Peromyscus Research Articles

Large nest building and high marble-burying: Two compulsive-like phenotypes expressed by deer mice (Peromyscus maniculatus bairdii) and their unique response to serotoninergic and dopamine modulating intervention

This study aimed to further dissect the deer mouse (Peromyscus maniculatus bairdii) model of compulsive-like behavior with respect to two persistent-like behavioral phenotypes viz. large nest building (LNB) and high marble-burying (HMB), which may be relevant to understanding the neurobiology of different symptom dimensions in obsessive-compulsive and related disorders. Since LNB is sensitive to chronic, high dose escitalopram intervention but HMB is not, we assessed whether the two behaviors could be further distinguished based on their response to 4 weeks of uninterrupted serotoninergic intervention (i.e. escitalopram; ESC; 50 mg/kg/day), dopaminergic antagonism, i.e. flupentixol; FLU; 0.9 mg/kg/day), dopaminergic potentiation (i.e. rasagiline; RAS; 5 mg/kg/day), and their respective combinations with escitalopram (ESC/FLU and ESC/RAS). Here we show LNB to be equally responsive to chronic ESC and ESC/FLU. HMB was insensitive to either of these interventions but was responsive to ESC/RAS. Additionally, we report that scoring preoccupied interaction with marbles over several trials is an appropriate measure of compulsive-like behavioral persistence in addition to the standard marble burying test. Taken together, these data provide further evidence that LNB and HMB in deer mice have distinctive neurobiological underpinnings. Thus, the naturally occurring compulsive-like behaviors expressed by deer mice may be useful in providing a platform to test unique treatment targets for different symptom dimensions of OCD and related disorders.

Prevalence and Genotypes of Cryptosporidium in Wildlife Populations Co-Located in a Protected Watershed in the Pacific Northwest, 2013 to 2016.

Between October 2013 and May 2016, 506 scat samples were collected from 22 species of wildlife located in a protected watershed of a major municipal water supply in the Pacific Northwest, USA. Overall prevalence of Cryptosporidium in the wildlife scat was 13.8% (70/506), with 15 species of wildlife found positive for Cryptosporidium. Prevalence of Cryptosporidium varied among species of wildlife, with higher prevalences observed in cougars (50.0%), mountain beavers (40.0%), and bobcats (33.3%), but none of these species are riparian-dependent. Genotyping of Cryptosporidium by sequencing PCR amplicons from the 18S rRNA gene were successful for seven species of wildlife, including bobcat, unknown predator, black-tailed deer, deer mouse, snowshoe hare, mountain beaver, and western spotted skunk. BLAST and phylogenetic analyses indicated that multiple species and genotypes of Cryptosporidium were present, with some isolates possibly co-circulating within and between wildlife populations in this protected watershed. Evidence of oocyst exchange between infected prey and their predators was also found. During the study period, several zoonotic Cryptosporidium species and genotypes that are uncommon in humans were detected in bobcat (99.58% identical to Cryptosporidium felis), unknown predator (100% identical to Cryptosporidium canis), snowshoe hare (100% identical to Cryptosporidium sp. skunk genotype), and mountain beaver (100% identical to Cryptosporidium ubiquitum). Novel sequences were also found in mountain beaver. To our knowledge, this is the first published report of a unique genotype or species of Cryptosporidium in mountain beaver (Aplodontia rufa).

The biodiversity effect in regulating the prevalence of Sin Nombre virus (SNV)

Sin Nombre virus (SNV), a virus that can cause fatal disease among humans, is primarily hosted by the deer mouse, Peromyscus maniculatus . To better understand the biodiversity effect in curbing the prevalence of the SNV infection in the deer mouse population, we analyze the Peixoto & Abramson (2006) “one host, one non-host alien” deterministic model. In this study, we focus on the relationship of carrying capacity and interspecific competition strength of both host and non-host species in relation to the prevalence of the infection. Bifurcation analysis is carried out to examine the dynamics of this eco-epidemiological system. Our results show that the non-host species have a certain degree of influence in suppressing the SNV prevalence, given that the environmental conditions are similar and the interspecific competition strengths are relatively weak between the host and non-host species.

