Rodent Community Research Articles

Chernov’s compensation principle and the effect of rodent community completeness on the variability of bank vole (Clethrionomys glareolus) population in the Middle Urals

Using methods of geometric morphometrics, significant differences have been revealed in manifestations of variability and morphological disparity in allochronous samples from the population of model species, the bank vole (Clethrionomys glareolus Schreb. 1780), in the Middle Urals at different levels of rodent community (taxocene) completeness in different years. Two states of the taxocene—oligospecific (two species) and polyspecific (five species)—and the level of relative abundance of bank voles (high or low) have been taken into account. Comparative analysis of variation in the size and shape of the mandible in same-aged (late-summer) young of the year has shown that significant morphogenetic differences exist between the animals sampled from the rodent taxocene at its different states (oligospecific and polyspecific) and, to a lesser extent, at high and low levels of abundance. The level of variation and the parameter of intragroup morphological disparity (MNND) in the mandible shape reach a maximum when the community has a reduced composition and decrease to a minimum when its composition is complete (i.e., in the oligo- and polyspecific taxocene). A parallelism is observed in the manifestation of morphofunctional changes of the mandible in male and female voles under conditions when the taxocene has high abundance and oligospecific composition or low abundance but polyspecific composition. Different morphogenetic responses of the population to oligo- and polyspecific composition of the community are considered as a compensatory increase of morphological disparity in the dominant species (the bank vole) under conditions of incomplete composition of the taxocene and low population density, in accordance with Chernov’s ecological compensation principle.

Shifts in an invasive rodent community favoring Black rats (Rattus rattus) following restoration of native forest

AbstractOne potential, unintended ecological consequence accompanying forest restoration is a shift in invasive animal populations, potentially impacting conservation targets. Eighteen years after initial restoration (ungulate exclusion, invasive plant control, and out planting native species) at a 4 ha site on Maui, Hawai'i, we compared invasive rodent communities in a restored native dry forest and adjacent non‐native grassland. Quarterly for 1 year, we trapped rodents on three replicate transects (107 rodent traps) in each habitat type for three consecutive nights. While repeated trapping may have reduced the rat (Black rat, Rattus rattus) population in the forest, it did not appear to reduce the mouse (House mouse, Mus musculus) population in the grassland. In unrestored grassland, mouse captures outnumbered rat captures 220:1, with mice averaging 54.9 indiv./night versus rats averaging 0.25 indiv./night. In contrast, in restored native forest, rat captures outnumbered mouse captures by nearly 5:1, averaging 9.0 indiv./night versus 1.9 indiv./night for mice. Therefore, relatively recent native forest restoration increased Black rat abundance and also increased their total biomass in the restored ecosystem 36‐fold while reducing House mouse biomass 35‐fold. Such a community shift is worrisome because Black rats pose a much greater threat than do mice to native birds and plants, perhaps especially to large‐seeded tree species. Land managers should be aware that forest restoration (i.e. converting grassland to native forest) can invoke shifts in invasive rodent populations, potentially favoring Black rats. Without intervention, this shift may pose risks for intended conservation targets and modify future forest restoration trajectories.

Impact of global climate in the diversity patterns of middle Miocene rodents from the Madrid Basin (Spain)

