bluuebunny/crossref_metadata_2025 huggingface dataset:
Endodontic and surgical treatment of a geminated maxillary incisor
Authors: Braun A. , Appel T. , Frentzen M.
Published: May 2003

Aim  A geminated maxillary incisor required complex multidisciplinary treatment to preserve health and restore aesthetics. This report describes the coordination of coronal division, root extraction, bone grafting, endodontic treatment and orthodontics in achieving treatment goals. It is the intention of this report to show how a difficult case could be managed by properly coordinated multidisciplinary care.

Summary  Pulp testing of the geminated central right maxillary incisor gave a normal response. Radiographic investigation indicated a connection of the pulp chambers. Both the mesial and distal root were filled with gutta‐percha. The connection between the two root canals was sealed with a flowable dentine‐bonded resin. After dividing the crown with a diamond bur, the mesial part of the tooth was removed and the extraction socket was filled with beta‐tricalcium phosphate ceramic (Cerasorb™). Radiographs taken immediately after surgery and after 6 months showed no periodontal or periapical lesions. No signs of external resorption were identified. The diastema between the central incisors was closed by orthodontic treatment.

Key learning points 

Geminated teeth may present aesthetic and functional problems which require multidisciplinary care.

Careful clinical and radiographic examination is essential to decide on the fate of the coronal and root halves involved.

A proper coordination between endodontic and surgical treatment may result in maintaining one tooth half, even if a midroot connection between the pulp chambers becomes evident.

Orthograde endodontic treatment, hemisection and orthodontics may solve the aesthetic problem of a geminated tooth.
Foraging efficiency and adjustment of energy expenditure in a pelagic seabird provisioning its chick
Authors: Weimerskirch Henri , Ancel André , Caloin Michel , Zahariev Alexandre , Spagiari Jérôme , Kersten Marcel , Chastel Olivier
Published: May 2003

Foraging determines the intake of resources that are expended on fitness related activities, and allocation links foraging and life‐history traits, but the extent to which individuals are able to adjust energy expenditure according to allocation decisions is still poorly studied.

To examine this, we studied for the first time the efficiency of foraging trips (defined as the ratio of energy gained over energy spent while foraging) in a pelagic seabird provisioning its chick by measuring simultaneously the energy flow to the chick, changes in adult body mass and foraging cost using doubly labelled water. The study was performed over two seasons.

Blue petrels (Halobaena caerulea) alternate between short foraging trips (average 1·9 days, range 1–4 days) where they maximize food delivery to the chick but loose mass, and long foraging trips (7·3 days, 5–10 days) where they increase in mass. They expend 1·5–2·2 times more energy per unit of time during short trips (2561 kJ day−1 kg−1, i.e. 3·2 times the resting metabolic rate) compared to long trips (1142–1676 kJ day−1 kg−1, i.e. 1·4–2·1 the resting metabolic rate).

The currency during long trips is therefore to maximize efficiency, whereas during short trips the currency is to maximize rate of energy delivery to the chick. Maximum efficiency peaks for 6‐day trips, i.e. when adult mass gain is highest, foraging costs are lowest and efficiency was extremely low during short trips. A duration of 6 days is therefore the optimal duration of long foraging trips but trips of 7 days were more common.

Our study shows that self‐feeding during long trips is crucial for the success of short trips because most of the energy used during short trips is probably derived from the energy stored during long trips. Self‐feeding during short trips is probably negligible.

The study indicates that surprisingly long distance foraging may not always result in higher foraging costs compared to shorter movements. It highlights the predominant role of body store usage as a mechanism for this animal to adjust energy expenditure and energetic efficiency during foraging for allocation purposes.
Variation and covariation in survival, dispersal, and population size in barn owls Tyto alba
Authors: Altwegg Res , Roulin Alexandre , Kestenholz Matthias , Jenni Lukas
Published: May 2003

Population dynamics are the result of variation in survival, recruitment, emigration and immigration rates. Covariation between these demographic rates critically affects the dynamics and magnitude of fluctuations in population size. Such covariation can arise by environmental factors affecting several rates in similar ways. Also demographic processes, such as the source–sink and the balanced dispersal process, are expected to lead to covariation between demographic rates.