Parasite species co-occurrence patterns on Peromyscus: Joint species distribution modelling.

Hosts are often infested by multiple parasite species, but it is often unclear whether patterns of parasite co-occurrence are driven by parasite habitat requirements or parasite species interactions. Using data on infestation patterns of ectoparasitic arthropods (fleas, trombiculid mites, cuterebrid botflies) from deer mice (Peromyscus maniculatus), we analyzed species associations using joint species distribution modelling. We also experimentally removed a flea (Orchopeas leucopus) from a subset of deer mice to examine the effect on other common ectoparasite species. We found that the mite (Neotrombicula microti) and botfly (Cuterebra sp.) had a negative relationship that is likely a true biotic species interaction. The flea had a negative association with the mite and a positive association with the botfly species, both of which appeared to be influenced by host traits or parasite life-history traits. Furthermore, experimental removal of the flea did not have a significant effect on ectoparasite prevalence of another species. Overall, these findings suggest that complex parasite species associations can be present among multiple parasite taxa, and that aggregation is not always the rule for ectoparasite communities of small mammals.

Naturalistic operant responses in deer mice (Peromyscus maniculatus bairdii) and its response to outcome manipulation and serotonergic intervention.

Investigating the motivational triggers underlying naturalistic compulsive-like behavior is generally regarded as challenging. To this extent, the current study aimed to establish a proof-of-concept for future investigation by probing unconditioned and naturalistic operant responses aimed at obtaining nesting material by normal (NNB) and large (LNB) nest building deer mice (Peromyscus maniculatus bairdii). LNB mice and NNB controls were individually placed in cages equipped with a lever-operated nesting material (cotton rope) dispenser and allowed to become accustomed to the response (lever press)-outcome (obtaining cotton rope) contingency over seven nights. Subsequently, the contingency was manipulated by withdrawing the nesting material (experiment 1) or punishing the lever-press response with a mild electrical foot shock (experiment 2). Mice were then treated for 28 days with escitalopram (50 mg/kg/d) and retested. Our results indicate that (1) LNB mice generally made more operant responses compared to NNB controls, (2) withdrawal of nesting material and institution of punishment bolstered responding in LNB but not NNB mice and (3) escitalopram treatment tended to reduce increased responding in LNB mice following experimental manipulation, while normalizing the total number of lever-press counts in the LNB cohort. Therefore, LNB seems to diverge from NNB, not only as a spontaneous phenotype, but also in terms of the motivation to obtain nesting material, despite demotivating feedback. That such differences were abrogated by chronic escitalopram intervention, indicates that the uniquely motivated operant interactions displayed by LNB mice, may be founded upon serotonergic mechanisms, a finding in line with the neurobiological theory of obsessive-compulsive disorder.

Body size trends in response to climate and urbanization in the widespread North American deer mouse, Peromyscus maniculatus

Body size decline is hypothesized to be a key response to climate warming, including warming driven by urban heat islands. However, urbanization may also generate selective gradients for body size increases in smaller endotherms via habitat fragmentation. Here we utilize a densely sampled, multi-source dataset to examine how climate and urbanization affect body size of Peromyscus maniculatus (PEMA), an abundant rodent found across North America. We predicted PEMA would conform to Bergmann’s Rule, e.g. larger individuals in colder climates, spatially and temporally. Hypotheses regarding body size in relation to urbanization are less clear; however, with increased food resources due to greater anthropogenic activity, we expected an increase in PEMA size. Spatial mixed-models showed that PEMA conform to Bergmann’s Rule and that PEMA were shorter in more urbanized areas. With the inclusion of decade in mixed-models, we found PEMA mass, but not length, is decreasing over time irrespective of climate or population density. We also unexpectedly found that, over time, smaller-bodied populations of PEMA are getting larger, while larger-bodied populations are getting smaller. Our work highlights the importance of using dense spatiotemporal datasets, and modeling frameworks that account for bias, to better disentangle broad-scale climatic and urbanization effects on body size.