Remarkable palaeoclimatic global changes have been recorded worldwide during the middle Miocene. The Miocene Climatic Optimum (~16.3 to ~15Ma), one of the warmest phases since the Eocene, was followed by the stepwise cooling trend of the Middle Miocene Climate Transition (~15 to ~13.7Ma). The entry into an Earth “Ice-house” climate state took place at the end of the latter (~13.76Ma) marked by one of the major cooling steps in middle Miocene climate recorded at a global scale (Mi3b event). The Madrid Basin, which is part of one of the main Cenozoic basins of the Iberian Peninsula, contains a well-represented small-mammal record from the lower middle Miocene to the upper middle Miocene (middle and upper Aragonian, ~15.9 to 12.8Ma), being an appropriate region to check how these climatic phases influenced the distribution of the mammalian faunas on the center of the Iberian Peninsula. Values of species richness, equitability and heterogeneity of rodents have been calculated for 25 localities of the Madrid Basin and compared to detailed climate isotope records from the marine realm (ODP Site 1146 from the South China Sea and the Mediterranean record of the Ras Il Pellegrin section on the Maltese Islands) and with palaeoprecipitation curves for southwest Europe (Calatayud-Montalbán Basin). The results show that the rodent community during the middle and upper Aragonian in the Madrid Basin was subject to the changing climate conditions imposed in the course of the middle Miocene. The palaeoecological curves witness periods of disturbance of the community during changing climate conditions (marked by important drops in equitability and, in some cases, gradual decreases in heterogeneity and species richness), followed by periods showing a recovery of the community and adaptation to the new climate circumstances (represented by more evenly distributed and diverse assemblages). The effects of the Miocene Climate Optimum and of three Mi-events (Mi2b, Mi3a and Mi3b) have been related to changes in the small-mammal community. Between ~15.8 and 15.3Ma, the likely extreme environment (high temperature and low precipitation) of part of the Miocene Climate Optimum may have imposed severe constraints on the fauna, resulting in a community with low values of equitability, heterogeneity and a decreasing number of species. The transition of the Miocene Climate Optimum to the Middle Miocene Climate Transition, reflected by the Mi2b event, has also procured a destabilization of the rodent assemblages, as an important drop in equitability is recorded between ~15 and 14.6Ma. In this interval, the drop in temperature and increase in rainfall derived from the Middle Miocene Climate Transition promote the southwards migration of northern invaders, leading to an increase in species richness in the Madrid Basin. Starting around 14.4Ma, the onset of a progressive drop in the rodent equitability and heterogeneity, which also coincides with a major stratigraphic discordance in the basin, is related to the first cooling step of the Middle Miocene Climate Transition (Mi3a event). Finally, the major cooling step in middle Miocene climate recorded at a global scale (Mi3b event) is poorly reflected in the palaeoecological curves. However, the taxonomical study of the rodent faunas of that interval (biozone E) has shown turnover rates and morphometric changes that indicate that this period represents one of the most variable in assemblage composition within the Aragonian. Although the Mi3b event has been correlated for a long time to the substitution of the early-middle Aragonian fauna by a late Aragonian community (E–F boundary), the study of the rodent assemblages of the Madrid Basin may point out that small changes in the small-mammal community started before (within biozone E).

Partitioning of Trophic Resource in Rodent Community on the Terek-Kuma Lowland of the Republic Dagestan

Partitioning of Trophic Resource in Rodent Community on the Terek-Kuma Lowland of the Republic Dagestan

洞庭湖洲滩及滨湖区鼠类分布格局及其多样性

洞庭湖洲滩及滨湖区鼠类分布格局及其多样性

Diversity of Muroid rodent communities in key habitats of the Skole Beskids (Eastern Carpathians)

Diversity of Muroid rodent communities in key habitats of the Skole Beskids (Eastern Carpathians)

The nightshift: Seed dispersal and consumption differences by rodents before and after dark

Seed burial by dispersal vectors in fire-prone ecosystems is thought to increase seed survival rates by protecting them from fire and other seed consumers. In the fire-prone fynbos, seed burial is usually performed by ants. Historically, rodents in the fynbos were viewed purely as seed consumers; however, more recent evidence suggests that some species may also disperse seeds. This is done by scatter-hoarding the seeds in caches buried below the soil surface. Since seed dispersal and consumption by rodents usually takes place unobserved, it has been difficult to positively confirm which rodents disperse seeds and which ones only consume them. Here, the dispersal and consumptive behaviour of 2 rodents, Rhabdomys pumilio and Gerbilliscus paeba, are disentangled by using a combination of camera traps and the temporal compartmentalisation of seed fate patterns into day versus night in a depauperate, Cape strandveld rodent community. In this study, it is clearly demonstrated that the nocturnal hairy-footed gerbil (G. paeba) dispersed Willdenowia incurvata (Restionaceae) seeds. Although G. paeba also consumes seeds, they cached more seeds than they consumed during the period of observation. In contrast, the diurnal 4-striped mouse (R.pumilio) consumed but never cached seeds left out during the day. These results demonstrate that ecological roles of Cape rodents vary between species and that rodents in general cannot simply be regarded as seed consumers or dispersers as they have in the past.

