Prairie Voles Microtus Ochrogaster Research Articles

Hymenolepis ackerti n. sp. (Eucestoda: Hymenolepididae) infecting cricetid rodents from the central Great Plains of North America

Hymenolepis ackerti n. sp., parasite of rodents from the tallgrass prairie ecoregion of North America is herein characterized. This tapeworm occurs in 3 species of rodents including the hispid cotton rat Sigmodon hispidus, the eastern woodrat Neotoma floridana, and the prairie vole Microtus ochrogaster. A comparison against the other 10 congeneric species known from North America reveals that this species is different based on the size of the scolex, length of rostellar capsule, testicular arrangement, and the size of cirrus sac, seminal receptacle and eggs. A comparison of mitochondrial DNA reveals that tapeworms present in sympatric mammals share the same mitochondrial haplotype and feature similar morphology, supporting their recognition as a single species. The phylogenetic position of H. ackerti relative to other species is still to be resolved, since there are no homologous sequences available for most species in the genus. Given the pervasiveness of these parasites across rodents in the continent, we recommend diligence among scientists to build public archives of tapeworm specimens collected from mammals across North America, and globally. In the present manuscript, we propose a method to sample DNA while still allowing specimens to be postfixed for staining or fluid-preserved for long term storage.

Physical separation from the mate diminishes male's attentiveness towards other females: a study in monogamous prairie voles Microtus ochrogaster.

We tested whether continuous cohabitation in monogamous voles affects the mated male’s attentiveness to his breeding partner versus another female. Each male was housed in a 3-chamber apparatus with a Focal female (FF) and a Control female (CF) for 13 days then placed in a T-maze to assess his attentiveness to and memory of those females. The Distal male remained physically separated from both females, but received their distal cues. The Separate male cohabited with the FF for 3 days then remained physically separated from both females. The Disrupt male’s continuous cohabitation with the FF was disrupted by having him physically separated from her after 10 days and placed with the CF for the last 3 days. The Continuous male cohabited continuously with the FF for 13 days. With females in the T-maze, the Separate and Disrupt males spent more time near the FF’s box and the Disrupt males spent more time manipulating the FF’s box than the CF’s box. The Separate males groomed themselves more when near the FF’s box than the CF’s box. The Distal and Continuous males’ attentiveness to the two females did not differ. Results suggest that physical distance from the partner may reduce male’s attentiveness toward other potential mates. Prairie voles might be similar to socially monogamous primates in using tactile cues as a signal for maintaining their social bonds.

Do females influence paternal responsiveness in male prairie voles Microtus ochrogaster by increasing the salience of infant odors?

Abstract Male prairie voles become more responsive to infants following cohabitation with a female. Exposure to female sensory cues prior to offspring birth may influence male paternal tendencies by modifying his response to infant odors in particular or to odors in general. To test these hypotheses, males were housed with an unfamiliar female or a same-sex sibling for 13 days then examined for their response towards either live infants or infant-like inanimate objects covered with one of three odors: water, infant, sub-adult. We recorded the number of males that retrieved and manipulated the infants or odor-covered objects and measured the frequency and duration of time males spent attending to them or engaged in other non-social activities. Female-Cohabited males approached the container holding infant-odor covered objects faster than Male-Cohabited males, but showed no differences in time spent manipulating those objects. Males in both groups spent more time manipulating live infants than odor-covered objects. However, Female-Cohabited subjects were more likely to manipulate odor-covered objects as well as live infants than Male-Cohabited subjects. Additionally, the frequency of self-grooming in Female-Cohabited males was higher for water-covered objects compared to Male-Cohabited males. In presence of water and live infants, Female-Cohabited males groomed themselves with greater frequency than in presence of infant odor or sub-adult odor. The data suggest that female cues increase the male’s sensitivity to infant odors and enhance the salience of non-social odors.

