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The marginated tortoise (''Testudo marginata'') is a species of tortoise found in Greece, Italy and the Balkans in southern Europe. It is the largest European tortoise, reaching a weight of up to and a length of . Its shell is oblong and has a notable thickness around the middle of the body. The posterior end of the shell has a saw-like formation, flanged outward like a bell. The carapaces of adult specimens are almost completely black, with yellow highlights. The front sides of the limbs are covered with large scales. The tail is notable for a lengthwise marking and for an undivided carapace over the tail. The marginated tortoise is herbivorous, and hibernates for the winter. ==Taxonomy== The marginated tortoise was formally described by German naturalist Johann David Schoepf in 1789; its specific epithet ''marginata'' is a straightforward derivation from the Latin term for 'marginated'. The nominate subspecies is the Greek marginated tortoise, ''Testudo marginata marginata''. Three additional subspecies of marginated tortoises have been named: The Sardinian marginated tortoise (''T. m. sarda'') is the name usually used to separate the population on the island of Sardinia. These tortoises have less strongly bent tiles in the posterior of their carapaces, and the posterior of the carapace is almost smooth compared with the saw-like ''T. m. marginata''. Clearly distinct according to morphology and entirely allopatric, it cannot be distinguished by mtDNA cytochrome ''b'' and nDNA ISSR sequence analysis.〔Fritz ''et al.'' (2005)〕 Lineage sorting has not occurred to a considerable degree; consequently, the more geographically isolated Sardinian population is presumably of quite recent origin. Indeed, it appears to derive from a deliberate introduction by humans.〔 Though it is not clear whether this occurred in prehistoric times or more recently, this might be resolved by dating subfossil remains. Sequence evolution at least in mtDNA is known to proceed much more slowly in some turtles and tortoises than in others;〔Avise ''et al.'' (1992)〕 the rate of the mitochondrial 12S rRNA gene in ''Testudo'' is probably a rather low 1.0-1.6% per million years (as this fits best the paleobiogeographical situation), limiting the resolution provided by molecular systematics.〔van der Kuyl ''et al.'' (2002)〕 An extinct subspecies described as ''T. m. cretensis'' persisted on Crete before the end of the last ice age and perhaps into early historic times. A population of small and light-colored marginated tortoises exists on the southwestern coast of the Peloponnesus, between Kalamata and south of Stoupa. The so-called "dwarf marginated tortoise" was described as a new species ''Testudo weissingeri'', but it is not recognizably distinct phylogenetically. Unlike the Sardinian population, it occupies an extremely restricted range with very arid habitat, and its apomorphies seem related to this. Considering ice age-associated climate and sea level changes, this population is probably not older than a few thousand years; as it is not geographically isolated, it should be considered a local form, and not even a subspecies ''T. m. weissingeri''. Notably, a similar situation is found in Hermann's tortoises living in the same region.〔Fritz ''et al.'' (2006)〕〔 ''Testudo marginata'' is also closely related to the Greek or spur-thighed tortoise (''Testudo graeca''). Both have very similar bodily characteristics - oblong carapaces, large scales on the front legs, large coverings for the head and cone-like scales on the upper thighs, undivided tail coverings, moveable stomach plates, and lack of tail spikes. Presumably, ''Testudo marginata'' diverged from ancestral ''Testudo graeca'' as a population more suited for life in the mountainous regions. Evidence in favor of this is the wide geographical region and the extremely large number of subspecies of ''Testudo graeca'', including a subspecies in Turkey with strongly bent carapace tiles, like the marginated tortoise. ''Testudo marginata'' on the other hand, despite the two subspecies, presents a much more unified appearance, which points toward an earlier appearance in evolutionary history. In captivity, the two species often cross-breed, but this should be avoided. According to the 2005 DNA sequence data,〔 these species do not seem to hybridize to a notable extent in the wild, though they are obviously very close relatives, and as evidenced by morphology, some allele flow still occurs, but slowly. The Egyptian tortoise appears to represent a lineage that diverged from the same ancestral stock southwards into northeastern Africa around the same time as the marginated tortoise's ancestors diverged in Greece. These two are actually more similar to each other than to ''T. graeca'' regarding DNA sequence data,〔van der Kuyl ''et al.'' (2002), Fritz ''et al.'' (2005)〕 but considering biogeography, this is either due to (rather unlikely) dispersal across the Mediterranean, or the supposed "clade" is invalid and the similarity due to convergent evolution. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Marginated tortoise」の詳細全文を読む スポンサード リンク
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