Nectar-sugar concentrations and flower visitors in the western Great Basin

v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Nectar - sugar concentrations and major flower visitors were determined for 15 species of plants in the Eagle Lake area of Northeastern California. Sugar concentrations for 12 of these are reported for the first time, with means ranging from a low of 10 percent in Mentzelia laevicaulis to a high of 63 percent in Ranunculus uncinatus. The utilization of the various nectar concentrations varied with the type of flower visitor as well as with the habitat and distributional ranges of the plant and/or animal. Hummingbirds and hawkmoths were not observed visiting the flowers they typically visit in other areas (e.g. Aquilegia and Ipomopsis, or Oenothera ), but here preferred more concentrated nectar ( Cirsium spp., with mean   of 57 percent sugar). Specialization in nectar use is reported at the generic and specific level in Hymenoptera and Lepidoptera; solitary bees, as a whole, used slightly less concentrated nectar ( mean = 38 percent sugar) than butterflies ( mean = 44 percent sugar).        

Colony isolation and isozyme variability of the western seep fritillary, Speyeria nokomis apacheana (Nymphalidae), in the western Great Basin

Thirteen Speyeria nokomis apacheana (Edwards) (Nymphalidae) populations from the western Great Basin were assayed for isozyme variability using starch-gel electrophoresis. Eight of the 25 presumptive isozyme loci analyzed were found to be polymorphic. Collections made in 1991and 1992 allowed for between-year comparisons of heterozygosity and the estimation of effective population size for five of the sampled populations. Speyeria nokomis apacheana populations exhibit lower mean heterozygosity levels than other nymphalids. This may be attributed to genetic drift in apparently isolated populations with small effective sizes.     

Modeling distributions of rare plants in the Great Basin, western North America

In this 2-phase study, we developed field-validated site and landscape-level predictive models for identifying potential rare and endemic plant habitat in the Great Basin of western North America. Four species were chosen to include a range of environmental variability and plant communities. Herbarium records of known occurrences were used to identify initial sample sites. The geographic coordinates, environmental attributes, and vegetation data collected at each site were used to develop 2 predictive models for each species: a field key and a probability-of-occurrence or predictor map. The field key was developed using only field data collected at the sites on environmental attributes and associated species. Predictive maps were developed with a geographic information system (GIS) containing slope, elevation, aspect, soils, and geologic data. Classification-tree (CT) software was used to generate dichotomous field keys and maps of occurrence probabilities. Predictions from both models were then field-validated during the 2nd phase of the study, and final models were developed through an iterative process, in which data collected during the field validation were incorporated into subsequent predictive models. Cross-validated models were >96% accurate and generally predicted presence with >60% accuracy. These models identified potential habitat by combining elevation, slope, aspect, rock type, and geologic process into habitat models for each species. ACRONYMS.—CEC—cation exchange capacity, CT—classification tree, DEM—digital elevation model, GAM—generalized additive model, GIS—geographic information system, GLM—generalized linear model, GPS—geographic positioning system, ROC—receiver operating curves, STATSGO—State Soil Geographic Database, USGS—United States Geological Survey, UTM—Universal Transverse Mercator. Nomenclature and distributions: Welsh et al. 2003, Shultz et al. 2005.     

Monoterpene concentrations in litter and soil of singleleaf pinyon woodlands of the western Great Basin

Mean monoterpene content of singleleaf pinyon ( Pinus monophylla [Torr.] Frem.) litter from stands growing on two soil series was 340 ± 310 ug/g air dry weight (adw). Individual monoterpene hydrocarbons suggested as potential allelopathic compounds occur in extremely small amounts, 0.5-1.10 ug/g adw. Mineral soils contained 50 times less total terpene, 6.6 ug/g ± 4.8 adw, than the litter immediately above. Results suggest that allelopathic effects would more likely occur in litter than mineral soil. These findings are substantiated by previous reports of decreased emergence and growth of herbaceous species in pinyon litter but not mineral soil.     

Drosophila pseudoobscura (Diptera: Drosophilidae) of the Great Basin IV: a release experiment at Bryce Canyon

Some populations of Drosophila pseudoobscura in the Great Basin have very little genetic variation for third chromosome inversion gene arrangements. These populations are essentially monomorphic for the Arrowhead gene arrangement. At Bryce Canyon, Utah, individuals with other gene arrangements (Standard, Pikes Peak, and Treeline) were released and their frequencies monitored. One generation after release, the released arrangements had increased in frequency from 0.7% to almost 10%. After overwintering, the arrangement frequencies were not statistically different from the prerelease samples. The samples did demonstrate a low-level retention of the released Pikes Peak arrangement. The decline in the released arrangements was probably the result of large population size at Bryce Canyon and the bottleneck effects of overwintering. The results do not seem consistent with a model of the released arrangements having a lowered fitness.     

