bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence of pesticide resistance in medium‐sized mammalian pests: a case study with 1080 poison and Australian rabbits
Authors: Twigg Laurie E. , Martin Gary R. , Lowe Tim J. 
Published: March 2003

Summary

Toxicant‐resistance is a potential, or very real, problem with many pest‐control programmes world‐wide. However, apart from rodents, pesticide‐resistance has not been well documented in vertebrates. We assessed the potential impact of developing resistance to 1080 in rabbit populations with differing levels of historical exposure to 1080‐baiting programmes in south‐western Australia.
The sensitivity to 1080 of three out of the four populations of rabbits Oryctolagus cuniculus examined had decreased significantly since Australian rabbits were last tested over 25 years ago. The lethal dose50 (LD50) values for these populations, as determined from formal toxicity trials, ranged from 0·744 to 1·019 mg pure 1080 kg−1, and were significantly greater (P < 0·05) than the previously reported values for Australian rabbits (LD50 range 0·34–0·46 mg pure 1080 kg−1). The LD50 value for the fourth population (0·584 mg pure 1080 kg−1), which has had the least exposure to 1080, did not differ from that reported previously (P > 0·05).
The lethal dose99 (LD99) values for the four rabbit populations tested ranged from 1·181 to 1·666 mg pure 1080 kg−1, and suggested that, theoretically, all rabbits should be killed during routine baiting campaigns provided that there is no loss of active ingredient from the bait. In reality, the efficacy of 1080 poison bait laid in trails for controlling free‐ranging rabbits was reduced in those populations where rabbits had decreased sensitivity to 1080. Mean reductions in rabbit numbers 7–9 days after trail baiting of resistant and sensitive populations ranged from 51·2% to 65·2%, and from 76·4% to 76·5%, respectively.
These findings suggest that genetic resistance to 1080 is developing in at least some populations of Australian rabbits. This has world‐wide implications for agricultural protection and wildlife conservation programmes that rely on a 1080‐baiting strategy for reducing the impact of vertebrate pests.
Is habitat linearity important for small mammal communities on farmland?
Authors: Tattersall F. H. , Macdonald D. W. , Hart B. J. , Johnson P. , Manley W. , Feber R. 
Published: March 2003

Summary

Farmland is readily divisible into linear habitats such as hedges, and non‐linear habitats such as fields and woodlots. In agricultural landscapes, conservationists have generally focused on enhancing linear habitats, but there are few data from which to judge whether or not this is a good strategy for biodiversity.
We investigated whether the linear or non‐linear character of habitat patches, mediated by edge effects, has an impact on the abundance, diversity and richness of the small mammal communities that live within and between them.
In particular, we hypothesized, first, that edge effects cause narrow linear habitats to be avoided by specialists such as the bank vole Clethrionomys glareolus, but not by generalists such as the wood mouse Apodemus sylvaticus; secondly, that edge effects lead to specialists being present in atypical habitat, through excursions at the interface between two habitats.
We tested these hypotheses by live‐trapping small mammals in grids in the centres of three non‐linear farmland habitats (woodlots, set‐aside and crop fields) and in field boundaries consisting of a series of adjoining linear habitats. We compared mammal communities in the non‐linear habitats with the field boundary as a whole, and with the individual linear habitat elements within the boundary.
There was no evidence that specialists avoided linear habitats. Indeed, the field boundary was the most species‐rich habitat surveyed, and bank voles were more abundant in linear hedgerow than in non‐linear woodland. Bank voles were present in linear set‐aside and in the crop edge, but never in non‐linear blocks of set‐aside or crop, implying that they diffused out of the hedgerow into the adjacent habitats. There was no evidence of an effect of habitat linearity on field voles Microtus agrestis, wood mice or common shrews Sorex araneus.
Our results suggest that on uncropped land such as set‐aside, the linear or non‐linear character of habitats will make little difference to small mammal abundance and diversity. We advocate similar assessments for other taxa so that the effects of farm management and habitat configuration on biodiversity can be understood more fully.
Mechanisms of 5‐hydroxytryptamine‐induced inhibition in the porcine myometrium
Authors:   Kitazawa, Takaoka K. , Taneike T. 
Published: March 2003

