bluuebunny/crossref_metadata_2025 huggingface dataset:
Habitat models of bird species' distribution: an aid to the management of coastal grazing marshes
Authors: Milsom T. P. , Langton S. D. , Parkin W. K. , Peel S. , Bishop J. D. , Hart J. D. , Moore N. P.
Published: March 2003

1. Coastal grazing marshes comprise an important habitat for wetland biota but are threatened by agricultural intensification and conversion to arable farmland. In Britain, the Environmentally Sensitive Area (ESA) scheme addresses these problems by providing financial incentives to farmers to retain their grazing marshes, and to follow conservation management prescriptions.

2. A modelling approach was used to aid the development of management prescriptions for ground‐nesting birds in the North Kent Marshes ESA. This ESA contains the largest area of coastal grazing marsh remaining in England and Wales (c. 6500 ha) and supports nationally important breeding populations of lapwingVanellus vanellusand redshankTringa totanus.

3. Counts of ground‐nesting birds, and assessments of sward structure, surface topography and wetness, landscape structure and sources of human disturbance were made in 1995 and again in 1996, on 19 land‐holdings with a combined area ofc. 3000 ha. The land‐holdings varied from nature reserves at one extreme to an intensive dairy farm at the other.

4. Models of relationship between the presence or absence of ground‐nesting birds and the grazing marsh habitat in each ofc. 430 marshes were constructed using a generalized linear mixed modelling (GLMM) method. This is an extension to the conventional logistic regression approach, in which a random term is used to model differences in the proportion of marshes occupied on different land‐holdings.

5. The combined species models predicted that the probability of marshes being occupied by at least one ground‐nesting species increased concomitantly with the complexity of the grass sward and surface topography but decreased in the presence of hedgerows, roads and power lines.

6. Models were also prepared for each of the 10 most widespread species, including lapwing and redshank. Their composition differed between species. Variables describing the sward were included in models for five species: heterogeneity of sward height tended to be more important than mean sward height. Surface topography and wetness were important for waders and wildfowl but not for other species. Effects of boundaries, proximity to roads and power lines were included in some models and were negative in all cases.

7. Binomial GLMMs are useful for investigating habitat factors that affect the distribution of birds at two nested spatial scales, in this case fields (marshes) grouped within farms. Models of the type presented in this paper provide a framework for targeting of conservation management prescriptions for ground‐nesting birds at the field scale on the North Kent Marshes ESA and on lowland wet grassland elsewhere in Europe.
Patterns of incubation and nest‐site attentiveness in relation to organochlorine (PCB) contamination in glaucous gulls
Authors: Bustnes J.O. , Bakken V. , Erikstad K.E. , Mehlum F. , Skaare J.U.
Published: March 2003

Although experimental studies show that organochlorines (OC) can affect bird behaviour, field assessments are invariably confounded by ecological differences between contaminated and uncontaminated sites. The behaviour of individual birds in the field has rarely been related to the contaminant burden.

We examined individual patterns of incubation and nest‐site attentiveness in relation to OC burden, measured as polychlorinated biphenyl (PCB) concentration in the blood, of 27 glaucous gullsLarus hyperboreusin two breeding areas at Bear Island, in the north‐eastern Atlantic.

Blood PCB concentrations ranged from 52 ng g‐1to 1079 ng g‐1(wet weight). There were significant differences between the two breeding areas, and females had significantly lower concentrations than males.

Gull behaviour differed significantly between breeding areas and sexes independently of PCB. Females incubated more than males (54% vs. 46%) but spent more time away from the nest site than males, both overall (23% vs. 12%) and when not incubating (50% vs. 21%). They were also absent for longer periods (4·5 vs. 2·8 h). Moreover, length of incubation bouts (6·4 vs. 4·4 h), the amount of time absent from the nest site when not incubating (51% vs. 25%) and length of absences (5·6 vs. 1·8 h) differed between breeding areas, probably due to different feeding specializations.

After controlling for these area and sex effects, the proportion of time absent from the nest site when not incubating, and the number of absences, were both significantly related to blood concentration of PCB.

Increased absence from the nest site in individual glaucous gulls with high blood concentrations of OC suggests effects on reproductive behaviour. We speculate that endocrine disruption or neurological effects might be involved, leading to increased energetic costs during incubation and reduced reproductive output.
Factors affecting predation by buzzards Buteo buteo on released pheasants Phasianus colchicus
Authors: Kenward R.E. , Hall D.G. , Walls S.S. , Hodder K.H.
Published: March 2003

Information on the effects of wildlife predation on game and livestock is required to allow improved management of all organisms involved. Monitoring of prey, predators and predation mechanisms each suggests important methods, illustrated here by data from common buzzards Buteo buteo and ring‐necked pheasants Phasianus colchicus.

Location data from 136 radio‐tagged common buzzards, together with prey remains from 40 nest areas, records from 10 gamekeepers and vegetation surveys, were used to investigate raptor predation at 28 pens from which pheasants were released in southern England.

