Sympatric Rodents Research Articles

Research on palatability of bait for targeted control of Brandt's vole (Lasiopodomys brandtii) in typical steppes

Chemical control is still the primary means of controlling wild rodent pests in China's grasslands; however current rodenticides are broad-spectrum and pose a risk to several other grassland ecosystems. Improving the precision of grassland rodent pest control and reducing collateral damage to non-target animals is an urgent problem. One solution to this problem is to ensure that bait choices are preferred by specific rodent. However, most studies on the development of rodenticides have neglected bait choice. We focused on Brandt's voles (Lasiopodomys brandtii), the dominant rodent species in the typical steppes of China, in this study. By measuring the percentage of feeding amount (PFA) different baits in a cafeteria setting, we sought to test the palatability of different candidate baits. We found that one of our blend baits was as popular as the wheat bait among Brandt's voles under laboratory conditions. However, our blended bait was preferred to the wheat bait when rodenticide was added. Non-target animals Columba livia, Gallus domesticus, Ovis aries, and sympatric non-target rodents feed less on blended bait than on wheat. We also used field trials to test whether baits were removed by Brandt's voles or PFA of partially consumed baits. In the wild, the removal time and PFA of Brandt's voles for the rodenticide + blend bait were better than those for the rodenticide + wheat bait. Mixing the wheat baits with bromadiolone rodenticide made poisoned baits less attractive to prey species than unpoisoned baits; however, Brandt’s voles were more likely to take the tainted baits than the unpoisoned baits when bromadiolone was added to the blends. Our results suggested that blend bait with 80 % Allium polyrhizum+ 20 % Stipa krylovii was highly palatable to Brandt's voles, did not become less palatable when poisoned with rodenticide, and was less likely to be eaten by non-target species including Columba livia, Gallus domesticus, Cricetulus barabensis, Phodopus campbelli and Ovis aries. Thus, blend bait has the potential to improve the pest management of Brandt's voles in China.

Bacterial microbiome and their assembly processing in two sympatric desert rodents (Dipus sagitta and Meriones meridianus) from different geographic sources

Abstract The microbiome of mammals has profound effects on host fitness, but the process, which drives the assembly and shift of mammalian microbiome remains poorly understood. To explore the patterns of small mammal microbial communities across host species and geographical sites and measure the relative contributions of different processes in driving assembly patterns, 2 sympatric desert rodent species (Dipus sagitta and Meriones meridianus) were sampled from 2 geographically distant regions, which differed in the environment, followed by 16S rRNA gene sequencing. The microbiomes differed significantly between D. sagitta and M. meridianus, and linear mixed modeling (LMM) analysis revealed that microbial diversity was mostly affected by species rather than the environment. For each rodent species, the microbiome diversity and structure differed across geographical regions, with individuals from lower rainfall environments exhibiting greater diversity. The null modeling results suggested dispersal limitation and ecological drift rather than differential selective pressures acting on the microbiome. In addition, each group had a different core genus, suggesting that the taxonomic composition of the microbiome was shaped most strongly by stochastic processes. Our results suggest that variation in the microbiome between hosts, both within and among geographic rodent populations, is driven by bacterial dispersal and ecological drift rather than by differential selective pressures. These results elucidated the diversity patterns and assembly processes of bacterial microbiomes in small desert mammals. Deciphering the processes shaping the assembly of the microbial community is a premise for better understanding how the environment-host-microbe interactions of mammals are established and maintained, particularly in the context of increased environmental disturbances and global changes.

Comparative Study of Thermoregulatory and Thermogenic Characteristics of Three Sympatric Rodent Species: The Impact of High-temperature Acclimation