Synergistic influences of phase, density, and climatic variation on the dynamics of fluctuating populations

Although ecologists have long recognized that certain mammalian species exhibit high-amplitude, often multiannual, fluctuations in abundance, their causes have remained poorly understood and the subject of intense debate. A key contention has been the relative role of density-dependent and density-independent processes in governing population dynamics. We applied capture-mark-recapture analysis to 25 years of monthly trapping data from a fluctuating prairie vole Microtus ochrogaster population in Illinois, USA, to estimate realized population growth rates and associated vital rates (survival and recruitment) and modeled them as a function of vole density and density-independent climatic variation. We also tested for phase dependence and seasonality in the effects of the above processes. Variation in the realized population growth rate was best explained by phase-specific changes in vole density lagged by one month and mean monthly temperatures with no time lags. The underlying vital rates, survival and recruitment, were influenced by the additive and interactive effects of phase, vole density, and mean monthly temperatures. Our results are consistent with the observation that large-scale population fluctuations are characterized by phase-specific changes in demographic and physiological characteristics. Our findings also support the growing realization that the interaction between climatic variables and density-dependent factors may be a widespread phenomenon, and they suggest that the direction and magnitude of such interactive effects may be phase specific. We conclude that density-dependent and density-independent climatic variables work in tandem during each phase of density fluctuations to drive the dynamics of fluctuating populations.

Alternative male reproductive tactics in a natural population of prairie voles Microtus ochrogaster

Alternative reproductive tactics have been described in male mammals, but little information exists regarding fitness benefits and whether males change tactics. Adult male prairie voles Microtus ochrogaster (Wagner, 1842) display alternative tactics described as resident and wanderer. Enclosure studies provide conflicting data concerning the relative success of each tactic and whether males display one tactic throughout adulthood. To characterize further residents and wanderers in this species, we examined data collected during 5 years of monitoring a natural population in Illinois, USA. We found that during the breeding period, wandering males survived longer, moved longer distances, and were more likely than residents to have scrotal testes. During the nonbreeding period, wandering and resident males differed only in whether or not they established residency. Data on sources and fates of resident and wandering males revealed that a substantial proportion of males switched tactics. Our estimate of the reproductive contribution of wandering males to the population, which is based on the premise that wandering males typically mate with single females, suggests that wanderers contribute 34–38% of young recruited during March through October and 4–12% in November, when single females are less common. Parentage studies in natural populations are necessary to test our estimates.

Nestling Survival and Population Fluctuations of the Prairie Vole Microtus ochrogaster

Nestling survival may be an important factor driving population fluctuations of arvicoline rodents, yet few data exist owing to the difficulties of monitoring survival at the nest. We examined survival of nestling prairie voles Microtus ochrogaster in alfalfa and bluegrass habitats over a 25-y period using the proportion of young estimated to have been born to pregnant females and to have survived to first capture at ≤13 g. Nestling survival did not differ between habitats, but was greater during spring-early autumn than during late autumn–winter and greater during late autumn than winter. Survival of nestlings was also greater during the increase phase than during the decline or trough phases irrespective of season. During most increase phases greater nestling survival may have resulted from hibernation of snakes. Predation from snakes did not appear to be involved in decreased survival during the decline phase, at least for declines occurring during late autumn-winter. We suggest extreme weather and maternal death from predation as potential causes of decreased survival of nestlings in winter declines.

Self‐Grooming as a Tactic Used by Prairie Voles Microtus ochrogaster to Enhance Sexual Communication

Observations of numerous mammals suggest males self‐groom more than females in response to the odours of opposite‐sex conspecifics. Two experiments tested the hypothesis that self‐grooming may be a tactic used by males to attract mates in prairie voles Microtus ochrogaster. In the first experiment, we measured the amounts of time voles self‐groomed during exposure either to male‐scented cotton bedding, female‐scented cotton bedding, or clean cotton bedding. Results from this experiment support the hypothesis and also show that female prairie voles self‐groom in response to odours of males. In addition, male prairie voles groom more in response to male odours than to female odours, suggesting that self‐grooming also serves a role in male–male competition. In the second experiment, male and female voles spent more time investigating scent marks of opposite‐sex conspecifics that recently self‐groomed at a higher rate than those of opposite‐sex conspecifics that self‐groomed at a lower rate. Female, but not male prairie voles, spent more time investigating scent marks of opposite‐sex conspecifics that self‐groomed at a high rate than those of same‐sex conspecifics that self‐groomed at a high rate. For prairie voles, self‐grooming may increase the detection of their scent marks by conspecifics. By self‐grooming, prairie voles may be attempting to attract opposite‐sex conspecifics, and males may also be attempting to deter encounters with male conspecifics.