Among 20 725 juvenile pheasants released in 1994–95, gamekeepers attributed 4·3% of deaths to buzzards, 0·7% to owls, 0·6% to sparrowhawks, 3·2% to foxes and 0·5% to other mammals.

Fresh pheasant remains were found on 7% of 91 visits to buzzard nests, and 8% of radio‐tagged buzzards had significantly more association than other buzzards with pheasant pens.

Predation by buzzards was most likely to be recorded at release pens with little shrub cover, deciduous canopies and a large number of released pheasants. The number of pheasants killed was greatest in large pens with extensive ground cover, and the highest proportion of released pheasants was killed in large pens where few were released. However, only 21% of 55 releases had > 2 pheasant kills per week.

Radio‐tagged buzzards were located most often at pheasant‐release pens with open, deciduous canopies. Pens were most likely to be visited by buzzards that had fledged nearby, but the proximity of buzzard nests had little influence on how much predation occurred.

Only a minority of buzzards associated frequently with pheasant pens, and predation was heavy at only a minority of sites, where pen characteristics and release factors probably made it easy for individual buzzards to kill pheasants. We suggest that the occasional heavy losses could be avoided by encouraging shrubs rather than ground cover in pens, by siting pens where there are few perches for buzzards, and perhaps also by high‐density releases.
Post‐war changes in arable farming and biodiversity in Great Britain
Authors: Robinson Robert A. , Sutherland William J.
Published: March 2003

Agriculture represents the dominant land use throughout much of western Europe, and a significant part of European biodiversity is associated with this habitat. We attempted to quantify the changes in agriculture and biodiversity in Britain since the 1940s.

There have been widespread declines in the populations of many groups of organisms associated with farmland in Britain and north‐west Europe. The declines have been particularly marked amongst habitat specialists; many of the taxa still common on farmland are habitat generalists.

Farming practices have become increasingly intensive in the post‐war period, with a dramatic reduction in landscape diversity. Since 1945, there has been a 65% decline in the number of farms, a 77% decline in farm labour and an almost fourfold increase in yield. Farms have become more specialized; the greatly increased use of machinery has made operations quicker and more efficient, but has resulted in the removal of 50% of the hedgerow stock. Autumn sowing of crops has become predominant, with winter stubbles now far less prevalent. The number and extent of chemical applications has increased greatly, but the net amount applied, and their persistence, has decreased in recent years.

Intensification has had a wide range of impacts on biodiversity, but data for many taxa are too scarce to permit a detailed assessment of the factors involved. Reduction in habitat diversity was important in the 1950s and 1960s; reduction in habitat quality is probably more important now.

As a case study, the declines in populations of seed‐eating birds populations were assessed in relation to changing agricultural management. Generally, the declines were likely to be caused by a reduced food supply in the non‐breeding season, although other factors may be important for particular species.

Agriculture will face a number of challenges in the medium term. While research into the mechanisms underlying species and habitat associations, and their interaction with scale, will be critical in under‐pinning management, consideration of farmer attitudes and socio‐economic factors is likely to be as important. Biodiversity may benefit from integrated farming techniques but these need to incorporate environmental objectives explicitly, rather than as a fringe benefit.
Long‐term changes in the trophic level of the Celtic Sea fish community and fish market price distribution
Authors: Pinnegar J. K. , Jennings S. , O’Brien C. M. , Polunin N. V. C.
Published: March 2003

The intensive exploitation of fish communities often leads to substantial reductions in the abundance of target species, with ramifications for the structure and stability of the ecosystem as a whole.

We explored changes in the mean trophic level of the Celtic Sea (ICES divisions VII f–j) fish community using commercial landings, survey data and estimates of trophic level derived from the analysis of nitrogen stable isotopes.

Our analyses showed that there has been a significant decline in the mean trophic level of survey catches from 1982 to 2000 and a decline in the trophic level of landings from 1946 to 1998.

The decline in mean trophic level through time resulted from a reduction in the abundance of large piscivorous fishes and an increase in smaller pelagic species which feed at a lower trophic level.

Similar patterns of decline in the trophic level of both catches and landings imply that there have been substantial changes in the underlying structure of the Celtic Sea fish community and not simply a change in fishery preferences.

We suggest that the reported changes in trophic structure result from reductions in the spawning stock biomass of traditional target species associated with intensive fishing, together with long‐term climate variability.

The relative distribution of fish market prices has changed significantly over the past 22 years, with high trophic level species experiencing greater price rises than lower trophic level species.

Although decreased abundance of high trophic level species will ultimately have negative economic consequences, the reduction in mean trophic level of the fish community as a whole may allow the system to sustain higher fishery yields.

Management objectives in this fishery will depend on the relative values that society attaches to economic profit and protein production.
Functional and numerical responses do not always indicate the most effective predator for biological control: an analysis of two predators in a two‐prey system
Authors: Lester P. J. , Harmsen R.
Published: March 2003

Functional and numerical responses are key components in the selection of predators for biological control. We examined the relevance of these responses for predicting the effectiveness of generalist predators, taking into account effects of alternative prey and multiple predators. Our system involved two acarine predators of two prey species on apple. Responses were measured on leaf discs in the laboratory, and predictions assessed on small potted apple trees. In particular, we tested three hypotheses.

