Modeling ecological minimum requirements for distribution of greater sage‐grouse leks: implications for population connectivity across their western range,U.S.A

Greater sage‐grouse Centrocercus urophasianus (Bonaparte) currently occupy approximately half of their historical distribution across western North America. Sage‐grouse are a candidate for endangered species listing due to habitat and population fragmentation coupled with inadequate regulation to control development in critical areas. Conservation planning would benefit from accurate maps delineating required habitats and movement corridors. However, developing a species distribution model that incorporates the diversity of habitats used by sage‐grouse across their widespread distribution has statistical and logistical challenges. We first identified the ecological minimums limiting sage‐grouse, mapped similarity to the multivariate set of minimums, and delineated connectivity across a 920,000 km² region. We partitioned a Mahalanobis D² model of habitat use into k separate additive components each representing independent combinations of species–habitat relationships to identify the ecological minimums required by sage‐grouse. We constructed the model from abiotic, land cover, and anthropogenic variables measured at leks (breeding) and surrounding areas within 5 km. We evaluated model partitions using a random subset of leks and historic locations and selected D² (k = 10) for mapping a habitat similarity index (HSI). Finally, we delineated connectivity by converting the mapped HSI to a resistance surface. Sage‐grouse required sagebrush‐dominated landscapes containing minimal levels of human land use. Sage‐grouse used relatively arid regions characterized by shallow slopes, even terrain, and low amounts of forest, grassland, and agriculture in the surrounding landscape. Most populations were interconnected although several outlying populations were isolated because of distance or lack of habitat corridors for exchange. Land management agencies currently are revising land‐use plans and designating critical habitat to conserve sage‐grouse and avoid endangered species listing. Our results identifying attributes important for delineating habitats or modeling connectivity will facilitate conservation and management of landscapes important for supporting current and future sage‐grouse populations.     

Multivariate analysis applied to tomato hybrid production

Summary Twenty characters were measured on 60 tomato varieties cultivated in the open-air and in polyethylene plastic-house. Data were analyzed by means of principal components, factorial discriminant methods, Mahalanobis D² distances and principal coordinate techniques. Factorial discriminant and Mahalanobis D² distances methods, both of which require collecting data plant by plant, lead to similar conclusions as the principal components method that only requires taking data by plots. Characters that make up the principal components in both environments studied are the same, although the relative importance of each one of them varies within the principal components. By combining information supplied by multivariate analysis with the inheritance mode of characters, crossings among cultivars can be experimented with that will produce heterotic hybrids showing characters within previously established limits.     

A Spatial Modeling Approach to Identify Potential Butternut Restoration Sites in Mammoth Cave National Park

Incorporation of disease resistance is nearly complete for several important North American hardwood species threatened by exotic fungal diseases. The next important step toward species restoration would be to develop reliable tools to delineate ideal restoration sites on a landscape scale. We integrated spatial modeling and remote sensing techniques to delineate potential restoration sites for Butternut (Juglans cinerea L.) trees, a hardwood species being decimated by an exotic fungus, in Mammoth Cave National Park (MCNP), Kentucky. We first developed a multivariate habitat model to determine optimum Butternut habitats within MCNP. Habitat characteristics of 54 known Butternut locations were used in combination with eight topographic and land use data layers to calculate an index of habitat suitability based on Mahalanobis distance (D²). We used a bootstrapping technique to test the reliability of model predictions. Based on a threshold value for the D² statistic, 75.9% of the Butternut locations were correctly classified, indicating that the habitat model performed well. Because Butternut seedlings require extensive amounts of sunlight to become established, we used canopy cover data to refine our delineation of favorable areas for Butternut restoration. Areas with the most favorable conditions to establish Butternut seedlings were limited to 291.6 ha. Our study provides a useful reference on the amount and location of favorable Butternut habitat in MCNP and can be used to identify priority areas for future Butternut restoration. Given the availability of relevant habitat layers and accurate location records, our approach can be applied to other tree species and areas.     