DNA Barcoding and Demographic History of Peromyscus yucatanicus (Rodentia: Cricetidae) Endemic to the Yucatan Peninsula, Mexico

The Yucatan Peninsula (YP) is a biotic province located in southeastern Mexico, delimited mainly by climatic variables. One endemic species of the YP is the Yucatan deer mouse Peromyscus yucatanicus. It is considered a member of the P. mexicanus species group, but some morphological characters and habitat preferences separate it from them. Herein, the DNA barcoding identification of P. yucatanicus, intraspecific relationships, and the level of genetic differentiation among its geographical distribution were examined. Sequences of the mitochondrial cytochrome c oxidase subunit 1 gene were used for the phylogenetic, demographic history, and genetic structure analysis. In addition, an ecological niche model was built and transferred to 6000 years ago in order to explore the current and past environmental suitability of the species. Results showed that P. yucatanicus was monophyletic and its phylogenetic relationships unresolved. Intraspecific analyses showed signatures of a scenario of demographic stability followed by population growth, and three genetic haplogroups were identified. Paleontological, paleoclimate, and the results presented here are useful to hypothesize that P. yucatanicus likely diverged in the Pleistocene and invaded the south of YP after the Last Glacial Period with the arrival of the current vegetation in the late Pleistocene—early-middle Holocene, and its demographic population was stable during the remaining Holocene epoch with slight growth at the late-middle Holocene resulting in the major precipitation changes that provided more plant coverage.

Coordinated changes across the O 2 transport pathway underlie adaptive increases in thermogenic capacity in high-altitude deer mice: High-altitude adaptation in deer mice

Coordinated changes across the O 2 transport pathway underlie adaptive increases in thermogenic capacity in high-altitude deer mice: High-altitude adaptation in deer mice

Populations of Small Mammals, Tallgrass Prairie and Prescribed Fire: A Fire-Reversal Experiment

We sampled small mammals in burned and unburned tallgrass prairie by using three sites in each of two contiguous ungrazed experimental fire-reversal treatments during 1999-2010. One of the experimental treatments (001A to R20A) had been burned in spring for >20 years and then was switched to an unburned research treatment after the spring fire in 2000. In contrast, the other treatment (020A to R01A) had been left unburned for 20 of 29 years before it was switched to an annually burned treatment beginning with the prescribed fire in spring 2001. Overall, we recorded 11 species of rodents and two of shrews for a total of 2,444 individuals. The white-footed mouse (Peromyscus leucopus) was the most abundant species followed by the hispid cotton rat (Sigmodon hispidus) and deer mouse (P. maniculatus). Of the seven common species (>25 individuals), six were strongly associated with one of the treatments, and several species showed positive associations with some part of the landscape within each treatment. Furthermore, white-footed mice, deer mice, prairie voles (Microtus ochrogaster), western harvest mice (Reithrodontomys megalotis) and Elliot's short-tailed shrews (Blarina hylophaga) showed significant temporal patterns of abundance in either R01A or R20A in one or both seasons (autumn or spring). Our study also supports a very important conservation message. That is, the white-footed mouse (a woodland species) and the hispid cotton rat (a colonizing species) were more numerically dominant than the most common rodent, the deer mouse, (a native prairie species) throughout the 10-year study. These observations demonstrate that areas not burned frequently allow encroachment by shrubs and then trees, which subsequently allow the white-footed mouse and hispid cotton rat to expand into these areas. Conversely, the stoppage of frequent fires ultimately degrades the mosaic of prairie habitats for native prairie small mammals [such as the deer mouse, prairie vole and western and plains harvest mice (R. montanus)] and these species move out as shrubs and trees become common. Visual observations indicate that the latter (degradation of native tallgrass prairie) occurs much more rapidly (potentially within a decade) than the restoration of native tallgrass prairie by the elimination of shrubs and trees by annual burning (potentially 50 or more years).