Feeding by the Great Basin spadefoot toad ( Spea intermontana ) (Anura: Pelobatidae)

The present study analyzed the stomach contents of 65 Great Basin spadefoot toads, Spea intermontana (Cope), collected in an area of irrigation runoff in south central Washington State. Toads were collected by pitfall trapping. Traps were maintained for 1 year beginning in April 2002. Toads consumed at least 56 different arthropod taxa belonging to the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, Orthoptera, Trichoptera, Collembola, and Araneae. Ants and darkling beetles were among the most common prey. Feeding appeared to be very generalized with the toads accepting almost anything they could capture and subdue.     

A new variety of Centaurium namophilum (Gentianaceae) from the Great Basin

An expression of Centaurium namophilum (Gentianaceae), long confused with C. exaltatum in the Great Basin of the western United States, is described and designated as var. nevadense. It may be separated from the Death Valley region endemic, var. namophilum, by its broader leaves, its diffuse corymbose cyme, the ultimate peduncles that are longer than the flowers, its medium to deep rose pink corolla, and its stamens that equal or exceed the style and are only slightly exserted from the corolla-tube. The var. nevadense occurs from eastern California to western Utah, and from southeastern Oregon and adjacent Idaho south to the northern Mojave Desert of southeastern California. Centaurium exaltatum may be distinguished from the new variety by its broader, more elliptical leaves, dichotomous peduncles, paler pink or bluish and generally four-merous flowers, shorter and more blunt corolla lobes, and a thicker, more included style and stigma.     

Genetic variation and population structure in the cliff chipmunk, Eutamias dorsalis , in the Great Basin of western Utah

Allelic variation at 21 of 39 electrophoretically resolved enzyme loci was used to examine patterns of geographic differentiation and population structure in six allopatric samples of Eutamias dorsalis . Coefficients of genetic similarity for paired combinations of E. dorsalis samples ranged from 0.955 to 0.975, except for one population that was 0.900. Conservative genic divergence among five populations is proposed to be the result of relatively recent isolation events. High positive F 18 values and chi– square analyses confirm a significant excess of homozygotes at several loci at the five localities for which sample sizes were statistically adequate. This may be partly attributable to inbreeding, a Wahlund effect, linkage disequilibrium, posttranslational modification, or some combination of these; but at present some of these alternatives cannot be excluded in favor of a single explanation. Some samples were collected across altitudinal gradients of over 800 m, suggesting that a Wahlund effect may be the most likely explanation for low levels of heterozygosity in these populations.     

Mimulus evanescens (Scrophulariaceae): a new annual species from the northern Great Basin

Recent taxonomic studies in Mimulus support the recognition of Mimulus evanescens , a new autogamous species morphologically allied with M. breviflorus and M. latidens . Initially known only from herbarium specimens, the most recent from 1958, M. evanescens was relocated in the field in 1990 in northern Lassen Co., CA. A second population was found in southern Lake Co., OR, in 1993. Mimulus evanescens is apparently confined to the Great Basin and its periphery, where it has been recorded from 10 localities across Idaho, Oregon, and California. Based on collection information and visits to the two extant populations, the new species appears to be restricted to vernally moist sites and fluctuating banks of intermittent streams or pools. Long-term utilization of such sites by livestock may have contributed to the present-day rarity of M. evanescens . The species should be added to federal and state lists of candidate endangered species pending the results of future field studies and surveys.     

Managing livestock grazing for mule deer ( Odocoileus hemionus ) on winter range in the Great Basin

History and technical literature describing potential effects of livestock grazing on mule deer ( Odocoileus hemionus ) populations and winter range habitat are reviewed. Recommendations for livestock grazing on winter ranges within the Great Basin are advanced.     

Use of a secondary nest in Great Basin Desert thatch ants ( Formica obscuripes Forel)

Workers of Great Basin Desert thatch ants ( Formica obscuripes Forel) dig simple secondary nests at the base of plants upon which they tend aphids and scales. These secondary nests house only foragers, with the number of foragers occupying each nest positively correlated with the number of worker-tended Homoptera feeding on plant foliage above. Thatch ant secondary nests are cooler than 25 cm below the dome top of the primary nest and maintain a significantly more constant temperature than is observed on the ground surface or in the plant canopy. Thatch ant foragers use secondary nests for at least two purposes: as a cool refuge for Homoptera tenders when midday plant canopy temperatures rise during the summer months, and as the primary place within which Homoptera tenders transfer honeydew to larger "honeydew transporters" for ultimate transport back to the primary nest.     

