Reproduction in laboratory colonies of Clethrionomys gapperi and Microtus pennsylvanicus: a comparison between species and among populations

1994 ◽  
Vol 72 (6) ◽  
pp. 995-1001
Author(s):  
Duncan G. L. Innes ◽  
John S. Millar
Keyword(s):  
Litter Size ◽  
Reproductive Effort ◽  
Microtus Pennsylvanicus ◽  
Clethrionomys Gapperi ◽  
General Hypothesis ◽  
Litter Mass ◽  
In The Wild ◽  
Eyes Open ◽  
Weaning Age ◽  
Laboratory Colonies

Reproduction in laboratory colonies of Clethrionomys gapperi and Microtus pennsylvanicus was examined by comparing six populations (three per species) to test the general hypothesis that populations subject to the lowest temperatures and the shortest breeding seasons would be at the "fast" end of the "fast–slow" continuum. All colonies were derived from three sites in western Canada from females that were inseminated in the wild. Postpartum mass, mass of adult females during lactation, litter size, litter and neonate masses at birth, litter mass at weaning, age when the eyes opened, and age at weaning as well as two variables describing the energetics of reproduction were examined between species and among populations within species. Three indices of physiological reproductive effort were also compared. Only neonate mass, age when eyes were open, and one index of reproductive effort differed between species. In C. gapperi, litter mass, litter size, age when the eyes opened, age at weaning, and one index of reproductive effort differed among populations. In M. pennsylvanicus, postpartum, litter (at birth and weaning), and neonate mass, age when eyes open, age at weaning, and maintenance costs during lactation were different among populations. In both species, some differences could be attributed to sampling biases, while others were simply a consequence of differences in maternal mass. In both species, the maximum difference in the age at weaning and the age when the eyes opened was less than 2 days. Differences among populations did not appear to be related to meteorological conditions, and populations in either species could not be ranked on a continuum.

Body weight, litter size, and energetics of reproduction in Clethrionomys gapperi and Microtus pennsylvanicus

1981 ◽  
Vol 59 (5) ◽  
pp. 785-789 ◽  
Author(s):  
Duncan G. L. Innes ◽  
John S. Millar
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Reproductive Effort ◽  
Reproductive Traits ◽  
Microtus Pennsylvanicus ◽  
Clethrionomys Gapperi ◽  
Field Vole ◽  
Litter Weight ◽  
Significant Difference ◽  
Postpartum Weight

A forest vole, Clethrionomys gapperi, and a field vole, Microtus pennsylvanicus, were examined for differences in a number of reproductive traits, including the energy required to raise a litter. Average postpartum weight, litter weight, and neonate weight of C. gapperi were significantly less than those of M. pennsylvanicus. Although C. gapperi had a significantly larger litter size than M. pennsylvanicus, the latter species used more energy to raise a litter than C. gapperi. Only one of three measures of physiological reproductive effort showed a significant difference between species. We conclude that there is no clear pattern between reproductive traits and habitat. Many traits appear to vary with body weight.

Timing is the only thing: reproduction in female yellow ground squirrels (Spermophilus fulvus)

2014 ◽  
Vol 92 (8) ◽  
pp. 737-747 ◽  
Author(s):  
N.A. Vasilieva ◽  
A.V. Tchabovsky
Keyword(s):  
Litter Size ◽  
Body Condition ◽  
Reproductive Effort ◽  
Individual Characteristics ◽  
Ground Squirrels ◽  
Offspring Survival ◽  
Litter Mass ◽  
Individual Offspring ◽  
Female Survival ◽  
Spermophilus Fulvus

Based on 4-year field observations of yellow ground squirrels (Spermophilus fulvus (Lichtenstein, 1823)), we determined whether female reproductive effort, annual reproductive success, and survival were dependent on age, body condition, time of emergence from hibernation, and previous reproduction. The probability of weaning a litter did not vary with female age, body condition, time of emergence, or previous reproduction. Litter size, litter mass, and offspring survival did not vary with age, whereas individual offspring mass was lower in yearlings than in older females. Body condition upon emergence had no effect on litter size, litter mass, offspring mass, and survival. Reproduction did not influence female survival, physical condition upon emergence next spring, or subsequent reproductive efforts. The only factor that affected the extent of reproductive effort and offspring survival was the date of emergence: the later a female emerged, the lower the total and mean offspring mass, and fewer offspring survived. The modulation of reproduction in female S. fulvus by only the timing of vernal emergence and independent of other individual characteristics can be explained by the high costs of missed reproductive opportunity because of short longevity combined with low costs of reproduction when resources are abundant enough to meet both somatic and reproductive needs.

