bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inferring landscape effects on gene flow: a new model selection framework
Authors: SHIRK A. J. , WALLIN D. O. , CUSHMAN S. A. , RICE C. G. , WARHEIT K. I. 
Published: August 2010

AbstractPopulations in fragmented landscapes experience reduced gene flow, lose genetic diversity over time and ultimately face greater extinction risk. Improving connectivity in fragmented landscapes is now a major focus of conservation biology. Designing effective wildlife corridors for this purpose, however, requires an accurate understanding of how landscapes shape gene flow. The preponderance of landscape resistance models generated to date, however, is subjectively parameterized based on expert opinion or proxy measures of gene flow. While the relatively few studies that use genetic data are more rigorous, frameworks they employ frequently yield models only weakly related to the observed patterns of genetic isolation. Here, we describe a new framework that uses expert opinion as a starting point. By systematically varying each model parameter, we sought to either validate the assumptions of expert opinion, or identify a peak of support for a new model more highly related to genetic isolation. This approach also accounts for interactions between variables, allows for nonlinear responses and excludes variables that reduce model performance. We demonstrate its utility on a population of mountain goats inhabiting a fragmented landscape in the Cascade Range, Washington.
Landscape modelling of gene flow: improved power using conditional genetic distance derived from the topology of population networks
Authors: DYER RODNEY J. , NASON JOHN D. , GARRICK RYAN C. 
Published: August 2010

AbstractLandscape genetics is a burgeoning field of interest that focuses on how site‐specific factors influence the distribution of genetic variation and the genetic connectivity of individuals and populations. In this manuscript, we focus on two methodological extensions for landscape genetic analyses: the use of conditional genetic distance (cGD) derived from population networks and the utility of extracting potentially confounding effects caused by correlations between phylogeographic history and contemporary ecological factors. Individual‐based simulations show that when describing the spatial distribution of genetic variation, cGD consistently outperforms the traditional genetic distance measure of linearized FST under both 1‐ and 2‐dimensional stepping stone models and Cavalli‐Sforza and Edward’s chord distance Dc in 1‐dimensional landscapes. To show how to identify and extract the effects of phylogeographic history prior to embarking on landscape genetic analyses, we use nuclear genotypic data from the Sonoran desert succulent Euphorbia lomelii (Euphrobiaceae), for which a detailed phylogeographic history has previously been determined. For E. lomelii, removing the effect of phylogeographic history significantly influences our ability to infer both the identity and the relative importance of spatial and bio‐climatic variables in subsequent landscape genetic analyses. We close by discussing the utility of cGD in landscape genetic analyses.
Was it an explosion? Using population genetics to explore the dynamics of a recent radiation withinProtea(Proteaceae L.)
Authors: PRUNIER RACHEL , HOLSINGER KENT E. 
Published: August 2010

AbstractAdaptive radiations likely underlie much of the world’s diversity, especially that of hyper‐diverse regions. They are usually characterized by a burst of speciation early in their evolutionary history, a pattern which can be detected using population genetic tools. The Cape Floristic Region (CFR) of southwestern South Africa is home to many spectacular plant radiations. Here, we investigate the white proteas (ProteasectionExsertae), a typical CFR radiation, to determine if it demonstrates the burst of speciation associated with adaptive radiations in recent models. Inferences from individual assignment, tree‐based population relationships, and pairwiseF‐statistics based on 10 microsatellite loci reveal that while the white proteas radiated recently they did not radiate explosively. In addition, we found evidence that there is little gene flow between sampled populations of most species. Taken together, these results demonstrate that within a small clade, the processes underlying the radiation are different from those envisioned by current models of adaptive radiation and suggest that geographical isolation could have played a role in the diversification of the group. Our study implicates both adaptive and non‐adaptive processes in the evolution of botanical diversity of the CFR.
Adaptive responses to purine starvation in Leishmania donovani
Authors: Carter Nicola S. , Yates Phillip A. , Gessford Sarah K. , Galagan Sean R. , Landfear Scott M. , Ullman Buddy 
Published: August 2010