Here, we study variation and covariation in survival, emigration, immigration, and the size of a Swiss barn owl (Tyto alba) population, and examine the factors associated with this variation. For practical reasons, survival and emigration are often confounded in studies of natural populations. We overcome this problem by jointly analysing live‐recapture and dead‐recovery data using recently developed statistical methods.

Mortality, emigration, the number of known immigrants, and population size were positively correlated over time. Neither the source–sink nor the balanced dispersal process is expected to lead to this pattern.

Survival was lower for juveniles than adults (mean 17% vs. 72%), and highly variable across years in both age classes. Snow cover, mean annual temperature and population density accounted for 32–47% of the variation in survival of juveniles and adults. Emigration was higher for juveniles than for adults, and adults emigrated more often when the population size was higher.

Our results showed that local population dynamics were affected by density dependence and the stochastic environmental factors snow cover and temperature. Rather than lending support to one of the two dispersal hypotheses, the patterns of correlation between survival, dispersal, and population size suggest strong fluctuations in environmental conditions that influence the dynamics of barn owl populations at a larger spatial scale.
Dispersal within a spatially structured population of lesser kestrels: the role of spatial isolation and conspecific attraction
Authors: Serrano David , Tella José L.
Published: May 2003

Factors governing dispersal rates have seldom been examined in spatially structured populations of vertebrates. We gathered information during 8 years on transfer rates between subpopulations in a spatially structured, growing population of colonial lesser kestrelsFalco naumanni, and analysed the contribution of several variables related to spatial isolation and characteristics of both subpopulation of origin and destination on probabilities of dispersal.

Lesser kestrels were highly philopatric to their subpopulations, but first‐breeders dispersed more often than adults (26% vs. 4%,n= 1706) because adults were reluctant to move from familiar areas. Frequency of subpopulation change was higher in females than in males (first‐recruiters: 30% vs. 22%,n= 987; adults 5% vs. 1%,n= 719), according to their different breeding roles. However, all populational factors had an equal effect on individuals of different sex and dispersal status.

Movement rates decreased with inter‐subpopulation distance – indicating that travelling to distant subpopulations may impose costs in terms of breeding prospects – and with the number of subpopulations, which increased during our study period.

Conspecific attraction strongly influenced the probability of dispersal: it was relatively higher in largely populated subpopulations, and individuals of large subpopulations were reluctant to change to others. These results were neither influenced by the size and breeding density of the subpopulations nor by habitat quality in terms of food availability or risk of predation, as indicated by breeding success of kestrels at each subpopulation. The number of conspecifics could be used by the kestrels as a cue of patch quality in terms of settlement options, and large subpopulations could be more easily detected by prospecting birds.

Our study highlights the fact that several assumptions of theoretical metapopulation modelling are often not fulfilled in nature. Both theoretical models and management strategies on spatially structured populations or metapopulations should thus consider the number, population size, and spatial distribution of local populations, as well as their relationships with the dispersal ability of the species.
Host preference and performance of lichenivorous Eilema spp. larvae in relation to lichen secondary metabolites
Authors: Pöykkö Heikki , Hyvärinen Marko
Published: May 2003

We compared the larval host preference of four lichenivorous Eilema (Lepidoptera, Arctiidae) species on four common epiphytic lichen species including Hypogymnia physodes, Melanelia exasperata, Vulpicida pinastri and Xanthoria parietina. Survival and growth of larvae on different species were monitored and correlation to qualitative and quantitative variation in lichen secondary compounds was analysed.

All moth species preferred M. exasperata, which does not contain polyphenolic substances, over other lichens, but also foraged on other lichens in the food preference experiment. All larvae reared on V. pinastri and H. physodes died during the growth and survival experiment. Survival of larvae on X. parietina and M. exasperata were equal. Larvae grew faster and and bigger on M. exasperata than on other lichens.

Consumption and utilization measurements also revealed that M. exasperata was of the highest quality, although the relative consumption rate was highest on X. parietina. Our results indicate that different secondary chemicals have different effect against lichenivores or that larvae are either well adapted to certain chemicals or that these chemicals may have other roles than antiherbivore function for lichens.