 Hypothesis I: the species with the higher predatory responses will be more effective in limiting prey populations. Neither predator had a consistently higher functional response, which depended on prey stage and species. Amblyseius fallacis had a (approximately two times) higher ovipositional response than Typhlodromus pyri. We therefore hypothesized that A. fallacis would be more effective in controlling prey. No evidence was found to support this hypothesis.

 Hypothesis II: alternative prey reduce the functional response of predators to target prey. Alternative prey did or did not reduce the functional response to target prey, depending on the predator, stage and species of alternative prey. The only consistent trend for both predators was that the predation of Panonychus ulmi deutonymphs was reduced when Tetranychus urticae was present.

 Hypothesis III: the predator species with the highest mean ovipositional response will out‐compete the other predator species. The number of predators observed in the mixed predator treatments depended on the prey composition. Although A. fallacis had a higher ovipositional response, it was never more abundant. Intraguild predation probably played a role in determining predator abundance, although prey composition altered intraguild effects.

 These results highlight the complex nature of predator and prey interactions. Because of these interactions, functional and numerical assays on single predator–single prey systems in simplified laboratory environments do not allow predictions of the growth of mixed populations in realistic habitats, or of the effectiveness of predators as biological control agents in the field.
Seedling establishment in an Australian tropical savanna: effects of seed supply, soil disturbance and fire
Authors: Setterfield S. A.
Published: March 2003

Australia's savannas typically are burnt every 1–3 years. Although there are concerns about the effect of frequent fire on recruitment of Australian savanna species, there is a lack of information. This research aimed to determine whether seed or microsite availability limits seedling recruitment of the overstorey tree Eucalyptus miniata and the midstorey shrub Acacia oncinocarpa, whether seed or microsite availability is affected by frequent fire, and the consequent effect on seedling recruitment.

Quadrats were established in unburnt areas. Experimental manipulations were addition of seed and/or disturbance of the soil surface to increase the number of microsites suitable for germination. In a second experiment, seed was added to quadrats established in three fire regimes after the annual burning event (unburnt, burnt early in the dry season, burnt late in the dry season).

In unburnt areas, seedling regeneration was limited by both seed supply and microsite availability. Both burning regimes reduced seedling emergence, possibly because the reduced canopy cover caused unfavourable microclimate, the increased grass and forb ground cover increased competition for resources, and there was increased loss of seed to seed harvesters.

The results indicate that sexual regeneration of these common species is disadvantaged by current burning practices because both seed supply and the number of microsites are reduced. Thus, long‐term changes in savanna floristic structure seem likely unless fire managers aim to increase the fire‐free intervals. The relative abundance of species able to reproduce vegetatively may increase under frequent fire regimes. Such a change may take a long time to detect given the fire‐resistant and long‐lived nature of overstorey species, and the capacity for vegetative regeneration in many savanna species. The impacts of fire on limiting seedling regeneration will require savanna managers to consider fire‐free intervals of several years for effective recruitment of dominant woody species.
Amplified fragment length polymorphism (AFLP) and biochemical typing ofPhotobacterium damselaesubsp.damselae
Authors: Botella S. , Pujalte M.-J. , Macián M.-C. , Ferrús M.-A. , Hernández J. , Garay E.
Published: March 2003

Aims: The aim of the present study was to characterize subspecifically Photobacterium damselae subsp. damselae strains isolated from cultured Sparus aurata and Dicentrarchus labrax by means of phenotypic and molecular typing techniques (amplified fragment length polymorphism, AFLP). Methods and Results: Seventy-one strains of P. damselae subsp. damselae were isolated from 38 cultured fishes at different fish farms located on the Mediterranean coast near Valencia, Spain. Most fish studied were asymptomatic and some were recovered during infectious outbreaks. Phenotypic characterization revealed a considerable degree of variability within the subspecies, including some characters, such as production of urease, which are used to differentiate P. damselae subsp. damselae from P. damselae subsp. piscicida. Genetic characterization was conducted on a selection of 33 strains, including two reference strains. Dice coefficient (Sd) and the unweighted pair group method with average linkage (UPGMA) were used for numerical analysis of banding patterns. AFLP type was defined on the basis of 100% similarity in the dendrogram obtained, yielding 24 distinct AFLP profiles. At 70% similarity, 13 clusters were defined, thus confirming the great variability observed for the phenotypic traits. Conclusions: The AFLP variability shown by the isolates was high enough to discriminate between different strains which colonize the same fish. However, closely related AFLP types were usually derived from strains isolated at the same fish farm, indicating an epidemiological relationship. Significance and Impact of the Study: This study has confirmed that the AFLP technique allows discrimination of individual strains within P. damselae subsp. damselae for epidemiological studies, and that this subspecies exhibits greater variability than that described for subspecies piscicida.
Modulation by nitric oxide of spontaneous mechanical activity in rat proximal colon
Authors: Mulè F. , D’Angelo S. , Amato A. , Contino I. , Serio R.
Published: March 2003

1 In order to examine the role of nitric oxide (NO) in the tonic neural inhibition in rat proximal colon, the effects of Nω‐nitro‐
l‐arginine methyl ester (L‐NAME) were studied on the spontaneous contractions of circular muscle (monitored as intraluminal pressure changes) and of longitudinal muscle (detected as isometric tension changes).

