bluuebunny/crossref_metadata_2025 huggingface dataset:
Enumeration of faecal coliforms from recreational coastal sites: evaluation of techniques for the separation of bacteria from sediments
Authors: Craig D.L. , Fallowfield H.J. , Cromar N.J.
Published: March 2003

Aims: To identify the most efficient techniques for the separation of micro-organisms from coastal sediments and, using these techniques, to determine the concentration of faecal indicator organisms in recreational coastal water and sediment. Methods and Results: Sediment samples were taken from a range of recreational coastal sites and subjected to various physical techniques to separate micro-organisms from sediment particles. Techniques investigated included manual shaking, treatment by sonication bath for 6 and 10 min, respectively, and by sonication probe for 15 s and 1 min, respectively. The use of the sonication bath for 10 min was the most successful method for removing micro-organisms from sediment particles where sediments consisted mainly of sand. When sediments contained considerable proportions of silt and clay, however, manual shaking was most successful. Faecal coliforms were then enumerated by membrane filtration in both water and sediment from three recreational coastal sites, chosen to represent different physical sediment characteristics, over a 12-month period. Faecal coliform concentrations were generally greater in sediment compared with overlying water for all samples. This was most evident in sediment consisting of greater silt/clay and organic carbon content. Conclusions: This study demonstrated the importance of sediment characteristics in determining the most efficient method for the separation of micro-organisms from coastal sediments. Sediment characteristics were also found to influence the persistence of micro-organisms in coastal areas. Significance and Impact of the Study: Recreational coastal sediments can act as a reservoir for faecal coliforms; therefore, sampling only overlying water may greatly underestimate the risk of exposure to potentially pathogenic micro-organisms in recreational waters.
Dopamine D2‐like receptors on human peripheral blood lymphocytes: a radioligand binding assay and immunocytochemical study
Authors: Amenta F. , Bronzetti E. , Felici L. , Ricci A. , Tayebati S. K.
Published: March 2003

1 Peripheral blood lymphocytes express dopamine D1‐like and D2‐like receptors which were investigated using radioligand binding assay and molecular biology techniques. Analysis of dopamine D2‐like receptors expressed by human peripheral blood lymphocytes with radioligand binding assay may offer a rapid technique for assessing receptor changes in disorders characterized by involvement of the dopaminergic system. However, the suitability of radioligand binding assay techniques to measure dopamine D2‐like receptors is questioned.

2 In view of the discrepancy between data of dopamine D2‐like receptor determination with molecular biology and radioligand binding assay techniques, we have assayed dopamine D2‐like receptors expressed by human peripheral blood lymphocytes using as radioligands the dopamine receptor agonist 7‐[3H]‐hydroxy‐N,N‐di‐n‐propyl‐2‐aminotetraline ([3H]‐7‐OH‐DPAT) and two antagonists ([3H]‐spiperone and [3H]‐nemonapride).

3 Analysis of saturation curves revealed a concentration‐dependent binding of all compounds to human peripheral blood lymphocytes. Dissociation constant (Kd) values averaged between 0.15 and 0.40 n
m for different radioligands. The maximum density of binding sites (Bmax) was low, ranging from 4.15 ± 0.05 fmol/106 cells with [3H]‐spiperone and 8.66 ± 0.04 fmol/106 cells with [3H]‐7‐OH‐DPAT.

4 Displacement curves of [3H]‐7‐OH‐DPAT, [3H]‐spiperone and [3H]‐nemonapride binding to human peripheral blood lymphocytes revealed, using radioligand concentrations giving the highest specific:non‐specific binding ratio, a pharmacological profile consistent with the labelling of dopamine D2‐like receptors. The use of higher radioligand concentrations resulted in a poorly displaceable and characterizable binding.

5 Detection of dopamine D2, D3 and D4 receptor immunoreactivity in cytospin centrifuged peripheral blood lymphocytes revealed dopamine D3 and D4 but not D2 receptor immunostaining.

6 The above findings indicate in agreement with molecular biology studies, that dopamine D2‐like receptors expressed by human peripheral blood lymphocytes belong to the D3 and D4 receptor subtypes. These receptors are detectable using either dopamine D2‐like receptor agonists and antagonists as radioligands if controlled experimental conditions are followed. The standardisation of immunocytochemical techniques for detecting human peripheral blood lymphocyte dopamine receptors may contribute to clarify their role in lymphocyte function or as a peripheral marker of the status of the dopaminergic system.
P2X7 receptors in rat parotid acinar cells: formation of large pores
Authors: Gibbons Simon J. , Washburn Katrina B. , Talamo Barbara R.
Published: March 2003

1 Permeabilization of cells mediated by P2X7 receptors occurs to varied degrees in native and heterologous expression systems. Previous studies on P2X7 receptors in parotid acinar cells suggested that ATP does not permeabilize these cells.

2 Modification of the assay conditions showed that ATP permeabilizes freshly dissociated rat parotid acinar cells to the fluorescent dye YOPRO‐1.

