Food web structure, energetics, and importance of allochthonous carbon in a desert cavernous limnocrene: Devils Hole, Nevada

We tested the hypothesis that allochthonous carbon is important in the diet of the endemic pupfish Cyprinodon diabolis over a 3-year period in Devils Hole, Nevada. Devils Hole is a cavernous limnocrene located in the Mojave Desert approximately 15 m below the land surface and receives direct solar radiation <7% of the total time during the year. The system is dominated by filamentous cyanobacteria in the summer and supports about 15 invertebrate species and the endemic pupfish C. diabolis . We examined food web structure and measured autochthonous carbon production and entry of allochthonous carbon with funnel traps. Stable isotopes were used to compare contributions of each carbon source. Allochthonous carbon contributed 2971 kj ⋅ yr -1 (60%) of the total available energy to the food web compared to only 2000 kj ⋅ yr -1 autochthonous production. A major stochastic rain event delivered more terrestrial carbon to Devils Hole in l hour than annual allochthonous carbon, estimated from data collected with funnel traps. Mixing models with δ 15 N, δ 13 C, and δ 34 S showed a seasonal shift in diet for C. diabolis from filamentous cyanobacteria in the summer to the collector/gathering insect Stenelmis calida in the winter. Stenelmis tissue had high proportions of allochthonous plant carbon in the winter.     

Effects of osmotic potential, potassium chloride, and sodium chloride on germination of greasewood ( Sarcobatus vermiculatus )

Greasewood ( Sarcobatus vermiculatus [Hook.] Torr.) (Chenopodiaceae) typically grows on salt-affected soils where its germination requirements may reflect characteristics necessary for establishment in saline environments. The objective of this study was to determine the effect of osmotic potential and specific ions on the germination of seeds from three populations of greasewood. Seeds were germinated at 20 C in solutions of polyethylene glycol with water potentials ranging from –0.3 to –2.2 MPa that contained 0 to 68480 µmol·L –1 sodium chloride (NaCl) or 0 to 53640 µmol·L –1 potassium chloride (KCl). Germination of two populations was reduced by increasing salt concentration and decreasing osmotic potential; germination of one population was reduced by declining osmotic potential. No seeds germinated at an osmotic potential lower than –1.6 MPa. For all populations, days to 50% of final germination increased and abnormal germination decreased as osmotic potential declined. Comparison of our results with those from other studies suggests geographic ecotypic development in response to osmotic potential and NaCl and KCl concentrations during germination.     

A survey and assessment of the rare vascular plants of the Idaho National Engineering Laboratory site

A two-year study of the rare vascular plants of the Idaho National Engineering Laboratory generated new data on the abundance, distribution, and habitat features of eight taxa presently under review at either the federal or state level, or recently proposed for such review. Astragalus ceramicus Sheld. var. apus Barneby is common on the INEL and adjacent areas and will be recommended for removal from further consideration at the federal level and placed on Idaho's Federal Watch List. Coryphanta missouriensis (Sweet) Britt. & Rose is common throughout east central Idaho, but will be recommended for retainment on the State Watch List. Gymnosteris nudicaulis (H. & A.) Greene and Oxytheca dendroidea Nutt. are also recommended for retention on the State Watch List. Four taxa not previously known to occur in Idaho or not known from the southeastern part of the state ( Astragalus gilviflorus Sheld., Astragalus kentrophyta Gray var. jessiae (Peck) Barneby, Gilia polycladon Torr., and Lesquerella kingii S. Wats. var. cobrensis Roll. & Shaw) were encountered and evaluated with reference to current or potential threats, and are recommended for placement on Idaho's State Watch List.         