It is suggested that lichenivorous lepidopteran species may have different adaptations, such as dietary mixing to receive nutrients in optimal proportions or compensatory feeding ability to ensure the maximal growth efficiency on a suboptimal host.
Measuring beta diversity for presence–absence data
Authors: Koleff Patricia , Gaston Kevin J. , Lennon Jack J.
Published: May 2003

Little consensus has been reached as to general features of spatial variation in beta diversity, a fundamental component of species diversity. This could reflect a genuine lack of simple gradients in beta diversity, or a lack of agreement as to just what constitutes beta diversity. Unfortunately, a large number of approaches have been applied to the investigation of variation in beta diversity, which potentially makes comparisons of the findings difficult.

We review 24 measures of beta diversity for presence/absence data (the most frequent form of data to which such measures are applied) that have been employed in the literature, express many of them for the first time in common terms, and compare some of their basic properties.

Four groups of measures are distinguished, with a fundamental distinction arising between ‘broad sense’ measures incorporating differences in composition attributable to species richness gradients, and ‘narrow sense’ measures that focus on compositional differences independent of such gradients. On a number of occasions on which the former have been employed in the literature the latter may have been more appropriate, and there are many situations in which consideration of both kinds of measures would be valuable.

We particularly recommend (i) considering beta diversity measures in terms of matching/mismatching components (usually denoted a, b and c) and thereby identifying the contribution of different sources of variation in species composition, and (ii) the use of ternary plots to express the relationship between the values of these measures and of the components, and as a way of understanding patterns in beta diversity.
Determinants of macroinvertebrate diversity in headwater streams: regional and local influences
Authors: Heino Jani , Muotka Timo , Paavola Riku
Published: May 2003

Multiscale determinants of diversity and the relationship between regional (RSR) and local richness (LSR) have recently attracted increased attention, yet such studies on stream organisms remain scarce. We studied the relationships among RSR, β‐diversity, LSR and local environmental variables in 120 headwater streams in Finland. Approximately similar‐sized areas of eight drainage systems were defined as regions, and 15 stream riffles (= locality) per region were sampled.

RSR showed a strong positive relationship with mean LSR (R2 = 0·686), and there was no sign of curvilinearity within the observed range of RSR. RSR was also positively, although non‐significantly, related to β‐diversity (r = 0·662).

In stepwise regression, RSR was the first variable to enter the model, and a model incorporating RSR and stream width explained 32·5% of variation in LSR. If RSR was omitted from the model, then stream width emerged as the most important variable, followed by water pH, which together accounted for 20·6% of variation in LSR.

At the within‐region scale, different variables were important in accounting for variation in LSR. Factors correlated with LSR reflected either stream size, spatial heterogeneity, adverse water chemistry conditions (pH), or a limiting resource base for macroinvertebrates (nutrient concentrations).

The major role of RSR in setting the upper limit to LSR suggests that macroinvertebrate assemblages of boreal headwater streams are unsaturated. This finding is supported by evidence from experimental studies, where it has been shown that competitive interactions among stream macroinvertebrates are effective only at very small spatial scales, and competitive exclusion is prevented typically by frequent disturbances. However, although RSR was generally the most influential variable contributing to LSR, it is far from clear whether RSR consistently sets the limits to LSR, or vice versa. For instance, uniformly adverse water chemistry conditions across a region may lead to low levels of local richness and low species turnover among sites, leading eventually to an impoverished regional species pool.

These findings do not deny the importance of local factors, but emphasize that understanding the organization of stream benthic communities requires simultaneous examination of factors prevailing at multiple spatial scales.
The relative impact of local and regional processes on macro‐invertebrate species richness in temporary pools
Authors: Kiflawi M. , Eitam A. , Blaustein L.
Published: May 2003

Freshwater temporary pools constitute insular habitats that can vary extensively in the richness of their macro‐invertebrate fauna, even within small spatial scales. While strictly statistical analyses may identify variables that account partially for this variation, they do not address explicitly the mechanisms that generate it.

Here we show how a simple island‐biogeographical model explains 62% of the variation in local species richness of 47 neighbouring pools, based solely on pool size and permanence. A regression of the observed richness on that predicted by the model did not indicate any systematic biases, and left residuals that were distributed according to the expected.

