''Testudo'', the Mediterranean tortoises, are a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

tortoise Tortoises () are reptiles of the family Testudinidae of the order Testudines (Latin: ''tortoise''). Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like ot ...

s found in

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in t ...

Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes A ...

, and

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

. Several species are under threat in the wild, mainly from

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

Background

They are small tortoises, ranging in length from 7.0 to 35 cm and in weight from 0.7 to 7.0 kg.

Systematics

The

systematics Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic t ...

and

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

of ''Testudo'' is notoriously problematic. Highfield and Martin commented:

Synonymies on ''Testudo'' are notoriously difficult to compile with any degree of accuracy. The status of species referred has undergone a great many changes, each change introducing an additional level of complexity and making bibliographic research on the taxa extremely difficult. Most early and not a few later checklists contain a very high proportion of entirely spurious entries, and a considerable number of described species are now considered invalid – either because they are homonyms, non-binomial or for some other reason.

Since then,

DNA sequence DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...

data have increasingly been used in systematics, but in Testudines (turtles and tortoises), its usefulness is limited: In some of these, at least

mtDNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondrion, mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mit ...

is known to evolve more slowly in these than in most other animals.

Paleobiogeographical Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, i ...

considerations suggest the rate of evolution of the mitochondrial

12S rRNA Mitochondrially encoded 12S ribosomal RNA (often abbreviated as 12S or 12S rRNA), also known as Mitochondrial-derived peptide MOTS-c or Mitochondrial open reading frame of the 12S rRNA-c is the SSU rRNA of the mitochondrial ribosome. In humans, ...

gene is 1.0-1.6% per million years for the last dozen million years or so in the present genus and ntDNA evolution rate has been shown to vary strongly even between different population of ''T. hermanni''; this restricts sequence choice for molecular systematics and makes the use of

molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleo ...

s questionable. The following extant species in the following subgenera are placed here: * Genus ''Testudo'' ** Subgenus '' Agrionemys'' *** Russian tortoise or Horsfield's tortoise, ''T. horsfieldii'' **** Subspecies: ***** Central Asian tortoise, ''T. horsfieldii horsfieldii'' ***** Fergana Valley steppe tortoise, ''T. horsfieldii bogdanovi'' ***** Kazakhstan steppe tortoise, ''T. horsfieldii kazakhstanica'' ***** Turkmenistan steppe tortoise, ''T. horsfieldii kuznetzovi'' ***** Kopet-Dag steppe tortoise, ''T. horsfieldii rustamovi'' **Subgenus '' Chersine'' *** Hermann's tortoise, ''T. hermanni'' **** Subspecies: ***** Eastern Hermann's tortoise, ''T. hermanni boettgeri'' ***** Western Hermann's tortoise, ''T. hermanni hermanni'' ** Subgenus ''Testudo'' *** Spur-thighed tortoise, Greek tortoise or common tortoise, ''T. graeca'' **** Subspecies: ***** Mediterranean spur-thighed tortoise, ''T. graeca graeca'' ***** Araxes tortoise, ''T. graeca armeniaca'' ***** Buxton's tortoise, ''T. graeca buxtoni'' ***** Cyrenaican spur-thighed tortoise, ''T. graeca cyrenaica'' ***** Asia Minor tortoise, ''T. graeca ibera'' ***** Morocco tortoise, ''T. graeca marokkensis'' ***** Nabeul tortoise, ''T. graeca nabeulensis'' ***** Souss Valley tortoise, ''T. graeca soussensis'' ***** Mesopotamian tortoise, ''T. graeca terrestris'' ***** Iranian tortoise, ''T. graeca zarudnyi'' *** Egyptian tortoise or Kleinmann's tortoise, ''T. kleinmanni'' *** Marginated tortoise, ''T. marginata'' The first two are more distinct and ancient lineages than the closely related latter three species. Arguably, ''T. horsfieldii'' belongs in a new genus (''Agrionemys'') on the basis of the shape of its

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the und ...

and plastron, and its distinctness is supported by

analysis. Likewise, a separate genus ''Eurotestudo'' has recently been proposed for ''T. hermanni''; these three lineages were distinct by the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million years ago) to 5.333 Ma. The ...

as evidenced by the fossil record. Whether these splits will eventually be accepted remains to be seen. The genus ''Chersus'' has been proposed to unite the Egyptian and marginated tortoises which have certain DNA sequence similarities, but their ranges are (and apparently always were) separated by their closest relative ''T. graeca'' and the open sea and thus, chance convergent

haplotype A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA or ...

sorting would better explain the

biogeographical Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

discrepancy. Conversely, the Greek tortoise is widespread and highly diverse. In this and other species, a high number of subspecies has been described, but not all generally accepted, and several (such as the "Negev tortoise" and the "dwarf marginated tortoise") are now considered to be local morphs. Some, such as the Tunisian tortoise, have even been separated as a separate genus ''Furculachelys'', but this is not supported by more recent studies.

Mating

''Testudo'' spp. are promiscuous creatures and they follow a

polyandrous Polyandry (; ) is a form of polygamy in which a woman takes two or more husbands at the same time. Polyandry is contrasted with polygyny, involving one male and two or more females. If a marriage involves a plural number of "husbands and wives" ...

mating system. Mating involves a courtship ritual of mechanical, olfactory and auditory displays elicited from the male to coerce a female into accepting copulation. Courtship displays are very energetically costly for males, especially because females tend to run away from courting males. The male will chase her, exerting more energy and elaborate displays of ramming and biting. Females are able to judge a male's genetic quality through these displays; only healthy males are able to perform costly courting rituals, suggesting endurance rivalry. These are considered honest signals that are then used to influence pre- and post-copulatory choice, as females are the choosy sex. Female mate choice offers no direct benefits (such as access to food or territory or parental care). There are, however, indirect benefits of mating with multiple males. Engaging in a polyandrous mating system offers a female guaranteed fertilization, higher offspring diversity and sperm competition to ensure that eggs are fertilized by a high quality male. This is in respect to the "good genes" hypothesis that females receive indirect benefits through her offspring by mating with a quality male, "a male's contribution to a female's fitness is restricted to isgenes" (Cutuli, G. et al., 2014). Mating order has no influence on paternity of a clutch so a female's inclination to mate with multiple males and her ability to store sperm allows for sperm competition and suggests cryptic female choice. However, some species do show size-assortative, ''T. marginata'', for example, where large males breed with large females and small males breed with small females. Other species form hierarchies; during male-to-male competition the more aggressive male is considered alpha. Alpha males are more aggressive with their courting as well and have higher mounting success rate than beta males. A female's reproductive tract contains sperm storage tubules and she is capable of storing sperm for up to four years. This sperm remains viable and when she goes a breeding season without encountering a male she is able to fertilize her eggs with the stored sperm. Storing sperm can also result in multiple paternity clutches; It is quite common among ''Testudo'' spp. females to lay a clutch that has been sired by multiple males. And females can lay one to four clutches a breeding season.

Sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

, promiscuity, long term sperm storage and elaborate courting rituals are factors that effect mate preference,

sperm competition Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and ...

and cryptic female choice in genus ''Testudo''.

References

External links

Mediterranean tortoises
* {{Taxonbar, from=Q662605 Turtle genera Taxa named by Carl Linnaeus