bluuebunny/crossref_metadata_2025_split huggingface dataset:
Explaining grass‐nutrient patterns in a savanna rangeland of southern Africa
Authors: Mutanga Onisimo , Prins Herbert H.T. , Skidmore Andrew K. , van Wieren Sipke , Huizing Herman , Grant Rina , Peel Mike , Biggs Harry 
Published: September 2010

AbstractAim  The search for possible factors influencing the spatial variation of grass quality is an important step towards understanding the distribution of herbivores, as well as a step towards identifying crucial areas for conservation and restoration. A number of studies have shown that grass quality at a regional scale is influenced by climatic variables. At a local scale, site factors and their interaction are considered important. In this study, we aimed at examining environmental correlates of grass quality at a local scale. The study also sought to establish if biotic factors interact significantly with abiotic factors in influencing a variation in grass quality.Location  The study area is located in the Kruger National Park of South Africa. The study area stretches from west (22°49′ S and 31°01′ E) to east, (22°44′ S and 31°22′ E) covering an area of about 25 × 6 km in the far northern region of the Kruger National Park.Methods  We collected environmental data such as soil texture, percentage grass cover and biomass as well as grass samples for chemical analysis from specific locations in the study area. In addition, a digital elevation model (DEM) with a resolution of 5 m was used to derive elevation, slope and aspect using a geographic information system (GIS), which were related to grass quality. We used correlation analysis and anova to relate environmental variables to grass quality. Multivariate analysis techniques were used to simultaneously analyse and explore the complex interactions between variables.Results and conclusions  Our results indicate that there is a significant relationship between grass quality parameters and site‐specific factors such as slope, altitude, percentage grass cover, aspect and soil texture. Relatively, percentage grass cover and soil texture were more critical in explaining a variation in grass quality. Plant characteristics such as species type interact significantly with slope, altitude and geology in influencing nutrient distribution. The results of this study may give a better insight on foliar nutrient distribution patterns at a landscape scale in savanna rangelands. Furthermore, the results of this study may help in the selection of ancillary information, which could be used in conjunction with other data such as remotely sensed data to map grass quality – an important step towards understanding the distribution and feeding patterns of wildlife. However, we acknowledge that this study is based on one seasonal snapshot, therefore some slightly different findings may be obtained during other times of the year. Nevertheless, the study has revealed that under the conditions experienced during the study period, nutrient distribution varies with varying biotic and abiotic factors.
An altitudinal comparison of caterpillar (Lepidoptera) assemblages on Ficus trees in Papua New Guinea
Authors: Novotny Vojtech , Miller Scott E. , Basset Yves , Cizek Lukas , Darrow Karolyn , Kaupa Borenke , Kua Joseph , Weiblen George D. 
Published: September 2010

AbstractAim  This analysis of caterpillar (Lepidoptera) beta‐diversity between tropical lowlands and highlands attempts to separate the effects of between‐site (1) turnover of herbivore species on particular host plants, (2) changes in host use by herbivores, and (3) turnover of plant species on changes in herbivore assemblages.Location  Two rain forest areas 130 km and 1700 altitudinal metres apart were studied in Papua New Guinea: one in the lowlands (100 m a.s.l.) on the northern coast of the island and one in the central New Guinean cordillera at 1800 m a.s.l.Methods  The analysis is based on caterpillar feeding records obtained by quantitative sampling and rearing of caterpillars from four Ficus species studied in the mountains and 21 Ficus species and 62 plant species from other genera and families studied in the lowlands, including three Ficus species studied in both areas.Results  Only 17% of species feeding on Ficus in the highlands also occurred in the lowlands. These species represented 1–46% of individuals in caterpillar assemblages on particular Ficus hosts. Widespread species included both Ficus specialists and generalists feeding on numerous plant families. Some of the Ficus specialists changed their preferred host species with altitude. High species turnover was not explained by changes in the species composition of host plants with altitude as lowland and montane assemblages feeding on the same Ficus species showed high turnover. Despite the rarity of widespread caterpillars, the lowland and montane Ficus assemblages were remarkably similar in their dominance structure, species richness, host specificity, generic composition and familial composition.Main conclusions  Ficus‐feeding Lepidoptera assemblages between tropical lowlands and highlands are characterized by substantial species turnover not explained by altitudinal changes in the composition of the vegetation. Further, species‐rich plant genera can support caterpillar assemblages with relatively low beta‐diversity compared with species‐poor genera as caterpillars can switch their host preferences from one congeneric host species to another along an altitudinal gradient. Closely related plant species can thus represent a broad, continuously distributed resource along such gradients.
A hypothetico‐deductive analysis of the environmental factors involved in the current reptile distribution pattern in the Canary Islands
Authors: Guerrero José C. , Mario Vargas J. , Real Raimundo 
Published: September 2010