Identifying Sites for Elk Restoration in Arkansas

Abstract: We used spatial data to identify potential areas for elk (Cervus elaphus) restoration in Arkansas. To assess habitat, we used locations of 239 elk groups collected from helicopter surveys in the Buffalo National River area of northwestern Arkansas, USA, from 1992 to 2002. We calculated the Mahalanobis distance (D²) statistic based on the relationship between those elk-group locations and a suite of 9 landscape variables to evaluate winter habitat in Arkansas. We tested model performance in the Buffalo National River area by comparing the D² values of pixels representing areas with and without elk pellets along 19 fixed-width transects surveyed in March 2002. Pixels with elk scat had lower D² values than pixels in which we found no pellets (logistic regression: Wald χ² = 24.37, P < 0.001), indicating that habitat characteristics were similar to those selected by the aerially surveyed elk. Our D² model indicated that the best elk habitat primarily occurred in northern and western Arkansas and was associated with areas of high landscape heterogeneity, heavy forest cover, gently sloping ridge tops and valleys, low human population density, and low road densities. To assess the potential for elk-human conflicts in Arkansas, we used the analytical hierarchy process to rank the importance of 8 criteria based on expert opinion from biologists involved in elk management. The biologists ranked availability of forage on public lands as having the strongest influence on the potential for elk-human conflict (33%), followed by human population growth rate (22%) and the amount of private land in row crops (18%). We then applied those rankings in a weighted linear summation to map the relative potential for elk-human conflict. Finally, we used white-tailed deer (Odocoileus virginianus) densities to identify areas where success of elk restoration may be hampered due to meningeal worm (Parelaphostrongylus tenuis) transmission. By combining results of the 3 spatial data layers (i.e., habitat model, elk-human conflict model, deer density), our model indicated that restoration sites located in west-central and north-central Arkansas were most favorable for reintroduction.     

Identification of hairs found in leopard seal (<Emphasis Type="Italic">Hydrurga leptonyx</Emphasis>) scats

The leopard seal is a top-order predator in the Southern Ocean ecosystem and preys on a wide variety of vertebrate species including seals and penguins. We assessed the use of hairs found in leopard seal scats to identify the species of pinniped consumed. A reference collection of hairs was obtained from four potential leopard seal prey species including crabeater, Weddell, Ross, and Southern elephant seals. Discrimination techniques applied to terrestrial mammals did not allow for identification of the seal hairs. Instead, a 2-dimensional (2-D) and 6-dimensional (6-D) analysis technique utilising Mahalanobis distances (D ²) was used. The smallest Mahalanobis distance together with the largest value of p(F) positively identified hairs from each species. The 6-D analysis was more accurate and applied to hairs found in the leopard seal scats. The majority of prey species were identified as crabeater seals, which are a known prey item of the leopard seal.     

Reductive methylation andpKa determination of the lysine side chains in calbindin D9k

The Lys residues in the 75-residue Ca²⁺-binding protein calbindin D_9k were reductively methylated with¹³C-enriched formaldehyde. The possible structural effects resulting from the chemical modification were critically investigated by comparing two-dimensional NMR spectra and the exchange rates of some of the amide protons of the native and the modified protein. Our results show that the protein retains its structure even though 10 Lys out of a total of 75 amino acid residues were modified. In the Ca²⁺- and apo-forms of the protein, the¹³C-methylated Lys residues can be detected with high sensitivity and resolution using two-dimensional (¹H,¹³C)-heteronuclear multiple quantum coherence (HMQC) NMR spectroscopy. ThepKa values of the individual Lys residues in Ca²⁺-calbindin D_9k and apo-calbindin D_9k were obtained by combiningpH titration experiments and (¹H,¹³C)-HMQC NMR spectroscopy. Each Lys residue in the Ca²⁺- and apo-forms of calbindin D_9k has a uniquepKa value. The LyspKa values in the calcium protein range from 9.3 to 10.9, while those in the apo-protein vary between 9.7 and 10.7. Although apo-calbindin D_9k has a very similar structure compared to Ca²⁺-calbindin D_9k, the removal of two Ca²⁺ ions from the protein leads to an increase of thepKa values of the Lys residues.     

