Variable levels of immunity to experimental Eimetia arizonensis infections in natural, seminatural, and laboratory populations of deer mice (Peromyscus maniculatus)

1996 ◽  
Vol 74 (4) ◽  
pp. 750-757 ◽  
Author(s):  
Claire A. Fuller

Acquired immunity to parasites may affect both host and parasite population dynamics. Although immunity has been studied experimentally in laboratory-reared hosts, less attention has focused on free-living animals. I examined acquired immunity of free-living deer mice (Peromyscus maniculatus) to naturally occurring and experimental infections of Eimeria arizonensis (Protozoa: Coccidia). In a mark – recapture study, I found evidence of complete immunity to natural infections in only 1 of 3 years and evidence of partial immunity in all years. I subsequently examined partial immunity to experimental infections by giving laboratory-reared, free-living, and enclosure populations of deer mice two or three consecutive E. arizonensis infections. Greater than 90% (13 of 14) of laboratory-reared animals developed immunity after only one exposure, suggesting that E. arizonensis is immunogenic. However, significantly fewer animals living under natural and seminatural conditions developed immunity after one exposure in two of three experiments. These observational and experimental results suggest that immunocompetence of free-living deer mice to E. arizonensis may be variable and may differ with respect to that of laboratory-reared animals.

2004 ◽  
Vol 118 (3) ◽  
pp. 299 ◽  
Author(s):  
Thomas P. Sullivan ◽  
Druscilla S. Sullivan ◽  
Eugene J. Hogue

There are often several rodent species included in the small mammal communities in orchard agro-ecosystems. This study was designed to test the hypothesis that the population levels of Deer Mice (Peromyscus maniculatus) and Yellow-pine Chipmunks (Tamias amoenus) would be enhanced in old field compared with orchard habitats. Rodent populations were intensively livetrapped in replicate old field and orchard sites over a four-year period at Summerland, British Columbia, Canada. Deer Mouse populations were, on average, significantly higher (2.5 – 3.4 times) in the old field than orchard sites in summer and winter periods. Mean numbers/ha of Deer Mice ranged from 12.1 to 60.4 in old field sites and from 3.3 to 19.9 in orchard sites. Breeding seasons in orchards were significantly longer than those in old field sites, in terms of proportion of reproductive male Deer Mice. Recruitment of new animals and early juvenile survival of Deer Mice were similar in orchard and old field sites. Populations of Yellow-pine Chipmunks ranged in mean abundance/ha from 5.6 – 19.0 in old field sites and from 1.9 – 17.5 on one orchard site, with no difference in mean abundance in 2 of 4 years of the study. Recruitment and mean survival of Yellow-pine Chipmunks also followed this pattern. This study is the first detailed comparison of the population dynamics of these rodent species in old field and orchard habitats. These species should be able to maintain their population levels and help contribute to a diversity of small mammals in this agrarian landscape.


2001 ◽  
Vol 79 (9) ◽  
pp. 1597-1603
Author(s):  
W Christopher Witt ◽  
Nancy Huntly

Effects of habitat isolation can differ among species, thereby influencing populations both directly and indirectly. We used naturally occurring forest patches surrounded by a sage–steppe matrix in southeast Idaho to test the hypothesis that a habitat specialist, the red-backed vole (Clethrionomys gapperi), would have movements restricted and therefore population densities reduced on forest patches isolated by distances equal to or greater than their typical home-range diameter. We hypothesized that the more generalized deer mouse (Peromyscus maniculatus) would not show effects of isolation at this scale. We tested for effects of isolation on these small mammals in 1999 and 2000 in forest patches that varied in distance to a mainland forest. Densities of red-backed voles decreased with isolation and those of deer mice did not. However, strong relationships were also found between red-backed vole densities and habitat characteristics, which themselves varied with isolation. Livestock apparently had disproportionate effects on the more isolated patches, thereby altering ground cover. Isolation by distances up to 450 m appears to reduce (filter) rather than eliminate immigration of red-backed voles; however, effects of livestock on isolated habitat patches may prevent successful dispersers from populating patches.


1989 ◽  
Vol 264 (10) ◽  
pp. 5593-5597
Author(s):  
C Norsten ◽  
T Cronholm ◽  
G Ekström ◽  
J A Handler ◽  
R G Thurman ◽  
...  

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