Altitudinal variation in reproductive strategy of the toad-headed lizard, Phrynocephalus vlangalii in North Tibet Plateau (Qinghai)

2007 ◽  
Vol 28 (4) ◽  
pp. 509-515 ◽  
Author(s):  
Yuan-Ting Jin ◽  
Nai-Fa Liu
Keyword(s):  
Litter Size ◽  
Altitudinal Gradient ◽  
Reproductive Effort ◽  
Reproductive Investment ◽  
Reproductive Traits ◽  
Tibet Plateau ◽  
Sand Lizard ◽  
Survival And Growth ◽  
The Common ◽  
Anatomical Constraints

Abstract Phrynocephalus vlangalii, a toad-headed viviparous sand lizard, is endemic in the Northern Tibet (Qinghai) Plateau in China. Lizards were collected from 14 localities along the large altitudinal gradient (2289-4565 m a.s.l) to analyze the variation of reproductive traits among localities. Both litter size and mean offspring (scaled embryo) mass were positively correlated with female snout-vent length (SVL). Females produced fewer and larger offspring with increasing elevation when the effect of body size (SVL) was removed. This strategy may possibly be correlated with early survival and growth of offspring. The decreased litter size cline along altitudinal gradient might be correlated with more anatomical constraints at higher altitudes. The lizard has lower coefficient of variation (CV) of litter size at higher environments. Moreover, females from higher elevations had less reproductive investment (relative litter mass, RLM). Study concluded that P. vlangalii fit into the common pattern of higher elevation animals that have smaller clutches of larger offspring and lower reproductive effort.

scholarly journals Cross-fostering as a conservation tool to augment endangered carnivore populations

2018 ◽  
Vol 99 (5) ◽  
pp. 1033-1041
Author(s):  
Eric M Gese ◽  
William T Waddell ◽  
Patricia A Terletzky ◽  
Chris F Lucash ◽  
Scott R McLellan ◽  
...  
Keyword(s):  
Life Span ◽  
Litter Size ◽  
Average Life ◽  
Canis Rufus ◽  
Average Life Span ◽  
Red Wolf ◽  
In The Wild ◽  
Red Wolves ◽  
Cross Fostering

Abstract Cross-fostering offspring with nonbiological parents could prove useful to augment populations of endangered carnivores. We used cross-fostering to augment captive-born and wild-born litters for the endangered red wolf (Canis rufus). Between 1987 and 2016, 23 cross-fostering events occurred involving captive-born pups fostered into captive litters (n = 8 events) and captive-born pups fostered into wild recipient litters (n = 15 events). Percentage of pups surviving 3 and 12 months was 91.7% for captive-born pups fostered into captive recipient litters. For pups fostered into wild litters, percentage of pups surviving 5 months was > 94% among fostered pups (pups fostered into a wild red wolf litter or replaced a hybrid litter), pups in recipient litters (wild-born litters receiving fostered pups), and pups in control litters (wild-born litters not in a fostering event) when using pups with known fates. Including pups with unknown fates as deaths, percentage of pups surviving 5 months was > 54% among fostered pups, pups in recipient litters, and pups in control litters. Among wild litters, percentage of pups surviving 12 months was > 82% among fostered pups, pups in recipient litters, and pups in control litters when using pups with known fates. Including pups with unknown fates as deaths, percentage of pups surviving 12 months was > 48% among fostered pups, pups in recipient litters, and pups in control litters. Although survival to 12 months was similar among the groups, average life span was different with pups in control litters living 3.3 years, pups in recipient litters living 4.6 years, and fostered pups living 5.6 years. Of fostered pups surviving > 12 months in the wild, 9 animals whelped or sired 26 litters. Cross-fostering was successful at augmenting litter size for red wolves without any deleterious effects on recipient litters, illustrating fostering as a tool for increasing populations of endangered carnivores.