Background: Ambient temperature is one of the important factors affecting the survival of small mammals in the wild and different animals have different ways of regulating when face the same environmental temperature and different temperatures will also make the same species adjust the energy budget. Therefore, it is helpful to further understand the survival and adaptation patterns of different animals to study the different adjustment modes of animals in the same region in the face of high temperature environment. Methods: In the present study, three rodents, Apodemus chevrieri, Eothenomys miletus and E. olitor, were exposed to a high temperature (Ta) of 30°C for 28 days. And then body mass, body temperature (Tb), resting metabolic rate (RMR) and thermal conductance (C) were measured at Ta from 5°C to 35°C. Result: The results showed that Tb of all three mammals increased significantly with the increase of Ta. And thermal neutral zones (TNZ) among three animals were all 25°C-30°C. Moreover, RMR increased with the increase of Ta above the upper critical temperature Within the range of 30°C to 35°C. C values in three mammals maintained stable within the Ta of 5°C-25°C, which increased with the increase of Ta above 25°C. All of the results suggested that three sympatric rodent species raised their Tb, narrowed their TNZ and changed C values to adapt to the high temperature. Moreover, change amplitudes of thermoregulation characteristics in E. olitor were small, indicating that E. olitor may have the strong adaptability under high temperature acclimation.

Springing into action: Comparing escape responses between bipedal and quadrupedal rodents.

Predation is a fundamental selective pressure on animal morphology, as morphology is directly linked with physical performance and evasion. Bipedal heteromyid rodents, which are characterized by unique morphological traits such as enlarged hindlimbs, appear to be more successful than sympatric quadrupedal rodents at escaping predators such as snakes and owls, but no studies have directly compared the escape performance of bipedal and quadrupedal rodents. We used simulated predator attacks to compare the evasive jumping ability of bipedal kangaroo rats (Dipodomys) to that of three quadrupedal rodent groups-pocket mice (Chaetodipus), woodrats (Neotoma), and ground squirrels (Otospermophilus). Jumping performance of pocket mice was remarkably similar to that of kangaroo rats, which may be driven by their shared anatomical features (such as enlarged hindlimb muscles) and facilitated by their relatively small body size. Woodrats and ground squirrels, in contrast, almost never jumped as a startle response, and they took longer to perform evasive escape maneuvers than the heteromyid species (kangaroo rats and pocket mice). Among the heteromyids, take-off velocity was the only jump performance metric that differed significantly between species. These results support the idea that bipedal body plans facilitate vertical leaping in larger-bodied rodents as a means of predator escape and that vertical leaping likely translates to better evasion success.

Impact of coarse woody debris on habitat use of two sympatric rodent species in the temperate Białowieża Forest

Abstract Importance of coarse woody debris (CWD) in habitat use of small mammals has not been thoroughly explored, especially for European species. Moreover, despite the growing awareness about the need for protecting CWD resources in forests, their amount is usually quantified with regard to current or desired volume. The area of forest floor covered by CWD is rarely considered, despite its potential importance for habitat use of small mammals. Over a period of three summer seasons (4800 trap-nights), we examined the populations of yellow-necked mouse Apodemus flavicollis and bank vole Clethrionomys glareolus through capture-mark-recapture trapping at three 1-hectare study sites, including both managed forests and a nature reserve in Białowieża Forest, Poland. We applied generalized linear mixed models on a sample of 236 adult individuals of yellow-necked mouse and 173 adult individuals of bank vole to establish that the access to CWD is a significant aspect of their habitat use. Our results suggest that both species prefer a certain minimum amount of CWD. After accounting for different aspects of forest undergrowth, we established that bank vole more frequently used areas with a relatively large amount of CWD (threshold of 0.75 m$^{3}$ CWD per 100 m$^{2}$), together with a propensity to choose areas with debris in the later stages of decay. Yellow-necked mouse was found more frequently in areas with at least 1.5 m$^{2}$ of CWD. We suggest that manipulating CWD distribution, or possibly vegetation characteristics, could be a strategy for managing the abundance and distribution of rodents in forest stands—especially when both CWD volume and coverage are taken into account.

Ecological Niche Characteristics of the Diets of Three Sympatric Rodents in the Meili Snow Mountain, Yunnan.