Coordinated changes across the O2 transport pathway underlie adaptive increases in thermogenic capacity in high-altitude deer mice.

Animals native to the hypoxic and cold environment at high altitude provide an excellent opportunity to elucidate the integrative mechanisms underlying the adaptive evolution and plasticity of complex traits. The capacity for aerobic thermogenesis can be a critical determinant of survival for small mammals at high altitude, but the physiological mechanisms underlying the evolution of this performance trait remain unresolved. We examined this issue by comparing high-altitude deer mice (Peromyscus maniculatus) with low-altitude deer mice and white-footed mice (P. leucopus). Mice were bred in captivity and adults were acclimated to each of four treatments: warm (25°C) normoxia, warm hypoxia (12 kPa O2), cold (5°C) normoxia or cold hypoxia. Acclimation to hypoxia and/or cold increased thermogenic capacity in deer mice, but hypoxia acclimation led to much greater increases in thermogenic capacity in highlanders than in lowlanders. The high thermogenic capacity of highlanders was associated with increases in pulmonary O2 extraction, arterial O2 saturation, cardiac output and arterial-venous O2 difference. Mechanisms underlying the evolution of enhanced thermogenic capacity in highlanders were partially distinct from those underlying the ancestral acclimation responses of lowlanders. Environmental adaptation has thus enhanced phenotypic plasticity and expanded the physiological toolkit for coping with the challenges at high altitude.

A linked-read approach to museomics: Higher quality de novo genome assemblies from degraded tissues.

High‐throughput sequencing technologies are a proposed solution for accessing the molecular data in historical specimens. However, degraded DNA combined with the computational demands of short‐read assemblies has posed significant laboratory and bioinformatics challenges for de novo genome assembly. Linked‐read or “synthetic long‐read” sequencing technologies, such as 10× Genomics, may provide a cost‐effective alternative solution to assemble higher quality de novo genomes from degraded tissue samples. Here, we compare assembly quality (e.g., genome contiguity and completeness, presence of orthogroups) between four new deer mouse (Peromyscus spp.) genomes assembled using linked‐read technology and four published genomes assembled from a single shotgun library. At a similar price‐point, these approaches produce vastly different assemblies, with linked‐read assemblies having overall higher contiguity and completeness, measured by larger N50 values and greater number of genes assembled, respectively. As a proof‐of‐concept, we used annotated genes from the four Peromyscus linked‐read assemblies and eight additional rodent taxa to generate a phylogeny, which reconstructed the expected relationships among species with 100% support. Although not without caveats, our results suggest that linked‐read sequencing approaches are a viable option to build de novo genomes from degraded tissues, which may prove particularly valuable for taxa that are extinct, rare or difficult to collect.

Ancient DNA From Museum Specimens and Next Generation Sequencing Help Resolve the Controversial Evolutionary History of the Critically Endangered Puebla Deer Mouse

Key insights into the evolutionary history of recently extinct or critically endangered species can be obtained through analysis of genomic data collected using high-throughput sequencing and ancient DNA from museum specimens, particularly where specimens are rare. For instance, the evolutionary history of the critically endangered Puebla deer mouse, Peromyscus mekisturus, remains unclear due to discordance between morphological and molecular phylogenetic analyses. However, previous molecular analyses were based on PCR and Sanger sequencing of only a few mitochondrial genes. Here, we used ancient DNA from historical museum specimens followed by target enrichment and high-throughput sequencing of several thousand nuclear ultraconserved elements and whole mitochondrial genomes to test the validity of the previous phylogenetic placement of P. mekisturus. Based on UCEs and mitogenomes, our results revealed that P. mekisturus forms a well-supported distinct lineage outside the clade containing all other members of the Peromyscus melanophrys group. Additionally, the mitogenome phylogeny further supports the placement of P. mekisturus as the sister species of the genus Reithrodontomys. This conflicts with the previous mtDNA phylogenetic reconstruction, in which P. mekisturus was nested within the species P. melanophrys. Our study demonstrates that high-throughput sequencing of ancient DNA, appropriately controlling for contamination and degradation, can provide a robust resolution of the evolutionary history and taxonomic status of species for which few or no modern genetic samples exist. In light of our results and pending further analysis with denser taxon sampling and the addition of morphological data, a re-evaluation of the taxonomy and conservation management plans of P. mekisturus is needed to ensure that the evolutionary distinctiveness of this species is recognized in future conservation efforts.