Effects of fragmentation on genetic variation in populations of the terrestrial earthworm Drawida japonica Michaelsen, 1892 (Oligochaeta,Moniligastridae) in Shandong and Liaodong peninsulas,China

Earthworms are excellent indicators of landscape fragmentation due to their widespread distribution and poor dispersal abilities over water. Based on field studies conducted in the Shandong and Liaodong peninsulas and their associated islands during summer 2009, we analysed the genetic variation of Drawida japonica Michaelsen, 1892 (Oligochaeta, Moniligastridae) using DNA sequences of the 16S and 28S ribosomal genes in samples obtained from 13 localities, 12 of which were islands, one artificially connected to the mainland by man (Yangma SC). We identified 55 haplotypes among 79 samples, based on 1094 bp, including 47 unique haplotypes. The phylogenetic tree topologies showed two distinct clades. A multiple-apex Poisson distribution using a mismatch analysis of nucleotides was also detected. Results of a Tajima D neutral test were not significant (p > 0.05). Genetic divergence among populations was much larger than within populations. A positive relationship between genetic diversity and island area was revealed, but no significant correlation between genetic diversity and distance to the nearest larger landmass was found. These results indicate that the intraspecific genetic diversity of D. japonica has been influenced by geographic isolation (i.e. island habitat). Passive transport via anthropogenic activities or nonhuman vertebrates (birds or mammals) may also play a key role in dispersal.     

Hip glands in a natural population of montane voles ( Microtus montanus )

Average linear movement by populations of Dipodomys ordii, Microtus montanus, Perognathus parvus, and Peromyscus maniculatus   was investigated over a 15-month period by live trapping on a low-level, radioactive waste disposal area in Idaho. No significant differences in movement among habitats were observed seasonally, excepting M. montanus in spring. Average linear movements within habitats ranged from 20 to 70 m for all species, but some patterns varied seasonally and among age classes for individual species. Although predation on contaminated small mammals from the disposal area is a vector of radionuclide transport, local movements by these rodents do not appear to be of sufficient magnitude to contribute significantly to redistribution of radioactive particles.     

Movements by small mammals on a radioactive waste disposal area in southeastern Idaho

Average linear movement by populations of Dipodomys ordii, Microtus montanus, Perognathus parvus, and Peromyscus maniculatus   was investigated over a 15-month period by live trapping on a low-level, radioactive waste disposal area in Idaho. No significant differences in movement among habitats were observed seasonally, excepting M. montanus in spring. Average linear movements within habitats ranged from 20 to 70 m for all species, but some patterns varied seasonally and among age classes for individual species. Although predation on contaminated small mammals from the disposal area is a vector of radionuclide transport, local movements by these rodents do not appear to be of sufficient magnitude to contribute significantly to redistribution of radioactive particles.     

Electrophoretic study of cutthroat trout populations in Utah

Thirty - nine Utah streams were sampled for cutthroat trout. Of these, 31 contain cutthroat or cutthroat / rainbow hybrid populations. By using starch gel electrophoresis, these populations were segregated into three groups. One group consisted predominately of fish from the Sevier River (of the Bonneville Basin) and Colorado drainages. A second was primarily populations from the Bear River Drainage (Bonneville Basin) as well as some scattered populations along the Wasatch Front (Bonneville Basin). The third consisted of Wasatch Front populations and populations that have hybridized with rainbow trout. Since different subspecies of cutthroat trout are native to the Colorado and Bonneville drainages, one would expect the populations from within the Bonneville Basin to be more similar to one another and less similar to the Colorado River populations. That this did not occur raises questions concerning the evolutionary relationships of the subspecies and the populations. It is clear that at least a northern (Bear River) and southern (Sevier River) form of the Bonneville cutthroat exists. The Wasatch Front may represent an intermediate zone where these two forms intergrade.         

Unusual geographic pattern of interpopulation variation in a spring snail Bythinella (Gastropoda: Prosobranchia)

Allozyme polymorphism, mean gene diversity, and a variety of pairwise genetic distances, theta and Nm were analysed for 20 populations of the spring snail Bythinella from Central Europe. Pairwise Mahalanobis' distances for morphological characters and geographic distances were also computed. Contrary to prior assumptions, the level of polymorphism was considerable, and correlations were found to be statistically significant between the genetic and geographic distances, as well as between Mahalanobis' and geographic distances. The present high level of isolation of local populations of the previously amphibious and continuously distributed snail is postulated to be due to a shift in climate and in the snail's habitat preference.     