AbstractAim  We analyse the influence of different factors on the inter‐insular colonization processes that yielded the current distribution pattern of endemic reptile species in the Canary Islands.Location  The seven main islands of the Canary Islands.Methods  We tested 11 hypotheses about factors that might have affected the colonization processes. We used Mantel and partial Mantel tests to establish the statistical significance of the relationship between the islands predicted by each hypothesis, and a parsimony analysis to detect the most parsimonious hypothesis.Results  The only significant relationships were those predicted by inter‐island distance, also taking area into account, and habitat similarity, considering current vegetation in the islands. The latter was the best hypothesis according to the parsimony criterion.Main conclusions  Our results support the hypothesis that habitat similarity between islands is the main factor affecting the colonization processes of the whole group, although inter‐insular distance seems to play a separate role in colonization events.
Inferring the mode of speciation in Indo‐West PacificConus(Gastropoda: Conidae)
Authors: Vallejo Benjamin 
Published: September 2010

AbstractAim This study aims to initially explore the mode of speciation in Indo‐West PacificConus.Location The Indo‐West Pacific island arc, Indian and Pacific Oceans.Methods Relating evolutionary divergence in a molecular phylogeny [T.F. Duda & S.R. Palumbi (1999)Proceedings of the National Academy of Science USA,96, 10272] using node height with modern range extents as a possible measure of allopatric or sympatric speciation following that of T.G. Barraclough, A.P. Vogler & P.H. Harvey [(1999)Evolution of Biological Diversity. Oxford University Press, Oxford] models of sympatric and allopatric speciation.Results The analysis seems to indicate that the relationship of sympatry with node height is not informative. Species that have diverged quite recently show 100% sympatry with the sister species. A clearer signal of recent allopatric speciation is observed in species whose distribution is at the edge of the Indian and Pacific Ocean basins. In the widely distributedConus ebraeusclade, the relationships of node heights and range extents of the member species support a key prediction of sympatric speciation. In highly ecologically specialized species, there is a smaller degree of sympatry than those species that are less specialized.Main conclusions The modes of speciation models presented in this study are not informative. This suggests that there had been large and possibly rapid changes in range size after speciation in the various clades. This could have been due to the fact that the wide dispersal life‐history strategy in the genus had been largely conserved inConusevolution. There is evidence of sympatric and parapatric speciation in oneConusclade. Overall, the patterns of phylogeny and range distribution when related to the timing of speciation lend circumstantial support to a Neogene centre of origin hypothesis but not to speciation on the Pacific Plate. Speciation is likely to have been associated with the Tethys Sea closure event, with rapid speciation occurring after closure.
Patterns of endemism of the eastern North American cave fauna
Authors: Christman Mary C. , Culver David C. , Madden Molly K. , White Denis 
Published: September 2010

