Morphological differentiation in Mus spicilegus and the taxonomic status of mound-building mice from the Adriatic coast of Yugoslavia

Difference in small mammal assemblages in the diet of the Common Barn-Owl Tyto alba between two landscapes

As an opportunistic predator, the Common Barn-owl (Tyto alba) proved to be an appropriate model organism to survey the composition of small mammal assemblages. This study analysed barn owls’ pellet samples from 14 localities containing 34 animal taxa and 4,088 prey items in two years (2015–2016). Two groups of samples (7–7 localities) were separated based on the dominance of semi-natural habitats and agricultural lands. Rarefaction analysis proved that the species richness and diversity of barn owls’ diet were significantly higher in semi-natural landscapes. The multiple regression analysis between PCA scores showed that in the agrarian landscape the abundance of generalist species was influenced by the proportion of forests, while the value of the trophic level index was determined by the size of arable fields. In the case of semi-natural landscapes, the abundance of the synantrop guild and generalist species, especially S. araneus and A. agrarius, was influenced by the proportion of urban areas, the number of habitats and the size of arable fields. The results of this study suggested that the small mammal consumption of the Common Barn-owl is significantly different in the two landscapes, which reflects the impact of habitat heterogeneity and agricultural activity on prey availability.

Sex and age differences in skull size in Myodes glareolus from Slovakia

The results of a craniometric analysis of the bank vole (Myodes glareolus) were evaluated in this study. Twenty cranial variables were measured and evaluated on 149 skulls (78 males, 71 females) with respect to sex and age. The main aim of this study was to test the sexual dimorphism in skull size. Overall, our results showed that on average, the values for adult and subadult females of M. glareolus were higher than for males. Results presented here thus reveal sexual differences in the measured cranial traits, most expressed for the length of the mandible and the height of the mandible. The effect size was very large for the length of the first upper molar. Comparison of our results with those from other countries confirmed that there are regional differences. These findings highlight the need for craniometric analysis of species also at the regional level.

The genetic diversity of the genus Mus (Linnaeus, 1758) in the eastern part of the North Caucasus

Background

There are two species of Mus in the Caucasus: M. musculus and M. macedonicus. M. musculus is widespread in the Caucasus, where the species is found everywhere from the Black to the Caspian Sea. M. macedonicus is ubiquitous Transcaucasia. The most north-astern border of its distribution in the Caucasus, according to the literature, is located in the Derbent region, near the border between Dagestan and Azerbaijan.

Results

Cytochrome b mt-DNA of genus Mus research in this study in the Eastern Caucasus. About 70% of M. musculus haplotypes from the lowlands of Dagestan were recorded for the first time. One of these haplotypes accounts for approximately 25% of the total species diversity of haplotypes. M. macedonicus was found in only one locality, the Sarykum barchans, where this species prevails in number and accounts for 70% of the total number mice of the genus Mus. The species is characterized by low values of genetic diversity and nucleotide variability, which may indicate that the population originated from a small number of founders and may explain its relative isolation from the main range. The dating of the appearance of the ancestors of M. musculus in the east of the Russian Caucasus corresponds to 99-66 thousand years ago (at a mutation rate of 3-10% per million years).

Conclusion

The results obtained suggest that the history of the appearance of M. musculus in the Eastern Caucasus is more ancient and is not associated with human agricultural activities.

We believe that possibly the ancestral range of M. musculus covered the eastern and western coasts of the Caspian Sea in the territory of southern Dagestan, Azerbaijan, and Iran. In this paper M. macedonicus, a Balkan-Asia Minor species, was registered for the first time in the North Caucasus. This species was registered in the center of Dagestan, where it inhabits sympatrically (on the territory) and syntopically (on the same biotope) with M. musculus. The low values of genetic diversity of M. macedonicus in the North Caucasus suggest that the population originated from a small group of founders.

Effect of early experience on neuronal and behavioral responses to con- and heterospecific odors in closely related Mus taxa: epigenetic contribution in formation of precopulatory isolation

BACKGROUND

The most effective learning occurs during sensitive periods. Olfactory plasticity to main social olfactory cues is limited to a critical period to a large degree. The objective was to evaluate the influence of early olfactory experience on the behavioral and neuronal responses of males to con- and heterospecific odors of receptive females in two species, M. musculus (subspecies musculus, wagneri) and M. spicilegus, and thus to determine the potential role of epigenetic contribution in the formation of precopulatory isolation.

RESULTS

Males were reciprocally cross-fostered shortly after the birth and were tested for response to con- and heterospecific urine odors of estrus females using two-choice tests at 70-85 days of age. Neuronal activity of non- and cross-fostered males was evaluated at 90-110 days of age in the MOB and AOB to con- and heterospecific female odor using fMRI (MEMRI). Non-cross-fostered males of three taxa demonstrated a strong preference for odor of conspecific females compared to odor of heterospecific ones. Spicilegus-nursed musculus preferred odor of heterospecific females. Wagneri-nursed spicilegus and spicilegus-nursed wagneri did not demonstrate significant choice of con - or heterospecific female odor. The level of MRI signal obtained from the evaluation of manganese accumulation in AOB neurons was significantly higher when the odor of conspecific estrus females was exposed, compared to urine exposure of heterospecific females. The response pattern changed to the opposite in males raised by heterospecific females. Response patterns of neuronal activity in the MOB to con- and heterospecific female odors were different in cross-fostered and control males.