2 L‐NAME (3 × 10−−6–3 × 10−−4 m) caused a concentration‐dependent increase in the amplitude of circular contractions, without affecting those of longitudinal muscle. This effect was prevented by
l‐arginine (1–5 × 10−−3 m), but not
d‐arginine.

3 In the presence of tetrodotoxin (10−−6 m), which per se induced increase of the pressure waves, L‐NAME (10−−4 m) caused no further effects on the amplitude of the spontaneous contractions.

4 The response to L‐NAME (10−−4 m) was unaffected by atropine (10−−6 m), guanethidine (10−−6 m), hexamethonium (up to 3 × 10−−4 m) or α‐chymotrypsin (up to 5 U ml−−1).

5 NK2 receptor antagonists, SR 48968 (3 × 10−−6 m) or MEN 10627 (10−−6 m), produced a reduction of the amplitude of the pressure waves but failed to affect the contractile response to L‐NAME (10−−4 m).

6 These findings suggest that tonic production of NO from inhibitory neurones influences the degree of contractions of circular muscle. An involvement of an inhibitory peptide as well as disinhibition of cholinergic or NK2‐tachykinergic excitatory neurotransmission in the mechanism of NO action can be ruled out.
The effect of sorbinil, an aldose reductase inhibitor, on aortic function in control and streptozotocin‐induced diabetic rats
Authors: Sellers D. J. , Chess‐Williams R.
Published: March 2003

1 The present study investigates the effect of treatment of 14‐day streptozotocin‐diabetic rats with the aldose reductase inhibitor, sorbinil, on changes ex vivo in aortic vasoconstriction and vasodilation.  2 Maximum contractile responses and aortic sensitivity to phenylephrine were significantly enhanced in aortae from 14‐day diabetic rats, in accordance with our previous data.  3 Endothelium‐dependent relaxations to carbachol were, in contrast, depressed, although endothelium‐independent relaxations to forskolin and sodium nitroprusside were unaltered.  4 Sorbinil treatment of diabetic animals failed to prevent any of these diabetes‐induced alterations in aortic function, and indeed exacerbated some of these alterations. In addition, sorbinil treatment caused altered aortic responses in control animals, which sometimes mirrored those found in diabetic animals.  5 It can be concluded that sorbinil may have actions in addition to, and independent of, polyol pathway inhibition. Thus, sorbinil may not be an effective tool for the investigation of aldose reductase inhibition within the vascular system of the rat.
Adrenoceptor‐mediated modulation of endothelial‐dependent vascular smooth muscle growth
Authors: Damon D. H.
Published: March 2003

1 Signals derived from endothelial cells (EC) and the sympathetic nervous system are known to independently modulate the growth of vascular smooth muscle (VSM). It is not known if and how these signals are integrated. The purpose of the present study was to test the hypothesis that activation of adrenoceptors by sympathetic‐derived catecholamines modulates EC regulation of VSM growth.  2 The effects of adrenergic agonists on VSM growth were studied in vitro in EC/VSM cocultures. EC stimulated VSM growth in EC/VSM cocultures. Activation of β‐adrenoceptors inhibited this stimulation. EC stimulation of VSM growth was 225±31% in the absence and 127±27% in the presence of 10 μm isoprenaline. Activation of α‐adrenoceptors had no effect on EC stimulation of VSM growth in coculture.  3 Isoprenaline did not affect the growth of VSM grown in the absence of EC, suggesting that it did not inhibit EC stimulation of VSM growth by directly inhibiting VSM growth.  4 Isoprenaline did not affect EC production of growth factors, as media conditioned by EC grown in the absence or presence of isoprenaline, stimulated VSM growth to the same extent. Isoprenaline did not alter EC, VSM or EC/VSM production of the VSM growth inhibitor transforming growth factor β‐1 (TGF‐β1).  5 These data provide evidence that catecholamines, via activation of β‐adrenoceptors, can modulate EC‐dependent VSM growth, and suggest that the sympathetic nervous system and EC coordinately regulate VSM growth.
Catecholamines in hyperpnoea‐induced airway constriction of guinea pigs
Authors: Lai Y.‐L. , Lee S.‐C. , Lai L.‐C. , Hu F.‐C. , Tsai T.‐L. , Tsai Y.‐F.
Published: March 2003

1 We found previously that propranolol augments hyperpnoea‐induced bronchoconstriction (HIB). This study was performed to investigate the underlying mechanism of this aug‐ menting action of propranolol.

2 In the first series, 45 young Hartley guinea‐pigs were divided into five groups: control; propranolol; adrenalectomy; metoprolol and reserpine. Each animal underwent three periods: baseline, hyperpnoea, and recovery. For each animal 1 ml of arterial blood was sampled during the baseline and recovery periods.