Experimental Manipulation of Herbivores in Native Tallgrass Prairie: Responses of Aboveground Arthropods

-A factorial field experiment was conducted in native tallgrass prairie of eastern Kansas in which pesticides were applied to reduce numbers of below and/or aboveground arthropods on small plots sited within enclosures containing varying densities of the prairie vole Microtus ochrogaster. The numbers of aboveground sucking phytophagous insects were particularly sensitive to the application of below and aboveground pesticides. Auchenorrhyncha (leafhoppers and planthoppers) increased in number on plots treated belowground with isofenphos and ethoprop, suggesting that these insects may interact competitively with belowground arthropods. Sternorrhyncha (primarily aphids) and chewing phytophagous insects (primarily grasshoppers and beetles) did not respond to the soil pesticide treatment. Application of carbaryl to foliage resulted in a decrease in Auchenorrhyncha and an increase in Sternorryncha but no consistent change in numbers of other aboveground arthropods, which apparently migrated readily among the small (9 m2) experimental plots. Varying mammal density did not result in any significant variation in density of aboveground arthropods, and no significant interactions with mammal density were detected in aboveground arthropod responses to either below or aboveground chemical treatment.

Home Range Overlap and Nest Cohabitation of Male and Female Prairie Voles

The degree of association between male and female prairie voles Microtus ochrogaster was assessed using radiotelemetry. Nine sets of males and females caught together in live traps were fitted with transmitters and monitored for 3-4 days; an additional three sets of voles were radiotracked for 10 days. Eleven of the 12 male-female pairs remained together during the radiotracking period. The areas used by the male and female of each of these pairs overlapped greatly. Furthermore, each pair cohabited in a nesting burrow. On an average of 34.6% of the occasions when simultaneous readings were taken for a male and female, they were together in a nest. These results contrast markedly with field studies of M. pennsylvanicus and M. montanus which have revealed no nest cohabitation by adult males and females. The results of this study support laboratory evidence and live-trapping data suggesting pair-bonding in M.

Late Holocene paleoecology of the Southern Plains

Analyses of pollen and land snails from rocksheter sites in the Osage Hills of northeastern Oklahoma indicate that the period 2000-1000 yr B.P. was moister than today. During that time, colonies of the prairie vole Microtus ochrogaster were present in the Texas Panhandle. About 1000 yr B.P. the climate changed to dry conditions that have persisted to the present. Disjunct colonies of small mammals in Texas became extinct at the beginning of the dry episode, thereby establishing the composition of the modern fauna. The climatic model for the origin of the Panhandle Aspect (A.D. 1200–1500) is questioned on the grounds that the Southern Plains experienced a long period of dry climate commencing A.D. 950.

Eimeria ochrogasteri n. sp. from the Prairie Vole Microtus ochrogaster*

SYNOPSIS. Eimeria ochrogasteri n. sp. (Coccidia, Eimeriidae) from a prairie vole Microtus ochrogaster (Rodentia, Cricetidae) is described. This is the first recorded coccidium in prairie voles. Sporulated oocysts spherical to ellipsoidal, mean 24.0 by 20.5 μ. Oocyst wall double, outer layer thick, yellow‐brown, deeply pitted, inner layer clear. Oocyst residuum varies from many small globules to a coalesced group of large and/or small globules. Polar granule present. Micropyle absent. Sporocysts ovoid with “capped” Stieda body, mean 12.3 by 8.2 μ. Sporocyst residuum present. Sporozoites average 14.9 by 2.9 μ with spherical anterior and oblong posterior refractile globules. This species was found in 1 of 71 voles from Weld county, Colorado.