AbstractAim  Over 250 species of obligate terrestrial cave‐dwelling animals (troglobionts) are known from single caves in the eastern United States. We investigate their geographical distribution, especially in relation to other troglobionts. We relate these patterns to taxonomic group, opportunities for dispersal and geographical location.Location  Caves of the United States east of the Mississippi River.Methods  We associated over 3000 records of more than 450 troglobiotic species and subspecies with hexagons of 1000, 5000 and 10,000 km2 in size. We calculated Moran's I, black–white joins and cubic regression of endemics on non‐endemics at all three spatial scales. For 5000 km2 hexagons, we modelled the spatial autocorrelation of the residuals of the cubic regression of endemics on non‐endemics.Results  Differences among orders in percentage single‐cave endemism were not significant, except for Pseudoscorpionida, which was higher (69%) than any other order. At all three scales, Moran's I and black–white joins were significant, indicating a clumped distribution of both single‐cave endemics and other troglobionts. Spatial patterns were similar at all three scales and Moran's I was highest at 5000 km2. The cubic fit of endemics to non‐endemics was consistently better, with less systematic error or residuals, than were linear or quadratic models. Residuals showed a significant geographical pattern with excess endemics in more southerly locations.Main conclusions  There was both a non‐spatial and spatial component to the pattern of single‐cave endemism. The non‐spatial component was the association of high levels of single‐cave endemism with areas of high diversity of non‐endemics. It may be that both are high because of high secondary productivity. Spatially, single‐cave endemism is high in central rather than peripheral areas and in the southern part of the range. It is not higher in areas of more dissected limestone, which would reduce migration rates; if anything endemism is lower. Regional spatial effects are important, indicating that cave communities cannot be understood (or protected) in isolation.
The fourth paradigm pattern of post‐glacial range expansion of European terrestrial species: the phylogeography of the Marbled White butterfly (Satyrinae, Lepidoptera)
Authors: Habel Jan Christian , Schmitt Thomas , Müller Paul 
Published: September 2010

AbstractAim  Three paradigm patterns of post‐glacial dispersal are known for terrestrial species in Europe. However, the possibility of a fourth arises with the Italian and the Balkan lineages expanding to central Europe and the Iberian one being trapped by the Pyrenees. We test this hypothesis by analysing the molecular biogeography of the Marbled White butterfly.Location  Twelve populations distributed over a major part of the European range of Melanargia galathea and M. lachesis.Methods  We studied 18 allozyme loci of 403 individuals from 12 populations. Butterflies were sampled in the field, frozen in liquid nitrogen and stored under these conditions until analysis. We used cellulose acetate plates for allozyme electrophoresis.Results  We detected three major genetic lineages within the M. galathea/lachesis complex. The M. lachesis sample from the southern Pyrenees was strongly genetically differentiated from M. galathea (FCT: 0.312). Melanargia galathea splits into two major genetic lineages (FCT: 0.115), which both were found in post‐glacially invaded regions. The further differentiation within these lineages was comparably low (FSC: 0.028). The genetic diversity within populations was high compared with other butterfly species.Main conclusions  Our findings support the existence of a fourth pattern with only the Iberian lineage not contributing considerably to the post‐glacial colonization of central Europe. Preliminary studies in other butterfly species of dry grasslands support the importance of this pattern possibly representing a fourth paradigm. The high genetic diversity within populations might be one reason for the recently observed expansions at the northern distribution limits.
Do fleas (Insecta: Siphonaptera) parallel their mammal host diversification in the Mexican transition zone?
Authors: Morrone Juan J. , Gutiérrez Ana 
Published: September 2010

AbstractAim The Mexican transition zone is a complex area where Neotropical and Nearctic biotic elements overlap. A previous study on mammal species has shown a great diversification in the area. We analyse the diversification of their flea species (Insecta: Siphonaptera), in order to determine if a diversification similar to their mammal host species has occurred.Location The area analysed corresponds to Mexico.Methods The panbiogeographical or track analysis was based on the comparison of the individual tracks of 112 species belonging to 48 genera and eight families of the order Siphonaptera. Generalized tracks were obtained based on the comparison of the individual tracks. Nodes were found in the areas where generalized tracks overlapped.Results Thirty‐four generalized tracks were obtained, distributed within the Mexican transition zone (20), the Nearctic region plus the Mexican transition zone (8), the Nearctic region (4) and the Neotropical region plus the Mexican transition zone (2). In the areas where they intersected, 26 nodes were identified: 23 in the Mexican transition zone and 3 in the Nearctic region.Main conclusions The nodes are concentrated in the Transmexican Volcanic Belt (14), Sierra Madre Oriental (5) and Sierra Madre del Sur (4) provinces of the Mexican transition zone. These results show a significant diversification of the flea taxa, in parallel with the diversification of their mammal hosts.
Did tree‐Betula, Pinus and Picea survive the last glaciation along the west coast of Norway? A review of the evidence, in light of Kullman (2002)
Authors: Birks Hilary H. , Larsen E. , Birks H. J. B. 
Published: September 2010