Chronic wasting disease (CWD) prion strains evolve via adaptive diversification of conformers in hosts expressing prion protein polymorphisms

Chronic wasting disease (CWD) is caused by an unknown spectrum of prions and has become enzootic in populations of cervid species that express cellular prion protein (PrPC) molecules varying in amino acid composition. These PrPC polymorphisms can affect prion transmission, disease progression, neuropathology, and emergence of new prion strains, but the mechanistic steps in prion evolution are not understood. Here, using conformation-dependent immunoassay, conformation stability assay, and protein-misfolding cyclic amplification, we monitored the conformational and phenotypic characteristics of CWD prions passaged through deer and transgenic mice expressing different cervid PrPC polymorphisms. We observed that transmission through hosts with distinct PrPC sequences diversifies the PrPCWD conformations and causes a shift toward oligomers with defined structural organization, replication rate, and host range. When passaged in host environments that restrict prion replication, distinct co-existing PrPCWD conformers underwent competitive selection, stabilizing a new prion strain. Nonadaptive conformers exhibited unstable replication and accumulated only to low levels. These results suggest a continuously evolving diversity of CWD conformers and imply a critical interplay between CWD prion plasticity and PrPC polymorphisms during prion strain evolution.

Ontogenesis of evolved changes in respiratory physiology in deer mice native to high altitude.

High-altitude environments are cold and hypoxic, and many high-altitude natives have evolved changes in respiratory physiology that improve O2 uptake in hypoxia as adults. Altricial mammals undergo a dramatic metabolic transition from ectothermy to endothermy in early post-natal life, which may influence the ontogenetic development of respiratory traits at high altitude. We examined the developmental changes in respiratory and haematological traits in deer mice (Peromyscus maniculatus) native to high altitude, comparing the respiratory responses to progressive hypoxia between highland and lowland deer mice. Among adults, highlanders exhibited higher total ventilation and a more effective breathing pattern (relatively deeper tidal volumes), for mice that were caught and tested at their native altitudes and those lab-raised in normoxia. Lab-raised progeny of each population were also tested at post-natal day (P)7, 14, 21 and 30. Highlanders developed an enhanced hypoxic ventilatory response by P21, concurrent with the full maturation of the carotid bodies, and their more effective breathing pattern arose by P14; these ages correspond to critical benchmarks in the full development of homeothermy in highlanders. However, highlanders exhibited developmental delays in ventilatory sensitivity to hypoxia, hyperplasia of type I cells in the carotid body and increases in blood haemoglobin content compared with lowland mice. Nevertheless, highlanders maintained consistently higher arterial O2 saturation in hypoxia across development, in association with increases in blood-O2 affinity that were apparent from birth. We conclude that evolved changes in respiratory physiology in high-altitude deer mice become expressed in association with the post-natal development of endothermy.

Long-Term Rodent Surveillance after Outbreak of Hantavirus Infection, Yosemite National Park, California, USA, 2012.

In 2012, a total of 9 cases of hantavirus infection occurred in overnight visitors to Yosemite Valley, Yosemite National Park, California, USA. In the 6 years after the initial outbreak investigation, the California Department of Public Health conducted 11 rodent trapping events in developed areas of Yosemite Valley and 6 in Tuolumne Meadows to monitor the relative abundance of deer mice (Peromyscus maniculatus) and seroprevalence of Sin Nombre orthohantavirus, the causative agent of hantavirus pulmonary syndrome. Deer mouse trap success in Yosemite Valley remained lower than that observed during the 2012 outbreak investigation. Seroprevalence of Sin Nombre orthohantavirus in deer mice during 2013–2018 was also lower than during the outbreak, but the difference was not statistically significant (p = 0.02). The decreased relative abundance of Peromyscus spp. mice in developed areas of Yosemite Valley after the outbreak is probably associated with increased rodent exclusion efforts and decreased peridomestic habitat.