3 Treatments of propranolol, metoprolol, and reserpine caused significant decreases in both dynamic respiratory compliance (Crs) and forced expiratory volume in 0.1 s (FEV0.1) during the baseline period. Hyperpnoea caused slight but not significant decreases in Crs, FEV0.1, and maximal expiratory flow at 50% total lung capacity (TLC) (V˙max50) during the recovery period in the control group. Propranolol, but not other treatments, significantly augmented these decreases (indicating HIB). Plasma noradrenaline and adrenaline levels in the reserpine group were not detectable. The above treatments or hyperpnoea did not induce any significant effect on the plasma noradrenaline level. Plasma adrenaline level of the control group was higher than that of either adrenalectomy or reserpine group during the baseline and the recovery periods.

4 In the second series, we avoided repeated blood samplings. Forty‐eight animals were evenly divided into two groups: control and propranolol. Each group was again evenly divided into three subgroups: baseline; hyperpnoea, and recovery. Five minutes into the recovery period, we demonstrated HIB in the control group. In terms of V˙max50, this HIB was significantly augmented by propranolol. Plasma noradrenaline and adrenaline levels, however, were not significantly altered by either hyperpnoea or propranolol.

5 Taken together, these data suggest that propranolol‐augmented HIB has no direct relationship with decreased catecholamine activity.
Faunal relationships and zoogeographical affinities of mammals in north‐west Africa
Authors: Dobson Mike , Wright Amanda
Published: March 2003

The nonmarine mammal fauna of the Maghreb region of north‐west Africa is related to that from three potential source areas: the northern Palaearctic (Europe and south‐west Asia; here referred to as the European fauna), subsaharan Africa (the African fauna) and the arid Palaearctic (Sahara Desert: the desert fauna).

On the basis of geographical distribution patterns, this fauna divisible into two groups: the bats, whose affinities are most closely related to southern Europe and south‐west Asia, and nonflying species, most closely related to subsaharan Africa but with an appreciable northern Palaearctic element. These affinities are even more pronounced if desert fauna are removed from the analysis.

The nonflying European fauna probably colonized via south‐west Asia and north Africa, rather than direct from western Europe.

The results demonstrate that terrestrial habitat barriers are less of an impediment to dispersal, for all mammals except bats, than even narrow stretches of water.

The fauna of the Maghreb may be undergoing faunal relaxation, following immigration from tropical Africa and south‐west Asia during mesic phases in the Late Pleistocene and early Holocene.
Evidence for the widespread occurrence of ancient forests on cliffs
Authors: Larson D. W. , Matthes U. , Gerrath J. A. , Larson N. W. K. , Gerrath J. M. , Nekola J. C. , Walker G. L. , Porembski S. , Charlton A.
Published: March 2003

AimThe objective of this work was to determine if the existence of ancient forests on cliffs was specific to the Niagara Escarpment, Canada, or part of a globally widespread pattern.

LocationSixty‐five cliff sites were visited in five countries in the temperate climatic zone, and trees were sampled for age and growth rate on forty‐six of these.

MethodsTwo hundred and twenty‐four core samples or cross‐sections were taken from trees on cliffs that varied in height, aspect, rock‐type, and exposure. General observations were also made of regeneration of the tree species forming the mature canopy, and other habitat conditions.

ResultsThe evidence shows that ancient slow‐growing forest occurs on most cliffs. Age and growth rate distributions were similar at all treed sites. Small‐staturedThuja, Juniperus, orTaxusstems with age estimates in excess of 1000 years were found in the United States, the United Kingdom and France, and smallPinus and Quercusstems nearly 400 years in Germany. There was a high rate of recurrence of plants in the generaPolypodium,Asplenium,Cystopteris,Campanula,Rosa,Prunus,Hedera, andSorbus. Most of the sites appear to be habitats of completely natural origin.

ConclusionsWe conclude that ancient natural forest is a normal feature of cliffs, at least in the temperate zone.
Pollen‐based biome reconstruction for southern Europe and Africa 18,000 yr bp
Authors: Elenga H. , Peyron O. , Bonnefille R. , Jolly D. , Cheddadi R. , Guiot J. , Andrieu V. , Bottema S. , Buchet G. , De Beaulieu J.‐L. , Hamilton A. C. , Maley J. , Marchant R. , Perez‐Obiol R. , Reille M. , Riollet G. , Scott L. , Straka H. , Taylor D. , Van Campo E. , Vincens A. , Laarif F. , Jonson H.
Published: March 2003

Pollen data from 18,000 14C yr bp were compiled in order to reconstruct biome distributions at the last glacial maximum in southern Europe and Africa. Biome reconstructions were made using the objective biomization method applied to pollen counts using a complete list of dryland taxa wherever possible. Consistent and major differences from present‐day biomes are shown.

Forest and xerophytic woods/scrub were replaced by steppe, both in the Mediterranean region and in southern Africa, except in south‐western Cape Province where fynbos (xerophytic scrub) persisted.