The model provides a robust working hypothesis, to which we apply a novel approach of quantifying the relative impact of local and regional factors on the species richness of individual pools. Using elasticity analysis of model parameters and invoking elasticity as a measure of parameter ‘importance’ we show, for example, that the impact of regional species richness on the richness of noninteractive communities should always exceed that of the probability of local extinction.

The analysis exposes potential difficulties in generalizing which factor – local or regional – has the greater relative importance, and to what extent, as the answer can depend on: (i) the specific factors being compared, and (ii) particular habitat characteristics of individual localities.
Size matters: competition within populations of the limpetPatella depressa
Authors: Boaventura Diana , Da Fonseca Luís Cancela , Hawkins Stephen J.
Published: May 2003

Competitive interactions within and between size‐classes of the limpetPatella depressaPennant were investigated in central Portugal. Experimental enclosures of 25 × 25 cm containing marked limpets were set up at mid‐tidal level on the shore. Twelve treatments with different combination of densities and size‐classes were assigned to the plots, with three replicates of each. Mortality was recorded every 15 days and length was measured monthly during the approximately 6 months of the experiment.

At the end of the experiment limpets were collected for determination of length, height, dry weight, sex and gonad development. The availability of food was assessed indirectly by determination of chlorophyll concentration with spectrophotometric analysis of rock chips. Reduced density treatments showed very low mortality and substantially increased growth. Both size‐classes of limpets showed increased mortality and reduced growth in increased density treatments. This effect was, however, more marked for large than small limpets when caged separately.

Although both size‐classes could negatively affect each other, the effect of large limpets on small was greater than the reverse. Large limpets are superior competitors that may modulate the abundance of small limpets on the shore. It is unlikely, however, that they will totally exclude small limpets due to intensity of competition within the large size‐class. Niche differentiation and high recruitment at low shore levels are other possible factors that can contribute to reduce competition between the size‐classes.
Importance of species identity and number for process rates within different stream invertebrate functional feeding groups
Authors: Jonsson Micael , Malmqvist Björn
Published: May 2003

The effects of decreasing species richness on process rates were investigated in laboratory experiments within three different stream invertebrate functional feeding groups: filter feeders, grazers and predators.

We found significant effects in all groups; however, the direction and magnitude varied. The effects were not due to species richness per se as species identity was the only significant factor in all analyses.

Filter‐feeding collectors showed a decreasing filtration rate with decreasing species richness in a first experimental trial while a second one showed no trend. In contrast, process rates increased with decreasing species richness in both grazers and predators.

Comparisons of expected with observed process rates in two‐ and three‐species treatments indicated underlying mechanisms. In grazers resource dominance by one species seemed to negatively affect the other species so that grazing rates decreased when species were combined. In predators interference by two of the species on a smaller predator species seemed to affect predation rates negatively.

Our results show that the effects of species loss greatly depend on what type of interactions the lost species participated in and that species identity may be the most important factor generating effects of species loss in cases when the interaction affects species differently.
Spatial dynamics and cross‐correlation in a transient predator–prey system
Authors: Tobin Patrick C. , Bjørnstad Ottar N.
Published: May 2003

We examined spatiotemporal data in a transient, seasonal system involving a specialist predatory beetle, Carcinops pumilio (Erichson), and its prey, larval Musca domestica L.

Prior to beetle colonization, larval fly populations were highly spatially structured, but as adult predatory beetles immigrated and colonized the field, the beetles became increasingly clustered at local spatial scales, causing spatial decorrelation in the dynamics of their prey. Larval flies appeared to regain local clustering as beetle abundance approached a carrying capacity with the prey population.

During exponential population growth, beetles were generally strongly negatively cross‐correlated with their prey at local spatial scales.

We were able to simulate these spatially–extended interactions in a predator‐prey coupled map lattice model. We used this model to investigate the effects of global and local prey reproduction, in the presence and absence of global stochasticity, on predator and prey spatial structuring and cross‐correlation.

The work shows in a uniquely detailed fashion how the transition from eruptive pest abundance to regulation by a specialist predator is associated with a transition in spatial structure.
Predicting abundance from occupancy: a test for an aggregated insect assemblage
Authors: Warren M. , Mcgeoch M. A. , Chown S. L.
Published: May 2003

The ubiquitous, positive abundance‐occupancy relationship is of potential value to conservation and pest management because of the possibility of using it to predict species abundance from occupancy measures.