3 The pharmacological and physiological properties of this effect indicate that permeabilization is mediated by the P2X7 receptor. Adenosine 5′‐triphosphate (ATP) and 3′‐O‐(4‐benzoyl)benzoyl adenosine 5′‐triphosphate (BzBzATP) were effective agonists with EC50 values of 49.3 and 0.6 μM, respectively.

4 Permeabilization was best observed in low divalent cation concentrations and at physiological temperatures. Previous studies failed to detect permeabilization because of the sensitivity of this effect to temperature and divalent cations.

5 An important consideration in understanding the effect of divalent cations is that the fluorescence of YOPRO‐1/nucleic acid complexes is directly quenched by addition of divalent cations. This must be considered if quantitative study of the interaction of divalent cations with P2X7 receptors is carried out using fluorescent DNA‐binding dyes.

6 In summary, our data show that P2X7 receptors in parotid acinar cells can form large pores in the plasma membrane. This property likely contributes to signalling and may be cytotoxic and have particular significance in damaged or inflamed salivary glands.
Effects of restraint stress on responsiveness of atria and vas deferens in Sprague–Dawley rats
Authors: Singh A. , Einstein R. , Lavidis N.
Published: March 2003

1 The effects of stress in rats were evaluated by measuring changes in body weight and in responsiveness to noradrenaline (NA) in the isolated vas deferens and atria after the animals had been exposed to restraint or restraint and isolation.

2 Animals which were subjected to restraint alone (1 h day−1 for 3, 7 or 28 days) had a significantly reduced rate of body weight gain. This effect was not potentiated by the additional stress of isolation.

3 Restraint alone did not produce significant changes in the responsiveness of the vas deferens to NA. However, adding isolation to restraint, as an additional stress, produced a further leftward shift of the NA dose–response curve for the vas deferens, so that there was a significant increase in sensitivity compared with control.

4 There was a significant rightward shift in the NA dose–response curves or reduction in sensitivity in the atria from animals which had been restrained for 7 or 28 days. Isolation did not produce a further rightward shift in the NA dose–response curve.

5 The results from this study indicate that the stress associated with repeated restraint reduces the rate of weight gain and reduces the responsiveness of the atria to NA. The responsiveness of the vas deferens to NA was increased by stress, but the combined effect of isolation and restraint was required to produce a significant effect. The differences in the effects of stress on these tissues could be associated with differences in presynaptic receptor populations.
Biogeographical links between steppe insects in the Monegros region (Aragón, NE Spain), the eastern Mediterranean, and central Asia
Authors: Ribera Ignacio , Blasco‐Zumeta Javier
Published: March 2003

Sixty‐two species of insects in thirty‐six families and nine orders, plus one species of Acari, were found to have disjunct distributions, or to belong to species groups with disjunct distributions, between the steppe areas in the central Monegros region (NE Spain) and the steppes in the eastern Mediterranean or central Asia. The accumulation of examples of a wide range of taxonomic groups, and the phyletic links of apparent endemic species of the central Ebro valley with eastern species, are considered to support the pre‐Pleistocene origin of their relict distributions, associated with the persistence of steppe habitats over gypsiferous soils in the area since the Late Tertiary. The case of disjunct distributions of phytophages and their parasitoids on plants with disjunct distributions themselves, such asKrascheninnikovia ceratoides(L.) Gueldenst. (Chenopodiaceae) or theJuniperus thuriferaL. −J. excelsaBieb. complex (Cupressaceae), would seem to provide strong evidence supporting the continuity of their presence in the central Ebro valley through the Quaternary.
Present‐day and mid‐Holocene biomes reconstructed from pollen and plant macrofossil data from the former Soviet Union and Mongolia
Authors: Tarasov Pavel E. , Webb III Thompson , Andreev Andrei A. , Afanas’eva Natalya B. , Berezina Natalya A. , Bezusko Ludmila G. , Blyakharchuk Tatyana A. , Bolikhovskaya Natalia S. , Cheddadi Rachid , Chernavskaya Margarita M. , Chernova Galina M. , Dorofeyuk Nadezhda I. , Dirksen Veronika G. , Elina Galina A. , Filimonova Ludmila V. , Glebov Feliks Z. , Guiot Joel , Gunova Valentina S. , Harrison Sandy P. , Jolly Dominique , Khomutova Valentina I. , Kvavadze Eliso V. , Osipova Irina M. , Panova Nata K. , Prentice I. Colin , Saarse Leili , Sevastyanov Dmitrii V. , Volkova Valentina S. , Zernitskaya Valentina P.
Published: March 2003

