We explored modularity and morphological integration of the ventral cranium during postnatal ontogeny in Martino’s vole (Dinaromys bogdanovi). Two closely related phylogenetic groups, originating ...from the Central and Southeastern part of the species range in the western Balkans, were considered. As expected, both phylogroups had similar patterns of ontogenetic changes in cranial size and shape variation, modularity and integration. At the level of within individual variation, the hypothesis that the viscerocranial and neurocranial regions are separate modules was rejected, indicating that the hypothesized modules are not developmental, but rather functional. At the level of among individual variation, the viscerocranium and the neurocranium could not be recognized as separate modules at the juvenile stage. The strength of association between the hypothesized modules becomes lower with age which finally results in a clear 2-module organization of the ventral cranium at the adult stage. On the other hand, patterns of morphological integration for the cranium as a whole, the viscerocranium and the neurocranium stay consistent across ontogenetic stages. The developmental mechanism producing integration of the cranium as a whole, as well as integration of the neurocranium, varies throughout postnatal ontogeny. In contrast, we detected the ontogenetic stability of the mechanism responsible for covariation of viscerocranial traits which could provide ongoing flexibility of the viscerocranial covariance structure for high functional demands during lifetime. Findings from our study most likely support the idea of the ‘palimpsest-like’ model of covariance structure. Moreover, similarity or dissimilarity in the patterns of within and among individual variation in different sets of analyzed traits and comparisons across ontogenetic stages demonstrate how studies on small mammals other than mice can give new insights into postnatal cranial development.
The Martino’s vole (
Dinaromys bogdanovi
) is a rare species that lives in differently structured karst habitats, varying from open rocky plains to deep fissures, mostly residing under boulders and ...in crevices. Populations of the species are declining, probably due to its strict habitat preferences and competition with the European snow vole. Since the species is difficult to study in the wild, we tested its behavioral response to a differently complex environment and novel object presence in captivity. We exposed 14 individuals to differentially complex setups, from open and unsheltered to rocky with covered tunnels. We measured the effect of the presented setup and season on vole behavior. Analysis showed seasonal differences with higher movement frequency and longer time spent still during the breeding season, and a higher number of attempts due to the lack of vole entry into the experimental terrarium in the non-breeding season. Additionally, movement significantly differentiated between an open and simple setup in comparison to more complex ones, with higher frequencies of moving and peeping and the duration of peeping in the simple setup, indicating restlessness. We also found significant differences between the novel object and control setup. The results of this study could be useful for future assessment of the influence of habitat complexity on mobility in the wild. Moreover, this is the first study on the behavior of this endemic and rare rodent.
Historical biogeography and evolutionary processes of cave taxa have been widely studied in temperate regions. However, Southeast Asian cave ecosystems remain largely unexplored despite their high ...scientific interest. Here we studied the phylogeography of Leopoldamys neilli, a cave-dwelling murine rodent living in limestone karsts of Thailand, and compared the molecular signature of mitochondrial and nuclear markers.
We used a large sampling (n = 225) from 28 localities in Thailand and a combination of mitochondrial and nuclear markers with various evolutionary rates (two intronic regions and 12 microsatellites). The evolutionary history of L. neilli and the relative role of vicariance and dispersal were investigated using ancestral range reconstruction analysis and Approximate Bayesian computation (ABC). Both mitochondrial and nuclear markers support a large-scale population structure of four main groups (west, centre, north and northeast) and a strong finer structure within each of these groups. A deep genealogical divergence among geographically close lineages is observed and denotes a high population fragmentation. Our findings suggest that the current phylogeographic pattern of this species results from the fragmentation of a widespread ancestral population and that vicariance has played a significant role in the evolutionary history of L. neilli. These deep vicariant events that occurred during Plio-Pleistocene are related to the formation of the Central Plain of Thailand. Consequently, the western, central, northern and northeastern groups of populations were historically isolated and should be considered as four distinct Evolutionarily Significant Units (ESUs).
Our study confirms the benefit of using several independent genetic markers to obtain a comprehensive and reliable picture of L. neilli evolutionary history at different levels of resolution. The complex genetic structure of Leopoldamys neilli is supported by congruent mitochondrial and nuclear markers and has been influenced by the geological history of Thailand during Plio-Pleistocene.
We examined, in the context of phylogeny, variations in ventral cranial shape in Martino's vole (Dinaromys bogdanovi), a rare rodent endemic to the western Balkans. Our analysis was based on 138 ...complete adult skulls, which were pooled into 3 phylogeographic groups (Northwestern, Central, and Southeastern). These groups were retrieved in an earlier study based on a 555–base-pair fragment of mitochondrial cytochrome b gene, which suggested a stepping-stone pattern of southward expansion followed by allopatry. Ventral skull shape was analyzed with geometric morphometrics using 23 two-dimensional landmarks. The primary shape differences across groups are the sizes of the auditory bulla and the foramen magnum, the length of the incisive foramen, and the width of the rostrum. Consistent geographic trends in shape changes were rare, and size was stable across phylogeographic groups. Morphological relationships among groups closely resemble genetic distances, implying their neutral evolution rate. We suggest that the adaptive zone occupied by Martino's vole imposes narrow limits to its phenotypic variation. Under the strong pressures of stabilizing selection for the normative (intermediate) phenotype, random drift in isolated populations produced only minor deviations in the ventral cranium.
We carried out a Capture-Mark-Recapture study on Martino's vole Dinaromys bogdanovi on Mt. Bjelašnica, central Bosnia. During two trapping sessions (June and September 2008) we recorded 21 ...individuals which were captured 33 times. Voles were trapped significantly more frequently during the night (85% of all captures). In June all the animals were adult females while three age classes (juvenile, subadult and adult) were distinguished in September. No reproductive activity was recorded in mid-June and not a single adult female was evidently pregnant in September. Also, subadults (N = 6) did not show reproductive activity. Martino’s voles proved sedentary and only two individuals moved between trap stations. Ten adults were captured in two sessions on an area of 5.67 ha, resulting in a population density of about 2.5 voles per hectare.
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