Scimitar Oryx - Taxonomy and Genetics

Taxonomy and Genetics

The nomenclature of this animal has undergone many changes since its discovery in the early 19th century. It was first described by Lorenz Oken, a German naturalist, in 1816 as Oryx algazel. But it was considered inappropriate by Sir John Ellerman (Second Baronet), English shipowner, natural historian and philanthropist, and Terence Morrison-Scott, a British zoologist and was replaced by Oryx tao in 1827. In 1827, another species name leucoryx was used, but was soon assigned a synonym to the Arabian oryx (Oryx leucoryx). All these names were soon replaced by Oryx dammah a decade later by Philipp Jakob Cretzschmar, a German physician. Though the oldest name Oryx algazel was reintroduced after the name leucoryx failed, but, in 1951, Ellerman and Morrison-Scott realized the name was not suitable. Finally in January 1956, the International Trust for Zoological Nomenclature accepted Oryx dammah as the scientific name, though many papers published shortly after created confusion by using other names.

The scimitar oryx has 58 chromosomes. It has one pair of large submetacentric autosomes and 27 acrocentric autosomal pairs. The X and Y chromosomes are the largest and smallest acrocentrics. In the first molecular study on this species, genetic diversity among European, North American and some other captive groups was observed. A deep divergence was marked within the mitochondrial DNA haplotypes. The estimated divergence time was traced back to 2.1 to 2.7 million years. The populations increased approximately 1.2 and 0.5 million years ago.

In another study to note genetic differences between Oryx species, karotypes of Oryx species - namely O. gazella gazella, O. g. beisa, O. g. callotis, O. dammah and O. leucoryx - were compared with the standard karotype of Bos taurus. The number of autosomes in all karotypes was 58. The X and Y chromosomes were conserved in all the five species. O. g. gazella was a different from other Oryx species due to the fixed 2;17 centric fusion, which reflected that it has been geographically isolated from other Oryx taxa, and agrees with the classification of O. gazella and O. beisa as distinct species. After the analysis, it was concluded that sterility in hybrids (produced due to interbreeding in Oryx species) had not yet developed and there was viability.