Fossil pollen data supplemented by tree macrofossil records were used to reconstruct the vegetation of the Former Soviet Union and Mongolia at 6000 years. Pollen spectra were assigned to biomes using the plant‐functional‐type method developed by Prentice et al. (1996). Surface pollen data and a modern vegetation map provided a test of the method. This is the first time such a broad‐scale vegetation reconstruction for the greater part of northern Eurasia has been attempted with objective techniques. The new results confirm previous regional palaeoenvironmental studies of the mid‐Holocene while providing a comprehensive synopsis and firmer conclusions. West of the Ural Mountains temperate deciduous forest extended both northward and southward from its modern range. The northern limits of cool mixed and cool conifer forests were also further north than present. Taiga was reduced in European Russia, but was extended into Yakutia where now there is cold deciduous forest. The northern limit of taiga was extended (as shown by increased
Picea pollen percentages, and by tree macrofossil records north of the present‐day forest limit) but tundra was still present in north‐eastern Siberia. The boundary between forest and steppe in the continental interior did not shift substantially, and dry conditions similar to present existed in western Mongolia and north of the Aral Sea.
Pollen‐based biome reconstructions for China at 0 and 6000 years
Authors: Yu Ge , Prentice I. Colin , Harrison Sandy P. , Sun Xiangjun
Published: March 2003

Biomization provides an objective and robust method of assigning pollen spectra to biomes so that pollen data can be mapped and compared directly with the output of biomgeographic models. We have tested the applicability of this procedure, originally developed for Europe, to assign modern surface samples from China to biomes. The procedure successfully delineated the major vegetation types of China. When the same procedure was applied to fossil pollen samples for 6000 years ago, the reconstructions showed systematic differences from present, consistent with previous interpretations of vegetation changes since the mid‐Holocene. In eastern China, the forest zones were systematically shifted northwards, such that cool mixed forests displaced taiga in northeastern China, while broad‐leaved evergreen forest extended c. 300 km and temperate deciduous forestc. 500–600 km beyond their present northern limits. In northwestern China, the area of desert and steppe vegetation was reduced compared to present. On the Tibetan Plateau, forest vegetation extended to higher elevations than today and the area of tundra was reduced. These shifts in biome distributions imply significant changes in climate since 6000 years ago that can be interpreted qualitatively as a response to orbital forcing and its secondary effects on the Asian monsoon.
Structure of communities of ground‐dwelling animals at the junction of two phytogeographic zones
Authors: Krasnov B. R. , Shenbrot G. I.
Published: March 2003

Changes in the structure of tenebrionid beetle, lizard and rodent communities along the aridity gradient that determines the position of a phytogeographic province boundary were studied to test: (1) whether there are two different species assemblages on either side of the boundary (2) the extent of their differentiation and (3) if they are composed of different or the same faunal elements. Several ordination methods were tested for their capacity to reflect community structure, and discriminant function analysis was selected as the primary method of ordination. Each of the ordination axes reflected a complex environmental gradient. The latter was different for each taxon. The gradient of productivity cross‐cuts ecological space for each animal group in an individual manner. Revealed spatial assemblages of species were related to the level of productivity. There was one assemblage of species at high productivity and one or two assemblages occurred at low productivity in each taxon. The α–diversity curve of rodents changed weakly along the productivity gradient, whereas those of lizard and beetle communities were distinctly unimodal and had maxima near the middle of the gradient. β–diversity curves of rodents had a concave shape, but those of lizard and beetle communities increased from low productivity values to the middle of the gradient and after that weakly declined to the upper (productive) end of the gradient. Seven types of ranges or areographic groups of species were distinguished. Each species assemblage was composed of different faunal elements. Comparison of the results of ecological and areographic analyses demonstrated that two assemblages of rodents and lizards represent different guilds within the same community rather than different communities. The phytogeographic border for these taxa is an ecological rather than a geographical boundary. The difference between the two tenebrionid assemblages appears to be zoogeographical rather than ecological, and coincides with the phytogeographic boundary.
Phylogeny and biogeography in the evolution of migration: shorebirds of the Charadrius complex
Authors: Joseph Leo , Lessa Enrique P. , Christidis Leslie
Published: March 2003

Aim We explore whether molecular phylogeny and biogeography can complement evolutionary ecology in developing a method to address a long‐standing issue in the evolution of migration: have migrations between breeding and non‐breeding grounds, which may be on different continents, evolved through origins in the breeding grounds with successive shifts of the non‐breeding distribution or vice versa?

Methods To accommodate the biology of migration, we treated breeding and non‐breeding distributions as characters to be mapped onto a phylogeny derived from mitochondrial DNA sequence data and so examined the ancestral home issue as a study in the direction of character evolution.

Results Our main findings from applying this approach to a subset of the Charadrius complex of shorebirds (Aves: Charadriinae) are that a case can be made for shifts of breeding distributions having occurred in the ancestries of C. alexandrinus and C. veredus as those species evolved their present migration patterns. Our results also argue for a southern hemisphere origin (specifically South America) for the Charadrius complex as a whole. A South American origin implies other shifts in breeding distributions having occurred in the evolution of the species C. semipalmatus and C. vociferus. On applying the methods we developed for dealing with phylogenetic uncertainty, these results are reinforced and the merit of testing them further is suggested.

