Complete mitochondrial genome analyzes of four gerbil species (Rodentia: Gerbillinae) distributed in Türkiye

The genus Meriones Illiger, 1811 is widely distributed in the Middle East, Northern Africa, and Central Asia. In spite of many studies evaluating the gerbil phylogeny, the systematics of this genus is controversial because studies analyzing a single gene region yield inconsistent results. The presented research provides the first complete mitogenomes of four gerbil species (Meriones crassus, Meriones persicus, Meriones tristrami, and Meriones vinogradovi) distributed in Türkiye and novel and strong results to clarify the phylogenetic relationships of these gerbils.

Next Generation Sequencing (NGS) was performed using the specimens from Türkiye. Other gerbil species (M. tamariscinus, M. meridianus (M. dahli), M. unguiculatus, M. libycus, Rhombomys opimus, Psammomys obesus, Brachiones przewalskii, and Gerbilliscus leucogaster) were also included in the phylogenetic analyses. In addition to determining the mitogenome characteristics, mean genetic distance values, haplotype and nucleotide diversity values, numbers of mutations and polymorphic sites were calculated, and a Bayesian Inference and Maximum Likelihood trees were constructed along with the divergence times.

Most of the 37 gene regions were encoded on the H-strand; the GC% ratio varied between 36.9 and 38.1% among the four species that show their genomes were AT-rich. Bayesian Inference and Maximum Likelihood trees gave well-supported genetic relationships: P. obesus and G. leucogaster were located as the most distant species, and M. tamariscinus and R. opimus were found to be closer. M. meridianus, M. unguiculatus, and M. persicus and M. tristrami, M. crassus, M. libycus, and M. vinogradovi formed two differentiated lineages. In the latter lineage, M. tristrami and M. crassus were clustered. Also, B. przewalskii was linked to the former two lineages. In addition, mean genetic distance values between Meriones species were determined to be 7.04-16.59%, in accordance with the results of the phylogenetic approach. It was also calculated that the species mentioned above diverged 11.04 MYA (95% HPD: 7.94-14.68), corresponding to the Late Miocene Epoch.

In contrast to previous studies, this study supports the paraphyly of subgenus Pallasiomys regarding the M. persicus' position with high reliability results. Besides, the paraphyletic status of the genus Meriones was proved with the phylogenetic relationship of B. przewalskii and Meriones species. It was also emphasized that mitogenome analyses are notably effective in order to study problematic systematics of rodent groups like Meriones.