Size, structure, and habitat characteristics of populations of Braya humilis var. humilis (Brassicaceae): an alpine disjunct from Colorado

Size, structure, and habitat characteristics were studied in three populations of Braya humilis var. humilis (C. A. Meyer) Robins, in Gray & Wats. (Brassicaceae), a small, herbaceous perennial of the alpine tundra in central Colorado. There was a significant association between numbers of reproductive, juvenile, and seedling individuals and population location. Plant size within reproductive, juvenile, and seedling size classes varied significantly among three populations. Plots containing Braya had significantly lower total plant cover, a different set of dominant plant species, more rock, bare ground, and less litter than plots without Braya . Braya appears to be restricted to calcareous substrates that experience a moderate level of disturbance, such as solifluction lobes and abandoned roads. Populations are small despite the existence of much potential habitat. Population studies are necessary for active conservation management of Braya .     

First reports of Draba pennellii and Draba pedicellata (Cruciferae) in Utah, and new distribution records for Draba kassii, Draba novolympica, and Hackelia ibapensis (Boraginaceae).

The discovery of Draba pennellii Rollins and D. pedicellata (Rollins & R.A. Price) Windham var. pedicellata, both previously known only from Nevada, is reported here from the Deep Creek Mountains of western Utah. The documentation of significant populations of D. pennellii and D. pedicellata var. pedicellata in Utah is important for accurate botanical inventories and floristic studies in both Utah and Nevada. New distribution records for D. kassii S.L. Welsh, D. novolympica Payson & St. John, and Hackelia ibapensis L.M. Shultz & J.S. Shultz are described, and the significance of these range extensions and new populations is discussed.     

Genetic analysis of the rare species Salix arizonica (Salicacea) and associated willows in Arizona and Utah

Management decisions affecting the rare plant Arizona willow ( Salix arizonica ) will be aided by understanding genetic similarities among populations of this species. Random Amplified Polymorphic DNA (RAPD) analysis was conducted on 20 populations of S. arizonica , 12 populations of 5 congeners, and 2 samples of outgroup, Populus tremuloides . A phenogram based on DNA markers shows clear separation of populations of S. arizonica from those of co-occurring willow species, but similarity is low (～ 37%) between Utah and Arizona populations of S. arizonica . Evaluation of the relationship of habitat characteristics and geographic distance to genetic similarity reveals that environment and genetic similarity are poorly correlated. Considering Arizona versus Utah populations, we found a significant negative relationship between geographic distance and genetic similarity ( r = 0.936), but no significant relationship between interpopulation distance and genetic similarity within Arizona or Utah. The wide geographic disjunction of S. arizonica populations in Utah and Arizona appears to have existed for a long period during which genetic drift, random mutations, and selection for somewhat different habitats have pushed the 2 regional complexes along separate evolutionary trajectories. Preservation of genetic variation within S. arizonica will require protection of multiple populations in Arizona and Utah.     

Mineral lick use by GPS radio-collared mountain goats in southeastern British Columbia

In most populations of mountain goats ( Oreamnos americanus ), mineral lick use is an essential part of the ecology of the species. In many areas, the distribution and use of licks in the landscape is poorly known, rendering planning for resource development difficult. We examined lick use by 28 GPS radio-collared mountain goats in 2 study areas in southeastern British Columbia during 2004–2005. Viewing collar-location movements on digital orthophotos, we assumed goat use of 6 previously known and 10 suspected mineral licks. Field visits verified that 9 of the 10 suspected sites were mineral licks. Thirteen of the 15 licks used by collared goats were within forests with commercial harvesting potential. All but 3 of the licks were ≤600 m from the closest logging block, and 5 licks were <100 m away. Number of annual visits to licks by individual goats ranged from 0 to 9. Goats often moved considerable distances (up to 17.3 km) to visit licks. Most visits by males occurred between early May and late June (median 9 June), and most visits by females occurred between early June and mid-July (median 21 June). Mean time spent at licks on each visit was 1.5 days for females and 1.6 days for males. Most of the licks were characterized by numerous cavities dug under trees (which we term “lick trees”). Using GPS collars, we were able to collect data on lower-elevation mineral licks not previously known to researchers.     