AbstractAim  We discuss the hypotheses proposed by Kullman [Geo‐Öko21 (2000) 141; Nordic Journal of Botany21 (2001) 39; Journal of Biogeography29 (2002) 1117] on the basis of radiocarbon‐dated megafossils of late‐glacial age from the central Swedish mountains that boreal trees survived the glaciation along the south‐west coast of Norway and subsequently migrated eastward early in the late‐glacial to early deglaciated parts of the central Swedish Scandes mountains.Methods  We assess these hypotheses on the basis of glacial geological evidence and four lines of palaeoecological evidence, namely macrofossil records of the tree species, vegetation and climate reconstructions from plant evidence, independent climate reconstructions from other proxies for the late‐glacial environment of south‐west Norway, and the patterns of post‐glacial spread of the tree species.Location  South and west Norway, central Swedish Scandes mountains (Jämtland).Results and conclusions  South‐west Norway and the adjacent continental shelf were under ice at the last‐glacial maximum (LGM). The late‐glacial vegetation of south‐west Norway was treeless and summer temperatures were below the thermal limits for Betula pubescens Ehrh., Pinus sylvestris L. and Picea abies (L.) Karst. Instead of spreading immediately after the onset of Holocene warming, as might have been expected if local populations were surviving, B. pubescens showed a lag of local arrival of 600 to > 1000 years, Pinus lagged by 1500 to > 2000 years, and Picea only reached southern Norway c. 1500 years ago and has not colonized most of south‐west Norway west of the watershed. Glacial geological evidence shows the presence of an ice sheet in the Scandes at the LGM and in the Younger Dryas, which was cold‐based near or at the area where the late‐glacial‐dated megafossils were recovered by Kullman. We conclude that the samples dated by Kullman (2002) should be evaluated carefully for possible sources of contamination. All the available evidence shows that the biogeographical hypotheses, based on these radiocarbon dates taken at face value, of late‐glacial tree survival at the Norwegian coast and subsequent eastwards spread to the mountains, are unsupportable.
Historical biogeography and diversification within the Neotropical parrot genus Pionopsitta (Aves: Psittacidae)
Authors: Ribas Camila C. , Gaban‐Lima Renato , Miyaki Cristina Y. , Cracraft Joel 
Published: September 2010

AbstractAim  We investigate spatial and temporal patterns of diversification within the Neotropical avifauna using the phylogenetic history of parrots traditionally belonging to the genus Pionopsitta Bonaparte 1854. This genus has long been of interest for those studying Neotropical biogeography and diversity, as it encompasses species that occur in most Neotropical forest areas of endemism.Location  The Neotropical lowland forests in South and Central America.Methods  Phylogenetic relationships were investigated for all species of the genus Pionopsitta and five other short‐tailed parrot genera using complete sequences of the mitochondrial genes cyt b and ND2 as well as 26 plumage characters. The resulting phylogeny was used to test the monophyly of the genus, investigate species limits, and as a framework for reconstructing their historical biogeography and patterns of diversification.Results  We found that the genus Pionopsitta, as previously defined, is not monophyletic and thus the Chocó, Central American and Amazonian species will now have to be placed in the genus Gypopsitta. The molecular and morphological phylogenies are largely congruent, but disagree on the position of one of the Amazon basin taxa. Using molecular sequence data, we estimate that species within Gypopsitta diversified between 8.7 and 0.6 Ma, with the main divergences occurring between 3.3 and 6.4 Ma. These temporal results are compared to other taxa showing similar vicariance patterns.Main conclusions  The results suggest that diversification in Gypopsitta was influenced mainly by geotectonic events, marine transgressions and river dynamics, whereas Quaternary glacial cycles of forest change seem to have played a minor role in the origination of the currently recognized species.
Process and pattern in the biogeography of New Zealand – a global microcosm?
Authors: McDowall R. M. 
Published: September 2010