Understanding the dietary preferences and ecological niche characteristics of mammals not only reveals their adaptive strategies under environmental changes but also reveals the interspecific relationships and coexistence mechanisms among sympatric species. Nevertheless, such data are scarce for rodents inhabiting areas spanning a wide altitude range. This study employed DNA metabarcoding technology to analyze the stomach contents of Apodemus ilex, Apodemus chevrieri, and Niviventer confucianus, aiming to investigate their dietary compositions and diversity in the Meili Snow Mountain in Yunnan Province, China. Levins's and Pianka's indices were used to compare the interspecific niche breadth and niche overlaps. The results revealed the following: (1) Insecta (relative abundance: 59.4-78.4%) and Clitellata (relative abundance: 5.2-25.5%) were the primary animal food sources for the three species, while Magnoliopsida (relative abundance: 90.3-99.9%) constitutes their main plant food source. Considerable interspecific differences were detected in the relative abundance of primary animal and plant foods among the three species; (2) There was partial overlap in the genus-level animal food between A. ilex and N. confucianus (Ojk = 0.4648), and partial overlap in plant food between A. ilex and A. chevrieri (Ojk = 0.3418). However, no overlap exists between A. chevrieri and N. confucianus, either in animal or plant food; (3) There were no significant interspecific differences in the α-diversity of animal and plant foods among the three species. The feeding strategies and ecological niche variations of these rodents support the niche differentiation hypothesis, indicating that they have diversified in their primary food sources. This diversification may be a strategy to reduce competition and achieve long-term coexistence by adjusting the types and proportions of primary foods consumed.

Diet comparison suggests limited competition between invasive black rats (Rattus rattus) and sympatric endangered rodents

Diet comparison suggests limited competition between invasive black rats (Rattus rattus) and sympatric endangered rodents

Seasonal breeding in three sympatric rodent species in semi-arid Tigray, northern Ethiopia

Abstract We investigated the breeding activity of three sympatric rodent species: Stenocephalemys albipes, Mastomys awashensis, and Acomys cahirinus, in the semi-arid region of Tigray in northern Ethiopia, using mark-recapture data, to determine the influence of rainfall on their breeding patterns within exclosure (i.e., protected area from livestock grazing). Breeding activities of S. albipes and M. awashensis commenced during the wet season, continued into the early dry season, and ceased during the subsequent dry season. The proportion of breeding females reached its peak during the wet season, gradually declining until the dry season. In contrast, A. cahirinus exhibited a different breeding strategy, with year-round breeding, including during the dry season, a period characterized by limited resources. A significant difference in the proportion of breeding females among the three species was observed across seasons. Furthermore, all species shared a common trend of heightened breeding activity, particularly at the conclusion of the wet season and the onset of the early dry season. These findings enhance our understanding of the interplay between rainfall and seasonal breeding within exclosures, while other variables remain constant. Moreover, the region’s future plans for managing rodents and the establishment of exclosures must take this information into account.

Predominance of the Blastocystis subtype ST5 among free-living sympatric rodents within pig farms in China suggests a novel transmission route from farms

Blastocystis is a parasitic protist that can infect humans and various domestic and wild animals. However, there is limited research on the prevalence of this parasite among rodents, particularly those living in pig farm settings. Therefore, to investigate the occurrence, molecular characterization, and zoonotic potential of Blastocystis among rodents within pig farm environments, we conducted an investigation of 227 rodents and shrews from 34 pig farms located in Henan, Shaanxi, and Shanxi provinces of China using nested PCR of the SSU rRNA gene of Blastocystis. The potential transmission and public health implications were also assessed from a One Health perspective. Blastocystis was detected in 86 (37.9%) fecal samples. The highest infection rate was observed among Ruttus norvegicus (73.7%, 42/58), followed by Ruttus tanezumi (30.1%, 41/136), and Mus musculus (12.0%, 3/25). However, it was not detected among individuals with Apodemus agrarius (n = 1) and Crocidura shantungensis (n = 7). Five known zoonotic Blastocystis subtypes (ST1–ST5) were identified, with ST4 (51.2%, 44/86) and ST5 (40.7%, 35/86) being the predominant ones, followed by ST1 (3.5%, 3/86), ST3 (3.5%, 3/86), and ST2 (1.2%, 1/86). ST4 was prevalent among R. norvegicus (83.3%, 35/42), while ST5 dominated R. tanezumi (70.7%, 29/41). Furthermore, ST5 exhibited the widest distribution at pig farm level, accounting for 65.0% (13/20) of Blastocystis-positive pig farms. This investigation presents the first documented Blastocystis infection in R. tanezumi and M. musculus, highlighting the predominant presence of the zoonotic ST5 subtype in rodents for the first time. The results demonstrate that sympatric rodents can serve as natural reservoirs for Blastocystis and play a role in its transmission. These findings provide information on the dynamics of rodent transmission and emphasize the potential public health threat posed by zoonotic Blastocystis subtypes spillover from pig farms.