Pocket gophers ( Thomomys talpoides ) in successional stages of spruce-fir forest in Idaho

This study examined (1) the relative abundance of the pocket gopher ( Thomomys talpoides ) in four successive stages (1–10, 11–39, 40–79, and 80+ years following disturbance) of spruce-fir forest; (2) the relationship between number of gopher sign (mounds and earth plugs) with gopher density; and (3) a method of sampling pocket gopher populations using a 500 by 4 m strip transect. The number of gopher mounds was significantly correlated with the number of earth plugs. Data were pooled and a categorical log linear analysis used to test for significant differences in pocket gopher sign between the four successive stages. The 1–10 and the 80+ -year-old sites had significantly more gopher sign than the 11–39 and the 40–79 year-old sites. No significant differences were found between the 11–39 and the 40–79-year-old sites, or between the 1–10 and the 80+ -year-old sites. The difference in population densities may be due to understory vegetation differences between the successional stages. There was a significant correlation between amount of gopher sign and gophers caught in each of the study sites. This indicates that counts of pocket gopher sign may be used to estimate pocket gopher density. The strip transect is recommended as the most appropriate method when sampling heterogeneous habitats or when there is cause to suspect gopher populations may be aggregated within the area rather than spaced randomly or regularly.     

Interpopulational variation of blood proteins in pika ( Ochotona princeps saxatilis )

Studies were undertaken to examine the degree of divergence in four populations of pika in Colorado. Separation of blood proteins was accomplished utilizing acrylamide - gel disc electrophoresis. Separate analyses of variance were carried out for the relative mobilities of two of the transferrins (designated RM β 1 and RM β 2 ), the mean relative distance difference of the two transferrins (DM), and the density of the most prominent albumin ( α 1 ) and transferrin ( β 2 ) bands. Although the four populations were characterized by a general similarity of the gel patterns, both interpopulational and sexual variations were observed. Variations between the sexes had to do with the amounts of protein, not with differences in protein mobility. The only significant populational differences were found in reference to density and DM. The interpopulational differences may serve as an indicator of populational divergence that has not been indicated by standard morphological characters. The significant patterns of variation observed in the blood proteins of the four populations studied may reflect a lack of gene now between isolated populations.     

Natural polyploidization within tetraploid and hexaploid populations of the desert shrub Atriplex confertifolia