1 The present experiments were designed to clarify the mechanisms of the inhibitory response of 5‐hydroxytryptamine (5‐HT) in the porcine uterine circular muscle. 2 Inhibitory responses induced by 5‐HT (1 n
m–1 μm) were not affected by apamin (1 μm), charybdotoxin (100 n
m) or glibenclamide (20 μm) but were significantly attenuated by 4‐aminopyridine (3 m
m) and tetraethylammonium (3 m
m). 3 Imidazole (100 μm) decreased but 3‐isobutyl‐1‐methylxanthine (30 μm), milrinone (30 μm) and Ro 20–1724 (10 and 30 μm) potentiated the 5‐HT‐induced inhibition. On the other hand, zaprinast (3–30 μm) had no significant effect on the inhibitory response of 5‐HT. 4 5‐HT caused a time (0–5 min)‐and concentration (1 n
m–1 μm)‐dependent increase in the tissue cyclic AMP level, but had no effect on the tissue cyclic GMP level. A significant correlation (P < 0.05) was observed between the inhibition of contraction and tissue cyclic AMP level. 5 The effect of 5‐HT on contractile force and cytosolic Ca2+ level ([Ca2+]i) was investigated using fura‐PE3‐loaded myometrial strips. A low concentration of 5‐HT (≤ 10 n
m) inhibited the spontaneous contraction without changing the amplitude of the spontaneous [Ca2+]i increase, but a higher concentration of 5‐HT (≥ 100 n
m) decreased the resting [Ca2+]i and inhibited both the spontaneous [Ca2+]i increase and spontaneous contraction. 6 High‐K+ (50 m
m) caused increases in muscle contractile force and [Ca2+]i. 5‐HT concentration‐dependently inhibited the high‐K+‐induced contraction (EC50, 45 n
m) with only a small decrease in [Ca2+]i increase. 7 Carbachol also caused increases in muscle contractile force and [Ca2+]i. 5‐HT significantly decreased both the carbachol‐induced contraction and [Ca2+]i increase, but was more potent at inhibition of contractile force than [Ca2+]i. 8 In Ca2+ ‐loaded myometrial strips, carbachol, but not caffeine, caused a transient increase in [Ca2+]i and contraction in the absence of external Ca2+ (EGTA, 1 m
m). 5‐HT inhibited both the carbachol‐induced increases in [Ca2+]i release and contractile force. 9 In the β‐escin permeabilized myometrium, 5‐HT significantly inhibited the Ca2+‐induced contraction. 10 The present results indicate that 5‐HT stimulates tissue cyclic AMP production, and inhibits the porcine uterine muscle contractility by a reduction in [Ca2+]i and in Ca2+ sensitivity of the contractile elements. Activation of K+ channels might be partially involved in 5‐HT‐induced inhibition of the myometrial contractility.
Characterization of mechanisms involved in presynaptic inhibition of sympathetic pressor effects induced by some 5‐HT1 receptor antagonists
Authors: Fernández M. M. , Calama E. , Morán A. , Martín M. L. , San Román L. 
Published: March 2003

