Journal of Mammalogy

Musser, Guy, G.;, Boeadi

doi: 10.2307/1379834pmid: N/A

Abstract A new genus is proposed for rintjanus, originally described as a species of Rattus (Sody, 1941). The rat is endemic to Rintja and Padar, two small islands between Flores and Komodo in Nusatenggara, Indonesia. Monsoon Forest covers parts of the islands; the external and cranial characteristics of rintjanus point to a ground dweller and reflect adaptations to dry or seasonally dry tropical forest where the structure of tall scrub and short, partly deciduous, trees provide dense cover above and sparse undercover at ground level. The new genus is not closely related to Rattus, and may be part of an old murid fauna known from Flores and some other islands to the east of the Sunda Shelf. This content is only available as a PDF. © 1980 The American Society of Mammalogists

Thaeler, Charles, S.

doi: 10.2307/1379835pmid: N/A

Abstract Published data concerning chromosome numbers of forms within the genus Thomomys are reviewed and additional data are presented. These indicate that the living species of the genus can be arranged in two groups, one with diploid chromosome numbers in the range of 40 to 60 and a second in the range of 74 to 82. Other morphological characters support this dichotomy, suggesting that each group is composed of closely related species. These relationships are best expressed by grouping the nine living and three extinct species into two subgenera: Thomomys and Megascapheus. A third subgenus, Plesiothomomys, includes three additional extinct species. This content is only available as a PDF. © 1980 The American Society of Mammalogists

Baccus,, R.;Joule,, J.;Kimberling, W., J.

doi: 10.2307/1379836pmid: N/A

Abstract During 1976 deermice (Peromyscus maniculatus) were sampled from 12 populations along the front range of the Rocky Mountains in eastern Colorado. Tissue samples for field-captured males, nonpregnant females, pregnant females, and field -conceived, laboratory-reared offspring were analyzed for 19 protein systems (loci) using starch-gel electrophoresis. Nine loci (ADH, ALB, EST-4, GOT-1, IDH, PEPT-1, 6-PGD, SDH, TRF) provided adequate polymorphism for linkage study; five were used for selection analysis. Lod-score analyses for linkage determinations were generated by pairwise loci comparisons over recombination levels of 0 to 50%. Most pairings reflected evidence for nonlinkage. Maximum evidence for linkage, not statistically significant (P > 0.05), was between the ADH and 6-PGD loci at 30% recombination. If a significant trend was found through further testing, this linkage relationship would be one of weak segregational integrity, either syntenic or interchromosomal. Other pairings that showed some evidence of linkage were ADH-GOT-1, ADH-IDH, ALB-PEPT-1, ALB-SDH, and EST-4-SDH. Four of five loci tested showed significant gene frequency changes using the Christiansen and Frydenberg (1973) method of selection analysis. Seventy-one percent of the changes occurred during prezygotic selection analysis. However, significant changes due to selection were shown over different life-history components in different populations, possibly suggesting strong populational subdivision along the altitudinal cline. This content is only available as a PDF. Author notes Present address of Baccus: Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720. Present address of Kimberling: Boystown Institute, School of Medicine, Omaha, NE 68178 © 1980 The American Society of Mammalogists

Hartman, Steve, E.

doi: 10.2307/1379837pmid: N/A

Abstract Geographic variation in 18 nonmetric cranial traits was assessed for 11 populations of Dipodomys ordii from Oklahoma, Texas, and New Mexico. Frequencies of all traits were examined for sex, size, and side dependencies in a geographically restricted sample of 272 crania. Two traits were significantly affected by sex, two by cranial size, and two exhibited different frequencies on the left side of the skull than on the right. Relatively few within-individual and among-population intertrait correlations were found. The distance measure used in testing for interpopulation trait frequency differences was the Mean Measure of Divergence (MMD), as modified by Green and Suchey (1976). Nonmetric multidimensional scalings of distance matrices derived from each of four trait subsets and a principal components analysis based on one subset gave similar results. The 11 samples were displayed in three-dimensional summaries approximately as expected on the basis of their geographic distribution. Because nonmetric traits may be adaptively neutral, frequency differences between populations may result from genetic drift. Nonmetric traits are clearly of value in studies of geographic variation in Dipodomys. I follow Sjøvold (1977) in suggesting that consideration be given to each trait with regard to how strongly it is influenced by dependencies (e.g., sex and size) that may confound interpretation of results. This content is only available as a PDF. Author notes Present address: Department of Anatomical Sciences, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, NY 11794 © 1980 The American Society of Mammalogists

Gingerich, Philip, D.

doi: 10.2307/1379838pmid: N/A

Abstract A new species of Palaeosinopa is described from the late Tiffanian Dell Creek Quarry in the Hoback Basin of western Wyoming. This is the oldest record of the genus Palaeosinopa. Palaeosinopa simpsoni Van Valen from the early Tiffanian is synonymized with Paleotomus senior (Simpson), and this taxon is regarded as a pantolestid as originally described, not a palaeoryctid as more recently proposed. Paleotomus is plausibly the ancestor of the middle and late Tiffanian pantolestid Niphredil, and it may be the ancestor of late Tiffanian, Clarkforkian, and Wasatchian Palaeosinopa as well. This content is only available as a PDF. © 1980 The American Society of Mammalogists

Patterson, Bruce, D.