SummaryStarvation of Leishmania donovani parasites for purines leads to a rapid amplification in purine nucleobase and nucleoside transport. Studies with nucleoside transport‐deficient L. donovani indicate that this phenomenon is mediated by the nucleoside transporters LdNT1 and LdNT2, as well as by the purine nucleobase transporter LdNT3. The escalation in nucleoside transport cannot be ascribed to an increase in either LdNT1 or LdNT2 mRNA. However, Western analyses on parasites expressing epitope‐tagged LdNT2 revealed a marked upregulation in transporter protein at the cell surface. Kinetic investigations of LdNT1 and LdNT2 activities from purine‐replete and purine‐starved cells indicated that both transporters exhibited significant increases in Vmax for their ligands under conditions of purine‐depletion, although neither transporter displayed an altered affinity for its respective ligands. Concomitant with the increase in purine nucleoside and nucleobase transport, the purine salvage enzymes HGPRT, XPRT and APRT were also upregulated, suggesting that under conditions where purines are limiting, Leishmania parasites remodel their purine metabolic pathway to maximize salvage. Moreover, qRT‐PCR analyses coupled with cycloheximide inhibition studies suggest that the underlying molecular mechanism for this augmentation in purine salvage occurs post‐transcriptionally and is reliant on de novo protein synthesis.
Seasonal pattern of abundance of honeyeaters and their resources in heathland areas near Sydney
Authors: PYKE GRAHAM H. 
Published: August 2010

AbstractAbundances of honeyeaters, flowers and flying insects, the daily nectar‐energy production per flower and the average size of flying insects were estimated every three weeks for circles of radius 20 m located in three heathland areas near Sydney. Seasonal fluctuations in honeyeater density showed no apparent relationship with seasonal fluctuations in nectar‐energy productivity or in biomass of flying insects. Variation between circles in honeyeater density was also unrelated to spatial variation in energy productivity and insect biomass. The relatively low incidence of nectar‐feeding and high incidence of flying exhibited by birds observed during troughs in nectar‐energy production suggest that many of these birds are transient and that their density may consequently be unrelated to local conditions.
Decomposition of litter in sub‐alpine forests of Eucalyptus delegatensis, E. pauciflora and E. dives
Authors: WOODS P. V. , RAISON R. J. 
Published: August 2010

AbstractThe rate of decomposition of summer leaf‐fall (abscised leaves), winter leaf‐fall (containing some green leaves) and mature green (picked) leaves was assessed in sub‐alpine forests of E. delegatensis (R. T. Baker), E. pauciflora (Sieb. ex Spreng) and E. dives (Schau.) in the Brindabella Range, Australian Capital Territory, using litter bag and tethered leaf techniques. The relative contribution of leaching, microbial respiration and grazing by invertebrate macrofauna to loss of leaf weight was determined. The effect of leaching and microbial respiration was assessed in terms of weight loss per unit area of leaf (specific leaf weight), while losses due to macro‐faunal grazing were assessed by measuring reductions in leaf area. Litter decomposition constants for litter components (leaf, bark, wood) and total litter were determined from long‐term records of litterfall and accumulated litter.Weight losses of abscised leaves during the initial 12 months ranged from 25% for E. pauciflora to 39% for E. delegatensis and were almost entirely due to reduction in specific leaf weight. Losses in the weight of leaves falling in winter ranged from 38 to 49%, while green leaves lost 45 ‐ 59%. Approximately 50% of the total weight loss of green leaves was due to a loss in leaf area caused by skeletonization by litter macrofauna. Thus abscised leaves rather than green leaves must be used for measuring litter decomposition rates since abscised leaves constitute most of the litterfall in eucalypt forests.Leaves placed in the field in autumn decomposed slowly during the first summer, while the rate increased during the second winter and summer. Low litter moisture content appears to limit decomposition in the initial summer period in all communities, after which litterfall provides a mulch which reduces the rate of desiccation of lower litter layers. A simple linear regression model relating decomposition rate to the number of days (D) when litter moisture content exceeded 60% ODW accounted for 63‐83% of the variation in decomposition of leaves in the field. Inclusion of mean monthly air temperature (T) and the product of D and T (day degrees when litter was wet) in a multiple linear regression increased the variation in decomposition accounted for to 80 – 90%.The rate of weight loss showed a positive linear relationship with the initial concentration of nitrogen (N) or phosphorus (P) in the leaf. These concentrations are an index of the decomposability of leaf substrates (e.g. degree of sclerophylly or lignification).The rate of loss of specific weight was similar for tethered leaves and for leaves enclosed in mesh bags. Measured loss in specific leaf weight after 70 – 90 weeks was less than that predicted using decomposition constants (k).
Suburban development and resultant changes in the vegetation of the bushland of the northern Sydney region
Authors: CLEMENTS ANNEMARIE 
Published: August 2010