AbstractAim  To describe New Zealand’s historical terrestrial biogeography and place this history in a wider Southern Hemisphere context.Location  New Zealand.Methods  The analysis is based primarily on literature on the distributions and relationships of New Zealand’s terrestrial flora and fauna.Results  New Zealand is shown to have a biota that has broad relationships, primarily around the cool Southern Hemisphere, as well as with New Caledonia to the north. There are hints of ancient Gondwanan taxa, although the long‐argued predominance of taxa derived by vicariant processes, driven by plate tectonics and the fragmentation of Gondwana, is no longer accepted as a principal explanation of the biota’s origins and relationships.Main conclusions  Most of the terrestrial New Zealand flora and fauna has clearly arrived in New Zealand much more recently than the postulated separation of New Zealand from Gondwana, dated at c. 80 Ma. There is a view that New Zealand may have disappeared completely beneath the sea in the early Cenozoic, and acceptance of this would mean derivation of the entire biota by transoceanic dispersal. However, there are elements in the biota that seem to have broad distributions that date back to Gondwanan times, and also some that are thought unlikely to have been able to disperse to New Zealand across ocean gaps, especially freshwater organisms. Very strong connections to the biota of Australia, rather than to South America, are inconsistent with the timing of New Zealand’s ancient and early separation from Gondwana and seem likely to have resulted from dispersal.
Surface imaging of thermally sensitive particulate and fibrous materials with the atomic force microscope: a novel sample preparation method
Authors: BALDWIN P. M. , FRAZIER R. A. , ADLER J. , GLASBEY T. O. , KEANE M. P. , ROBERTS C. J. , TENDLER S. J. B. , DAVIES M. C. , MELIA C. D. 
Published: September 2010

SummaryHigh‐resolution surface imaging by atomic force microscopy (AFM) of particulate materials is often problematic, principally as a result of the large height (z) variations in sample topography that either prevent the probe scanning over the particle or cause probe self‐imaging. This paper reports a novel method of embedding thermally sensitive particulate and fibrous materials which overcomes many of these problems and facilitates AFM imaging of these difficult materials. The process involves partial embedding of the sample in a cyanoacrylate film polymerized at room temperature. The sample heating required in currently used methods of particulate embedding is avoided and the method is therefore suitable for thermolabile materials. The cyanoacrylate film provides a flat hard surface which is ideal for AFM imaging, and the method has allowed successful imaging of relatively large particulate and fibrous samples such as starch granules and cellulose fibres. The cyanoacrylate has the added benefit that shrinkage holes in the film allow easy visual identification of areas where the film may have partially covered the sample.
The continuum normalization method for quantification of X‐ray spectra in biological microanalysis. 1. Generalized bremsstrahlung production cross‐sections and analysis using standards
Authors: Nicholson W. A. P. , Hall T. A. 
Published: September 2010

The thin self‐supporting biological specimens used for quantitative X‐ray microanalysis are problematical because the sections are most unlikely to be uniform in thickness or density, so the intensities of the characteristic lines alone are not a good measure of composition. The method developed to overcome these problems was introduced by T. A. Hall in 1971 and uses the bremsstrahlung or continuum intensity recorded in the X‐ray spectrum to normalize each characteristic line, and hence is frequently referred to as the continuum normalization (CN) procedure. Reformulating the CN method of quantification in terms of generalized cross‐sections and calculating more accurate values of bremsstrahlung production using a formula allows us a better understanding of the options open to the analyst of biological thin sections by which the errors in the measurement may be reduced. If one chooses to use the original Hall (1971) method using Kramers cross‐sections, the window measuring the continuum for normalization should be set in the 4–7 keV region for typical scanning electron microscope and microprobe beam energies, 20–40 kV, and above 10 keV for transmission electron microscope energies of 80 kV and above. Although it is clear that peak counts must not contribute to the white count, the window should be as wide as possible to reduce statistical errors.