1 In a previous study, we showed that the presynaptic inhibitory action of 5‐hydroxytryptamine receptor agonists on sympathetic pressor effects obtained in the pithed rats were mainly mediated by activation of 5‐HT1A and 5‐HT1D receptor subtypes. At the time, we observed that some 5‐HT1 receptors antagonists – WAY 100,635 and NAN‐190 (both 5‐HT1A receptor antagonists), methiothepin (a 5‐HT1,2,5,6,7 receptor antagonist) and spiperone (a 5‐HT1,2 receptor antagonist) – reduced per se the pressor effects obtained by electrical stimulation. The aim of the present work was to investigate the mechanism participating in this inhibitory effect. 2 The inhibition induced by WAY 100,635 (1000 μg kg−1, i.v.) was blocked after i.v. treatment with idazoxan, an α2‐adrenoceptor antagonist (300 and 1000 μg kg−1) and was not modified after i.v. treatment with propranolol, a β‐adrenoceptor antagonist (1000 μg kg−1) and sulpiride, a D2 receptor antagonist (1000 μg kg−1). The inhibition induced by spiperone (500 μg kg−1 i.v.) was significantly blocked by sulpiride (1000 μg kg−1) and was not modified by idazoxan or propranolol. 3 Sulpiride (1000 μg kg−1) partially blocked the inhibition induced by methiothepin (50 μg kg−1 i.v.). Only pretreatment with idazoxan (300 μg kg−1) modified the inhibition induced by NAN‐190 (100 μg kg−1 i.v.), such inhibition increasing after intravenous administration of idazoxan. 4 All the antagonists used in our experiments failed to inhibit the pressor responses elicited by i.v. noradrenaline administration. 5 The above results suggest that the inhibitory effects of these 5‐HT1 receptor antagonists are presynaptic in nature, but not related to the blockade of 5‐HT1 receptors subtypes. The simultaneous activation or inhibition of other receptor systems could explain the inhibition produced by each 5‐HT1 receptor antagonist studied.
Interannual variability of NDVI and its relationship to climate for North American shrublands and grasslands
Authors: Paruelo José M. , Lauenroth William K. 
Published: March 2003

Abstract. Our objective was to analyse the interannual variability of different characteristics of the seasonal dynamics of NDVI and their relationships with climatic variables for grassland and shrubland sites of North America. We selected twenty‐five sites located in relatively undisturbed areas. We analysed the variability of seven traits derived from the annual dynamics of the NDVI at each site: the annual integral, the difference between maximum and minimum NDVI, the dates of the inflection points of a double logistic model fitted to the NDVI curve, the difference between these dates, the date of maximum NDVI, and the coefficient of determination of the double logistic model.The temporal variability of traits that integrated aspects of primary productivity over the year was lower than those related to seasonality. This suggests that from year to year, grassland and shrubland ecosystems would differ more in the timing of production and senescence than in the total amount of carbon fixed. The integral of NDVI showed less temporal variability than annual precipitation. The coefficient of variation of both precipitation and the NDVI integral were positively related. The slope of the relationship was significantly lower than 1, indicating that the variability of ecosystem function is a lower proportion of the variability of annual precipitation in areas with a high relative variability of this climatic variable than in areas of low variability. The variability of most of the NDVI traits analysed showed a negative and, in general, non‐linear relationship with annual precipitation. The same kind of relationship has been reported elsewhere for annual precipitation and its coefficient of variation. Mean annual precipitation has been reported as the main control of above‐ground net primary production in grassland and shrubland ecosystems. Our results suggest that this climatic variable is also associated with the interannual variability of carbon gains, such as the primary production and its seasonality.
Environmental correlates of species richness for native freshwater fish in Oregon, U.S.A.
Authors: Rathert D. , White D. , Sifneos J. C. , Hughes R. M. 
Published: March 2003

Summary Aim To better understand how environmental factors affect fish species richness across the state of Oregon. Location Oregon, U.S.A. Methods A database showing collection locations of 4911 fish specimens in the Oregon State University museum was modified by the Oregon Natural Heritage Program to include probable occurrences, and mapped within a grid of 375 hexagons that cover the state. The individual species maps of freshwater fish in Oregon were reviewed and revised by thirty regional fish biologists and then synthesized into a single map of native species richness. We used regression tree analysis (RTA) and multiple linear regression (MLR) to assess patterns of fish species richness with twenty environmental, three anthropogenic, and two historical variables. Results RTA explained 66% of the variation in native species richness, associating richness with annual air temperature range, minimum January temperature, introduced species richness, and stream density. MLR explained 68% of native species richness variation and associated richness with maximum July temperature, air temperature range, standard deviation of monthly temperature, stream density, introduced species richness, and basin connectivity. Main conclusions We conclude that for these data and at this scale, native fish species richness in Oregon is associated with annual climatic extremes, spatial variability of climate, stream density, basin connectivity, and introduced fishes.
Woodland biodiversity, palaeo‐human ecology and some implications for conservation management
Authors: Tipping Richard , Buchanan James , Davies Althea , Tisdall Eileen 
Published: March 2003