The effect of seed size on seed fate in a subtropical forest, southwest of China

Abstract: Scatter-hoarding rodents acting both as seed predators and dispersers usually play an important role in seed dispersal of many plant species. Seed size is thought to essentially affect rodent scatter-hoarding processes. However, studies to date have frequently shown many controversial results regarding the effect of seed size on rodent foraging. In this study, we explored how seed size affects scatter-hoarding rodent foraging preferences in order to identify the possible reasons underlying the conflicting results reported in the scientific literature. We surveyed rodent seed predation and dispersal of five common tree species in a natural subtropical forest located in southwestern China along two seasons which were different in both seed abundances and rodent communities. Our results showed that a similar effect of seed size on rodent scatter-hoarding behavior existed in both seasons, although the seeds in spring were harvested more quickly than in autumn. Larger seeds of the small-seeded species (Castanopsis wattii, Lithocarpus hancei, Machilns yunnanensis and Lithocarpus pachyphyllus) were harvested, removed, and finally cached by the rodents more frequently. For the largest-seeded species (Lithocarpus xylocarpus), seeds with smaller size were preferred during the rodent scatter-hoarding processes. Our findings support the hypothesis that scatter-hoarding rodents preferably feed on large seeds at early stage of seed dispersal, but only up to a certain threshold of seed size.

Assessment of nonselective elimination effects in rodent communities by methods of geometric morphometrics

Methods of geometric morphometrics and population phenogenetics have been used to evaluate morphogenetic rearrangements in two sympatric species of Myodes voles (M. glareolus Schreb. 1780 and M. rutilus Pall. 1779) from syntopic populations recovering after exposure to local “ecological vacuum” created as a result of rodent extermination in a natural focus of hemorrhagic fever in the southern taiga subzone of the Udmurt Republic. The model used in the study simulates the situation that arises upon nonselective elimination of rodent populations and communities in spring and their subsequent recovery. Analysis of variation in the size and shape of the mandible and in a complex of 30 nonmetric cranial characters has revealed similar (parallel) and species-specific morphogenetic and epigenetic changes occurring during the recovery of local rodent community. Species-specific differences in the pattern of change in the parameter characterizing within-group morphological disparity in the mandible shape (MNND) have been revealed between the dominant species (M. glareolus) and the subdominant species competing with it for territory (M. rutilus). Different reactions of close Myodes species in the course of filling the ecological vacuum are considered as a result of reduction in the level of competition for the subdominant species and a compensatory increase of morphological disparity in the dominant species under conditions of low density and incomplete composition of the community, in accordance with Chernov’s (2005) ecological compensation principle.

Biotic resistance and disturbance: rodent consumers regulate post-fire plant invasions and increase plant community diversity.

Biotic resistance and disturbance are fundamental processes influencing plant invasion outcomes; however, the role of consumers in regulating the establishment and spread of plant invaders and how disturbance modifies biotic resistance by consumers is unclear. We document that fire in combination with experimental exclusion of rodent consumers shifted a native desert shrubland to a low-diversity, invasive annual grassland dominated by Bromus tectorum (cheatgrass). In contrast, burned plots with rodents present suppressed invasion by cheatgrass and developed into a more diverse forb community. Rodents created strong biotic resistance to the establishment of aggressive plant invaders likely through seed and seedling predation, which had cascading effects on plant competition and plant community diversity. Fire mediated its positive effects on plant invaders through native plant removal and by decreasing the abundance and diversity of the rodent community. The experimental disruption of plant and consumer-mediated biotic resistance of plant invaders using fire and rodent exclusion treatments provides strong evidence that native plants and rodents are important regulators of plant invasion dynamics and plant biodiversity in our study system. While rodents conferred strong resistance to invasion in our study system, fluctuations in rodent populations due to disturbance and climatic events may provide windows of opportunity for exotic plant species to escape biotic resistance by rodent consumers and initiate invasions.