Flea sharing among sympatric rodent hosts: implications for potential plague effects on a threatened sciurid

AbstractFor vector‐borne diseases, the abundance and competency of different vector species and their host preferences will impact the transfer of pathogens among hosts. Sylvatic plague is a lethal disease caused by the primarily flea‐borne bacterium Yersinia pestis. Sylvatic plague was introduced into the western United States in the early 1900s and impacts many species of rodents. Plague may be suppressing populations of the threatened northern Idaho ground squirrel (Urocitellus brunneus) if a competent flea community is allowing plague to be maintained within the few extant sites that support this rare ground squirrel. We collected fleas from four species of sympatric rodents in central Idaho: northern Idaho ground squirrels, Columbian ground squirrels (Urocitellus columbianus), yellow‐pine chipmunks (Tamias amoenus), and deer mice (Peromyscus maniculatus). We evaluated which flea species were present and whether fleas were shared among the rodent community. We documented seven species of fleas among 3356 fleas collected from the four host species of rodents, and all seven species of fleas are known vectors of plague. Three of the seven flea species were detected on all four rodent species, demonstrating potential for spillover of plague (bridge vectors) in the rodent community. We used generalized linear mixed models to evaluate which abiotic and biotic factors influence flea abundance (total number of fleas, regardless of flea species, on each individual host of the four rodent host species). Factors that impacted flea abundance varied among the four host species, but flea abundance: (1) changed over summer depending on host species, (2) was greater on males, and (3) was impacted by summer and winter precipitation depending on host species. Our results suggest this diverse flea community has the capacity to transfer Y. pestis among populations of the four rodents if Y. pestis is present. Furthermore, the disease may be more likely to persist in some locations than others, those that have higher flea abundances, more sympatric hosts, or optimal conditions for fleas, and such high‐risk sites can be identified based on their abiotic and biotic factors.

Effects of trap confinement on personality measurements in two terrestrial rodents.

In recent years, consistent individual differences in behavior, or personalities, have been a topic of increasing interest as researchers strive to understand and predict the responses of individuals and populations to anthropogenic changes. Behavioral studies in wild populations often require that animals are live trapped before behavioral observation can occur, and this is especially true in studies investigating animal personalities. However, it is unknown whether the amount of time confined to a live trap may regulate the behavior of trapped individuals. Specifically, if the duration of trap confinement directly influences behavior, then by obtaining wild animals through live trapping we may be confounding the very measurements of greatest interest. To investigate whether the duration of trap confinement influences the behavior of trapped individuals, we performed a study on two small mammal species, focusing specifically on personality traits. We positioned high-definition trail cameras facing Longworth small mammal traps in the field to observe capture events and record the time of capture. We then measured personality in captured deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi) using three standardized tests, and through linear and generalized linear models we found that the time an animal had spent confined to a trap before testing did not affect 86% of behaviors exhibited. Our results showed two weak behavioral effects of confinement duration on boldness and docility resulting from an interaction between the duration of confinement and whether or not an individual was naïve to trapping. Our results suggest that behavioral measurements of wild, trapped small mammals are not determined by the time spent confined to a trap. However, researchers should use caution and consider whether an animal is naïve to trapping during analysis since habituation to the live trap may play a role in the effects of confinement duration on behavior.