He & Gaston (2000a) developed a model, and a parameterization method, for the prediction of abundance from occupancy based on the negative binomial distribution. There are to date few empirical tests of either the estimation method or model. Here we conduct such a test in a field‐based mesocosm experiment using a Drosophilidae assemblage associated with decaying fruit.

With individual (and groups of) fruit as minimum mapping units, abundance estimates derived using the parameterization method of the He‐Gaston model differed significantly from measured values, and were least accurate for the most abundant species.

Substitution of k‐values corrected for species density in the model did not improve abundance predictions significantly. However, substitution of k‐values calculated directly from the negative binomial distribution yielded highly accurate abundance predictions.

Although the distribution of fly species did not deviate significantly from the negative binomial distribution, and the finest possible minimum mapping units were used (individual fruit), the parameterization method in the He‐Gaston model consistently underestimated the abundance of species in the assemblage because individuals were very highly aggregated within fruit.

Because of its potential importance, this model and parameterization method require further exploration at fine scales, commonly represented by individual habitat units, for highly aggregated species. The incorporation of spatially explicit information may provide a means of improving abundance predictions in this regard.
Effects of floristics, physiognomy and non‐native vegetation on riparian bird communities in a Mojave Desert watershed
Authors: Fleishman Erica , Mcdonal Neil , Nally Ralph Mac , Murphy Dennis D. , Walters Jack , Floyd Ted
Published: May 2003

In the deserts of the south‐western United States of America, as in many ecoregions around the world, invasion of non‐native plants is modifying the structure and composition of riparian vegetation.

Restoration of native plant species frequently proves to be ecologically and economically difficult. In the Muddy River drainage in the Mojave Desert (Nevada, USA), eradication of one the most aggressive invasive plants,Tamarix ramosissima(salt‐cedar), often reduces the structural and compositional diversity of the remaining vegetation. This can have negative effects on native animals, including birds.

The objectives of our work were (i) to examine relationships between avian diversity and measures of vegetational diversity (species richness, dominance of non‐native plants and vegetation structure [total vegetation volume]), (ii) to explore the extent to which avian community composition was associated with vegetation composition (floristics) or vegetation structure (physiognomy), and (iii) to consider the potential effects of alternative land management and ecological restoration strategies on the biodiversity of birds and other native fauna in watersheds in the arid south‐western USA.

Species richness of all birds and of breeding birds was best modelled by total vegetation volume alone. Neither species richness of plants nor dominance of non‐native plants had a statistically significant effect on species richness, abundance or evenness of birds.

Species composition of birds between sites was more similar when floristics was more similar, and vice versa. Species composition of birds was not correlated with physiognomy.

Species richness of native birds in the Muddy River drainage appears not to suffer from invasion of non‐native plants, provided that the vegetational community retains sufficient structural diversity.

The composition of the bird community is closely related to floristics, and other taxonomic groups may exhibit different responses to vegetation structure and composition. Therefore, explicit strategies for landscape‐scale management, restoration and maximization of native faunal diversity should consider how removal of invasive plants may affect physiognomy and floristics of the vegetational community as a whole.
The effect of helping behaviour on the survival of juvenile and adult long‐tailed tits Aegithalos caudatus
Authors: McGowan Andrew , Hatchwell Ben J. , Woodburn Richard J. W.
Published: May 2003

In the cooperative breeding system of the long‐tailed tit Aegithalos caudatus failed breeders may become helpers at the nest of another pair to whom they are usually related. The aim of this study was to determine the effect of helping behaviour on the survival of helpers and the recipients of their help.

We used capture–mark–recapture data and the MARK program to analyse survival of 482 birds ringed as fledglings and 155 birds ringed as adults.

Juvenile males had a higher survival probability than juvenile females across all years whilst their subsequent adult survival was constant. Within sex, the survival probability of juveniles that fledged from nests with helpers was higher than those that did not receive help as nestlings.

Failed breeders that became helpers had a higher survival probability (56%) than those failed breeders that did not become helpers (46%). Successful breeders had a survival probability of 56% regardless of whether they received help or not.

