Chromosomal diversity in mole-rats of the species Nannospalax ehrenbergi (Rodentia: Spalacidae) from South Anatolia, Turkey

The rodent fauna from the Neolithic human settlement of Tepecik-Çiftlik (Niğde, Turkey)

The primary aim of this study was to establish for the very first time the results on the rodent fauna gathered from the ongoing Neolithic excavations at the Tepecik-Çiftlik site in southern Cappadocia (Niğde, Turkey). So far, the fauna being study is represented by species of arvicolines (Microtus cf. arvalis and Arvicola cf. amphibius), murines (Mus cf. musculus), sousliks (Spermophilus xanthoprymnus), hamsters (Mesocricetus brandti) and mole-rats (Spalax xanthodon), and their remains are described in detail. Paleoenvironmental assumption based on common preferences of the fauna elements indicates, at first sight, a rather dry steppe environment with sparse plant cover or perennial short grasses. On the other hand, the presence of Arvicola cf. amphibius points out streams and marsh-like vegetation cover with bodies of water . The predation or burn marks observed on some specimens and the presence of subterraneous rodents raise questions concerning their taphonomy.

Heterochromatin distribution and localization of nucleolar organizing regions in the 2n = 52 cytotypes of Nannospalax xanthodon and N. ehrenbergi from Turkey

BACKGROUND

The blind mole rats (Spalacinae) are fossorial rodents exhibiting exceptionally extensive variation in the karyotype. The taxonomy of this group is not definitively resolved, and the species discrimination is often not clear, even with the use of chromosomal analyses.

RESULTS

We have studied the karyotype of three populations of blind mole rats (Spalacinae) from Anatolia classified tentatively as Nannospalax xanthodon (Bolu and Içel provinces) and Nannospalax ehrenbergi (Gaziantep province). C-banding and AgNOR staining were used in the cytogenetic analysis. In all populations, the karyotype comprised 52 chromosomes including 8 to 10 bi-armed and 17 to 15 acrocentric autosomal pairs. The centromeric position varied in the sex chromosomes between the populations. The C-positive centromeric bands occurred in most of the bi-armed autosomes and the sex chromosomes and in some of the acrocentric autosomes. The nucleolar organizer regions were localized in three (N. xanthodon) or five (N. ehrenbergi) autosomalpairs.

CONCLUSIONS

It is difficult to find particular chromosomal differences between the studied populations which could enable unequivocal species identification. This finding emphasizes the need of taxonomic revision of the species structure within the Nannospalax genus.

Is evolution of blind mole rats determined by climate oscillations?

The concept of climate variability facilitating adaptive radiation supported by the “Court Jester” hypothesis is disputed by the “Red Queen” one, but the prevalence of one or the other might be scale-dependent. We report on a detailed, comprehensive phylo-geographic study on the ∼4 kb mtDNA sequence in underground blind mole rats of the family Spalacidae (or subfamily Spalacinae) from the East Mediterranean steppes. Our study aimed at testing the presence of periodicities in branching patterns on a constructed phylogenetic tree and at searching for congruence between branching events, tectonic history and paleoclimates. In contrast to the strong support for the majority of the branching events on the tree, the absence of support in a few instances indicates that network-like evolution could exist in spalacids. In our tree, robust support was given, in concordance with paleontological data, for the separation of spalacids from muroid rodents during the first half of the Miocene when open, grass-dominated habitats were established. Marine barriers formed between Anatolia and the Balkans could have facilitated the separation of the lineage “Spalax” from the lineage “Nannospalax” and of the clade “leucodon” from the clade “xanthodon”. The separation of the clade “ehrenbergi” occurred during the late stages of the tectonically induced uplift of the Anatolian high plateaus and mountains, whereas the separation of the clade “vasvarii” took place when the rapidly uplifting Taurus mountain range prevented the Mediterranean rainfalls from reaching the Central Anatolian Plateau. The separation of Spalax antiquus and S. graecus occurred when the southeastern Carpathians were uplifted. Despite the role played by tectonic events, branching events that show periodicity corresponding to 400-kyr and 100-kyr eccentricity bands illuminate the important role of orbital fluctuations on adaptive radiation in spalacids. At the given scale, our results supports the “Court Jester” hypothesis over the “Red Queen” one.