Sites in the tropical highlands, characterized today by evergreen forest, were dominated by steppe and/or xerophytic vegetation (cf. today’s Ericaceous belt and Afroalpine grassland) at the last glacial maximum.

Available data from the tropical lowlands are sparse but suggest that the modern tropical rain forest was largely replaced by tropical seasonal forest while the modern seasonal or dry forests were encroached on by savanna or steppe. Montane forest elements descended to lower elevations than today.
Abundance–distribution relationships on interacting trophic levels: the case of lake‐nesting waterfowl and dytiscid water beetles
Authors: Elmberg Johan , Sjöberg Kjell , Pöysä Hannu , Nummi Petri
Published: March 2003

Aim

To compare patterns in local abundance, regional distribution and body size in waterfowl and dytiscid beetles sampled from the same lakes.

Location

Thirty Swedish lakes, 56–63° N.

Methods

Birds were censused repeatedly, at which time submerged activity traps were placed on the littoral to catch invertebrates. Avian patterns were analysed separately for four different selections of species, each motivated on functional or phylogenetical grounds. Patterns in dytiscid beetles have been described earlier in Nilsson, Elmberg & Sjöberg (1994).

Results

Although there were large differences between individual lakes, there was no significant latitudinal gradient at the lake level in either species richness or abundance in any of the bird groupings. Lakes which were rich in species and numbers of dytiscid beetles were also rich in species and numbers of all four waterfowl groups. Three of the four bird groups conform with the general pattern of widely distributed species being more abundant locally, as do dytiscid beetles in the same lakes. Body mass and local abundance were correlated in one of the four birds groups only, i.e. dabbling ducks, (Anas spp.).

Main conclusions

We find evidence for a similar and positive local abundance–distribution relationship in dytiscid beetles and waterfowl breeding in the same lakes, but no common general pattern in local abundance vs. body size.
What is the origin of the carabid beetle fauna of dry, anthropogenic habitats in western Europe?
Authors: Andersen Johan
Published: March 2003

Aim

To study the origin of the carabid beetle fauna of dry, open anthropogenic habitats.

Location

Various parts of Europe.

Methods

Collecting by hand in habitats influenced by humans (arable land, sand pits, ruderal places, road verges, meadows) and naturally open habitats such as talus, supralittoral sand dunes, alvar as well as littoral habitats in south and central Scandinavia. Studies made in other parts of Europe were included in the discussion.

Results and conclusion

The material comprises about 37,700 specimens. About 8% of the Scandinavian species occurring in anthropogenic habitats may have a littoral origin, about 10% may originate from forests whereas about 9% are euryoecious. A majority of the species (about 66%) originate from primarily open, dry habitats and many of them constitute a steppe or steppe‐like element. They invaded the bare landscape soon after the deglaciation and probably survived in naturally open habitats (supralittoral sand dunes, talus, alvar, old riverbeds) during the postglacial warm period, but some species have a recent origin in Scandinavia.
The flora of the South Sandwich Islands, with particular reference to the influence of geothermal heating
Authors: Convey P. , Lewis Smith R. I. , Hodgson D. A. , Peat H. J.
Published: March 2003

Aim  To carry out as comprehensive a survey as practicable of the flora (higher plants, mosses, liverworts, lichens, basidiomycete fungi and diatoms) of the isolated, volcanically active, South Sandwich Islands archipelago in the southern South Atlantic. To relate the components of this flora to (1) the influence of local geothermal heating and (2) wider regional floras.

Location  South Sandwich Islands, southern South Atlantic Ocean, maritime Antarctic (56–60° S, 26–28° W).

Methods  Ice‐free accessible sites on all 11 of the major islands in the archipelago were visited by helicopter in January 1997. During each visit, voucher specimens of each floral group were collected. The comprehensiveness of collections obtained at each site varied with the duration of each visit (a function of tight logistic constraints) and extent of site. Visit duration varied from 1 to 9 h at most sites, with longer periods spent on Bellingshausen Island (2 days) and Leskov Island (1 day). Candlemas Island was examined in greater detail over a 4‐week period in February 1997. At all sites, particular attention was given to areas influenced by geothermal heating.

Results  Data obtained in 1997 are combined with updated records from the only previous survey (in 1964) to provide a baseline description of the flora of the archipelago, which currently includes 1 phanerogam, 38 mosses, 11 liverworts, 5 basidiomycete fungi, 41 lichenised fungi and 16 diatoms with, additionally, several taxa identified only to genus. Major elements of the moss and liverwort floras are composed of South American taxa (32% and 73%, respectively), with a further 45% of mosses having bipolar or cosmopolitan distributions. These two groups show low levels of Antarctic endemicity (11% and 18%, respectively). In contrast, 52% of lichens and 80% of basidiomycete fungi are endemic to the Antarctic. A further 36% of lichens are bipolar/cosmopolitan, with only 5% of South American origin.