Failed breeders that became helpers had a lower probability of successfully breeding in a subsequent year (27%) when compared to those failed breeders that did not become helpers (38%).

6. We conclude that helpers gain kin‐selected fitness benefits through the increased survival of related offspring but not through the increased survival of related breeders. Furthermore, helpers gain direct fitness benefits through increased personal survival, but at a cost of reduced probability of successful future personal reproduction.
Interactions over four trophic levels: foodplant quality affects development of a hyperparasitoid as mediated through a herbivore and its primary parasitoid
Authors: Harvey Jeffrey A. , Van Dam Nicole M. , Gols Rieta
Published: May 2003

Related plant species with different spatial and/or temporal life‐history characteristics often possess differences in secondary chemistry and thus direct defensive capability. These differences are often attributed to a range of divergent selection pressures from herbivores and pathogens. Most studies of insect–plant interactions have examined the effects of plant defence on herbivore performance, with less attention being paid to higher trophic levels, such as parasitoid wasps. Moreover, to date it is not known whether secondary plant compounds may affect organisms in the fourth trophic level.

Here, we study interactions in a four‐trophic‐level system. The development of a solitary secondary hyperparasitoid,Lysibia nana, and its primary endoparasitoid host,Cotesia glomerata, are compared when reared from a primary herbivore host,Pieris brassicae, which was itself reared on two cruciferous plants with contrasting life histories. WhereasL. nanais known to attack the pupae of a number of primary parasitoids in the genusCotesia, bothC. glomerataandP. brassicaeare intimately associated with plants in the family Brassicaceae.

Insects were reared from a feral population of the spring perennial,Brassica oleracea, and a naturally occurring population of a summer annual,B. nigra. Like other cruciferous plants, both species are known to produce glycoside toxins (= glucosinolates) after they are attacked by foliar herbivores. However, concentrations of glucosinolates were more than 3·5 times higher in young shoots ofB. nigrathan in corresponding shoots ofB. oleracea.

Cocoon weight inC. glomeratawas unaffected by the foodplant on whichP. brassicaewas reared, whereas in 24‐h‐old host cocoons emerging adult hyperparasitoid body mass increased significantly with cocoon size and wasps were significantly larger, and survived better onB. oleraceathan onB. nigra. Moreover, body mass inL. nanawas typically larger in young (c.24 h), than in older (c.72 h) cocoons ofC. glomerata. Egg‐to‐adult development time inL. nanagenerally increased with host size and age, and wasps on younger hosts completed their development more rapidly onB. nigra.

Our results clearly demonstrate that qualitative differences in herbivore diet can differently affect the performance of interacting organisms across several trophic levels, and suggest that bottom‐up forces may also play a role in mediating interactions involving plants–herbivores–parasitoids and hyperparasitoids.
Morphometric characterization of thalassohaline Artemia franciscana populations from the Colombian Caribbean
Authors: Camargo W. N. , Ely J. S. , Sorgeloos P.
Published: May 2003

Aim To establish possible interpopulation relationships among Colombian Artemia franciscana (Crustacea, Anostraca) populations.

Location Colombian Caribbean coast (Manaure, Galerazamba, Salina Cero and Tayrona) and a similar thalassohaline reference population from San Francisco Bay (SFB‐USA).

Methods Morphometric characters of male and female cultured individuals of A. franciscana were measured. The populations were grouped according to: (1) population type (populations grouped according to two broad regions of origin: North America and the Caribbean coast), and (2) specific geographical origin (populations selected according to five specific local origins: Manaure, Galerazamba, Salina Cero, Tayrona and SFB) and evaluated using forward stepwise discriminant analysis (SPSS, Ver. 10).

Results Optimal discriminant variables for males grouped by the type of population were left setae and antenna length, and for females they were abdominal length and antenna length. However, for males grouped by their specific geographical origin, the optimal variables were furca length, left setae, antenna length, eye separation, abdominal width and abdominal length, and for the females, they were furca length, abdominal length, left setae and eye separation. Male and female Colombian Caribbean populations were separated from the North American populations. However, our results show that the classification based on male characters provides better group membership than females.