CONCLUSION

The maternal environment, including odor, had a greater effect on the level of MRI signal in the AOB than the genetic relationships of the recipient and the donor of the odor stimulus. Behavioral and neuronal responses to con- and heterospecific odors changed in closely related Mus taxa as a result of early experience. We demonstrated the importance of early learning in mate choice in adulthood in mice and the possibility of epigenetic contribution in the formation of precopulatory reproductive isolation.

Genetic variation and phylogeography of free-living mouse species (genus Mus) in the Balkans and the Middle East

This work presents a study of the distribution and pattern of variation throughout the ranges of three free-living mouse species of the genus Mus-M. macedonicus, M. spicilegus, and a M. cypriacus - based on sequencing of two segments of the mitochondrial DNA (mtDNA) control region. The study shows a similar level of variability in the three species and suggests their recent population expansion. The highest proportion of variation is found within populations indicating low genetic structuring. Phylogenetic analysis confirms the significant divergence of a mitochondrial lineage of M. macedonicus from Israel, recently described as a new subspecies, M. macedonicus spretoides. Conversely, no genetic hiatus is revealed between European and Asian populations of M. macedonicus macedonicus. Although phylogenetic relationships among M. spicilegus populations could not be unravelled precisely, the results suggest a recent westward expansion of the species. The mtDNA divergence between M. macedonicus and M. spicilegus is 7.3%, suggesting their split between c. 700,000 and 1 million years ago. These dates correspond with a coalescent estimate about 720,000 years ago. On the other hand, M. cypriacus appeared almost twice as divergent from the former species (4.5%) as from the latter (8.8%) suggesting a divergence of c. 430,000-610,000 years ago (coalescent approximately 490,000 years ago) and 830,000-1.2 million years ago (coalescent approximately 780,000 years ago), respectively. Approximate times of population expansion have also been estimated for all taxa and groups of populations. Existence of several glacial refuges and various colonization scenarios are discussed; since all estimated divergence times fall within interglacial periods it seems that climatic oscillations did not play a crucial role in the evolution of the three species.

Short-term contact elicits heterospecific behavioral discrimination of individual odors in mound-building mice (Mus spicilegus)

The authors used a habituation-dishabituation procedure to test the ability of male mound-building mice (Mus spicilegus) to discriminate individual odors from males of another species of mouse. Male mound-building mice failed to spontaneously discriminate individual odors from Mus musculus musculus males, a natural competitor. After 24-hr contact with a male of one of the M. musculus subspecies (M. m. musculus or M. m. domesticus), experienced M. spicilegus males discriminated the individual odors of unfamiliar males of the same subspecies. These results confirm that discrimination of individual chemosignals is not confined to olfactory cues of a single species and provide new information about the effect of short-term contact on discrimination of individual odors across species.

Two deeply divergent mitochondrial clades in the wild mouse Mus macedonicus reveal multiple glacial refuges south of Caucasus

A survey of 77 individuals covering the range of Mus macedonicus from Georgia in the East to Greece and Bulgaria in the West and Israel in the South has shown the existence of two deeply divergent mitochondrial clades. The southern clade was until now undetected and characterises mice from Israel. Nuclear genes also show some amount of regional differentiation tending to separate the southern M. macedonicus from the northern ones. These results point towards the fact that the eastern Mediterranean short-tailed mouse, which was seen as a fairly homogeneous monotypic species, has in fact a more complex phylogeographic history than has been suspected, and that it warrants the existence of two subspecies. The reasons for this non-uniformity probably ought to be looked for in the history of faunal movements linked to glacial periods, underlining the possible existence of at least two refugia south of the Caucasus.

Evolutionary biogeography of water shrews (Neomys spp.) in the western Palaearctic Region

We studied the morphology, DNA sequence, and Recent and Pleistocene distributions of three species of the water shrew genus Neomys (N. fodiens, N. anomalus, and N. teres) represented by samples from the Balkans and Asia Minor. Adaptations to semi-aquatic life (large body size, fringes of stiff hairs bordering the hind foot, and a tail keel) were most developed in N. fodiens and N. teres and least developed in N. anomalus. However, sympatric N. fodiens and N. anomalus did not differ significantly in relative braincase size. The three Neomys species clearly differed in glans penis morphology, N. teres being the most distinct, with a longer glans (length = 10.8-14.6 mm) than N. anomalus (7.0-8.0 mm) or N. fodiens (7.5-8.5 mm). Phylogenetic analysis placed N. fodiens as a sister-group to the anomalus-teres clade, based on both cytochrome b and 12S rRNA fragments. Palaeodistribution maps are presented for the three Recent taxa and the palaeospecies N. newtoni and N. browni. Possible evolutionary scenarios are proposed.