Subspecies, Hybrids and Mutations

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Duvernoy first described Meriones shawi in detail in 1842 from specimens he observed in Oman, Algeria. Its common name is Shaw's Jird. The Smithsonian national museum of natural history currently lists 11recognised synonyms of M.Shawi which have been regarded as subspecies in various publications by several authors. Although not all authors agree on each subspecies, the majority do agree on several that are included in the list below:

  • albipes
  • richardii
  • crassibulla
  • savii
  • grandis (Morocco)
  • sellysii
  • isis (Egypt)
  • trouessarti
  • laticeps
  • longiceps
  • auziensis

The Shaw's Jird belongs to the family genus Meriones within the subgenus Pallasiomys.

Meriones genus

At present there is no modern systematic revision available for species within the genus Meriones. Early revision was done by researchers J.L.Chaworth-Musters and J.R.Ellerman (1947) This was further updated and modified by J.R.Ellerman and T.C.S.Morrison-Scott (1951) and also later by G.B.Corbet (1978). These studies represent the most current review of the species within the genus. If any systematic revision work is done in the future it is predicted that it will most likely uncover a greater number of species within this genus.

D.M.Lay and C.F.Nadler researched chromosomal data involving Meriones species in 1967. This was accomplished when assessing relationships among the species within the group. Lay and Nadler also conducted hybridisation attempts in the laboratory amongst several species of the Meriones genus in 1969. Further data on chromosome research was completed by T.Benazzou, E.Viegas-Pequignot, F.Petter and B.Dutrillaux in 1982 when conducting research on 4 different species of Meriones, M.tristrami, M.crassus, M.libycus,and M.persicus. It was found that about twenty chromosomal arrangements separate these species into two groups. Further research then compared the previously studied 4 species with two more species of Meriones, M.shawi and M.unguiculatus, a Taterillus species T.gracilis, and one Gerbillurus species G.tytonis. The study showed how the chromosomal arrangements effectively split the meriones genus into two groups, and showed how the genuses Taterillus and Gerbillurus evolved from the branch that connected the two groups.

There are several subspecies of Shaw's Jird, and Shaw's Jirds themselves are similar enough to two other North African species, the Libyan Jird (M.libycus) and Sundervall jirds (M.crassus) to have clouded previous research and caused much confusion over the years to taxonomists researching the genus. M.shawi and M.libycus are often confused in museum collections and even published reports. Also for many years M.shawi were regarded by taxonomists to be no more than a subspecies of the Libyan Jird. Several Libyan forms which were initially allocated to M.libycus by taxonomists, on further research in later reviews it was found they really should have been allocated to M.shawi .An example of this is when specimens referred to Meriones libycus libycus collected from fig groves on the Mediterranean coast west of Alexandria were in actual fact specimens of Meriones shawi isis.

The Shaw's Jirds habitat is mostly North of M.libycus but lives side by side with the species in several regions. In North Africa M.libycus inhabits the Sahara desert, but populations of this Jird extend to the Mediterranean in Morocco, Algeria, and Libya where both M.shawi and M.libycus populations overlap and they occupy the same habitat. They exist together as similar but separate species because of biological/reproductive isolating mechanisms within each of the species. This doesn't mean that cross breeding doesn't take place in the wild, it does, but its effect on the overall populations are negligible. Generally the hybrid individuals are less capable of successful breeding than purebred individuals of either of the parent species.

U.K. Shaws Jirds

The U.K. Shaw's Jird is quite clearly a unique rodent that has been selectively bred now for well over 20 years. They are now a well established gerbil of specific type that are quite different from their wild ancestors that initially founded the U.K. population. One of the factors that enabled this particular gerbil species to evolve unhindered in the U.K. was the strict rabies control laws during the 1980's and '90's, which effectively isolated our U.K. population from abroad.

The Shaw's Jirds we describe in the U.K. are very dissimilar to what are described as Shaws Jirds on the continent. Their phenotype is also markedly different from scientific descriptions of the rodent, and even illustrations from antique publications about small mammals look very different from our U.K.Shaws, as can be seen from this picture on the N.G.S. website by J Smith which was published in the Proceedings of the Zoological Society in 1884. As you can see the jird in the handcoloured print looks far more like the continental Shaw's than the U.K Shaw's Jird.

There are plausible reasons for this. Shaw's Jirds have been available in the U.K. since the mid 1980's and most likely they were available before this date. There are also earlier records of gerbils known as Libyan Jirds available within the U.K. during the late 1970's and 1980's. Although I cannot locate any available information or pictures available of these Jirds or indeed any concrete evidence to support whether these Jirds were actually true Libyan Jirds or simply another form of Shaw's Jird. These earlier animals were also reported as being of a nervous nature, less tame and more inclined to bite their owners.

As has been mentioned earlier, Shaw's Jirds and Libyan Jirds are quite similar in size, behaviour, and appearance. Take a look here at some Kuwaiti Libyan jirds, to see the similarities between Shaw's jirds and Libyan jirds. Wild populations inhabit overlapping areas of Northern Africa, and it has been proved in breeding experiments (Lay and Nadler) that both species have a limited ability to interbreed. In the first generation the hybrid males are all infertile, but by repeatedly backcrossing the females to Libyan Jirds a population is created that are almost fully fertile.

According to the scientific literature available Shaw's are generally larger than Libyan Jirds, their tail is thicker and shorter with less of a tuft, their ears have some pigmentation, whereas the Libyan Jird although a very variable species depending on where it lives, has unpigmented ears, a slightly narrower face, and has dark nails unlike Shaws Jirds which possess clear nails. U.K. Shaws have a mixture of these features that are typical to both species, but are a much bigger animal than both of the species discussed as they are described in scientific literature. In some cases they can resemble Libyan Jirds by having dark nails, whereas other distinct types have resembled true Shaw's in having clear nails and only partially pigmented ears. However the vast majority of U.K. specimens have a mixture of characteristics from both species including that of a mixture of dark and clear nails. In some cases this unusual effect can often be seen on the same paw of the rodent.

There are major differences between U.K. Shaw's Jirds and those populations found in the Netherlands and Germany. U.K. Shaw's have a large robust skull which is longer and squarer than the Dutch or German Shaw's. U.K. Shaw's also have larger, erect ears, more so than European Shaw's, whose ears tend to fold back quickly when nervous. They also seem more gregarious, non- aggressive and relaxed in the presence of humans and display no fear towards them, whereas Dutch or German equivalents seem generally timid and nervous around unfamiliar humans. Some sources have even reported that the two species even smell different!

So what actually are U.K. Shaw's Jirds?

As has been mentioned the physical evidence shows that our U.K. Shaw's share many characteristics to both Shaw's and Libyans as they are described in scientific literature. Even skull comparisons between U.K. Shaw's and Libyan jirds and true Shaw's Jirds show that our U.K. Shaw's share skull characteristics between both of the species. All the evidence seems to lead us to the conclusion that the U.K. has a population of Shaw's X Libyan Jird hybrids that may have been inadvertently created in the 1980's by breeders who didn't realise they had two different, but very similar looking species in their hands.

Of course there are other alternatives to this hypothesis. Libyan Jirds have a very wide range of habitats from Morocco to Afghanistan. The wild populations that exist in these different locations can differ greatly in physical appearance, just as specimens within the subspecies of Shaw's can differ greatly from individual to individual depending on which region that they are caught. This can include features like coat colour to actual physical differences from facial features to actual body size and shape. It is also feasible that our U.K. Shaw's may be derived from a different region from the Dutch or German varieties, and therefore has evolved from a different subspecies, or even the result of hybridisation of two similar subspecies.

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