Mound-building Mouse Mus Spicilegus Research Articles

Сучасна теріофауна лівобережжя Каньйонового Придністер’я

The article analyses the current state of the mammal fauna of part of Podolian Transnistria, which lies between the rivers Zbruch and Zolota Lypa (southern Ternopil Oblast, Ukraine). To designate the region, the publication uses a term from old Polish sources—Canyon Transnistria—which reflects the prevailing landform. The area of research in old faunal summaries is mentioned only as part of wider regions, such as Galicia, western Ukraine, or Ternopil Oblast. Over the past decades, the number of publications on the mammal fauna of this particular region has increased substantially, which makes it possible to make a summary overview. The modern mammal fauna of the region comprises 60 species belonging to 7 orders, 20 families, and 41 genera. Over the past 70 years, the mammal fauna of the studied region has undergone significant changes. Its dynamic component is almost 27%. It includes species of recent immigrants (Blyth’s pipistrelle Pipistrellus lepidus, mound-building mouse Mus spicilegus, muskrat Ondatra zibethicus), as well as two species that recovered their range (Eurasian beaver Castor fiber, wildcat Felis silvestris); the dynamic component also includes three extinct or probably extinct species—Geoffroy’s bat (Myotis emarginatus), Podolian ground squirrel (Spermophilus odessanus), and European rabbit (Oryctolagus cuniculus). A group of phantom species has been singled out, which are known only from single old finds, and modern studies of these species are far from sufficient to understand their status. It includes the lesser mouse-eared bat (Myotis oxygnathus), Nathusius’s pipistrelle (Pipistrellus nathusii), southern birch mouse (Sicista loriger), and Podolian mole rat (Spalax zemni). Such species as the long-eared bat (Plecotus austriacus) and the pygmy field mouse (Sylvaemus uralensis) appeared in the lists of the mammal fauna of the region due to changes in taxonomy. The rare component of the mammal fauna comprises 18 species (30%). The article provides a brief description of the current state of mammal populations in the region. Conservation recommendations are given for rare species.

Small rodents — permanent reservoirs of toxocarosis in different habitats of Slovakia

Abstract The study aimed to estimate the role of small rodents in the circulation of larval toxocarosis in light of their different habitats. From 2005 to 2008, a total of 1523 small rodents, belonging to 11 species, were captured in 5 different habitats of Slovakia. Anti-Toxocara antibodies were detected in 6.6 % animals. The dominant reservoirs of toxocarosis were striped-field mouse Apodemus agrarius (11.7 %) and mound-building mouse Mus spicilegus (10.7 %), while the seropositivity of voles was low. Sexually active adults were infected more frequently (10.8%) in comparison with inactive ones (5.2 %). According to habitats, seroprevalence of toxocarosis in windbreaks (2.4 %) was significantly lower (p < 0.05) than in agrocoenoses (6.7 %), alluvia (8.5 %) and ecotones (7.5 %). Log-linear analysis performed in A. agrarius indicates that type of habitat and sexual activity affect the seropositivity to Toxocara infection. The highest seroprevalence was observed in alluvium (21.2 %) while the lowest in windbreak (1.8 %) (χ2 = 17.232, p < 0.001) and sexually active mice were characterised by 22.5 % and sexually inactive by 6.4 % seroprevalence (χ2 = 30.634, p < 0.001). The occurrence pattern of toxocarosis in small rodents suggests that they are permanent reservoirs for Toxocara spp. in nature and significant indicators of Toxocara egg contamination in environs.

Behavioral differentiation during collective building in wild mice Mus spicilegus

Although well documented in social insects, the possibility of behavioral differentiation during collective building has been poorly studied in mammals. In this context, the mound-building mouse Mus spicilegus is an interesting model. Under natural conditions, juveniles from different litters gather vegetal material and build a sophisticated structure, the mound, under which the mice will spend winter. The first steps of this complex building process may be elicited under laboratory conditions by offering cotton balls as building material. Spatio-temporal distribution of both animals and cotton balls was automatically recorded by RFID (Radio-Frequency Identification Device) technique. Our results revealed a behavioral differentiation during a collective building task. In a group of six individuals, only two mice (called carriers) transported 80% of the building material whereas the contribution of the remaining mice was weak or even non-existent. The proportion of carriers was constant in all of the six groups studied. This behavioral differentiation was implemented immediately after the building material was made available and remained stable during the 4 days of experiment. The high contribution level of carriers did not result from resource monopolization, nor did it depend on the gender or parental origin of the mice.