Fatal leptospirosis in endangered Barbary macaques (Macaca sylvanus) kept in captivity: Assessing the role of sympatric rodents

Between December 2020 and January 2021, an outbreak of acute mortality in endangered Barbary macaques (Macaca sylvanus) kept in captivity was detected in a zoo in Spain. The main findings observed in the two fatally affected animals at post-mortem evaluation were jaundice, renal tubular necrosis and interstitial nephritis. Leptospira spp. infection was confirmed by real time PCR (qPCR) in different tissues in both individuals. Analyses of secY gene from a positive individual showed 100% homology with a previously published sequence corresponding to Leptospira interrogans serovar Copenhageni. Free-living sympatric brown rats (Rattus norvegicus) from the affected zoo were also analyzed, and showed a prevalence and seroprevalence of Leptospira spp. of 18.2% (4/22; 95% CI: 2.1–34.3) and 41.9% (26/62; 95% CI: 29.7–54.2), respectively. We detected seropositive sera to five different serovars of Leptospira spp. (Copenhageni, Grippotyphosa, Pomona, Canicola and Hardjo) in the rodent population, with L. Copenhageni being the predominant one. This study describes for first time an outbreak of fatal leptospirosis in captive non-human primates in Europe. Our results show that Barbary macaques, an endangered species, are highly susceptible to Leptospira spp. infection, with sympatric wild rodents being the most likely reservoir animals involved in transmission in this outbreak. Our results suggest that rodent control could be an effective measure for minimizing exposure to Leptospira spp. in zoological collections. Given the potential implications for conservation, animal and public health, non-human primates and rodents should be included in surveillance programs for Leptospira spp. in zoos.

Wild sympatric rodents inhabiting pig farm environments may facilitate the spillover of Enterocytozoon bieneusi from pig farms.

Enterocytozoon bieneusi is a zoonotic pathogen prevalent in mammalian and avian hosts across the globe. Wild small mammals, being abundant worldwide, serve as important sources of zoonotic disease transmission to humans. Here, 227 fecal samples were collected from five rodent and shrew species on 34 pig farms in China to investigate the prevalence and molecular characterization of E. bieneusi. The overall prevalence of E. bieneusi was 17.18% (39/227), with a distribution of 23.53% (32/136) in Rattus tanezumi, 8.62% (5/58) in Rattus norvegicus, and 8.00% (2/25) in Mus musculus. Eight E. bieneusi genotypes were identified, comprising four known genotypes: D (n=8), EbpC (n=8), PigEBITS7 (n=9), and EbpA (n=2), and four novel genotypes: CHPR1 (n=7), CHPR2 (n=1), CHPR3 (n=2), and CHPR4 (n=2). This study is the first to report E. bieneusi in rodents from pig farms in Henan, Shaanxi, and Shanxi Provinces in China. The host range of genotype EbpC was expanded with its first detection in M. musculus and R. tanezumi. All identified E. bieneusi genotypes belong to group 1, raising concerns about these sympatric rodents being reservoirs of zoonotic transmission. Moreover, the widespread distribution of genotype EbpC suggests potential cross-species transmission between sympatric rodents and domestic pigs. Our findings highlight the potential role of sympatric rodents in facilitating the spillover of E. bieneusi from pig farms, which could pose a potential public health threat.

Differential burdens of blacklegged ticks (Ixodes scapularis) on sympatric rodent hosts.

In the United States, there has been a steady increase in diagnosed cases of tick-borne diseases in people, most notably Lyme disease. The pathogen that causes Lyme disease, Borrelia burgdorferi, is transmitted by the blacklegged tick (Ixodes scapularis). Several small mammals are considered key reservoirs of this pathogen and are frequently-used hosts by blacklegged ticks. However, limited studies have evaluated between-species host use by ticks. This study compared I. scapularis burdens and tick-associated pathogen presence in wild-caught Clethrionomys gapperi (southern red-backed voles) and Peromyscus spp. (white-footed mice) in forested areas where the habitat of both species overlapped. Rodent trapping data collected over two summers showed a significant difference in the average tick burden between species. Adult Peromyscus spp. had an overall mean of 4.03 ticks per capture, while adult C. gapperi had a mean of 0.47 ticks per capture. There was a significant association between B. burgdorferi infection and host species with more Peromyscus spp. positive samples than C. gapperi (65.8% and 10.2%, respectively). This work confirms significant differences in tick-host use and pathogen presence between sympatric rodent species. It is critical to understand tick-host interactions and tick distributions to develop effective and efficient tick control methods.