Main Conclusions  The flora of the South Sandwich Islands is clearly derived from those of other Antarctic zones. The flora of unheated ground is closely related to that of the maritime Antarctic, although with a very limited number of species represented. That of heated ground contains both maritime and sub‐Antarctic elements, confirming the importance of geothermal heating for successful colonisation of the latter group. The occurrence of several maritime Antarctic species only on heated ground confirms the extreme severity of the archipelago’s climate in comparison with well‐studied sites much further south in this biogeographical zone.
Biogeography of Southeast Asia and the West Pacific
Authors: Turner H. , Hovenkamp P. , van Welzen P. C.
Published: March 2003

The biogeography of Southeast Asia and the West Pacific is complicated by the fact that these are regions on the border of two palaeocontinents that have been separated for a considerable period of time. Thus, apart from any patterns of vicariance, two general patterns relating to dispersal can be expected: a pattern of Southeast Asian elements, perhaps of Laurasian origin, expanding into Australian areas, and a reverse pattern for Australian elements, perhaps of Gondwanan origin. On top of this, both Australian and Southeast Asian elements occur in the Pacific. They dispersed there as the Pacific plate moved westward, bringing the different islands within reach of Southeast Asia and Australia. In order to reconstruct the biotic history of these areas, two large data sets consisting of both plants and animals were generated, one for each pattern, which were analysed using cladistic methods. The general patterns that emerged were weakly supported and do not allow general conclusions.
The biogeographical relations of the frogs and snakes of Sundaland
Authors: Inger Robert F. , Voris Harold K.
Published: March 2003

Aim

We seek to relate the present distributions of frogs and snakes of Sundaland and the known geological history of the region.

Location

From the Isthmus of Kra to Java and Sulawesi.

Methods

We relate the known ecological requirements of frogs and snakes to their geographical distributions and information on geological history.

Results

Microhabitat requirements for larvae of various groups of frogs are strong predictors of the breadth of their geographical distributions. At the species level, the frog faunas of the Malay Peninsula and Sumatra are the most similar. The Sulawesi frog fauna, mainly derived from Sundaland lineages, shows almost no similarity to the other frog faunas at the species level. The ecological zones occupied by snake species show association with the breadth of their geographical distributions There are only minor differences among similarity ratios for the Malay Peninsula–Sumatran, Malay Peninsula–Borneo, and the Borneo–Sumatra pairs. The Sulawesi snake fauna has distinctly lower similarity with the faunas of the other areas. The similarity ratios between faunas are larger for snakes than for frogs. This difference between the two groups reflects the difference between them in ability to cross salt water barriers, frogs being extremely vulnerable to saline water. Also snakes may establish founder populations more easily as a single gravid female or one carrying stored sperm may introduce a clutch into previously unoccupied territory.

Conclusions

A few species of frogs and snakes probably reached their present, almost ubiquitous distributions in Sundaland within the last few millenia or even more recently. Other widely distributed species may have been able to disperse among land masses within Sundaland until 10,000–17,000 yr BP; the frogs of this category are common in environments that almost certainly characterized the exposed area of the South China Sea. The distributions of other frogs common to the Malay Peninsula, Sumatra and Borneo probably antedate the Pleistocene, as their larval development requires hilly topography which was not generally available on the Pleistocene‐exposed bed of the South China Sea. Many of the endemic species of frogs and snakes probably owe their origins to events of the Miocene or earlier. Several genera of frogs and one genus of snakes have undergone extensive speciation and display considerable sympatry and elevational stratification of species, suggesting their present distributions are the result of events as old as the Eocene. We have cast these conclusions in the form of hypotheses that can be tested mainly by the use of molecular genetics, but in some cases, by additional field sampling.
Stepping stones to Hawaii: a trans‐equatorial dispersal pathway forMetrosideros(Myrtaceae) inferred from nrDNA (ITS+ETS)
Authors: Wright Shane D. , Yong Catherine G. , Wichman Stephen R. , Dawson John W. , Gardner Richard C.
Published: March 2003

Aim

The majority of Hawaii's plants are derived from the south and west of the Pacific rim, suggesting that at least some of the founders have crossed the climatic discontinuity at the equator. However, the pathways of these dispersal events are not well understood. We sought to elucidate such a pathway for the plant genusMetrosiderosBanks ex Gaertn., which appears to have colonized Hawaii from New Zealand.

Location

We have previously analysed the internal transcribed spacer (ITS) sequence of nrDNA for thirty‐six taxa ofMetrosiderossubgenusMetrosiderosdistributed across Melanesia and Polynesia. Further we collected two taxa from the Austral and Marquesas Islands.

Methods

Phylogenetic analysis was undertaken using both the ITS and external transcribed spacer (ETS) regions of nrDNA for twenty‐three taxa from Polynesia and East Melanesia.

Results

The increased resolution achieved by combining ETS data with that of ITS allowed discrimination of two subclades in eastern Oceania. One subclade groups all the Hawaiian taxa together withM. collina(J. R. & G. Forst.) A. Gray from the Marquesas Islands.