doi: 10.2307/1379839pmid: N/A

Abstract Patterns of bacular morphology in the Eutamias quadrivittatus species complex were analyzed to determine the identity of the Eutamias population inhabiting the Organ Mountains of southcentral New Mexico. The bacula of 124 animals from all geographically adjacent taxa in this complex (E. q. quadrivittatus, E. einereicollis cinereus, E. c. cinereicollis, E. canipes sacramentoensis, E. c. canipes, and E. bulled durangae) were examined. Bacular data demonstrate the close phyletic relation of the Organ Mountain population with E. q. quadrivittatus, rather than with E. cinereicollis cinereus to which it is currently assigned. This conclusion is supported by karyotypic evidence. However, aspects of morphology and ecology indicate that the Organ Mountain population represents a new subspecies. The divergence of this form from E. q. quadrivittatus probably occurred in Recent time as a consequence of isolation, small population size, and a unique environment. This content is only available as a PDF. © 1980 The American Society of Mammalogists

Nagy, Kenneth, A.;Montgomery, G., Gene

doi: 10.2307/1379840pmid: N/A

Abstract Metabolic rates (CO2 production) and water fluxes were measured using doubly labeled water in free-living three-toed sloths (Bradypus variegatus) on Barro Colorado Island, Panama Canal Zone. Feeding rates were calculated from metabolic rates using natural tracer estimates of energy assimilation efficiency. Field metabolic rates averaged about 147 kj (kg day)−1 and did not differ significantly among nonre-productive females, lactating females, and males. This rate is only about 74% of the predicted mammalian basal metabolic rate, but is about 1.8 times the actual basal rate of these animals. Field water fluxes, ca. 38 ml h2O (kg day)−1, were also comparatively low and can be accounted for by dietary water input and metabolic water production alone. This indicates that sloths probably did not drink, even though rain fell during the study. The two lactating females allocated 5% and 11% of their water and assimilable energy intake, respectively, to producing milk for their offspring. We estimate that a 4-kg sloth consumes 60 g dry mass of food per day, and that the three-toed sloths on Barro Colorado Island eat 138 kg dry mass of food per ha per year. This is about 2% of the yearly leaf production. This content is only available as a PDF. © 1980 The American Society of Mammalogists

Glass, Gregory, E.;Slade, Norman, A.

doi: 10.2307/1379841pmid: N/A

Abstract Terman's (1974) model of interspecific competition based on the frequency of interspecific contact (FIC) predicted that the degree of spatial association between cotton rats and prairie voles could be determined from characteristics of the cotton rat population. To test Terman's model, annual changes in cotton rat population structure were examined for correlations with spatial association between voles and cotton rats. Coefficients of association varied systematically with changes in cotton rat population density, numbers of adults, and numbers of reproductive adults. The results tend to support Terman's general model based on FIC. However, the relationships between cotton rat population structure and spatial association were not linear. This content is only available as a PDF. © 1980 The American Society of Mammalogists

Beacham, Terry, D.;Krebs, Charles, J.

doi: 10.2307/1379842pmid: N/A

Abstract Four populations of Microtus townsendii were trapped concurrently with live-traps and pitfall traps from May 1976 until June 1978. The number of voles enumerated by pitfall traps in both increasing and peak populations was up to two times larger than the number enumerated by live-traps. Pitfall traps generally caught voles under 40 g, live-traps over 40 g. About 45% of 3,677 voles captured first by pitfall traps were never caught by live-traps. Among those voles subsequently entering livetraps, over 50% stayed away for more than 5 weeks, and 10% stayed away for more than 20 weeks. Pitfall traps previously caught more animals that dispersed than did livetraps. An index of juvenile survival based on data derived from live-traps may not be indicative of actual trends. Voles caught only in pitfall traps have faster growth rates than those first caught in pitfall traps and later in live-traps. Live-traps and pitfall traps sample different segments of the population with respect to size, wounding levels, and parasite loads. This content is only available as a PDF. Author notes Present address of Beacham: Department of Fisheries and Oceans Pacific Biological Station, Nanaimo, BC V9R 5K6, Canada © 1980 The American Society of Mammalogists

Andersen, Douglas, C.;MacMahon, James, A.;Wolfe, Michael, L.

doi: 10.2307/1379843pmid: N/A

Abstract All common herbivorous mammals were censused along a successional gradient in northern Utah in order to assess some of the changes in ecosystem attributes predicted to occur by Odum (1969). Biomass (B) and energy flow [Production (P), Respiration (R), and P + R (e)] through each of nine species in each of four serai stages (montane meadow, Populus-dominated forest, Abies-dominated forest, and Picea-dominated forest) were estimated. Tests of eight predicted trends were supportive in five cases (P/R ratio, P/B ratio, B/e ratio, net community production, and species richness), inconsistent in two cases (total organic matter and species evenness/general diversity) and ambiguous in one (size of organism). Community stability, as measured by changes in average community biomass between years of relatively normal and extremely low precipitation, increased with ecosystem maturity. Individual species, however, fluctuated greatly in biomass between the 2 years. Our results are consistent with the hypothesis that mammals are determinants of successional patterns only insofar as they affect plant colonization. However, a continuum probably exists between completely passive species and those that strongly influence successional patterns in plant communities through their effects on plant recruitment and/or mortality. Changes in the plant community in turn affect the composition of the herbivorous mammal community. This content is only available as a PDF. © 1980 The American Society of Mammalogists