Behavioral adaptation of sympatric rodents to early germination of oak acorns: radicle pruning and embryo excision.

The seed germination schedule is a key factor affecting the food-hoarding behavior of animals and the seedling regeneration of plants. However, little is known about the behavioral adaptation of rodents to the rapid germination of acorns. In this study, we provided Quercus variabilis acorns to several rodent species to investigate how food-hoarding animals respond to seed germination. We found that only Apodemus peninsulae adopted embryo excision behavior to counteract seed germination, which is the first report of embryo excision in nonsquirrel rodents. We speculated that this species may be at an early stage of the evolutionary response to seed perishability in rodents, given the low rate of embryo excision in this species. On the contrary, all rodent species preferred to prune the radicles of germinating acorns before caching, suggesting that radicle pruning is a stable and more general foraging behavior strategy for food-hoarding rodents. Furthermore, scatter-hoarding rodents preferred to scatter-hoard and prune more germinating acorns, whereas they consumed more nongerminating acorns. Acorns with embryos excised rather than radicles pruned were much less likely to germinate than intact acorns, suggesting a behavioral adaptation strategy by rodents to the rapid germination of recalcitrant seeds. This study provides insight into the impact of early seed germination on plant-animal interactions.

Food preference strategy of four sympatric rodents in a temperate forest in northeast China.

Rodents are well known as both seed predators and dispersers of various plant species in forest ecosystems, and they play an important role in the regeneration of vegetation. Thus, the research on seed selection and vegetation regeneration by sympatric rodents is an interesting topic. To understand the characteristics of preferences of rodents for different seeds, a semi-natural enclosure experiment was performed with four rodent species (Apodemuspeninsulae, Apodemusagrarius, Tscherskiatriton, and Clethrionomysrufocanus) and the seeds of seven plant species (Pinuskoraiensis, Corylusmandshurica, Quercusmongolica, Juglansmandshurica, Armeniacasibirica, Prunussalicina, and Cerasustomentosa) to investigate the differentiation in niches and patterns of resource utilization of sympatric rodents. The results showed that all the rodents had consumed many seeds of Pi.koraiensis, Co.mandshurica, and Q.mongolica but differed significantly in how they selected the different seeds. The rate of utilization (Ri) of Pi.koraiensis, Co.mandshurica, and Q.mongolica exhibited the highest values. The Ei values indicated that the rodents tested exhibited differences in their priorities used to select the seeds from different plant species. All four species of rodents exhibited obvious preferences for certain seeds. Korean field mice preferentially consumed the seeds of Q.mongolica, Co.mandshurica, and Pi.koraiensis. Striped field mice favor the seeds of Co.mandshurica, Q.mongolica, P.koraiensis, and Nanking cherry. Greater long-tailed hamsters prefer to consume the seeds of Pi.koraiensis, Co.mandshurica, Q.mongolica, Pr.salicina, and Ce.tomentosa. Clethrionomysrufocanus likes to eat the seeds of Pi.koraiensis, Q.mongolica, Co.mandshurica, and Ce.tomentosa. The results supported our hypothesis that sympatric rodents overlap in food selection. However, each rodent species has a marked preference for food selection, and different rodent species differ in their food preferences. This reflects the role of distinct food niche differentiation in their coexistence.