Altitudinal variation in the diversity and structure of the desert rodent community from Jebel Al Jais, United Arab Emirates

In arid areas where organisms are subjected to environmental extremes, ecological communities are simple and provide useful models for studying community organisation. We used capture, mark and release methods between November 2014 and May 2015 to assess the rodent community in the Hajar Mountains of Ras Al Khaima along an altitudinal gradient from 460 m to 1650 m. We captured three rodent species; Arabian Spiny Mouse, Acomys dimidiatus, Wagner’s Gerbil, Gerbillus dasyurus and a Black Rat, Rattus rattus (the latter only represented by a single specimen on one occasion). The structure of rodent communities varied altitudinally with the relative abundance of Spiny Mice decreasing and Wagner’s Gerbils increasing with altitude.

Effects of habitat modification on cotton rat population dynamics and rodent community structure

Concerns over climate change and finite fossil fuels have generated interest in biofuels. Switchgrass (Panicum virgatum), a biofuel feedstock, was planted in intensively managed loblolly pine (Pinus taeda) stands to investigate sustainability of this system for producing an alternative energy source. We hypothesized that changes in understory habitat conditions caused by intercropping switchgrass in pine stands would affect rodent population and community dynamics within three years. Therefore, we assessed effects of three treatments (control pine, switchgrass intercropped in pine, and switchgrass monocrop) on rodent population (abundance, survival, and recruitment) and community (diversity, richness, evenness, and community assemblages) measures. We conducted vegetation surveys and live-trapping during 2013–2015 summers in Kemper County, Mississippi, USA. We conducted 6 trapping sessions each summer (n=14,112 trap nights per year) and captured 1,733 cotton rats (Sigmodon hispidus), 102 Oryzomys palustris, 31 Mus musculus, 28 Reithrodontomys fulvescens, 22 Reithrodontomys humulis, 20 Peromyscus leucopus, 9 Microtus pinetorum, 9 Peromyscus gossypinus, and 2 Neotoma floridana. We found greater cotton rat abundance and lower recruitment in monocrop versus control plots. Rodent diversity was lower in monocrop than control plots. Intercropped plots had intermediate levels of cotton rat abundance and recruitment, and rodent diversity. More dispersal may have occurred in monocrop plots because of high population abundance and limited habitat availability. Cotton rat survival and rodent community assemblage were similar among treatments but differed among years. Although rodents responded negatively to monocrop plots, our results suggested intercropped plots would be an appropriate management practice in pine plantations to produce biofuel feedstocks while maintaining rodent diversity.

Erratum to: Environmental Variables Associated with Hantavirus Reservoirs and Other Small Rodent Species in Two National Parks in the Paraná Delta, Argentina: Implications for Disease Prevention.

Hantavirus pulmonary syndrome (HPS) is a severe zoonotic disease caused by hantaviruses hosted in various rodents species. In Argentina, its transmission to humans has been associated to exposure during activities such as farming, recreation, and tourism which are carried out in wild and rural areas. The aim of this study was to analyze the macro- and micro-habitat use and spatio–temporal variation of small sylvan rodents in Pre Delta and Islas de Santa Fe national parks, located in an HPS-endemic area of Argentina. Rodent communities were studied at six sites: two islands, a riparian forest, an inland forest, a marsh, and the margins of a pond. A total of 453 individuals of five species were captured with a trapping effort of 9471 trap-nights. Maximum species richness was found at the marsh and the pond margin sites. Abundance of rodents was influenced by flooding events. Two hantavirus reservoirs, Oligoryzomys flavescens and Akodon azarae, were identified in the area. O. flavescens was captured in every habitat, but it was dominant in Islas de Santa Fe National Park where its abundance was strongly influenced by flooding. A. azarae was captured in every habitat except on the islands. A. azarae behaved as a generalist species at a micro-habitat scale in every habitat of Pre Delta National Park except for the marsh where it selected patches with low vegetation height. Based on these results, several disease prevention measures, including the use of rodent-proof containers for food, and keeping the grass short in the camp site, are proposed in order to reduce the risk to visitors and residents of contracting HPS.

Environmental Variables Associated with Hantavirus Reservoirs and Other Small Rodent Species in Two National Parks in the Paraná Delta, Argentina: Implications for Disease Prevention.