Habitat Use of Sympatric Rattlesnake Species Within the Gulf Coastal Plain

Abstract: The eastern diamondback rattlesnake (Crotalus adamanteus) and timber rattlesnake (Crotalus horridus) are sympatric throughout most of southern Georgia, USA. We used rattlesnake sightings to quantify and compare habitat use by these 2 species in the Gulf Coastal Plain. At the largest scale examined, univariate statistics and logistic regression models indicated that eastern diamondback rattlesnakes were associated with roads but not with any of the specific habitat types we examined. In contrast, timber rattlesnakes were closely associated with hardwood habitat and riverine systems but not with roads and edges. To effectively conserve and manage both species in the Southeast, a habitat matrix of large intact patches of both hardwood and pine (Pinus spp.) forest may be necessary.     

Identifying habitat linkages to maintain connectivity for corridor dwellers in a fragmented landscape

Anthropogenic habitat fragmentation typically precedes conservation planning; maintaining remaining linkages among core habitat areas can thus become a key conservation objective. Identifying linkages for dispersal and ensuring those linkages have long-term protection and management are challenging tasks for wildlife managers. These tasks can be especially daunting for smaller species with low mobility, termed corridor dwellers, which must maintain sustainable populations within corridors. Between May 2007 and June 2009, we collected occurrence locations for a corridor dweller, the Palm Springs pocket mouse (Perognathus longimembris bangsii), from museums, previous research, and our own field sampling. We used those data to model their suitable niche space and then identify suitable linkages between proposed conservation areas. We used a partitioned Mahalanobis D² statistic to create a spatially explicit niche model describing the distribution of a suitable niche space, and we validated the model statistically, with live trapping and with burrowing owl (Athene cunnicularia) diets. Our model identified soil characteristics, topographic ruggedness, and vegetation as variables delimiting Palm Springs pocket mouse habitat; sand content of the soils was an especially important characteristic. Our historic distribution model identified 120,000–90,000 ha as historically potential Palm Springs pocket mouse habitat; roughly 39% of that has been lost to more recent development. Most of the remaining suitable habitat occurred in the northwestern portion of the valley. We modeled habitat within core reserves as well as within proposed linkages between those reserves as having high similarity to known occupied habitats. Live trapping in areas with high (≥0.95) Habitat Suitability Index (HSI) values resulted in captures at 66% of those locations and, along with burrowing owl diets, refined a qualitative model as to what constituted a suitable Palm Springs pocket mouse corridor. While most corridor analyses have focused on mobile species which may traverse corridors in hours, days, or weeks, linkages for corridor dwellers must include habitat for sustaining multi-generational populations. This requires evaluating whether continuous suitable habitat exists within proposed corridors. Our research demonstrates how niche modeling can provide a landscape-scale view of the distribution of suitable habitat to evaluate conservation objectives for connectivity. © 2011 The Wildlife Society.     

Habitat Assessment for Giant Pandas in the Qinling Mountain Region of China

ABSTRACT Because habitat loss and fragmentation threaten giant pandas (Ailuropoda melanoleuca), habitat protection and restoration are important conservation measures for this endangered species. However, distribution and value of potential habitat to giant pandas on a regional scale are not fully known. Therefore, we identified and ranked giant panda habitat in Foping Nature Reserve, Guanyinshan Nature Reserve, and adjacent areas in the Qinling Mountains of China. We used Mahalanobis distance and 11 digital habitat layers to develop a multivariate habitat signature associated with 247 surveyed giant panda locations, which we then applied to the study region. We identified approximately 128 km²of giant panda habitat in Foping Nature Reserve (43.6% of the reserve) and 49 km²in Guanyinshan Nature Reserve (33.6% of the reserve). We defined core habitat areas by incorporating a minimum patch-size criterion (5.5 km²) based on home-range size. Percentage of core habitat area was higher in Foping Nature Reserve (41.8% of the reserve) than Guanyinshan Nature Reserve (26.3% of the reserve). Within the larger analysis region, Foping Nature Reserve contained 32.7% of all core habitat areas we identified, indicating regional importance of the reserve. We observed a negative relationship between distribution of core areas and presence of roads and small villages. Protection of giant panda habitat at lower elevations and improvement of habitat linkages among core habitat areas are important in a regional approach to giant panda conservation.     