Main conclusions Male morphometric characters separated the type of population groups more clearly than the female characters, because all Colombian populations were correctly positioned in the Caribbean coast region and the SFB population in the North American region, with no overlapping between the two types, as was the case for the female individuals. Likewise, male individuals correctly position the Salina Cero population to its neighbouring Galerazamba population and to the other Colombian populations. In contrast, female individuals from Salina Cero did not cluster with the other Colombian coast populations (Galerazamba, Tayrona and Manaure) or with the SFB population.
Did Native Americans influence the northward migration of plants during the Holocene?
Authors: MacDougall Andrew
Published: May 2003

AbstractLong‐distance plant dispersal explains the rapid northward migration of plant species during the Holocene but the mechanisms by which it occurred are poorly understood. Given that Native Americans spread numerous cultigens over thousands of kilometres during the late Holocene, I examined historical literature for evidence of non‐cultigen dispersal or cultivation in North America's eastern woodlands. Cultivation references are included because a strong relationship between dispersal and indigenous flora husbandry is assumed. Sixty‐seven texts describing Native American lifestyle, cultural activities, and land management reported some form of plant use. Most accounts, however, focus on cultigen production or the use of indigenous flora for medicine or food without mention of dispersal. Twenty‐four of the texts described the trade, transport, or cultivation of plants indigenous to eastern North American woodlands. Most accounts focus on the informal production of food plants, especially trees and shrubs. Confounding these reports was clear evidence of observer bias, limited botanical knowledge, acculturation, and secrecy by Native American informants. Because of these shortcomings, the likelihood of widespread long‐distance plant dispersal by Native Americans could not be determined using historical literature. This activity was either not widespread or was not observed by, or revealed to, Europeans. To adequately test the Native American plant dispersal hypothesis, direct evidence from other sources (e.g. archaeobotancial data) will be required.
Variation in invertebrate–bryophyte community structure at different spatial scales along altitudinal gradients
Authors: Andrew N. R. , Rodgerson L. , Dunlop M.
Published: May 2003

Aim  This study assessed changes in diversity and assemblage composition in bryophytes and their associated invertebrates along altitudinal gradients in Australia and New Zealand. The importance of altitude in shaping these communities and for the diversity of both invertebrates and bryophytes was examined at different spatial scales, including local, altitudinal, regional and biogeographical.

Location  Samples were taken from four Australasian mountain ranges between 42° and 43°S: Mt Field and Mt Rufus, Tasmania, Australia, and Otira Valley and Seaward Kaikoura Mountains, South Island, New Zealand.

Methods  On both Tasmanian mountains, five altitudes were assessed (250, 500, 750, 1000 and 1250 m). At each location (mountain/altitude combination) two sites were chosen and six samples were taken. Six altitudes were assessed on New Zealand mountains (Otira: 250, 500, 750, 1000, 1250 and 1500 m; Kaikoura: 1130, 1225, 1325, 1425, 1525 and 2000 m). Bryophyte substrate was collected, and all samples were stored in 70% ethanol. Invertebrates were extracted from bryophytes using kerosene‐phase separation and all invertebrates were identified to family. At each location in Tasmania, all bryophyte species within six 25‐cm2 grids per site were collected and identified to species. Bryophytes from New Zealand were identified to species from the invertebrate sample substrate because of sampling constraints.

Results  Altitude did have a significant effect on diversity, however, no general trend was found along the altitudinal gradient on the four mountains. There were distinct differences in diversity between biogeographical regions, mountains, altitudes and sites. In Tasmania, Mt Field had the highest diversity in invertebrates and bryophytes at 750 m. In contrast, Mt Rufus had consistent low invertebrate and bryophyte diversity along the entire altitudinal gradient. There were also distinctive differences between locations in the composition of invertebrate and bryophyte communities in Tasmania. Along the two altitudinal gradients in New Zealand, Otira had highest diversity for both invertebrates and bryophytes at low altitudes, whereas Kaikoura had highest invertebrate and lowest bryophyte diversity at the highest altitude.