Main conclusions

From an origin in New Zealand, the woody angiospermMetrosiderosis likely to have crossed the equator to Hawaii using a staging point in the remote Marquesas Islands. Colonization of Hawaii by the wind‐borne seed of these plants has been achieved against the flow of the prevailing Trade winds north of the equator. A possible climatic mechanism for this dispersal is described.
Towards a hierarchical framework for modelling the spatial distribution of animals
Authors: Mackey Brendan G. , Lindenmayer David B.
Published: March 2003

Aim

A hierarchical framework is presented for modelling the spatial distribution of terrestrial vertebrate animals.

Location

The location of the study is the montane ash forests of the Central Highlands of Victoria, south‐eastern Australia.

Methods

The framework is illustrated using as a case study the distribution of Leadbeater’s Possum [Gymnobelideus leadbeateri McCoy, 1867, (Marsupialia: Petauridae)], a small arboreal marsupial. The framework is based upon quantifying the environmental response of a species in terms of a five‐level environmental hierarchy defined by scales (global‐, meso‐, topo‐, micro‐ and nano‐scales) that represent natural breaks in the distribution and availability of the primary environmental resources. Animal response is examined in terms of a species’ distribution as observed in four biological units (the species in toto, meta‐population/population, group/colony, and individual organism). We define the spatial occurrence and abundance of the target species in each of these units as its ‘distributional behaviour’.

Results

Predictions of the potential spatial distribution of Leadbeater’s Possum are presented at meso‐, topo‐, micro‐ and nano‐scales. These spatial predictions utilize Geographical Information System (GIS)‐based spatial models of long term mean monthly climate and terrain‐modified surface radiation, together with vegetation cover and individual tree attributes from air‐photo interpretation and field survey.

Main conclusions

Ideally, species’ responses at each level in the environmental hierarchy should be empirically derived using statistical models based on field observation of a species’ distribution and abundance. Spatial modelling of species’ responses becomes problematic at finer scales because of the lack of suitable environmental data. The key characteristics of the modelling framework are generic, but the influence of additional scales and processes will be important in other ecosystems and species.
Biogeography of Indo‐Pacific Pontoniinae (Crustacea, Decapoda): a PAE analysis
Authors: De Grave Sammy
Published: March 2003

Aim

Pontoniid shrimps are one of the most abundant coral reef associated taxa in the Indo‐Pacific. Although taxonomically well known, their ecology, life history and biogeography appears virtually unstudied. The object of the present contribution is to derive a basin wide biogeographical hypothesis, using a limited number of operational geographic units (OGU).

Location

Twelve OGU’s were selected, spanning the entire Indo‐Pacific, from the East coast of Africa and the Red Sea to the Tropical Eastern Pacific (TEP).

Methods

Analysis was based on a species by OGU matrix, in which presences (1) and putative occurrences (?) were coded. Parsimony analysis of endemicity (PAE) was applied to the data set, using Dollo and Wagner Parsimony.

Results

A hierarchical pattern of area relationships was derived, with the TEP occupying a basal position, Hawaii and French Polynesia occupy positions higher up in the cladogram, whilst the Melanesian OGU maintains a sister‐area relationship to the crown clade. The latter consists of the Indo‐Philippine area, the Australian and all Indian Ocean OGUs.

Main conclusions

Pontoniinae exhibit a clear hierarchical pattern of area relationships, which is congruent with previous biogeographical studies on coral reef and other taxa. The observed pattern can be explained by a combination of dispersal and vicariant events, whilst the importance of sea level changes is recognized.
Fire and species range in Mediterranean landscapes: an experimental comparison of seed and seedling performance amongCentaureataxa
Authors: Riba Miquel , Rodrigo Anselm , Colas Bruno , Retana Javier
Published: March 2003

Aim

Fire is a major disturbance event in Mediterranean landscapes. In this paper, we experimentally assess the effects of fire and post‐fire conditions on seed germination and establishment of twentyCentaureataxa to test whether differences among taxa are associated with range size.

Methods

The taxa (species and subspecies) considered were classified as rare and widespread according to their `area of occupancy' in the Mediterranean coast of Spain and France. In a first experiment, we analyse the effects of heat‐shock (particularly, room temperature, 70 and 110 °C) on percentage germination and speed of germination (T50). In a second experiment, we analyse the effects of post‐fire conditions (shading and soil type: burned/unburned) on seed germination and establishment ability.

Results

Temperatures over 120 °C resulted in 100% mortality, while temperatures in the range of those expected to be found in the first centimetres down the soil profile during a wildfire (70–110 °C) had no effect on seed germination. Differences in germination percentage and T50 among taxa were not related to rarity. In the post‐fire conditions experiment, decreased radiation (shading) increased percentage germination and T50 in most taxa, while burned soil decreased germination in some of them. The effects of post‐fire conditions on seedling growth (number of leaves and leaf size) were also different among taxa, but such differences were not related to rarity. However, rarity was associated with low establishment ability, as rare taxa tended to show smaller seedling size and higher mortality rates under the whole range of conditions tested.

Main conclusions

The results obtained indicate that fire has a negative effect upon the survival of populations in all the taxa considered, and that rare‐common differences in germination and seedling establishment are not directly related to disturbance by fire. As far as interspecific differences in range size are concerned, other factors, either alone or in combination with a low regeneration ability after fire, need to be explored further.