Shadscale ( Atriplex confertifolia ) is a wind-pollinated dioecious shrub of western North America with an unusual development of apparently autoploid races, showing all even ploidy levels from 2x to 12x (base x = 9). Of these, tetraploid races are the most frequently encountered, with octoploids the next most common, and hexaploids being much less common. In this study, the occurrence of neopolyploid individuals within tetraploid and hexaploid populations of shadscale was examined at natural sites in order to investigate the pathways by which octoploids may be formed and to find a possible explanation for the predominance of octoploids over hexaploids. The frequencies of apparent neopolyploid individuals among adults and the frequencies of their backcrosses were tabulated, as was the occurrence of neopolyploidy among seeds of female plants from some of the same populations. The neopolyploids encountered in these surveys were almost exclusively those expected from unions involving single unreduced gametes. 6x presumed neopolyploid plants were observed in tetraploid populations at a frequency of 0.20%, and 6x seeds were observed at a frequency of 1.91%. Within examined hexaploid populations, 9x adults were not encountered, but 9x seeds were observed at a rate of 0.52%. Evidence was obtained for the operation of some postulated autoploid pathways for generation of octoploids, but these routes did not operate at rates comparable to those for the production of hexaploids. Although the question needs to be studied by genetic methods, the most probable reason for scarcity of hexaploids in nature appears to be that some tetraploid races are diploidized, which would result in irregularities of meiosis in their neohexaploids and a failure to form new races due to infertility and inviability. El “shadscale” ( Atriplex confertifolia ) es un arbusto dioico del oeste de Norteamérica polinizado por el viento que exhibe el desarrollo inusual de razas aparentemente poliploides, con todos los niveles pares de ploidía desde 2x hasta 12x (x base = 9). De éstos, los más comunes son los tetraploides y luego los octoploides. Los hexaploides son mucho menos comunes. En este estudio, examinamos la presencia de individuos neopoliploides entre poblaciones tetraploides y hexaploides del shadscale en sitios naturales para investigar los medios por los cuales se pueden formar los octoploides y para encontrar una posible explicación para el predominio de los octoploides sobre los hexaploides. Tabulamos la frecuencia de individuos aparentemente neopoliploides entre adultos y su descendencia retrocruzada, así como la presencia de neopoliploides entre semillas de las plantas femeninas de algunas de las mismas poblaciones. Los neopoliploides encontrados en estos muestreos fueron casi exclusivamente los que se esperarían de la unión de un gameto no reducido y un gameto reducido. Observamos plantas 6x presunta mente neopoliploides en poblaciones tetraploides con una frecuencia del 0.20%, o del 1.91% en las semillas. Entre las poblaciones examinadas de hexaploides, no encontramos adultos 9x, aunque los observamos con una frecuencia del 0.52% en las semillas. Obtuvimos evidencia de la operación de algunos procesos autoploides postulados para explicar la generación de octoploides, pero estos procesos no operan a frecuencias comparables a aquellas para la producción de hexaploides. Aunque es preciso investigar el tema mediante métodos genéticos, la causa más probable para la escasez de los hexaploides en entornos naturales parece ser que algunas razas tetraploides son diploidizadas, produciendo irregularidades meióticas en sus neohexaploides, los cuales no logran formar razas nuevas debido a su infertilidad o inviabilidad.     

Biochemical differentiation in the Idaho ground squirrel, Spermophilus brunneus (Rodenta: Scuridae)

Spermophilus brunneus is restricted to a 90 × 125-km area of west central Idaho, with two distinct (northern and southern) groups of populations within this limited range. Morphological differences in pelage length and coloration, external and cranial measurements, and bacula suggest that these groups are either very distinct subspecies or species. We used starch-gel electrophoresis to estimate the amount of genetic differentiation accompanying these morphological differences by assaying genetic variation at 31 loci in the two geographic groups. Fifteen loci were polymorphic (13 in the northern group, 12 in the southern), and mean heterozygosity (H) was high (12.3% northern and 10.8% southern). Nei's genetic distance (0.057) is in the range usually associated with subspecific differences. However, Jaccard's association coefficient (0.893) is about the same as that found between several ground squirrel taxa currently recognized as species. The high levels of heterozygosity suggest that S. brunneus is a neoendemic rather than a paleoendemic species.     

Decreases of juniper woodland in the Utah and Salt Lake valleys since settlement

Although pinyon-juniper woodland is common throughout most of Utah, it is less so in Utah and Salt Lake valleys. Even so, stands do occur in the valleys and are known to have been there since presettlement times. Three such stands occurring along the eastern sections of the valleys have shown major decreases in area since settlement times, and one has all but disappeared. Their disappearance is attributed to early use for fuel, agricultural, and urbanization purposes.       

Aquatic birds of the White River, Uintah County, Utah

Abundance, seasonal use, and species composition of waterfowl and other aquatic birds are described along a 32.8 km stretch of the White River, Uintah County, Utah, at the site of the proposed White River Dam. Fourteen species of waterfowl and eight other species of aquatic birds were recorded. Waterfowl populations along the river were highest in April, but densities were much lower than on lakes and reservoirs at nearby Ouray National Wildlife Refuge.         