AbstractBushland sites in the northern suburbs of Sydney were compared to sites in Brisbane Waters National Park, Ku‐ring‐gai Chase National Park and Royal National Park which are relatively unaffected by suburban development. Both shale‐derived and sandstone‐derived soil in four physiographical locations were examined, with three replicates of each of the 16 combinations.Phosphorus levels are higher in the soils of suburban sites compared to soils derived from similar rock bases in non‐suburban sites. Phosphorus levels are also higher on shale‐derived than on sandstone‐derived soils, and lower on hilltops than in other physiographic positions. Suburban sandstone sites have soil phosphorus levels similar to those of non‐suburban shale sites.Three major and three minor clusters of species were distinguished using a hierarchical agglomerative clustering. The major clusters consisted of (1) species commonly associated with wet sclerophyll forests and rainforest margins, (2) species directly or indirectly related to the presence of man, and (3) species associated with dry sclerophyll forests and heaths.Using analyses of variance and covariance, and logit models, the abundance of the first main cluster was related to nutrient‐rich soils and the abundance of the third main cluster to low nutrient soils whereas the presence of the second main cluster was almost entirely restricted to sites surrounded by suburbs.The development of suburbs around vegetation patches has led to an increase in the abundance of native and exotic mesomorphic species and the addition of phosphorus to the soils. The data presented in this paper indicates that high phosphorus levels and presence of mesomorphic species are related.
Short note Successive approximation in pattern analysis
Authors: BUCKLEY R. C. 
Published: August 2010

AbstractThe analysis of vegetation pattern in semi‐arid eucalypt woodland by Harrington et al, (1981), and its recent critique by Dale (1982), place insufficient emphasis on the important role of successive approximation in pattern analysis. A single stage analysis can reveal first order patterns effectively, but is generally ineffective and inefficient in revealing vegetation patterns of higher order, no matter how sophisticated the numerical techniques employed. For a given total analytical effort, a more effective and efficient strategy to reveal such higher order patterns will generally be to partition the overall analytical effort into successive stages of sampling and interpretation, one stage for each order of pattern, with the sampling strategy at each stage based on the patterns determined during previous stages.
Decomposition of litter from common woody species of kauri (Agathis australisSalisb.) forest in northern New Zealand
Authors: ENRIGHT N. J. , OGDEN J. 
Published: August 2010

AbstractRates of weight loss and release of Na, K, Ca, Mg and P were investigated for common components of kauri forest litterfall in experiments using mesh bags. Weight loss over both 3 and 12 months was maximal for broadleaf mesophyllous species such asMelicytus ramiflorusand minimal for gymnosperms (e.g.Phyllocladus trichomanoides)and sclerophyllous broadleaf species (e.g.Knightia excelsa).Tree fern and palm frond material, common in these forests, was also slow to decompose, being grouped with the gymnosperm and sclerophyllous species.The order of release of nutrients from decomposing litter was P < Mg ∼ Ca < Na ∼ K. This order varied somewhat with species and litter type. Sodium and K are lost rapidly regardless of the rate of weight loss while Mg and Ca tend to follow the weight loss trend more closely. Loss of weight and nutrients was faster for freshly picked green leaves than for senesced leaves.Agathis australislitter, which may represent up to 50% of total litterfall, loses both weight and nutrients more slowly than broadleaf mesophyll species.
Population dynamics of the shrub Acacia suaveolens (Sm.) Willd.: Survivorship throughout the life cycle, a synthesis
Authors: AULD TONY D. 
Published: August 2010