Conclusions By way of a new approach to the evolution of migration, our study adds to a consensus emerging from the evolutionary ecology of migrant birds, arguing that shifts of breeding distributions are commonly, though not necessarily exclusively, involved in the evolution of migration.
An alternative hypothesis for the origin of Amazonian bird diversity
Authors: Nores Manuel
Published: March 2003

AimTo determine the origin of the high diversity of birds and other animals and plants in Amazonia. Previous hypotheses are: palaeogeography hypothesis, river hypothesis, river‐refuge hypothesis, refuge hypothesis, disturbance‐vicariance hypothesis, gradient hypothesis, pest‐pressure hypothesis, intermediate disturbance hypothesis, riverine disturbance hypothesis, models of fine‐scale habitat heterogeneity, lake hypothesis, and museum hypothesis.

MethodsAt present there is agreement between areas of high species diversity and sites located over 100 m. As these sites would have been islands during a sea‐level rise of this value, it was important to determine the probable distribution of these islands in Amazonia during a marine transgression. For that purpose, I traced the 100 m contour line from topographic maps.

ResultsTwo broad marine transgressions would have been produced from the Atlantic Ocean via the Amazon and Orinoco rivers. Two very large islands would have been formed to the north of the Amazon River, and other islands and archipelagos would have been formed along the coastal lowlands of Guiana, and at the periphery of the Amazon basin. The area located between the SolimoÃ½es and Negro rivers and in the lower Branco would have been completely covered by the sea.

Main conclusionsA substantial part of the high diversity of forest and nonforest birds in lowland Amazonia can be hypothetysed to have originated during sea‐level rises of about 100 m in the Quaternary and late Tertiary. These transgressions would have fragmented the Amazonian lowland into a large number of true islands and archipelagos, thus favouring active allopatric speciation. Values appreciably higher than 100 m above the present sea‐level during previous periods of the Tertiary would have produced segregation of the biota earlier than the Tertiary–Quaternary boundary. Sea‐level rises and vegetational changes (by aridity or cooling) would thus have driven the speciation pump, and local disturbances and other processes, would maintain the diversity.
Early Holocene plant and animal remains from North‐east Greenland
Authors: Bennike Ole , Björck Svante , Böcher Jens , Hansen Louise , Heinemeier Jan , Wohlfarth Barbara
Published: March 2003

Aim The aim of this paper is to describe and interpret early Holocene floras and faunas.

Location The floras and faunas come from various localities in North‐east Greenland.

Methods Sediment samples were wet sieved, and macrofossils picked out and dated by the AMS radiocarbon‐dating method.

Results
Sediments, dated to the first centuries after the last glacial stage came to an abrupt end, contain a macroflora of bryophytes and a few herbs, and we suggest that these plant remains represent a pioneer vegetation entirely without woody plants. The named species of herbs are either confined to the northern parts of Greenland at present, or they become increasingly more important towards the north. Crowberry is the oldest woody plant recovered; it was present at 10.4 cal. ka BP, and it appears to have been common during the early Holocene in East Greenland.

Main conclusions We suggest that the majority of the extant flora of vascular plants of East Greenland arrived by long distance dispersal during the Holocene. Some species may also have arrived during the late‐glacial, and a few hardy species that are adapted to low summer temperatures may have survived the last glacial stage in nonglaciated areas. Some hardy animals may also have survived, but the majority of the fauna are considered Holocene immigrants. We suggest that migrating birds and storms, perhaps in combination, are under‐appreciated dispersal vectors.
From bobolinks to bears: interjecting geographical history into ecological studies, environmental interpretation, and conservation planning
Authors: Foster David R.
Published: March 2003

In these days of supercomputer‐based global climate models, large ecosystem experiments including Biosphere II, and aircraft‐borne sensors of ozone holes it is often overlooked that many fundamental insights into ecological processes and major environmental issues come not through reductionist or high‐tech studies of modern conditions but from thoughtful consideration of nature’s history. In fact, it is foolhardy to make any ecological interpretation of modern landscapes or environments or to formulate policy in conservation or natural resource management without an historical context that extends back decades, at least, but preferably centuries or millennia. Oftentimes, the ecological and conservation communities, in their search for more detail on the present and simulation of the future, appear to have forgotten the value of a deep historical perspective in research and application. However, the willingness of the geographical sciences to embrace broad temporal and spatial perspectives and to consider cultural as well as natural processes is worth emulating as we address environmental subjects in the new millennium.
Pollen signatures of the arid to humid grasslands of North America
Authors: Hoyt C. A.
Published: March 2003

Aim

Many studies have shown that the pollen record can be used to distinguish grasslands from other vegetation types at the biome level, but few have attempted to use pollen to distinguish between specific prairie types. This study was undertaken to determine whether the tallgrass, mixed‐grass, shortgrass, and desert grasslands of North America have unique pollen signatures that can be used to distinguish between grasslands at the community‐scale, rather than at the scale of the biome.

Location

Data was collected from the southern North American grasslands of Oklahoma, Texas, and New Mexico.

Methods

High resolution, annual pollen‐influx data gathered in Tauber pollen traps were analyzed using cluster analysis to summarize the pollen signature from each trap locality and to catagorize the samples into discrete grassland groups.