Food preferences and mound-building behaviour of the mound-building mice Mus spicilegus

Optimal foraging strategies and food choice are influenced by various factors, e.g. availability, size and caloric content of the food type and predation risk. However, food choice criteria may change when food is not eaten immediately but has to be carried to a storage site for later use. For example, handling time in terms of harvesting and transport time should be optimized, particularly when the risk of predation is high. Thus, it is not clear whether food selected by hoarding animals reflects their food preference due to intrinsic features of the food type, e.g. size, caloric or lipid content, or whether the food type selected is a compromise that also considers the handling time required for harvesting and transport. We investigate this question in relation to food hoarding behaviour in mound-building mice. In autumn, mound-building mice Mus spicilegus collect seeds and other plant material and cover it with soil. Such above-ground storage is quite unusual for rodents. Here, we investigated whether there is a relationship between the seed species preferred as building materials and those preferred for food. We conducted a seed preference test using three most collected weed species for mound building. Controlling factors like food availability or predation risk, mice prefer Setaria spp. as food, although Amaranthus spp. and Chenopodium spp. were preferentially harvested and stored. By including the availability of the three species, our experimental results were confirmed, namely, a clear preference for Setaria spp. Also, handling time and seed size revealed to influence plant choice.

Paternal care in the mound-building mouse reduces inter-litter intervals

In many rodent species males display paternal behaviour. The primary reported effect of this paternal care is to increase pup survival. In mammal females, pregnancy and lactation are energetically demanding, especially when they are concurrent in post-partum reproduction. To face this energy requirement, females generally lengthen the duration of their post-partum pregnancy. In the present study we tested whether paternal care could affect this duration in the monogamous mound building mouse Mus spicilegus. In this species, females have a short reproductive life that does not exceed 4 months. Reduction of inter-delivery latencies would then be an efficient way to increase reproductive success. In a male removal experiment, we showed that inter-delivery latency was shortened by male presence. Moreover, behavioural estimations of paternal involvement were correlated with inter-delivery latency. The longer the male spent inside the nest the shorter the inter-delivery latency. In the mound-building mouse, the female might be able to monopolise the parental care of a single male, which could be important for the evolution of monogamy. The characteristics of first reproduction as compared to post-partum reproduction suggest that it may contribute to the formation of a strong and exclusive social bond between the reproductive partners.

Male-female associations and female olfactory neurogenesis with pair bonding in Mus spicilegus

Mound-building mice Mus spicilegus exhibit life-history traits that are unique among the Mus species complex, such as the cooperative mound-building behaviour that gives the species its common name. In this and other socially coordinated activities, such as those associated with reproduction, these mice should be able to recognize individuals (via discrimination based on kinship, population and species) to mediate their interactions. Our previous studies have provided evidence of population and species recognition in M. spicilegus. The aims of the present study were: (i) to study associations of mice during their reproductive period (in outdoor enclosures), (ii) to investigate whether there is an influence of relatedness of females in these associations, (iii) to determine whether female M. spicilegus are able to make kin vs. non-kin discriminations, and (iv) to study certain neurobiological correlates of male-female bonds. Stable male-female associations were found in almost all the experimental groups, both those with unrelated and unfamiliar females and those with unfamiliar sisters. Kinship between females did not affect female associations in our enclosure experiment, but in our kin discrimination experiment females did distinguish between unfamiliar sisters and unfamiliar unrelated females. Shared kinship may not encourage cooperative rearing of pups but could enhance cooperation in building mounds where mice over-winter. Male-female associations could be based on a social bond, as hypothesized from previous laboratory experiments. This was substantiated in this study by increased olfactory bulbar neurogenesis in females that preferred (in two choice tests) their sexual partner 3 weeks after their first mating. Based on these results there is clear evidence to suggest that the mating system of M. spicilegus is social monogamy.