Sympatric rodents in a desert shrubland differ in arthropod consumption

The foraging ecology of sympatric mammals within xeric habitats is poorly understood. In this study, we surveyed the diets of two sympatric woodrat species, Neotoma bryanti, N. lepida and their hybrids in a desert shrubland during the dry season using stable isotope analyses of hair and arthropod DNA metabarcoding of feces. We found that woodrats regardless of their ancestry fed on similar plants during the same season across multiple years. However, stable isotope analyses and arthropod metabarcoding were consistent with greater arthropod ingestion by N. bryanti compared to N. lepida or hybrids. These results suggest that while the diets of these sympatric woodrats largely overlap during the dry season in terms of the plant components, they differ in terms of arthropod ingestion. This arthropod feeding may serve to reduce interspecific competition or act as dietary supplementation during nutritionally challenging periods. These results demonstrate that integrating DNA metabarcoding approaches with stable isotope tracers enables a more rigorous evaluation of animal foraging behavior.

Cryptic diversity of Crocidura shrews in the savannahs of Eastern and Southern Africa

Crocidura (Eulipotyphla, Soricidae) is the most species-rich genus among mammals, with high cryptic diversity and complicated taxonomy. The hirta-flavescens group of Crocidura represents the most abundant and widespread shrews in savannahs of eastern and southern Africa, making them a suitable phylogeographical model for assessing the role of paleoclimatic changes on current biodiversity in open African habitats. We present the first comprehensive study on the phylogeography, evolutionary history, geographical distribution, systematics, and taxonomy of the group, using the integration of mitochondrial, genome-wide (ddRAD sequencing), morphological and morphometrical data collected from specimens over most of the known geographic distribution. Our genomic data confirmed the monophyly of this group and its sister relationship with the olivieri group of Crocidura. There is a substantial genetic variation within the hirta-flavescens group, with three highly supported clades showing parapatric distribution and which can be distinguished morphologically: C. hirta, distributed in both the Zambezian and Somali-Masai bioregions, C. flavescens, known from South Africa and south-western Zambia, and C. cf. flavescens, which is known to occur only in central and western Tanzania. Morphometric data revealed relatively minor differences between C. hirta and C. cf. flavescens, but they differ in the colouration of the pelage. Diversification of the hirta-flavescens group has most likely happened during phases of grassland expansion and contraction during Plio-Pleistocene climatic cycles. Eastern African Rift system, rivers, and the distinctiveness of Zambezian and Somali-Masai bioregions seem to have also shaped the pattern of their diversity, which is very similar to sympatric rodent species living in open habitats. Finally, we review the group's taxonomy and propose to revalidate C. bloyeti, currently a synonym of C. hirta, including the specimens treated as C. cf. flavescens.

Similar adaptative mechanism but divergent demographic history of four sympatric desert rodents in Eurasian inland

Phenotypes associated with metabolism and water retention are thought to be key to the adaptation of desert species. However, knowledge on the genetic changes and selective regimes on the similar and divergent ways to desert adaptation in sympatric and phylogenetically close desert organisms remains limited. Here, we generate a chromosome level genome assembly for Northern three-toed jerboa (Dipus sagitta) and three other high-quality genome assemblies for Siberian jerboa (Orientallactaga sibirica), Midday jird (Meriones meridianus), and Desert hamster (Phodopus roborovskii). Genomic analyses unveil that desert adaptation of the four species mainly result from similar metabolic pathways, such as arachidonic acid metabolism, thermogenesis, oxidative phosphorylation, insulin related pathway, DNA repair and protein synthesis and degradation. However, the specific evolved genes in the same adaptative molecular pathway often differ in the four species. We also reveal similar niche selection but different demographic histories and sensitivity to climate changes, which may be related to the diversified genomic adaptative features. In addition, our study suggests that nocturnal rodents have evolved some specific adaptative mechanism to desert environments compared to large desert animals. Our genomic resources will provide an important foundation for further research on desert genetic adaptations.

Do animal personalities promote species coexistence? A test with sympatric boreal rodents.

