here. An additional 28 species are known from this country that are not within the Mediterranean Basin, making a total of 124 for the country.|
Although the percentage of threatened reptile species is not particularly high in the Mediterranean Basin, there are a few concentrations of species at risk (see Figure 3). The most notable is in Lebanon and Israel / Palestine, extending to the northern part of Sinai in northeastern Egypt. Species of particular concern in this region include Testudo werneri, Cyrtopdion amictopholis, Acanthodactylus beershebensis, Lacerta fraasii, L. kulzeri and Montivipera bornmuelleri. Another lesser concentration of threatened species occurs in northern Morocco and northeastern Algeria. The thirteen Critically Endangered species are widely scattered through the region, with five species in Spain (three of these in the Canary Islands), three in Egypt, two in Israel / Palestine and in Libya, and one each in Algeria, France, Italy, Morocco and Tunisia (note that some Critically Endangered species occur in more than one country).
Major threats to reptiles
The major threats to each species were coded using the IUCN Major Threats Authority File. A summary of the relative importance of the different threatening processes is shown in Figure 4. Habitat loss and degradation have by far the largest impact on both threatened and non-threatened species, currently affecting 38 of the 46 threatened species, and almost 200 reptile species overall. Over-harvesting has the next largest impact, currently affecting 81 species, 14 of them threatened. Human disturbance, pollution and invasive alien species are also significant threats for some species. Many species, mainly snakes, are persecuted, but only a few of them are threatened. Likewise, vehicle collision impacts several snake and turtle species, but not normally at levels that cause them to qualify as globally threatened species. Invasive alien species impact a small number of reptile species, but a relatively high proportion of these are threatened.
Results for amphibians
|Table 4. Summary of the global Red List status for all the amphibians of the Mediterranean Basin|
|IUCN Red List categories||No. species|
|Extinct in the Wild (EW)||0|
|Threatened categories||Critically Endangered (CR)||1|
|Near Threatened (NT)||17|
|Least Concern (LC)||61|
|Data Deficient (DD)||0|
|Total number of amphibians assessed||106|
The number of species in the different IUCN Red List Categories is shown in Table 4, and in Figure 5. To summarize, 25.5% of the Mediterranean amphibian species are threatened, with 0.9% Critically Endangered, 12.1% Endangered and 12.1% Vulnerable. The overall threatened status of amphibians is much higher than that for reptiles (13%) in the Mediterranean Basin, although the percentage of Critically Endangered amphibians is less than that for reptiles (3.7%). Just one amphibian species is Critically Endangered, Lyciasalamandra billae, compared with 13 reptile species. So although amphibians as a class are almost twice as threatened as reptiles, the number of species on the brink of extinction is much higher among reptiles. The percentage of threatened amphibian species in the Mediterranean Basin is less than the global average of 32.5%. A total of 57.5% (61 species) of amphibians are assessed as Least Concern, and no species are Data Deficient (compared with 5.4% of reptiles). One species is listed as Extinct, the painted frog from Israel / Palestine, Discoglossus nigriventer.
The level of threat varies greatly between the amphibian orders. Frogs and toads have a relatively low level of threat, with nine species (14.1%) being threatened. Among the salamanders and newts, the percentage of threatened species is higher – 42.9% (18 species). Interestingly, none of the 11 newt species of the genus Triturus are globally threatened, but all but one of the remaining salamander genera contain threatened species. Among the frogs and toads, six of the nine threatened species are from the genus of true frogs, Rana. Two of the remaining threatened frogs are midwife toads (Alytes) from the family Discoglossidae, and there is reason to believe that the threat level in this genus might increase (see section 4.3).
Patterns of species richness
|Table 5. The number of amphibians in the countries of the Mediterranean Basin.|
|Bosnia and Herzegovina||18||0||0||0||0||0|
|Israel / Palestine||6||0||1||0||0||0|
|Libyan Arab Jamahiriya||4||0||0||0||0||0|
|Serbia and Montenegro||21||2||0||0||0||0|
|Syrian Arab Republic||7||0||0||0||0||0|
|* Note that the total number of amphibian species in Turkey is higher than is shown here. An additional four species are known from the non-Mediterranean part of this country, making a total of 27.|
Species richness of amphibians
Information on the species richness of amphibians within orders and families has already been given in section 1.2.2 and Table 1. The geographic distribution of amphibian species richness in the [[Mediterranean Basin is presented in Figure 6. Diversity is highest in Europe, especially in areas of higher rainfall, notably in northern Italy, France, western and northern Spain, Portugal, Slovenia and Croatia. Diversity is much lower in the eastern and southern parts of the region. This pattern is completely different from that of reptiles (Figure 2). Amphibians clearly avoid arid areas, and are absent from most of the Sahara. In Turkey, unlike with reptiles (Figure 2), all species of amphibians have distribution maps, including those species occurring only in the northeastern part of the country. There are four amphibian species known from northeastern Turkey, but not from the Mediterranean part.
The species richness of amphibians in the countries of the Mediterranean Basin is given in Table 5. As expected, higher species totals occur in the European countries of the western Mediterranean, especially France, Italy and Spain. Slovenia, Croatia and Switzerland have relatively diverse amphibian faunas, given their small sizes.
Species richness of threatened amphibians
Although the percentage of threatened amphibian species is high in the Mediterranean Basin, there are only a very few places with concentrations of species at risk (see Figure 7). The most notable is Sardinia, but even here a maximum of only three threatened species occur in the same area. Otherwise, the main places where more than one threatened species occurs together are in northern Algeria, western Slovenia, and southwestern Turkey (the only Critically Endangered species in the region occurring in the last area).
Major threats to amphibians
The threats to each species were coded using the IUCN Major Threats Authority File. A summary of the relative importance of the different threatening processes is shown in Figure 8. Habitat loss and degradation have the largest impact on both threatened and non-threatened species, currently affecting 19 of the 27 threatened species, and 86 amphibian species overall. However, pollution also has a major impact, and it currently affects 67 species, 13 of them threatened. Invasive alien species have the next largest impact, currently affecting 38 species, six of them threatened. Over-harvesting, natural disasters, human disturbance and disease are also significant for some species. Unlike reptiles, persecution and vehicle collision have very little impact. There is a risk that the disease chytridiomycosis could become a more serious threat to amphibians in the Mediterranean Basin in the future. This disease has been implicated in catastrophic amphibian declines in many parts of the world, and was first recorded in the Mediterranean Basin in Spain in 1997. It has since been implicated in declines of the Mediterranean populations of the midwife toad Alytes obstetricans and the fire salamander Salamandra salamandra. If this fungal disease starts to become as pathogenic to Mediterranean amphibians as it has done to species elsewhere in the world, then it could rapidly become a much more serious threat. The other species of midwife toad (i.e., Alytes cisternasii, A. dickhilleni, A. maurus and A. muletensis) may be susceptible to the disease. If this is the case, species infected with the disease, especially those with small ranges, could quickly move into a higher threat category.
The patterns of distribution and threat for reptiles and amphibians are very different from each other in the Mediterranean Basin, and as a result, the conservation priorities vary accordingly. Island species are often in need of more urgent conservation attention. Although amphibians (especially salamanders) have a high tendency to be threatened, and reptiles much less so, there are many more reptile species on the edge of extinction in the region than amphibians. The main threats also vary greatly between reptiles and amphibians, although habitat loss is the most serious problem for both groups. The challenge now is to ensure that the information collated and presented here, and stored in the SIS database, is made readily available to policy makers and planners in a format that can easily be integrated into the development planning process.
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