Landscape partitioning by nocturnal rodent assemblages in the Llanos de Ojuelos,in Mexico’s Central High Plateau

Aim The Llanos de Ojuelos in Mexico’s Central High Plateau supports unique Opuntia scrublands and the southernmost Chihuahuan grasslands. Although human activities have modified strongly its landscape and impacted its biodiversity at an unknown scale, such impacts are poorly known. We aimed at understanding how nocturnal rodent species distributed across the landscape and formed assemblages and on the role and integration of the different habitats at the landscape level. Location The study was carried out at 43 sites in a study area of approximately 3350 km² in the Llanos de Ojuelos. Methods During the Spring of 2008, we surveyed nocturnal rodents, through live‐trapping. We redefined habitat classes based on log‐linear multinomial regressions of rodent captures. Species rarefaction curves and true alpha, beta and gamma diversities were calculated for the different habitat classes. A map of the different habitats was constructed based on Landsat imagery. Results We captured 458 individuals of 20 rodent species. Multinomial regressions caused the merger of 11 a priori defined habitat classes into 7. Leguminous scrub and mixed nopaleras, both secondary habitats, had the highest alpha and gamma diversity values. Closed arboreal nopaleras and grasslands had the highest within‐habitat variability (¹D_β) and the lowest area coverage. Within‐habitat ¹D_β was larger than landscape ¹D_β, because of the great overlap in rodent assemblage composition between the habitats. Main conclusions There are no ‘typical’ rodent assemblages per habitat class, but they are organized loosely and have fuzzy borders. Rodent community organization was highly species‐centred. At the landscape level, secondary habitats have a profound effect on rodent diversity and should be included in management schemes for biological conservation. The most endangered habitats seem to be the closed arboreal nopaleras and grasslands. Any conservation efforts must consider their conservation and an increase in the size of remaining patches.     

Serological characterization of previously unknown H-2 molecules identified in the products of theK d andD k region

The molecular relationship between H-2 private and some public specificities was studied in C3H.OH (H-2 ⁰² ) mice using surface-antigen re-distribution methods. Besides the K^d- and D^k-region antigens, which can be capped by antisera against the private and public specificities characteristic for a given allele, a previously unknown type of molecule was found in the products of both theK ^d andD ^k regions. These can be capped by the respective anti-private serum but not by antisera against some public specificities. The two K^d-region molecules are provisionally named H-2K1^d and H-2K2^d. We detected them onH-2 ⁰² (K ^d ,I ^d ,S ^d ,D ^k ) and also onH-2 ^dx (K ^d ,I ^f ,S ^f ,D ^dx ) T lymphocytes. Similarly, the two types of molecules detected on the products of theD ^k region are provisionally named H-2D1^k and H-2D2^k. The serological characteristics of these molecules are described. When compared with the products of theD ^d region, in which we previously described three different molecules (H-2D^d, H-2M^d, and H-2L^d), the mutual relationship between H-2K1^d and H-2K2^d as well as between H-2D1^k and H-2D2^k appears to be similar to that between H-2D^d and H-2M^d. In the absence of relevant recombinants or informative biochemical data, it is, however, difficult to establish homology between molecules produced by differentK- andD-region alleles.     

Ranking Mahalanobis Distance Models for Predictions of Occupancy From Presence-Only Data

ABSTRACT The Mahalanobis distance statistic (D²) has emerged as an effective tool to identify suitable habitat from presence data alone, but there has been no mechanism to select among potential habitat covariates. We propose that the best combination of explanatory variables for a D² model can be identified by ranking potential models based on the proportion of the entire study area that is classified as potentially suitable habitat given that a predetermined proportion of occupied locations are correctly classified. In effect, our approach seeks to minimize errors of commission, or maximize specificity, while holding the omission error rate constant. We used this approach to identify potentially suitable habitat for the Olympic marmot (Marmota olympus), a declining species endemic to Olympic National Park, Washington, USA. We compared models built with all combinations of 11 habitat variables. A 7-variable model identified 21,143 ha within the park as potentially suitable for marmots, correctly classifying 80% of occupied locations. Additional refinements to the 7-variable model (e.g., eliminating small patches) further reduced the predicted area to 18,579 ha with little reduction in predictive power. Although we sought a model that would allow field workers to find 80% of Olympic marmot locations, in fact, <3% of 376 occupied locations and <9% of abandoned locations were >100 m from habitat predicted by the final model, suggesting that >90% of occupied marmot habitat could be found by observant workers surveying predicted habitat. The model comparison procedure allowed us to identify the suite of covariates that maximized specificity of our model and, thus, limited the amount of less favorable habitat included in the final prediction area. We expect that by maximizing specificity of models built from presence-only data, our model comparison procedure will be useful to conservation practitioners planning reintroductions, searching for rare species, or identifying habitat for protection.     