Hantavirus pulmonary syndrome (HPS) is a severe zoonotic disease caused by hantaviruses hosted in various rodents species. In Argentina, its transmission to humans has been associated to exposure during activities such as farming, recreation, and tourism which are carried out in wild and rural areas. The aim of this study was to analyze the macro- and micro-habitat use and spatio-temporal variation of small sylvan rodents in Pre Delta and Islas de Santa Fe national parks, located in an HPS-endemic area of Argentina. Rodent communities were studied at six sites: two islands, a riparian forest, an inland forest, a marsh, and the margins of a pond. A total of 453 individuals of five species were captured with a trapping effort of 9471 trap-nights. Maximum species richness was found at the marsh and the pond margin sites. Abundance of rodents was influenced by flooding events. Two hantavirus reservoirs, Oligoryzomys flavescens and Akodon azarae, were identified in the area. O. flavescens was captured in every habitat, but it was dominant in Islas de Santa Fe National Park where its abundance was strongly influenced by flooding. A. azarae was captured in every habitat except on the islands. A. azarae behaved as a generalist species at a micro-habitat scale in every habitat of Pre Delta National Park except for the marsh where it selected patches with low vegetation height. Based on these results, several disease prevention measures, including the use of rodent-proof containers for food, and keeping the grass short in the camp site, are proposed in order to reduce the risk to visitors and residents of contracting HPS.

The influence of wildlife water developments and vegetation on rodent abundance in the Great Basin Desert

AbstractRodent communities have multiple functions including comprising a majority of the mammalian diversity within an ecosystem, providing a significant portion of the available biomass consumed by predators, and contributing to ecosystem services. Despite the importance of rodent communities, few investigations have explored the effects of increasing anthropogenic modifications to the landscape on rodents. Throughout the western United States, the construction of artificial water developments to benefit game species is commonplace. While benefits for certain species have been documented, several researchers recently hypothesized that these developments may cause unintentional negative effects to desert-adapted species and communities. To test this idea, we sampled rodents near to and distant from wildlife water developments over 4 consecutive summers. We employed an asymmetrical before-after-control-impact (BACI) design with sampling over 4 summers to determine if water developments influenced total rodent abundance. We performed an additional exploratory analysis to determine if factors other than free water influenced rodent abundance. We found no evidence that water developments impacted rodent abundance. Rodent abundance was primarily driven by vegetation type and year of sampling. Our findings suggested that water developments on our study area do not represent a significant disturbance to rodent abundance and that rodent abundance was influenced by the vegetative community and temporal factors linked to precipitation and primary plant production. Our findings represent one of the 1st efforts to determine the effects of an anthropogenic activity on the rodent community utilizing a manipulation design.

Coexistence and habitat partitioning at micro- and macro-scales of rodent species in a North African desert (Bou-Hedma National Park, Tunisia)

Deserts rodents coexistence has been mainly attributed to resource partitioning at different scales, from macro to microhabitat. We explore the structure of a rodent community in a North African desert under the hypothesis of resource partition. We present the first data of habitat selection by several Gerbilline rodent species in North Africa (Tunisia). Animals were trapped during one season in four locations of the Tunisian desert (Bou-Hedma National Park). Macrohabitat selection was assessed by RDA and variance partitioning. The effect of macrohabitat variables on species richness was assessed by Poisson GLZ and multimodel averaging. Microhabitat selection was evaluated by GLMM and multimodel averaging. Our results support the configuration of two desert rodents assemblages in this region: one characterized by species requiring disaggregated soil, probably for burrowing necessities (Gerbillus tarabuli, Meriones crassus, Gerbillus campestris); and the other one characterized by species maximizing shrub cover, presumably related to food availability and predation risk (Meriones shawii and Gerbillus amoenus). Gerbillus gerbillus seems to have a specially distinctive microhabitat selection pattern. Our results at the microhabitat scale highlight the role that floristic composition can play to segregate between rodent species.

Investigating the Influence of Climate Changes on Rodent Communities at a Regional-Scale (MIS 1-3, Southwestern France).

Terrestrial ecosystems have continuously evolved throughout the Late Pleistocene and the Holocene, deeply affected by both progressive environmental and climatic modifications, as well as by abrupt and large climatic changes such as the Heinrich or Dansgaard-Oeschger events. Yet, the impacts of these different events on terrestrial mammalian communities are poorly known, as is the role played by potential refugia on geographical species distributions. This study examines community changes in rodents of southwestern France between 50 and 10 ky BP by integrating 94 dated faunal assemblages coming from 37 archaeological sites. This work reveals that faunal distributions were modified in response to abrupt and brief climatic events, such as Heinrich events, without actually modifying the rodent community on a regional scale. However, the succession of events which operated between the Late Pleistocene and the Holocene gradually led to establishing a new rodent community at the regional scale, with intermediate communities occurring between the Bølling and the Allerød.