Optimal litter size: Does it cost more to raise a large litter in Caluromys philander?

1992 ◽  
Vol 70 (8) ◽  
pp. 1511-1515 ◽  
Author(s):  
Martine Atramentowicz
Keyword(s):  
Food Intake ◽  
Reproductive Success ◽  
Litter Size ◽  
Body Length ◽  
Weaning Food ◽  
Daily Food Intake ◽  
Litter Mass ◽  
Large Litter ◽  
Daily Food ◽  
Optimal Litter Size

Food intake of lactating Caluromys philander, a didelphid marsupial, was recorded from parturition until weaning of the pouch young. Variation in the average caloric value of daily food intake throughout lactation, in relation to litter size, showed no significant differences, but females increased food intake during late lactation, prior to weaning. Food intake was positively correlated with total litter mass at weaning. Moreover, there were significant differences in body mass and body length of offspring at first pouch exit (3 months) and at weaning (4 months): young born in small litters (1–3) were bigger than those born in large litters (6–7). Reproductive success is discussed on the assumption that pouch-young survival depends on food resources.

A reexamination of litter size in some North American microtines

1978 ◽  
Vol 56 (7) ◽  
pp. 1488-1496 ◽  
Author(s):  
Duncan G. L. Innes
Keyword(s):  
Litter Size ◽  
North American ◽  
Clethrionomys Gapperi ◽  
Multiple Correlation ◽  
Independent Variables ◽  
Species Specific

Data from the literature on litter sizes of several species of Microtus and Clethrionomys were examined in relation to latitude and elevation by single and multiple correlation. Litter size in these genera was significantly correlated with latitude, as it was with latitude and elevation together. In Microtus, litter size within species was not significantly correlated with either of the independent variables. Litter size in Clethrionomys gapperi was significantly correlated with latitude and with latitude and elevation together. Multiple range tests revealed that some species which occur at the same latitudes and elevations have significantly different litter sizes from each other. Litter size may be species specific and not primarily determined by latitude and elevation.

Seasonal dynamics and distribution of American dog tick, Dermacentor variabilis (Say), larvae and nymphs at Birds Hill Park, Manitoba

1985 ◽  
Vol 63 (12) ◽  
pp. 2748-2755 ◽  
Author(s):  
V. I. Burachynsky ◽  
T. D. Galloway
Keyword(s):  
Dermacentor Variabilis ◽  
Microtus Pennsylvanicus ◽  
Tamiasciurus Hudsonicus ◽  
Clethrionomys Gapperi ◽  
Spermophilus Tridecemlineatus ◽  
Mammal Species ◽  
Tamias Striatus ◽  
Sorex Cinereus ◽  
Spermophilus Franklinii ◽  
Dog Tick

During a 2-year study on the relationships between immature Dermacentor variabilis and their small-mammal hosts near Birds Hill, Manitoba, 739 captures of 427 mammals were examined for ticks. Captures represented 11 mammal species: Clethrionomys gapperi, Lepus americanus, Microtus pennsylvanicus, Mus musculus, Peromyscus maniculatus, Sorex cinereus, Spermophilus franklinii, Spermophilus tridecemlineatus, Tamias striatus, Tamiasciurus hudsonicus, and Zapus hudsonius. Clethrionomys gapperi, M. pennsylvanicus, P. maniculatus, S. franklinii, and Z. hudsonius were most frequently encountered and, with the exception of S. franklinii, infested with larvae and nymphs. Clethrionomys gapperi were most frequently infested by D. variabilis and produced 42.6% and 60.5% of larvae collected in 1979 and 1980, respectively, and over 85% of all nymphs. Peak larval infestation occurred between the last week of May and the middle of June; that for nymphs occurred in July in both 1979 and 1980. Dermacentor variabilis appeared to have a 2-year life cycle in Manitoba. Larvae were spatially aggregated during both years and aggregates were located in different areas of the plots each year. Nymphs were less aggregated than larvae. The distribution of nymphs overlapped that of larvae each year and occupied a greater area on the plots.