Detection of H-2Db antigen on osmotic shock-treated friend leukemia virus particles

Antisera specific for either H-2K^b, H-2D^b, H-2K^k or H-2D^k antigenic determinants were examined for their capacity to neutralize Friend virus (FV) collected from the serum of infectedH-2 ^b /H-2 ^k heterozygous mice. Neutralizing activity was detected (1) only withanti-H-2D ^b antisera, (2) only when the surface of virus particles had been mildly deranged by osmotic shock treatment and (3) only in the assay for the defective spleen focus-forming virus component of FV.     

POPULATION STRUCTURE OF MORPHOLOGICAL TRAITS IN CLARKIA DUDLEYANA. II. CONSTANCY OF WITHIN-POPULATION GENETIC VARIANCE

Recent quantitative genetic studies have attempted to infer long-term selection responsible for differences in observed phenotypes. These analyses are greatly simplified by the assumption that the within-population genetic variance remains constant through time and over space, or for the multivariate case, that the matrix of additive genetic variances and covariances (G matrix) is constant. We examined differences in G matrices and the association of these differences with differences in multivariate means (Mahalanobis D²) among 11 populations of the California endemic annual plant, Clarkia dudleyana. Based on nine continuous morphological traits, the relationship between Mahalanobis D² and a distance measure summarizing differences in G matrices reflected no concomitant change in (co)variances with changes in means. Based on both broad- and narrow-sense analyses, we found little evidence that G matrices differed between populations. These results suggest that both the additive and nonadditive (co)variances for traits have remained relatively constant despite changes in means.     

Morphology of the vertebral centra in dolphins from the southwestern South Atlantic: A 3D morphometric approach and functional implications

In dolphins, centrum shape is one of the features that allows determination of stable and flexible regions in the vertebral column. The Commerson's (Cephalorhynchus commersonii; n = 37), Peale's (Lagenorhynchus australis; n = 24), dusky (Lagenorhynchus obscurus; n = 29), and hourglass dolphins (Lagenorhynchus cruciger; n = 10) are closely related species inhabiting the Southern Hemisphere that have diverse prey and habitat preferences. We applied 3D geometric morphometrics to describe differences in centrum shape along the vertebral columns of these species, and hypothesize how these differences may affect swimming. On each column, we chose a maximum of eight vertebrae and digitized 18 landmarks on each centrum with a Microscribe G2X. We explored shape differences amongst regions employing principal components analyses and computing Mahalanobis distances. We describe differences in centrum shape in relation to functional regions and among species; and analyze shape changes in relation to particular biomechanical requirements. The species studied here may be partially sympatric in the Southern Hemisphere, but they have important differences in foraging ecology and habitat preferences that could be related to differences in centrum shape along the vertebral column.     

A seasonal study of phosphorus deficiency in a eutrophic reservoir

• 1 Seston elemental composition (C, N, P) and the orthophosphate uptake rate constant, k(upt), were measured in the epilimnion of the eutrophic ?ímov Reservoir in the period March-August 1989.
• 2 Seasonal series of log C/P, log N/P and log [k(upt)] values were highly correlated (r² in the range 0.84–0.93), but, based on literature-derived criteria, k(upt) values indicated stronger P deficiency than did the C/P values.
• 3 The results showed moderate to strong phosphorus deficiency in summer, moderate deficiency at the end of the spring peak of phytoplankton, and no deficiency early in the spring or during the spring clear-water period.