SummaryThis paper appraises the role of prehistoric human societies in modifying the natural woodland biodiversity of several regions throughout Scotland. It draws attention to the likelihood that, contrary to popular belief, biodiversity was enhanced by interactions between agricultural communities and woodlands. The possible purposefulness of such interactions is discussed.Mindful of the present concern to re‐establish ‘native’ woodlands in many parts of northern Britain, we then review three approaches to the identification of native tree types in Scotland, and conclude that insufficient attention in reafforestation schemes is being paid to (a) the palaeoecological record as a record of native woodland or (b) the likely former high taxonomic diversity of woodlands. Both these failings will lead to the creation of new woodlands lacking in species diversity.
Plant survival in Iceland during periods of glaciation?
Authors: Rundgren Mats , Ingólfsson Ólafur 
Published: March 2003

SummaryAimThe paper addresses the classical question of possible plant survival in Iceland during the last glacial period in the light of a palaeobotanical record from northern Iceland, spanning the period 11,300–9000BP, including the Younger Dryas stadial. We review the Late Cenozoic fossil plant record, the past debate on glacial plant refugia in Iceland, and the evidence for ice‐free areas during the Weichselian.LocationThe investigated lake sediment record comes from Lake Torfadalsvatn, which is situated in the northwestern part of the Skagi peninsula in northern Iceland.MethodsThe sediment chronology was constructed from the cccurrence of the Vedde Ash and the Saksunarvatn ash, two well‐dated Icelandic tephras, together with the results from five AMS and conventional radiocarbon dates performed on bulk sediment samples. The vegetational reconstruction was based on detailed pollen analysis of the sediment sequence.ResultsThe pollen analysis revealed that many of the taxa present in the area prior to the Younger Dryas stadial continued to produce pollen during that cold event. The more or less immediate reappearance of a few other pollen taxa at the Younger Dryas‐Preboreal boundary suggests that these plants also survived, even if they did not produce sufficient pollen to be recorded during the Younger Dryas stadial.Main conclusionsWe conclude that the relatively high plant diversity found in high Arctic areas and present‐day nunataks in Iceland and Greenland, together with the fact that many plant species were able to survive the Younger Dryas stadial on the Skagi peninsula, suggest that species with high tolerance for climate fluctuations also survived the whole Weichselian in Iceland. This conclusion is supported by recent palaeoclimatic data from ice‐cores and deep‐sea sediments, indicating that Icelandic climate during the last glacial was only occasionally slightly colder than during the Younger Dryas stadial.
Distribution patterns of páramo plants in Ecuador
Authors: Sklenář P. , Jørgensen P. M. 
Published: March 2003

SummaryWe will analyse the geographical and vertical distributions of Ecuadorian high páramo plants. Lists of species were prepared for six Ecuadorian mountains, and floristic relationships among them were expressed by means of Sørensen's index of similarity. A mantel test was employed to analyse the pattern of geographical distribution of the species to see if the distance between the mountains was sufficient to explain the differences discovered. Altitudinal range and mean altitude of species occurrence were tested against the number of mountains from which the species were recorded using a Kruskal–Wallis nonparametric test. We found that distance as a single factor can not fully explain the pattern of floristic similarity shared by the mountains. Other important factors are involved. Altitudinal range of the species examined was positively correlated with their distribution in Ecuador. Species with a broad altitudinal occurrence were found on several mountains, whereas species with narrow altitudinal distribution were found on fewer mountains.
Analysis of plant species diversity with respect to island characteristics on the Channel Islands, California
Authors: Moody Aaron 
Published: March 2003