Results

Based on the results of the cluster analysis, each grassland produces a distinctive pollen signature that can be used to distinguish between grassland types. In addition, pollen influx is shown to be closely correlated with annual precipitation.

Main conclusions

The ability to distinguish between grassland types and to relate annual influx to annual precipitation has important implications for understanding the evolution of grasslands during the Holocene, for palaeoclimatic studies, and for monitoring ecosystem changes in the present‐day grasslands.
Ichthyofaunistic biogeography of the Japan (East) Sea
Authors: Kafanov Alexander I. , Volvenko Igor V. , Fedorov Vladimir V. , Pitruk Dmitry L.
Published: March 2003

Aim

The aim of the present study is the distribution analysis of species richness of ichthyofauna at the east and west coasts of the Japan Sea for the purpose of identification of natural biogeographic boundaries, subsequent faunistic zoning and comparison between faunistic and bioclimatic (bio‐oceanographic) zoning patterns.

Location

Japan Sea (Korean–East Sea).

Methods

All statistical procedures are based on well‐tried and widely accepted numerical methodology and the statistica program package. For identifying the statistically meaningful (non‐random) maxima and minima in species richness, arithmetical differences in the number of species at ith and i + 1st latitudes are calculated, also trend residuals obtained by smoothing the moving average by three points and residuals in polynomial trends are analysed. Subsequent clustering of species lists for separate biogeographical units marked by local maxima and minima in species richness permits to identify the extent of mutual correspondence between the units and to make an outline for faunistic zoning. Similarity degree of faunistic lists was estimated in terms of Czekanowski–Sörensen coefficient.

Results

Quantitative analysis of latitudinal distribution of species richness (1130 species) of the Japan Sea ichthyofauna is indicative of the position of the following 10 local maxima and minima: at 35, 40, 43, 47, 49 and 51° N on the west coast and at 36, 39, 43 and 46° N on the east coast. In most cases local minima of the polynomial trend residuals are coincident with southern boundaries of faunistic units while local maxima with northern boundaries. Separated analysis of qualitative composition of ichthyofauna of the west and east coasts of the Japan Sea discloses 11 areas of the greatest faunistic similarity.

Main conclusions

The latitudinal variations in the species richness near both sea coasts represent an alternation between relatively flattened smooth portions (each 1 unit long) and sufficiently steep jumps between them. Regular interchange between local minima and maxima of species richness is accountable to spatial non‐uniformity of hydrological structure resulting from alternation of variously directed and differently heated (warm and cold) circulations of waters and frontal zones. It is notable that faunistic zoning does not initially require any exact knowledge of biotic taxonomic composition and may be produced only from the variation pattern of the species richness under study. The suggested faunistic zoning scheme distinguishes the following provinces: South Korea, East Korea, South Primorie, North Primorie, Northern Japan Sea, Middle Honshu, Uetsu, Tsugaru, Soya and West Sakhalin. The comparison between faunistic units and distribution of temperature parameters and currents permits identification of subarctic, cold–temperate, mild–temperate and warm–temperate bioclimatic zones existing in the Japan Sea.
Detecting migration routes and barriers by examining the distribution of species in an apomictic species complex
Authors: Tyler Torbjörn
Published: March 2003

Aim

The distribution of taxa (‘microspecies’) in the apomictic species complexes Hieracium L. sect. Hieracium and H. sect. Vulgata (Griseb.) Willk. and Lange have been analysed to test whether the geographical distribution of species within each complex will reflect historical processes and phenomena, e.g. historical barriers to migration and range expansion. It is argued that apomictic species can be used for phylogeographic analysis in the same way as organelle haplotypes or multilocus genotypes.

Location

The investigated area is the Nordic countries excluding Iceland, together with the Baltic islands of Saarema (Estonia) and Rügen (Germany).

Methods

The presence or absence of 160 species of H. sect. Hieracium and 165 species of H. sect. Vulgata was recorded in 39 geographical areas. Based on this dataset, Jaccard similarity indices were calculated and subjected to upgma cluster analysis and non‐metric multidimensional scaling (MDS).

Results

For both species complexes, the larger water surfaces were found to represent discontinuities in species composition, interpreted as migration barriers. Some inland migration barriers were also indicated, e.g. in northern‐central Sweden. The Scandes seems to have constituted a migration barrier for H. sect. Vulgata. Some areas in south‐western Sweden represent discontinuities in the distribution of species within H. sect. Hieracium.

Main conclusions

The revealed geographical patterns in species composition, as well as the differences in the patterns for the two species complexes, are readily explainable as reflecting historical migration routes and barriers. Further analysis using apomictic taxa as ‘markers’ may give important phylogeographic insights. The pros and cons of using microspecies, as opposed to molecular markers, in historical biogeography is discussed.
Maps of Pleistocene sea levels in Southeast Asia: shorelines, river systems and time durations
Authors: Voris Harold K.
Published: March 2003

Aim

Glaciation and deglaciation and the accompanying lowering and rising of sea levels during the late Pleistocene are known to have greatly affected land mass configurations in Southeast Asia. The objective of this report is to provide a series of maps that estimate the areas of exposed land in the Indo‐Australian region during periods of the Pleistocene when sea levels were below present day levels.