Experimental addition of cover lowers the perception of danger and increases reproduction in meadow voles (Microtus pennsylvanicus)

2017 ◽  
Vol 95 (7) ◽  
pp. 463-472 ◽  
Author(s):  
M.M. Dehn ◽  
R.C. Ydenberg ◽  
L.M. Dill
Keyword(s):  
Reproductive Effort ◽  
Predation Rate ◽  
Cost Of Reproduction ◽  
Microtus Pennsylvanicus ◽  
Meadow Voles ◽  
Predation Danger ◽  
Population Consequences ◽  
Giving Up Density ◽  
Quality Of Food

Predation danger is pervasive for small mammals and is expected to select strongly for behavioural tactics that reduce the risk. In particular, since it may be considered a cost of reproduction, predation danger is expected to affect the level of reproductive effort. We test this hypothesis in a population of meadow voles (Microtus pennsylvanicus (Ord, 1815)) under seminatural conditions in field enclosures. We manipulated the voles’ perception of predation danger by adjusting the available cover and measured giving up density (GUD) in food patches to verify that the perception of danger differed between high- and low-cover treatments. Treatments did not differ in actual predation rate, in vole density, or in the quantity or quality of food. During the experiments, we measured indices of vole reproductive effort including activity (electronic detectors), foraging intensity (fecal plates), and the number of young produced (livetrapping). Voles in the high-cover (lower danger) treatments were more active, foraged more, and produced 85% more young per female per trap period than voles in the low-cover (higher danger) treatment. We briefly discuss the population consequences of this adaptive behavioural flexibility.

Growth and its relationship to the initial annual cycle of the golden-mantled ground squirrel, Spermophilus lateralis

1981 ◽  
Vol 59 (6) ◽  
pp. 865-871 ◽  
Author(s):  
John A. Phillips
Keyword(s):  
Litter Size ◽  
Annual Cycle ◽  
Ground Squirrel ◽  
Growth And Development ◽  
Reproductive Effort ◽  
Ground Squirrels ◽  
Active Season ◽  
Spermophilus Lateralis ◽  
Significant Difference ◽  
Two Populations

Thirty-eight litters of golden-mantled ground squirrels (Spermophilus lateralis), from two populations that experienced different lengths of active season, were born and raised in the laboratory. Growth and development in young were inversely related to litter size. Offspring from smaller litters were both able to attain their prehibernation peak of body mass sooner and hibernate after fewer days of homeothermy than squirrels from larger litters. Young that remained homeothermic throughout the initial overwintering period were always from large litters and among the slowest growing littermates. Fecundity was lower in females from the temporally compressed environment. There was no significant difference between populations in the nutrition provided by mothers to their litters. The results suggest that reproductive effort is more conservative in populations of ground squirrels that experience short seasons of activity, yet this conservatism allows the offspring of those populations to reach independence and attain the prehibernation state of preparedness at an earlier age than their counterparts from populations of more moderate climates.

REPRODUCTION AND GROWTH IN THE CREEPING VOLE, MICROTUS OREGONI SERPENS MERRIAM

1954 ◽  
Vol 32 (3) ◽  
pp. 198-208 ◽  
Author(s):  
Ian McT. Cowan ◽  
Margaret G. Arsenault
Keyword(s):  
Litter Size ◽  
Growth Rates ◽  
Growth Data ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
In Captivity ◽  
In The Wild ◽  
Annual Turnover ◽  
Growth And Reproduction

The growth and reproduction of the cricetine rodent, Microtus oregoni serpens Merriam, has been studied in the laboratory and in the wild. Growth data arise largely from 28 captive born litters. It has been determined that gestation is [Formula: see text] to 25 days; that mean litter size is 2.95; that a postparturient oestrus is usual but frequently does not occur; that puberty occurs at 22–24 days in females and 34–38 days in males; that there is a sterile period of 5 to 14 days between first oestrus and first conception; longevity in captivity exceeded 320 days but in the wild there was a complete annual turnover. Instantaneous relative growth rates have been determined for four distinguishable phases of growth. A limited experiment using light and heat to stimulate increased reproduction had equivocal results.

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