Abstract Survivorship in Acacia suaveolens was assessed through seedling and adult stages. Moisture stress was found to be the critical factor limiting early seedling survival. Both seedling and adult populations were characterized by periods of low mortality interspersed with pulses of high mortality. A composite survivorship curve for A. suaveolens based on nine sites predicts that some 20–25 years after afire, established plants should disappear from the above‐ground flora if another fire does not occur. Fecundity and survivorship data were used to estimate the flux of seed in the soil over time in a hypothetical A. suaveolens population. From this it was predicted that, following establishment of plants after a fire, the seed‐bank would rapidly reach a maximum after 6 years and thereafter slowly decline, until after 60 years there would be only as many seeds as there were original parental plants. The situation would vary with predispersal seed predation, seed predation on the soil surface, seed dispersal by ants to ‘unsafe sites’ and the size of the initial seed‐bank prior to establishment. Only after a very long inter‐fire period would A. suaveolens be eliminated from a site. Elimination of the species is also possible under very frequent fires. A 2–5 year fire‐free period is needed for plants to reach maturity and another 6 years are needed to maximize seed input into the soil seed‐bank. In addition, seedling recruitment following cool burns is low to non‐existent as dormancy is not broken for most seeds in the soil during such burns.
Nectar dispersion patterns in three Australian plant species
Authors: ZIMMERMAN MICHAEL , NAGY ERIC S. , GALLOWAY LAURA 
Published: August 2010

Abstract Standing crops of floral nectar were measured from three species of plants: Dampiera stricta, Goodenia bellidifolia and Aotus ericoides. The amount of nectar in nearest neighbour blossoms in nine of the 10 samples were significantly correlated with one another suggesting that patches of high and low reward quality exist in these species. The patterns further suggest that the pollinators of these species employ arearestricted searching behaviour. The range of variability in standing crops for all three species was quite high. The nature of that variability suggests that A. ericoides is less variable in its rate of nectar production than are the other two species and, therefore, that it has the potential to be more tightly co‐evolved with its pollinators.
Pollen movement to flowering canopies of pistillate individuals of three rain forest tree species in tropical Australia
Authors: HOUSE SUSAN M. 
Published: August 2010

AbstractThis study measured the quantities of effective pollen vectors and their pollen loads arriving at the canopies of dioecious tropical rain forest trees in north‐east Queensland. Population flowering synchrony, effective pollinator populations and pollen loads transferred between staminate and pistillate trees were compared among three insect‐pollinated tree species. All three were visited by a wide range of insects, 75% of which (mostly 3–6 mm long) carried conspecific pollen. Fewer than 8% of individual insects were found to be carrying single‐species pollen exclusively and none could be described as specialist pollen foragers. The introduced honeybee carried greater quantities of pollen than any native species but was not necessarily a reliable pollinator.The brief flowering periods in Neolitsea dealbata (3–4 weeks) and Litsea leefeana (4–5 weeks) populations were synchronized among individuals. Flowering in the Diospyros pentamera population extended over 15 weeks and most individuals were in flower for most of this period. Staminate trees began flowering earlier, produced more flowers and attracted relatively more insects than did pistillate trees, suggesting a density‐dependent response of pollinators to flowering performance. Pollen was trapped in greater quantities on insects at staminate trees than at pistillate trees.Insect numbers increased at peak flowering periods and Diptera were the most abundant flower visitors. Anthophilous Coleoptera were more numerous at staminate than at pistillate trees in all three tree species populations. Larger quantities of pollen were mobilized during peak flowering times although the greatest quantities were transferred to pistillate canopies towards the end of the population flowering periods. Diptera carried pollen more often to pistillate N. dealbata and L. leefeana trees than did other groups whereas Coleoptera carried pollen more often to pistillate D. pentamera trees. The two contrasting flowering performances in the three tree species are discussed with reference to mechanisms that facilitate pollen transfer between staminate and pistillate trees.
Fire temperatures and follicle‐opening requirements in 10 Banksia species
Authors: ENRIGHT NEAL J. , LAMONT BYRON B. 
Published: August 2010