The coexistence of competing species requires density feedbacks that have a larger effect on their own species' population growth than they do on others in the assembly. The feedbacks are often associated with behavioral tradeoffs that enable species to differentially exploit underlying axes of heterogeneity. Conjoining theories of species coexistence with foraging behavior and density-dependent habitat selection reveals that such tradeoffs impinge on invasion probabilities and equilibrium dynamics emerging from species' differences in habitat use. The resulting habitat separation promotes coexistence by reducing the overall interaction among species. Differential habitat selection depends on the behavioral abilities of organisms to identify and exploit the most profitable habitats and resource patches. One might thus expect that each species will evolve behavioral types distinct from those of other potential competitors. Accordingly, we exposed four coexisting species in four genera of boreal rodents to open-field tests. We used principal components (PC) to summarize their behaviors along three independent axes corresponding with clines of exploratory, vigilant, and apprehensive personalities. We confirmed that the axes represented repeatable behaviors (personalities) and assessed differences among species with a general linear model (GLM). The GLM revealed highly distinct differences among species, and between pairs of species, on each PC. Even so, it is difficult to infer the adaptive advantages of personality to the habitat segregation that reduces otherwise high interactions among species. Rather, personalities are best interpreted as co-adaptive behaviors reflecting the complex of morphological, physiological and behavioral attributes that dictate tradeoffs and enable coexistence.

Recovering an endangered vole and its habitat may help control invasive house mice

Greater understanding of intraguild dynamics in rodent communities and of how house mice, Mus musculus, interact with wild sympatric rodents is needed. House mice can be a particularly virulent invasive species, presenting a potential threat to native biodiversity. In the Mojave Desert, western harvest mice, Reithrodontomys megalotis and the endangered Amargosa vole, Microtus californicus scirpensis, inhabit a fragmented desert wetland ecosystem. The Amargosa vole relies heavily on bulrush, Schoenoplectus americanus, for food, as well as thermal and predator refuge. We used two species occupancy models and estimated activity pattern overlap to explore spatial and temporal interactions within this rodent guild. For each species pairing, we compared the relative performance of a series of candidate occupancy models, with the most supported model structures and components distinguished by AICc and AICc weight. We found that voles reduced the detectability of western harvest mice and house mice, but did not spatially exclude them. Our findings also suggested that voles were more detectable in bulrush stands as bulrush cover increased, whereas house mice and western harvest mice were negatively associated with bulrush cover. House mice and western harvest mice had high activity pattern overlap, (Δ̂4 0.89, 95% CI = 0.85-0.96), which was greater with each other than with voles (Δ̂4 0.69, 95% CI = 0.57-0.75 and Δ̂4 0.66, 95% CI = 0.49-0.70, respectively). House mice were also more detectable in the presence of western harvest mice, suggesting niche overlap or an attraction to them. Our observations suggest that, during the summer months, Amargosa voles could be a limiting factor on the behaviour and/or population densities of smaller rodent species in bulrush habitat. Drought exacerbated habitat changes may have contributed to house mouse expansion and vole decline in the region. While a deeper understanding of trophic dynamics is required, continued efforts to preserve the endangered Amargosa vole and it's habitat may also help mitigate any potential harm caused by free-living house mice in these desert wetlands.

The genetic structure and connectivity in two sympatric rodent species with different life histories are similarly affected by land use disturbances

The negative impact of habitat fragmentation due to human activities may be different in different species that co-exist in the same area, with consequences on the development of environmental protection plans. Here we aim at understanding the effects produced by different natural and anthropic landscape features on gene flow patterns in two sympatric species with different specializations, one generalist and one specialist, sampled in the same locations. We collected and genotyped 194 wood mice (generalist species) and 199 bank voles (specialist species) from 15 woodlands in a fragmented landscape characterized by different potential barriers to dispersal. Genetic variation and structure were analyzed in the two species, respectively. Effective migration surfaces, isolation-by-resistance (IBR) analysis, and regression with randomization were used to investigate isolation-by-distance (IBD) and the relative importance of land cover elements on gene flow. We observed similar patterns of heterozygosity and IBD for both species, but the bank vole showed higher genetic differences among geographic areas. The IBR analysis suggests that (i) connectivity is reduced in both species by urban areas but more strongly in the specialist bank vole; (ii) cultivated areas act as dispersal corridors in both species; (iii) woodlands appear to be an important factor in increasing connectivity in the bank vole, and less so in the wood mouse. The difference in dispersal abilities between a generalist and specialist species was reflected in the difference in genetic structure, despite extensive habitat changes due to human activities. The negative effects of fragmentation due to the process of urbanization were, at least partially, mitigated by another human product, i.e., cultivated terrains subdivided by hedgerows, and this was true for both species.