     

HIERARCHICAL PATTERNS OF GENETIC POPULATION STRUCTURE IN BLACK RAT SNAKES (ELAPHE OBSOLETA OBSOLETA) AS REVEALED BY MICROSATELLITE DNA ANALYSIS

We investigated the distribution of variation at six microsatellite loci in the black rat snake (Elaphe obsoleta obsoleta). Sampling occurred at three hierarchical scales ranging from communal hibernacula to regional populations, with most locales situated within the Frontenac Axis region of eastern Ontario. We detected no statistically significant pairwise differentiation (F_ST and R_ST) between hibernacula within the same subpopulations (interhibernaculum distance <6 km). However, isolation-by-distance was evident among locales within the Frontenac Axis (maximum of 50 km) and among regional populations (maximum of 1500 km). Conservative estimates of N_c derived from heterozygosity values ranged from approximately 600 to 2000. These values suggest relatively large genetic neighborhoods encompassing many communal hibernacula. Our results considered together suggest viscosity of gene flow over relatively short distances (tens of kilometers), but substantial genetic exchange among local hibernacula.     

Analysis of theD-region products ofH-2444using monoclonal antibodies reveals the expression of a new class I-like molecule

To analyze how many D-region-encoded molecules could be detected inH-2 ^q , we produced a panel of nine monoclonal antibodies from AKR (K^kD^k) anti-AKR.M (K^kD^q) immunizations. All of the D_q region antibodies cross-reacted on D^d and/or L^d, and all except one cross-reacted on D^b, confirming the previously observed serologic and amino acid sequence homology between theD-region products ofH-2 ^d ,H-2 ^b , andH-2 ^q . All of these monoclonal antibodies precipitated 46 000 dalton molecules from both cell-surface-labeled and biosynthetically labeled BIO.AKM spleen cells, indicating that all were reactive with class I-like molecules. Sequential immunoprecipitation analysis with one of these antibodies, 66-3-5, reveals the presence of a previously unidentified class I-like molecule. Tryptic peptide map analysis reveals that this molecule may be the product of a newly describedH-2D ^q -region gene.     

Purification and Subsite Affinities of exo-lnulinase from Penicillium trzebinskii

An exo-inulinase was highly purified from the culture broth of Penicillium trzebinskii by anion exchange, hydrophobic, and gel filtration chromatographies. The enzyme was homogeneous by disc electrophoresis. The molecular weight was 8.7 × 10⁴, and the isoelectric point was pH 4.3. The enzyme hydrolyzed not only inulin and sucrose but also inulooligosaccharides [1^F(1-β-D-fructofuranosyl)_n-1fructose, F_n (n= 2—5)] and fructooligosaccharides [1^F(1-β-D-fructofuranosyl)_n-1 sucrose, GF_n, (n = 2—8)] liberating the nonreducing terminal fructose of the substrates. The substrate specificity was investigated. The K_m (mM) and k_o (sec^?1were: inulin, 0.042 and 159; sucrose, 6.5 and 169; F₂, 2.1 and 62.8; F₃, 0.40 and 126; F₄, 0.47 and 171; and F₅, 0.47 and 131, respectively. Dependence of K_m and k_o values on the degree of polymerization of substrates was observed. The subsite affinities in the active site were 1.05, 4.57, 1.45, 0.09, and — 0.16kcal/mol for subsite 1, 2, 3, 4, and 5, respectively.     

Molecular Dynamics Simulation Studies of the Density and Temperature Dependence of Self-diffusion in a Cylindrical Micropore

We report Molecular Dynamics calculations of radial density profiles and self-diffusion coefficients of Lennard-Jones fluids in a cylindrical pore of radius 2σ, for a wide range of temperatures and densities. At n _p σ³ = 0.825 the self-diffusion coefficient parallel to the pore walls D _∥*. follows a monotonic (nearly linear) increase with kT/ε and is very similar to that of the bulk self-diffusion coefficient D _b *. At n _p σ³ = 0.4 and kT/ε ≤ 1.0 the curve of D _∥* vs. kT/ε shows a distinct inflection in the region 0.7 ≤ kT/ε ≤ 0.9 and values of D _∥* are much less than D _b * decreasing to near solid state values at very low temperatures. At the highest temperature studied, kT/ε = 2.98, D _∥* is almost inversely proportional to density and in a fairly close agreement with that of D _b *. At KT/ε = 0.49, D _∥* is much smaller than D _b *. The motion of adsorbate particles normal to the walls is also discussed.