Early Small Mammal Responses to Bison Reintroduction and Prescribed Fire in Restored Tallgrass Prairies

The restoration of tallgrass prairies is often centered on reestablishing plants, with only minor efforts directed to the fauna that inhabit these areas. Small mammals play important ecological roles in many ecosystems, so understanding how management techniques such as the reintroduction of bison (Bison bison) and prescribed fire affect them can assist in a more comprehensive evaluation of restoration efforts in sites being actively restored. Our objective was to assess impacts of reintroduced bison and prescribed fire in restored prairies on small mammals in the first two years of bison presence. Small mammal abundance decreased with restoration age and time since fire. Small mammal diversity increased with restoration age and was slightly lower in sites where bison were present. Differences in diversity were driven primarily by prairie voles (Microtus ochrogaster), and abundance was driven by deer mice (Peromyscus maniculatus). The mechanism for these impacts is likely habitat availability: fires remove litter and residual dead vegetation, which are important habitat for voles. The removal of litter and residual dead vegetation with fire usually results in a higher amount of bare ground being exposed relative to pre-fire conditions. Although bison impacts may continue to change over time as grazing effects accrue, we demonstrate relatively weak effects of this megaherbivore on small mammal communities. Our results underscore that utilizing bison reintroductions and prescribed fire in concert and employing them to maximize habitat heterogeneity is likely to best maintain small mammal diversity across restored prairies.

KARAKTERISTIK MORFOLOGI TIKUS HUTAN EKOR PUTIH (Maxomys hellwandii) DI TANGKOKO BATUANGUS BITUNG

MORPHPLOGICAL CHARACTERISTICS OF WHITE TAILED MICE (Maxomys hellwandii) IN NATURE RESERVE FOREST OF TANGKOKO BATUANGUS BITUNG. This study aims to determine the types of white tailed mice that exist around the forest in Tangkoko, Batuputih village. This research was conducted using the observation method. The research results, it is known that there are two types of white tailed mice. A rat with a total length from head to tail for males with an average of 51.1 cm and females with an average of 45.6 cm, and an average body weight for males 272.1 g and for females 266.5 g. The tail is partially black and most is white, with an average length of 27.7 cm for males and 24.6 cm for females. Rat B in this study obtained mice that were only male and female and with a female body length of 49 cm. This rat weighs 305 g with live habitat at the root of the tree and likes to eat fruit. Base on observation result can be concluded that type A mice are included in the Maxomys helwandii type, while for type B rats are not yet known but are commonly referred to by local residents as deer mice because they have a deer head shape. Keywords: White tail forest rat, Morphological, Batuangus Nature Reserve.

Life-long exposure to hypoxia affects metabolism and respiratory physiology across life stages in high-altitude deer mice (Peromyscus maniculatus).

Hypoxia exposure can have distinct physiological effects between early developmental and adult life stages, but it is unclear how the effects of hypoxia may progress during continuous exposure throughout life. We examined this issue in deer mice (Peromyscus maniculatus) from a population native to high altitude. Mice were bred in captivity in one of three treatment groups: normoxia (controls), life-long hypoxia (∼12 kPa O2 from conception to adulthood) and parental hypoxia (normoxia from conception to adulthood, but parents previously exposed to hypoxia). Metabolic, thermoregulatory and ventilatory responses to progressive stepwise hypoxia and haematology were then measured at post-natal day (P) 14 and 30 and/or in adulthood. Life-long hypoxia had consistent effects across ages on metabolism, attenuating the declines in O2 consumption rate (V̇O2 ) and body temperature during progressive hypoxia compared with control mice. However, life-long hypoxia had age-specific effects on breathing, blunting the hypoxia-induced increases in air convection requirement (quotient of total ventilation and V̇O2 ) at P14 and P30 only, but then shifting breathing pattern towards deeper and/or less frequent breaths at P30 and adulthood. Hypoxia exposure also increased blood-O2 affinity at P14 and P30, in association with an increase in arterial O2 saturation in hypoxia at P30. In contrast, parental hypoxia had no effects on metabolism or breathing, but it increased blood-O2 affinity and decreased red cell haemoglobin content at P14 (but not P30). Therefore, hypoxia exposure has some consistent effects across early life and adulthood, and some other effects that are unique to specific life stages.