Location

The maps presented here cover tropical Southeast Asia and Austral‐Asia. The east–west coverage extends 8000 km from Australia to Sri Lanka. The north–south coverage extends 5000 km from Taiwan to Australia.

Methods

Present‐day bathymetric depth contours were used to estimate past shore lines and the locations of the major drowned river systems of the Sunda and Sahul shelves. The timing of sea level changes associated with glaciation over the past 250,000 years was taken from multiple sources that, in some cases, account for tectonic uplift and subsidence during the period in question.

Results

This report provides a series of maps that estimate the areas of exposed land in the Indo‐Australian region during periods of 17,000, 150,000 and 250,000 years before present. The ancient shorelines are based on present day depth contours of 10, 20, 30, 40, 50, 75, 100 and 120 m. On the maps depicting shorelines at 75, 100 and 120 m below present levels the major Pleistocene river systems of the Sunda and Sahul shelves are depicted. Estimates of the number of major sea level fluctuation events and the duration of time that sea levels were at or below the illustrated level are provided.

Main conclusions

Previous reconstructions of sea‐level change during the Pleistocene have emphasized the maximum lows. The perspective provided here emphasizes that sea levels were at their maximum lows for relatively short periods of time but were at or below intermediate levels (e.g. at or below 40 m below present‐day levels) for more than half of each of the time periods considered.
What is the upper size limit for cosmopolitan distribution in free‐living microorganisms?
Authors: Wilkinson David M.
Published: March 2003

A comparison of testate amoebae assemblages from the Arctic and Antarctic (areas of similar habitat a maximum distance apart) is used to try and answer the question ‘What is the upper size limit for cosmopolitan distribution in free‐living microbes?’ Species restricted to either the Arctic or Antarctic exhibited sizes up to 230 μm while the largest cosmopolitan species was 135 μm in size. Comparison of the testate assemblages using a multivariate classificatory technique (TWINSPAN) also suggested more restricted distribution for the larger species. There was a negative relationship between species size and number of sites at which it was recorded (rs=−0.261, P < 0.05), with all the more widespread species having a size of below 100 μm. It is suggested that for testate amoebae cosmopolitan distributions become common below 100–150 μm. This suggests that most species of testate (indeed most free‐living microbes) have low species richness because of lack of opportunities for allopatric speciation as most are below 100 μm and so geographical isolation is unlikely. It is suggested that if this is correct, only the largest free‐living microbes (> 150 μm) are likely to be of conservation concern because of their smaller ranges. However, I point out that currently different studies are giving very different answers to the question, how ubiquitous and species rich are free‐living microbes? The subject requires further work to try and reconcile these different results.
When simplicity is not parsimonious: a priori and a posteriori methods in historical biogeography
Authors: Van Veller Marco G. P. , Brooks Daniel R.
Published: March 2003

Despite using the same null hypothesis, a priori and a posteriori approaches in historical biogeography differ fundamentally. Methods such as Component Analysis (CA) and Reconciled Tree Analysis (RTA) may eliminate or modify input data in order to maximize fit to the null hypothesis, by invoking assumptions 1 and 2. Methods such as Brooks Parsimony Analysis (BPA) modify the null hypothesis, if necessary, to maintain the integrity of the input data, as required by assumption 0. Two exemplars illustrate critical empirical differences between CA/RTA and BPA: (1) CA rather than BPA may select the incorrect general area cladogram for a set of data (2) BPA, not RTA, provides the most parsimonious interpretation of all available data and (3) secondary BPA, proposed in 1990, applied to data sets for which dispersal producing areas with reticulate histories is most parsimonious, provides biologically realistic interpretations of area cladograms. These observations lead to the conclusion that BPA and CA/RTA are designed to implement different research programmes based on different conceptual frameworks. BPA is designed to assess the biogeographic context of speciation events, whereas CA/RTA are designed to find the best fitting pattern of relationships among areas based on the taxa that inhabit them. Unique distributional elements and reticulate (hybrid) histories of areas are essential for explaining complex histories of speciation. The conceptual framework for BPA, thus, assumes biogeographical complexity, relying on parsimony as an explanatory tool to summarize complex results, whereas CA/RTA assumes biogeographical simplicity, assuming conceptual parsimony a priori.
Plant diversity and endemism in sub‐Saharan tropical Africa
Authors: Linder H. P.
Published: March 2003

Aim

This paper has as its central aim the location of centres of species richness and endemism in the sub‐Saharan African flora. Previous postulation of these centres has been based on an intuitive interpretation of distributional data; this paper provides a test of these centres. A second aim is to establish whether the two indices, richness and endemism, locate the same centres. Thirdly the relationship between species richness and endemism, and latitude and rainfall are explored.

