Life histories of Clethrionomys and Microtus (Microtinae)

Abstract

Although there have been numerous life‐history reviews of mammals at high taxonomic levels (e.g. among families within orders), there are far fewer studies at lower taxonomic levels (e.g. among species within genera). Data on adult weights, litter size, gestation length, neonate weight, age and weight at weaning, growth rate to weaning, maximum life span, and length of the breeding season were compiled from the literature on five species of Clethrionomys and 33 species of Microtus. Variability in litter size and male body weights was not significantly different when compared between cyclic and non‐cyclic populations. Coefficients of variation were also calculated for the three species with the most data (C. gapperi, C. glareolus and M. pennsylvanicus). These values showed that the amount of intraspecific variation differed among traits as well as among species. Gestation length was the most invariable of all traits and variation in adult weights, neonate weight, gestation length, and litter size had similar values to those reported for Peromyscus maniculatus. Five and eight traits differed among Clethrionomys and Microtus species, respectively. Differences in litter size, adult weights and length of the breeding season were common to both genera. Male weight, gestation length and neonate weight as well as length of the breeding season were different between genera. Very few traits covaried within C. gapperi, C. glareolus or M. pennsylvanicus. Similarly, few traits covaried among all Clethrionomys populations. However, among all Microtus populations and Microtus species, 11 and 12 correlations were significant. Many of the patterns found in Microtus involved positive relationships between female weight and some other trait. These patterns have also been found by broader surveys at higher taxonomic levels. Large species of Microtus had larger offspring, a greater litter size and occurred in short‐season environments relative to small species of this genus.

Life-long shedding of Puumala hantavirus in wild bank voles (Myodes glareolus)

“…However, in these two studies, the timing of seroconversion was based on IgG antibody avidity, which has been shown to be unreliable in low antibody titres (Varner & Dearing, 2011). In the present study, we were able to determine the time of seroconversion with a more reliable accuracy (±13 to ±24 days), followed individual wild hosts much longer than in previous studies and showed hantavirus shedding to last throughout the typical life span (Innes & Millar, 1994;Prévot-Julliard et al, 1999) of the rodent host species without drastic decline.…”

Hantavirus infections in fluctuating host populations: the role of maternal antibodies

“…Infected females commonly transfer maternal antibodies (MatAbs) to their offspring, providing temporary protection against the infection(s) the mother has encountered (Grindstaff et al 2003;Bouliner & Staszewski 2008;Hasselquist & Nilsson 2009). Hantavirus-infected female rodents transfer MatAbs to their offspring in utero and during lactation (Dohmae et al 1993), and the temporary immunity against PUUV lasts for up to 80 days in bank voles (Gavrilovskaya et al 1990;Kallio et al 2006a), a relatively long period when compared with their average lifespan, three to five months (Innes & Millar 1994). The presence of MatAbs among young individuals has been acknowledged in several hantavirus studies (e.g.…”

Impacts of cattle grazing on small-rodent communities: an experimental case study

“…Their diet sometimes includes arthropods and mushrooms (Desrosiers et al 2002). Both species have a promiscuous mating system (Birdsall and Nash 1973;Boonstra et al 1993b) and have short gestation times (Innes and Millar 1994;Mihok and Boonstra 1992;Millar and McAdam 2001). Even if they can breed all year long, they show a seasonal pattern in temperate zones (i.e., highest reproductive rates occur between May and October).…”

“…Reproductive maturity is reached at around 40 days old with four to seven young per litter. The longevity can reach several years, but mean age is thought to be shorter than a year (Neuburger 1999;Innes and Millar 1994;Bunker 2001;Millar and McAdam 2001).…”