AbstractAimSpecies richness of native, endemic, and exotic plant groups is examined relative to island area, disturbance history, geological history, and other physical characteristics. Of particular interest are the biogeographic factors that underlie (a) differences in species‐area and species‐isolation relationships between plant groups; and (b) adherence or departure of individual islands and/or plant groups from expected patterns.LocationThe eight Channel Islands lie along the continental margin between the U.S./Mexico border and Point Conception, CA. They range in size from 2.6 to 249 km2, and are located from 20 to 100 km off the coast. The islands are known for their high degree of plant endemism, and they have undergone a long history of human occupation by indigenous peoples, followed by over a century of intensive grazing and other biotic disturbances.MethodsThe study is based on linear regression and residual analysis. Cases where individual islands and/or specific plant groups do not adhere to patterns expected under species‐area and species‐isolation paradigms, are evaluated with respect to other island characteristics that are not captured by considering only island size and isolation.ResultsAll three plant groups exhibit strong, positive relationships between species richness and island size. For native species, the variance that remains after consideration of island size is largely explained by island isolation. For exotic species, residuals from the species‐area relationship are unrelated to isolation. For endemic species, residuals from the species‐area relationship are negatively related to isolation. Several islands are outliers for endemic and exotic species, for which richness values are not explained by either island area or isolation.Main conclusionsSpecies‐area and species‐isolation relationships for native, endemic, and exotic plant groups differ in accordance with hypothesized differences in the biogeographic factors that govern species diversity for these three groups. Most notably, endemic richness increases with isolation, suggesting the influence of this variable on processes of speciation and relictualism. These general relationships persist despite a long and varied history of human activity on the islands. Analysis of residuals suggests that deviations from expected patterns correspond to island‐specific biogeographic factors. It is hypothesized that primary among these factors are land‐use history, island environmental characteristics, and community‐type richness.
Latitude and latitudinal extent: a global analysis of the Rapoport effect in a tropical mammalian taxon: primates
Authors: Harcourt A. H. 
Published: March 2003

AbstractAimAnalyses of the Rapoport effect (species at high latitudes have broader latitudinal ranges) usually indicate only a weak effect in the tropics. However, studies of tropical taxa are rare. This study used a global analysis of a tropical order, primates, to ask two questions. Is there a Rapoport effect in this tropical, terrestrial mammal, globally or per continent? If so, can the effect be explained by greater adaptability of higher latitude taxa.LocationGlobe.MethodsGeographical data for the majority of primates species are available. Genera, rather than the species, were the main data used because the genus is a more stable taxonomic level for this order. Regressions and Spearman correlations were used to test for the effect. Generic ranges are the sum of the constituent species’ ranges. In addition, phylogenetic effects were controlled for to minimize dependence of data.ResultsThe Rapoport effect is apparent globally when Madagascar and outlier taxa are excluded. It is also present separately in Africa, Asia and Madagascar when outlier genera are excluded, but not in South America. The effect persists globally, and in Africa and Asia when phylogeny is controlled for.Climatic variation (temperature or precipitation) correlates with either mid‐latitude or extent of latitude of genera in Africa, Asia and the Americas (insufficient data for Madagascar), but controlling for phylogeny confirms only the African and Asian correlations. The four measures of adaptability of taxa (number of dietary types, number of habitat types, body mass and number of species per genus) correlated variously with latitudinal extent of the taxa, but the correlations did not always match the existence of a Rapoport effect in the respective continents.Main conclusionsThe intercontinental variation apparent in the Rapoport effect in the tropics should be fruitful material for further study of the causes of the Rapoport effect. The discovery of significant associations of measures of adaptability with latitudinal extent in both the presence and the absence of a Rapoport effect indicates that care is needed in using such associations to explain the Rapoport effect.