Location

The study area includes much of sub‐Saharan Africa, but excludes the species‐poor southern margin of the Sahara and the Namib–Kalahari regions.

Methods

Analyses were based on 1818 species, scored on a 2.5 × 2.5 degree grid. Species richness was inferred from a simple grid‐diversity count; endemism was determined by three measures: the number of species restricted to two grids, the sum of the inverse of the ranges of the component species of each grid, and the proportion of the species in each grid that have restricted ranges.

Results

The African flora shows a remarkably profound patterning, both in species richness and endemism. The two measures locate largely the same centres, although the rank order among them differs. These centres are: the Cape Floristic Region, East Coast, Congo‐Zambezi watershed, Kivu, Upper and Lower Guinea. Richness is strongly related to maximum rainfall, but there are no obvious correlations between modern climate and endemism. Species richness and endemism north of the equator is much more concentrated into centres than south of the equator.

Main conclusions

There are strongly developed refugia in sub‐Saharan Africa. North of the equator, these refugia are sharply delimited and rather small, separated by large areas of very low endemism. South of the equator endemism tends to be more generally distributed. Variation in species richness in sub‐Saharan Africa can be explained largely by modern rainfall, while endemism may be related to palaeoclimatic fluctuations. Both species richness and endemism show a strong skewing towards the south, indicating that the fluctuations in the Sahara might have influenced the modern distribution of plants in Africa.
Psychobiogeography: meanings of nature and motivations for a democratized conservation ethic
Authors: Trudgill Stephen
Published: March 2003

The language of ecosystem science is pervaded by value‐laden terms such as pristine, fragile, disturbance, balance, dominance and alien species. Such terms have high status and are often used in the rhetoric of the conservation ethic. Here, I consider the possibility of the use of less value‐laden terms such as change, increase, decrease and so on. This would distinguish between values and perceived trends or states and leave ecosystem science to deal with what is verifiable. However, I also consider the opposite point of view, in that the value‐laden terms, like ‘the balance of nature’, relate to how a wide range of people feel about nature and are effective emotive motivators of the conservation ethic in society, providing a common language for a discourse between ecosystem scientists and other people.
Why isSolidago shortiinarrowly endemic andS. altissimageographically widespread? A comprehensive comparative study of biological traits
Authors: Walck Jeffrey L. , Baskin Jerry M. , Baskin Carol C.
Published: March 2003

Aim and location

Solidago shortiiT. and G. occurs in a small area of north‐central Kentucky (USA), whereasS. altissimaL. is geographically widespread in North America and is naturalized in Europe, Asia and Australia.Solidago shortiigrows in a variety of habitats, but primarily in rocky/shallow soil areas, andS. altissimaoccurs in adjacent old fields/pastures. The purpose of this study was to identify differences in the biology of these two species that might contribute to an explanation for differences in their geographical distribution and habitat.

Methods

Results of an extensive literature review and of original research by the authors were used in a detailed comparison of the two species. The most ecologically relevant aspects of the biology investigated were morphology, genetics, geography, life cycle, life history, reproductive biology, physiology, biotic interactions and response to disturbance.

Results

AlthoughS. shortiiandS. altissimaare quite similar in many aspects of their biology, there are some important differences.Solidago altissimais a better competitor thanS. shortiivia its greater height, larger leaf area and more extensive clonal growth. On the other hand,S. shortiiis a better drought‐stress tolerator thanS. altissimavia allocation of a higher percentage of biomass to roots, higher root/shoot ratio and (seemingly) greater capacity to maintain leaf turgor (i.e. not wilt as readily) under xeric conditions. Moreover, higher seed production inS. altissimaand its capacity to form a larger‐ and longer‐lived soil seed bank thanS. shortiiprobably contribute to differences in colonization abilities. Landscape disturbances and metapopulation dynamics are important factors in maintenance of the species population ofS. shortii, and in prevention of its extinction.

Main conclusions

Solidago shortiiprobably is a relatively young species that as had insufficient time to expand its range. Furthermore, it is not well suited for migration to, or colonization of, habitats outside its range due to poor competitive and colonization abilities.
Modelling butterfly distribution based on remote sensing data
Authors: Luoto Miska , Kuussaari Mikko , Toivonen Tuuli
Published: March 2003

Aim

We tested the usefulness of satellite based remote sensing data and geographical information system (GIS) techniques (1) in explaining the observed distribution of the threatened clouded apollo butterfly (Parnassius mnemosyne) and (2) in predicting the occurrence of the butterfly in two independent test areas with different landscape structure.

Location

The three study areas are located along the rivers Rekijoki and Halikonjoki in a boreal agricultural landscape in south‐western Finland (60°40′ N; 23°20′ E).

Methods

Landsat satellite images were used to generate habitat maps of the three study areas. Topographical variables were calculated from a digital elevation model. These data were used to construct a multiple logistic regression model fitted with the observed occurrence of clouded apollo in 126 grid squares of 0.25 km2within an area of 31.5 km2(model building area). The parameterized model was used to predict the occurrence of the butterfly in an adjacent test area with a similar landscape structure as in the model building area, as well as in a more distant test area with a more fragmented pattern of semi‐natural grassland.