Distribution and dynamics of waterbird habitat during spring in southern Oregon–northeastern California

The southern Oregon–northeastern California and extreme northwestern Nevada (hereafter “SONEC”) region provides critical spring migration habitat for waterfowl and other waterbirds in the Pacific Flyway. Information on the dynamics and distribution of waterbird habitats in SONEC during spring is needed to guide conservation efforts in the region. We grouped 1992 National Land Cover Data classes into 5 potential waterbird habitat types and used Landsat 5 Thematic Mapper and Landsat 7 Enhanced Thematic Mapper Plus satellite imagery to map flooding of these habitat types in SONEC during February–May, 2002 and 2003. SONEC included 13,727 km 2 of potential waterbird habitat comprised of grasslands (37.1%), pasture/hay (24.6%), marsh (15.9%), open wetland (11.8%), and croplands (10.6%). On average, 11.9% of this potential habitat was flooded during spring; but the percentage, area, and composition varied within and among years and subregions. Total flooding increased from 693 km 2 in February to 2099 km 2 in April during 2002 and from 1630 km 2 in February to 2125 km 2 in May during 2003. Open wetland comprised 58%–74%, marsh 8%–18%, pasture/hay 4%–11%, grassland 4%–17%, and cropland 3%–8% of the flooded habitat in SONEC. Satellite imagery and land-use data provided useful estimates of waterbird habitat availability in SONEC during spring, but other methods should be tested to more accurately measure flooding of densely vegetated habitats such as marsh. With <12% of the potential habitat flooded on average during spring, conservation programs have ample opportunity to improve the SONEC landscape for migrating waterbirds.     

Survival, reproductive output, and transplant potential of Penstemon tubiflorus (tube penstemon)

Survival, reproductive output, and transplant success were studied for an Iowa population of Penstemon tubiflorus (tube penstemon), a species that is rare to uncommon through much of its range. The population was discovered in 2003 and is one of only 6 populations that have been documented in Iowa. I began monitoring the new population when 2 cohorts were permanently marked, the first in 2005 and the second in 2007. I estimated survival, flowering, and reproductive output. Then, I introduced greenhouse-grown transplants to 2 new sites and the original site. Survival data showed that P. tubiflorus is a short-lived perennial (approximately 50% survival after 3 years) with substantial variation in the percentage of individuals that flower in a given year. Recruitment over the 5 years of monitoring varied from zero to 26 individuals per year. Transplant survival was site-specific. However, high survival and robust reproduction output of transplants at one site indicated that there are additional suitable sites near the parent population and suggested that these sites remain unoccupied due to limited seed dispersal. While it is unlikely that pollinator limitation is the cause of low reproduction, further study is needed on the pollination syndrome of the Iowa populations of this and other Penstemon species. Future studies should investigate the possibility that the species is limited by site-specific factors that inhibit germination and the survival of small seedlings. Estudiamos la supervivencia, el rendimiento reproductor y el éxito de transplante en una población de Penstemon tubiflorus (tube penstemon) en Iowa, una especie rara o poco común en gran parte de su rango. Esta población fue descubierta en 2003 y es una de sólo seis poblaciones documentadas en el estado. El monitoreo de la nueva población comenzó cuando se marcaron permanentemente dos cohortes, una en 2005 y la segunda en 2007. Se estimó la supervivencia en la floración y el rendimiento reproductor. Transplantes crecidos en invernadero se introdujeron en dos nuevos sitios y en el sitio original. Los datos de supervivencia indicaron que esta especie es una planta perenne efímera (con una supervivencia de aproximadamente 50% después de tres años), con variación considerable en el porcentaje de individuos que florecen en un año determinado. El reclutamiento de la población nativa durante los cinco años fue monitoreado y varió de cero a 26 individuos entre años. La supervivencia de los transplantes fue específica de cada sitio. No obstante, una alta supervivencia y vigorosa rendimiento reproductor de los transplantes en un sitio indicaron que existen sitios adecuados adicionales cerca de la población parental, y sugiere que estos sitios permanecen desocupados debido a la limitada dispersión de semillas. Aunque es improbable que la causa de la baja reproducción se deba a una escasez de polinizadores, se requiere más investigación sobre el síndrome de polinización de las poblaciones de Iowa de esta y otras especies de Penstemon. Se debe investigar la posibilidad de que la especie se vea limitada por factores específicos al sitio que inhiben la germinación y la supervivencia de las plántulas. Normal.dotm 0 0 1 231 1322 Iowa State University 11 2 1623 12.0 0 false 18 pt 18 pt 0 0 false false false /* 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-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:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";}