Long-term density fluctuations and microhabitat use of sympatricApodemus flavicollisandMyodes glareolusin central Italy

The role and importance of interspecific competition for rodent communities have been much debated issues, with some early authors suggesting that these are important, and several recent articles suggesting the contrary. In this paper, we studied, for 14 years at a mountainous locality in central Italy, the coexistence dynamics of a two-species system (Apodemus flavicollis, Myodes glareolus) within a 1.44 ha trapping grid, by Capture-Mark-Recapture. Overall, we captured over 1000 rodents during the study period, with annual abundance ranging 2-7 individuals × ha−1. However, the density of the two species varied substantially across years and between sectors of the study plot. Thus, the distributions of the two species on the scale of the study grid were not related to one another. Density of a given species did not affect the percentage of lactating females in either A. flavicollis or M. glareolus. Individual traps differed in their rate of capture such that about 40% of traps were associated more with a particular species. Considering the spatial distribution of traps, we determined that three areas were associated with high probability of capture for only one of the two study species, two of these areas being associated to A. flavicollis and one to M. glareolus. Our analyses suggest that interspecific competition may be present at the local micro-scale, as explained by the fact that in the great majority of the cases in which a given trap was highly successful in capturing one species, it was also very unsuccessful in capturing the other species. However, manipulation experiments are needed to confirm that suggestion.

Molecular Survey of Bartonella Species and Yersinia pestis in Rodent Fleas (Siphonaptera) From Chihuahua, Mexico.

Rodent fleas from northwestern Chihuahua, Mexico, were analyzed for the presence of Bartonella and Yersinia pestis. In total, 760 fleas belonging to 10 species were tested with multiplex polymerase chain reaction analysis targeting the gltA (338-bp) and pla genes (478-bp) of Bartonella and Y. pestis, respectively. Although none was positive for Y. pestis, 307 fleas were infected with Bartonella spp., resulting in an overall prevalence of 40.4%. A logistic regression analysis indicated that the presence of Bartonella is more likely to occur in some flea species. From a subset of Bartonella-positive fleas, phylogenetic analyses of gltA gene sequences revealed 13 genetic variants clustering in five phylogroups (I–V), two of which were matched with known pathogenic Bartonella species (Bartonella vinsonii subsp. arupensis and Bartonella washoensis) and two that were not related with any previously described species or subspecies of Bartonella. Variants in phylogroup V, which were mainly obtained from Meringis spp. fleas, were identical to those reported recently in their specific rodent hosts (Dipodomys spp.) in the same region, suggesting that kangaroo rats and their fleas harbor other Bartonella species not reported previously. Considering the Bartonella prevalence and the flea genotypes associated with known pathogenic Bartonella species, we suggest that analysis of rodent and flea communities in the region should continue for their potential implications for human health. Given that nearby locations in the United States have reported Y. pestis in wild animals and their fleas, we suggest conducting larger-scale studies to increase our knowledge of this bacterium.

Are All Hosts Created Equal? Partitioning Host Species Contributions to Parasite Persistence in Multihost Communities.

Many parasites circulate endemically within communities of multiple host species. To understand disease persistence within these communities, it is essential to know the contribution each host species makes to parasite transmission and maintenance. However, quantifying those contributions is challenging. We present a conceptual framework for classifying multihost sharing, based on key thresholds for parasite persistence. We then develop a generalized technique to quantify each species' contribution to parasite persistence, allowing natural systems to be located within the framework. We illustrate this approach using data on gastrointestinal parasites circulating within rodent communities and show that, although many parasites infect several host species, parasite persistence is often driven by just one host species. In some cases, however, parasites require multiple host species for maintenance. Our approach provides a quantitative method for differentiating these cases using minimal reliance on system-specific parameters, enabling informed decisions about parasite management within poorly understood multihost communities.