Variation of the auditory system in the Indian Gerbil, Tatera indica Hardwicke, 1807, (Muridae, Rodentia) from the east of Iran

Skull variation in populations of the Indian gerbil Tatera indica (Gerbillinae, Rodentia) sampled across its broad geographic range

Populations of broadly distributed species often exhibit geographic structuring, which is sometimes reflected in phenotype. The monotypic Indian gerbil (Tatera indica) is an example of a widely distributed species, with its range encompassing much of Asia. This study aims to determine if T. indica populations exhibit marked variation in skull morphology—this structure is particularly adaptable and thus could be amenable to show such variation. Furthermore, the potential drivers of skull variation are examined, including the role of climate and geography. To achieve these goals, 21 linear measurements were measured on the skulls of 509 specimens, coming from 111 different localities, across this species wide range. The specimens were then assigned into one of four broad geographic groups (≈ populations) based on their geographic proximity, and the overall and the pairwise differences in the 21 skull measurements among these groups were assessed. Specimens from Pakistan significantly differed from those belonging to the West Iran, East Iran, and India populations, which in turn did not significantly differ from each other. Pairwise bioclimatic and geographic distances between the localities explained a significant, yet small amount of variation in the measurements. Thus, while the Pakistani T. indica population was distinct in skull measurements, both climatic and non-climatic spatial factors seem not to account largely for its distinctiveness (from the other populations).

Morphological and molecular characterization of Tatera indica Hardwicke 1807 (Rodentia: Muridae) from Pothwar, Pakistan

Genus Tatera is comprised of 12 species, but only one species, Tatera indica, exists in Asia. T. indica is considered an agricultural pest and host of a few zoonotic diseases. However, the data on morphological characteristics are published, but the aspect of molecular characterization is lacking to confirm the status of subspecies in most of the Asian countries including Pakistan. Therefore, the present study is the first study on morphological and molecular characterization of T. indica to get a phylogenetic relationship with the population of T. indica in Pakistan. Almost all the morphometric, cranial, and dental values of T. indica were lower in the present study as compared to the specimen from Iran, Syria, and Turkey. The molecular analysis indicated the presence of sub-species of T. indica. Interestingly, the cytochrome b gene sequence showed more resemblance to the Iranian rat than the previously reported sequence of a Pakistani T. indica. Iran shares a border with Pakistan, and migration between the two countries could be a possible reason. The resembling morphometric data on Iranian rats also explain this phenomenon. The present study found, although minor, evidence of the presence of sub-species even within Pakistan. Unfortunately, the previously submitted sequence from Pakistan was not supplemented with morphometric data and the exact capturing site of the rat. Therefore, further molecular and morphometric data from other regions are required to confirm the presence of sub-species.

Keeping an ear out: size relationship of the tympanic bullae and pinnae in bandicoots and bilbies (Marsupialia: Peramelemorphia)

Bandicoots and bilbies (Order Peramelemorphia) occupy a broad range of habitats across Australia and New Guinea, from open, arid deserts to dense forests. This once diverse group has been particularly vulnerable to habitat loss and introduced eutherian predators, and numerous species extinctions and range retractions have occurred. Understanding reasons for this loss requires greater understanding of their biology. Morphology of the pinnae and tympanic bullae varies markedly among species. As hearing is important for both predator avoidance and prey location, the variability in ear morphology could reflect specialization and adaptation to specific environments, and therefore be of conservation relevance. We measured 798 museum specimens representing 29 species of Peramelemorphia. Controlling for phylogenetic relatedness and head length, pinna surface area was weakly negatively correlated with average precipitation (rainfall being our surrogate measure of vegetation productivity/complexity), and there were no environmental correlates with effective diameter (pinna width). Controlling for phylogenetic relatedness and skull length, tympanic bulla volume was negatively correlated with precipitation. Species that inhabited drier habitats, which would be open and allow sound to carry further with less obstruction, had relatively larger pinnae and tympanic bullae. In contrast, species from higher rainfall habitats, where sounds would be attenuated and diffused by dense vegetation, had the smallest pinnae and bullae, suggesting that low-frequency hearing is not as important in these habitats. Associations with temperature did not reach statistical significance. These findings highlight linkages between hearing traits and habitat that can inform conservation and management strategies for threatened species.