Genetic variation of woodrats ( Neotoma cinerea ) and deer mice ( Peromyscus maniculatus ) on montane habitat islands in the Great Basin

Seventeen loci were examined for polymorphism in four populations of Neotoma cinerea and Peromyscus maniculatus on isolated mountain ranges in the Great Basin, one population of each in the Sierra Nevada, and one of each in the Rocky Mountains. All Peromyscus populations had higher levels of heterozygosity than syntopic Neotoma populations.     

Biogeographic and taxonomic relationships among the mountain snails (Gastropoda: Oreohelicidae) of the central Great Basin

Described here are 4 species of mountain snails, Oreohelix , isolated on mountains in the central Great Basin of Nevada and Utah since the end of the Pleistocene. Forty-three mountains were searched during an 18-year period, resulting in 24 mountains found with no oreohelicids present. One population, Oreohelix loisae (19 mm to 23 mm in shell diameter), is described here as a new species related to, but geographically isolated from, the species Oreohelix nevadensis (17 mm to 22 mm diameter). Oreohelix loisae is present only in the Goshute Mountains while O. nevadensis is represented in 3 geographically adjacent ranges in the central Great Basin. These 2 species are possibly related to the Oreohelix haydeni group from the northern Wasatch Range. The subspecies Oreohelix strigosa depressa (15 mm to 21 mm diameter) is present on 11 ranges from western Utah west to east central Nevada. This subspecies is closely related to populations found today in the northern Wasatch Mountains of Utah. The smallest species in diameter (8 mm to 14 mm), Oreohelix hemphilli , is centered in the central Great Basin and found on 16 ranges often in sympatry with 1 or 2 of the larger conspecifics. Both qualitative and quantitative information on shell characters and soft anatomy is provided here for these 4 species. Shell characters, soft anatomy, geographical isolation, and statistical analysis suggest that 4 distinct species inhabit the central Great Basin today. Xeric and calciphilic species include O. hemphilli and O. loisae , while O. strigosa and O. nevadensis typically are associated with permanent water and both metamorphic and limestone mountains.     

Allozyme variability, isolation, and dispersal of Eusattus muricatus (Coleoptera: Tenebrionidae) within Silver State Dune Complex, Great Basin, western North America

Genetics of Eusattus muricatus (Coleoptera: Tenebrionidae) populations within Silver State Dune Complex in the northern Great Basin of North America were assayed using allozyme electrophoresis. Hierarchical F -statistics showed no significant population subdivision among 3 valleys comprising Silver State Dune Complex. A regression of estimated pairwise gene flow ( Nm ) against pairwise geographic distance was not significant for populations within these valleys, but it was significant over larger distances. A neighbor-joining phenogram did not represent geographic relationships among populations in the 3 valleys but reflected the past geologic history of these dunes. Pairwise divergence times were low (>7000 yr) for populations within Silver State Dune Complex but were high (>18,000 yr) in outgroups.     

Plant adaptation in the Great Basin and Colorado Plateau

Adaptive features of plants of the Great Basin are reviewed. The combination of cold winters and an arid to semiarid precipitation regime results in the distinguishing features of the vegetation in the Great Basin and Colorado Plateau. The primary effects of these climatic features arise from how they structure the hydrologic regime. Water is the most limiting factor to plant growth, and water is most reliably available in the early spring after winter recharge of soil moisture. This factor determines many characteristics of root morphology, growth phenology of roots and shoots, and photosynthetic physiology. Since winters are typically cold enough to suppress growth, and drought limits growth during the summer, the cool temperatures characteristic of the peak growing season are the second most important climatic factor influencing plant habit and performance. The combination of several distinct stress periods, including low-temperature stress in winter and spring and high-temperature stress combined with drought in summer, appears to have limited plant habit to a greater degree than found in the warm deserts to the south. Nonetheless, cool growing conditions and a more reliable spring growing season result in higher water-use efficiency and productivity in the vegetation of the cold desert than in warm deserts with equivalent total rainfall amounts. Edaphic factors are also important in structuring communities in these regions, and halophytic communities dominate many landscapes. These halophytic communities of the cold desert share more species in common with warm deserts than do the nonsaline communities. The Colorado Plateau differs from the Great Basin in having greater amounts of summer rainfall, in some regions less predictable rainfall, sandier soils, and streams which drain into river systems rather than closed basins and salt playas. One result of these climatic and edaphic differences is a more important summer growing season on the Colorado Plateau and a somewhat greater diversification of plant habit, phenology, and physiology.     