Results

In the model building area probability of clouded apollo occurrence increased with connectivity of semi‐natural grassland, cover of deciduous forest, cover of semi‐natural slope grassland and topographical heterogeneity. The model accuracy was high, the correct classification rate being 98.4% overall and 95.0% for the butterfly presence squares. In both test areas the overall correct classification of the model prediction was high (c. 92%). However, in predicting the actual butterfly presence squares the model succeeded substantially better in the adjacent than in the distant test area (correct classification rates 91.3% and 66.7%, respectively).

Main conclusions

The results showed that the distribution of a habitat specialized butterfly may be quite successfully explained and predicted based on pure satellite imagery and topographical data. Nevertheless, the decrease of accuracy of the model prediction when applied to a different landscape structure than the one in which the model was parameterized suggests that the useful application of such models is limited by the environmental variability of the original model building data.
Quaternary evolutionary history of Austrocedrus chilensis, a cypress native to the Andean–Patagonian forest
Authors: Pastorino M. J. , Gallo L. A.
Published: March 2003

Aim

The Quaternary life history of a species determines its current range and the degree and distribution of its present genetic variation. Past climates, ecological relationships and disturbances in connection to evolutionary factors have determined the genetic and geographical distribution patterns of the current vegetation, and consequently, evolutionary processes can be inferred from those patterns. The aim of the present study is to find a plausible evolutionary explanation for the current natural range and genetic variation patterns of Austrocedrus chilensis (D. Don) Florin et Boutelje in Argentina.

Location

The studied species ranges naturally over a narrow strip not wider than 50 km that runs parallel to the Cordillera de los Andes from 32°39′ S in Chile to 43°44′ S in Argentina. The studied populations are located in the Argentine range, especially in its central part.

Methods

Information on palynological data, current geographical distribution and on amount and distribution of genetic variation of the species in Argentina was the basis for an integrating analysis and discussion.

Results

Palynological evidence of the past reported the presence of A. chilensis before and immediately after last glaciation on the east side of the Andes. The most conspicuous present populations of A. chilensis are located in areas that were covered by ice during the Last Glacial Maximum. The allelic multiplicity and diversity as well as the population differentiation of the species in Argentina were shown to be small, while the levels of heterozygosity were moderate. A latitudinal gradient trend was recognized as a pattern of distribution of variation in Argentina, the northerly populations being more variable. Extreme marginal populations located in the steppe, out of the glaciated area, show the greatest levels of variation.

Main conclusions

Evidence was shown supporting that the major factor responsible for the variation pattern found in A. chilensis were the glacial processes. In the Argentine side of the Cordillera de los Andes the species could survive only in a narrow strip between the coldness of the ice sheet and the dryness of the steppe. That implies a generalized genetic drift process. Multiple small refuges in the eastern side of the Cordillera are hypothesized where this cypress would have survived to glaciation. Those refuges are postulated to have been chiefly localized slightly eastward to the present distribution area and most probably in a northern location, at least from 42°S of latitude to the north.
Fire on the New England landscape: regional and temporal variation, cultural and environmental controls
Authors: Parshall T. , Foster D. R.
Published: March 2003

Aim  We use a retrospective approach to reconstruct the past distribution of fire in New England and to investigate the important drivers of this pattern across the period of European arrival to North America.

Location  Our study sites are in New England, and range from pitch pine and oak forests of coastal Massachusetts, pine and hardwood forests of central Massachusetts, and northern hardwood and spruce fir forests of northern Massachusetts and Vermont.

Methods  We collected sediment profiles from eighteen lakes across the study area to assess fossil charcoal and pollen abundance over the past 1000 years, including the time period of European arrival and settlement.

Results  Based on presettlement pollen composition, our study sites are divided into three vegetation types: (1) pitch pine and oak, (2) oak, pine and hardwood and (3) northern hardwoods. The abundance of presettlement charcoal in these lakes is closely related to climate and the composition of surrounding vegetation. Charcoal is most abundant in pitch pine forests and least common in northern hardwood forests. Following the arrival of Europeans, charcoal abundance increased at most sites substantially, and vegetation composition changed in a direction of either greater dominance by pitch pine or white pine, depending on whether the forests were located in the southern or northern part of New England.

Main conclusions  The major factor influencing the distribution of fire across New England is climate, which has a direct effect on the physical conditions conducive to fire ignition and spread and an indirect effect on fire through its control on the distribution of vegetation at this spatial scale. We find evidence that other factors exert some control over local fire regimes as well including landforms and their impact on vegetation composition, firebreaks and prevailing winds. Native Americans likely influenced the local occurrence of fire, but their impact on regional fire regimes in New England is not apparent from this or other studies. However, additional palaeoecological, archaeological and historical work needs to be carried out to better address this question. In contrast, Europeans had a dramatic effect on fire throughout the New England landscape, increasing its occurrence almost everywhere.