AbstractTemperature requirements for follicle rupture were assessed in 10 Banksia species from south‐western Australia. Species examined varied in degree of serotiny, persistence of dead florets, height, follicle size and number, and dependence on seed for regeneration.When treated for 2 min at temperatures over the range 100–500°C, follicles of some species ruptured at quite low temperatures (e.g. Banksia tricuspis with 50% opening at 145°C). Others required substantially higher temperatures (e.g. Banksia hookeriana with 50% opening at 390°C). There was a significant correlation between temperature requirements for follicle rupture and persistence of the highly combustible florets. However, there was no overall correlation between degree of serotiny and temperature requirements, nor with the other biological attributes assessed.Cone temperatures and follicle rupture in five co‐occurring Banksia species were monitored for an experimental spring burn in Banksia‐ dominated shrubland. Temperatures recorded at follicle surfaces were higher than those needed for follicle rupture in the four species with persistent florets. Critical temperatures were rarely reached for the weakly serotinous Banksia menziesii which possesses bare cones and an open canopy.
Reproduction and perennation of Chondrilla juncea L. (skeleton weed) in the Western Australian wheatbelt
Authors: PANETTA F. D. 
Published: August 2010

AbstractSurvivorship of first‐year plants of Chondrilla juncea was considerably higher on a deep yellow sand than on a yellow duplex soil. Mortality on the latter soil was associated with drying of the Al horizon during early summer. No plants produced seeds in their first year of growth on the duplex soil. However, during both years of the study, first‐year individuals of both forms of C. juncea produced viable seeds when growing on the deep sand. Higher population growth rates could be expected on deep sands, owing to a combination of earlier reproduction and greater survivorship through the first summer. It is suggested that whilst the entire wheatbelt might be climatically suitable for C. juncea, the invasive potential of this weed might be restricted by edaphic characteristics over large areas.
Contribution of oribatid and mesostigmatid soil mites in ecologically based estimates of global species richness
Authors: Osler Graham H. R. , Beattie Andrew J. 
Published: August 2010

AbstractErwin’s method for estimating total global species richness assumes some host‐specificity among the canopy arthropods. This study examined possible host habitat specialization in two major groups of soil arthropods, the oribatid and mesostigmatid mites, by sampling beneath three tree species:Eucalyptus pilularisSmith,Eucalyptus propinquaDeane and Maiden andAllocasuarina torulosa(Aiton) L. Johnson. The sample sites were in the Lansdowne State Forest, New South Wales, Australia and the three tree species were selected on the basis of their known differential effects on soil. Sampling was conducted over three seasons, and 79 oribatid and 34 mesostigmatid species were identified from 25 196 and 3634 individuals, respectively. Tree species had little effect on mite species composition with only three oribatid species and no mesostigmatid species identified as host‐habitat specialists using a niche breadth measure. Of mite species found underE. pilularis,E. propinquaandA. torulosatrees, 2%, 1% and 0% were defined as host‐habitat specialists, respectively. In contrast, tree species had significant and consistent effects on mite community structure, which differed in relative abundance of the oribatid species, their size class distributions and species rankings. In the mesostigmatid communities, there was a difference in the ranking of the mite species among tree species. Although it was demonstrated that tree species have an impact on the soil environment, the differences between tree species were insufficient to change species composition. The low degree of host‐habitat specialization suggested that other factors were more important for determining mite species composition at a site, and soil mite host‐habitat specialization may not make a large contribution to estimates of total global species richness using methods such as those proposed byErwin (1982).