Herbivorous and parasitic insect guilds associated with Great Basin wildrye ( Elymus cinereus ) in southern Idaho

Insects inhabiting Great Basin wildrye ( Elymus cinereus Scribn. & Merr.) were surveyed at two sites on the Snake River Plain in southern Idaho during 1982 and 1983. Forty-six species of phytophagous insects were observed. In addition, eight parasitoid species were reared from insect hosts in the plant culms and identified. Lifestage, abundance, plant part utilized, and study site were recorded for each insect species collected. Insect guilds at the two sites were compared based on species presence utilizing Sorensen's similarity index. Overall, 26 insect species were common to both sites, yielding a moderate similarity index of 0.62. The majority of the species that constitute the wildrye herbivore guilds were oligophagous (restricted to grasses). Many of these insects feed on grain crops as well as other native and introduced grasses. The relatively high diversity of phytophages on wildrye may be due to its tall, bunchgrass growth form, its abundance within its habitat, its broad geographic range, and the large number of related species of grasses in the region.     

Biogeography and physiological adaptations of the brine fly genus Ephydra (Diptera: Ephydridae) in saline waters of the Great Basin

Four species of the genus Ephydra are commonly found in saline waters within the hydrologic Great Basin: E. hians, E. gracilis, E. packardi , and E. auripes . Though none of these brine flies is endemic (distributions also occur outside the Great Basin), they all inhabit distinctive habitat types and form the characteristic benthic insect fauna of inland saline-water habitats. The affinities of each species for different salinity levels and chemical compositions, and ephemeral to perennial habitats, appear to form the basis for Biogeographic distribution patterns. Within any habitat, changing salinity conditions over time may impose physiological or ecological constraints and further alter patterns of population productivity and the relative abundance of co-inhabiting species. Based on the physiology of salt tolerance known for these species, high salinity conditions favor E. hians in alkaline water and E. gracilis in chloride water. At lower salinities, based on limited habitat data, E. auripes and E. packardi are often more common, again showing respective preferences for alkaline and chloride chemical conditions. Specialized adaptations for alkaline carbonate waters are found in the larval Malpighian tubule lime gland of the alkali fly E. hians , while high salt tolerance in E. gracilis appears to be conferred by high hemolymph osmolality. Adaptation to ephemeral and low salinity conditions may be accomplished by swift adult colonizing ability and rapid larval development rates. It is hypothesized that adaptive specialization in both physiology and life history and varied geochemistry of saline water habitats across the Great Basin produce the Biogeographic pattern of distributions for species in this genus. This perspective on the genus Ephydra , and possibly other biota of mineral-rich Great Basin waters, suggests that interconnections among pluvial lakes may be less relevant to aquatic biogeography than chemical profiles developing in remnant lakes and ponds with the progression of arid post-pluvial climatic conditions.     

Succession in pinyon-juniper woodlands following wildfire in the Great Basin

Twenty - one areas in pinyon ( Pinus monophylla ) - juniper ( Juniperus osteosperma ) woodlands burned by wildfire from approximately 1 to 60 years prior to sampling and adjacent unburned mature woodland stands were studied in Nevada and California to determine successional patterns and individual species responses to burning and to changing plant communities through time. One year after burning, all late successional woodland species were present in postburn plant communities except tree species. Increases in both cover and occurrence of annual and perennial forbs resulted in their dominance on early successional sites. Shrubs and annual grasses dominated midsuccessional sites, subsequently giving way to tree, shrub, and perennial grass dominance in late succession. North and east slopes generally supported high cover and occurrence of shrubs, perennial grasses, and perennial forbs, and south and west slopes generally supported high cover and occurrence of annual forbs and annual grasses. The ability to group species according to preferential occurrence on various aspects and successional stages can be used to predict plant community composition in time and space in the pinyon - juniper woodlands.         

Spring waterfowl migration in the Uinta Basin of northeastern Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Spring waterfowl migrations at Ouray National Wildlife Refuge and Pelican Lake, Uintah County, Utah, were monitored during 1975 and 1976. Peak numbers occurred during the first week in April 1975 when 11,440 birds were counted. In 1976 the highest count, 9,650 birds, was made on 15 March. Most numerous earlyseason migrants were Mallards and Pintails. Important midseason migrants included Blue - winged and Cinnamon Teal, Canvasbacks, and Redheads. Late season migrants were Gadwall and Ruddy Ducks. Surveys conducted only at Ouray Refuge or at Pelican Lake would not adequately have reflected species composition of spring migration. Results point up the advisability of sampling large open water areas to obtain a representative view of waterfowl species composition in a given area during spring migration.