Deficit in reproduction in polygynously mated females of the monogamous mound-building mouse Mus spicilegus

In monogamous mound-building mice Mus spicilegus, facultative polygyny was observed in April, at the beginning of the reproductive season. In order to evaluate the cost of polygyny, we compared, under laboratory conditions, the reproductive success of trios and pairs composed of sister females mated with unrelated brother males. Females in trios were able to tolerate each other during the reproductive period and to reproduce with the same male under spatial constraints. Nevertheless, polygyny had a strong negative effect on the reproductive success of the females. The average number of young per litter was smaller in trio females than in paired females, whereas the interval between two successive litters was higher. As a result, the number of litters and the number of young per time unit were smaller in each of the trio females compared with paired females. Agonistic behaviour being absent in trios, our results strongly suggest that living in trios led to pheromonal production that affected the female physiological state and reproduction. Males of trios did not obtain a better reproductive success than males in pairs.

Seasonal reproduction and delayed sexual maturity in mound-building mice Mus spicilegus.

In the mound-building mouse, Mus spicilegus, which is found from Central to Eastern Europe, reproduction is seasonal and limited to spring and summer. In autumn, the mice build voluminous mounds composed of vegetable matter covered with earth, where juvenile animals (autumnal individuals) over-winter in groups without reproducing. Autumnal animals delay reproduction until the next spring when they are 6 months old. The influence and interactions of environmental (short light period and cold temperature (C conditions) compared with long light period and temperate temperature (T conditions)) and social factors (lack of odours from breeding adults (NB conditions) compared with presence of odours from breeding adults (B conditions)) on reproduction and sexual maturation were studied. Forty groups of three autumnal individuals (two males and a female or two females and a male) were placed in four experimental conditions (CB, CNB, TB and TNB), corresponding to interactions between environmental and social factors (n = 10 groups for each condition). Of the 40 groups only one initiated reproduction during the 18 weeks of cohabitation. Subsequently, animals were separated and isolated for 1 month and then paired with unfamiliar partners. Reproduction was monitored for an additional month, and 24 out of 39 females reproduced. In addition, of eight reproducing pairs placed in C conditions and 10 reproducing pairs maintained in T conditions, all but one pair continued reproduction. It was concluded that the delay in reproduction observed in autumnal individuals was the result of the social effects of living in groups as opposed to the environmental conditions of winter.

A comparative study of parental care between two rodent species: implications for the mating system of the mound-building mouse Mus spicilegus

Paternal care is uncommon in mammals where males are more often involved in sexual competition than in providing care for their own offspring. However some species present some form of paternal care and, most of the time, this phenomenon is associated with a monogamous mating system. Mice of the genus Mus, such as the house mouse Mus musculus domesticus, are commonly considered to be polygamous–polygynous species. In Mus spicilegus, the mound-building mouse, previous results on female sexual preferences have suggested the existence of pair bonding more compatible with a monogamous mating system than with a polygamous one. We therefore tested the hypothesis that male M. spicilegus present a higher level of paternal care than males of the polygynous house mouse. Results showed that male M. spicilegus spent significantly more time covering the young during the first week after birth than male M. m. domesticus, particularly when the female was exploring, and retrieved stray pups significantly more frequently and more rapidly than male M. m. domesticus. There were practically no differences between the females of these two species. M. spicilegus parents also more significantly alternated their protection of the pups than M. m. domesticus parents. We discuss the evolution of paternal care in M. spicilegus in relation to monogamy.

Social structure of the mound-building mouse Mus spicilegus revealed by genetic analysis with microsatellites.

The Mound-building mouse Mus spicilegus possesses a unique behaviour amongst mice. It constructs large earthen mounds and associated nesting chambers which serve to store food for immature individuals during the winter nesting period. We have used genetic analysis of four autosomal and four X-linked microsatellite loci to determine relationships between individuals inhabiting 40 mounds in Bulgaria. We show that, in almost all cases, individuals in a mound are the product of multiple parentage. We estimate the minimum number of males and female parents contributing offspring to each mound and demonstrate that at least two male and two female parents contribute offspring to a minimum of seven mounds. Analyses of relatedness coefficients and allele sharing values demonstrate that parents of different sibships within mounds are more related than if they had been chosen at random from the population and suggest that it is the female parents that contribute this excess relatedness. These results suggest that the mechanism by which individuals congregate to build mounds is kin-based and that the evolution of mound building and communal nesting in M. spicilegus is due in part to kin selection. This study represents a novel approach to the study of mammalian behavioural ecology. We have used a genetic dataset to construct an outline of social structure in the absence of behavioural data. These inferences can now be used to direct further work on this species.