Main conclusions  There was an effect of altitude, however, there were no consistent changes in diversity or composition on the four different mountains. There was considerable local and regional variation, and, despite a strong sampling design, no underlying altitudinal trends were detectable. This study demonstrates the importance of examining a range of spatial scales if patterns in community structure along altitudinal gradients are to be studied. The implications of this study are discussed with reference to survey design, taxonomic resolution, climate change and conservation of habitat.
What limits the distributions of coastally restricted terrestrial invertebrates? The case of coastal landhoppers (Crustacea: Amphipoda: Talitridae) in southern Tasmania
Authors: Richardson Alastair M. M. , Swain Roy , McCoull Colin
Published: May 2003

Aim  A number of terrestrial invertebrates are known to have distributions limited to the immediate coastal zone, but the factors controlling their distributions are not well understood. This study was planned to correlate the distribution of a coastal terrestrial amphipod, Austrotroides maritimus Friend 1987, which is only found within 100 m of the high tide mark, with soil characteristics and salt deposition.

Location  South Cape Rivulet Bay on the south coast of Tasmania (146°47′ E, 43°36′ S).

Methods  Abundance of the amphipods was examined at four sites c. 200 m apart that varied in their exposure to onshore westerly winds. At each site four replicate transect lines were established 3 m apart, with pitfall traps set at 2‐m intervals. The lines were at right angles to the high water mark and extended beyond the inland limit of A. maritimus. Amphipods were trapped at three times of the year, in winter, spring and summer (1993–94), and the sodium content, organic content and moisture content of the soil at each trap site were measured. The sodium content of rain falling on the transects, was also measured, and lysimeters were used to assess the concentration of sodium in water penetrating the soil profile.

Results  The inland penetration of A. maritimus varied between 18 and 44 m from the seaward edge of woody terrestrial vegetation (itself <10 m horizontally from the high tide mark). Inland penetration increased from west to east around the bay, following an apparent gradient of increased exposure to onshore winds. At the most easterly and apparently most exposed site, however, the species penetrated only 18 m, but this site differed markedly from the others in its topography, caused by erosion of the dunes, with an 8‐m cliff at its seaward end. The soils at this site were also unusually clayey and waterlogged. Amphipod abundance did not correlate strongly with any of the soil parameters. The salt content of rainfall generally declined inland, as did the concentration of lysimeter leachate, but the inland declines were not all smooth, and both rainfall and lysimeter leachate concentration showed some tendency to increase inland at the most sheltered site.

Main conclusions  Austrotroides maritimus is strongly restricted to the immediate coastal zone. The extent of its inland penetration correlates with exposure to onshore winds, and circumstantial evidence supports the hypothesis that this may be due to differences in the amount of salts deposited.
Hawaiian biogeography and the islands’ freshwater fish fauna
Authors: McDowall R. M.
Published: May 2003

Aim  This paper describes known patterns in the distributions and relationships of Hawaiian freshwater fishes, and compares these patterns with those exhibited by Hawaii's terrestrial biota.

Location  The study is based in Hawaii, and seeks patterns across the tropical and subtropical Indo‐west Pacific.

Methods  The study is based primarily on literature analysis.

Results  The Hawaiian freshwater fish fauna comprises five species of goby in five different genera (Gobiidae). Four species are Hawaiian endemics, the fifth shared with islands in the western tropical Pacific Ocean. All genera are represented widely across the Indo‐west Pacific. All five species are present on all of the major Hawaiian islands. All five species are amphidromous – their larval and early juvenile life being spent in the sea. Although there has been some local phyletic evolution to produce Hawaiian endemics, there has been no local radiation to produce single‐island endemics across the archipelago. Nor is there evidence for genetic structuring among populations in the various islands.

Main conclusions  In this regard, the freshwater fish fauna of Hawaii differs from the well‐known patterns of local evolution and radiation in Hawaiian Island terrestrial taxa. Amphidromy probably explains the biogeographical idiosyncrasies of the fish fauna – dispersal through the sea initially brought the fish species to Hawaii, and gene flow among populations, across the archipelago, has hitherto inhibited the evolution of local island endemics, apparently even retarding genetic structuring on individual islands.
The relationship between British ground beetles (Coleoptera, Carabidae) and land cover
Authors: Eyre M. D. , Luff M. L. , Staley J. R. , Telfer M. G.
Published: May 2003

Aims and methodsGround beetle and satellite‐derived land cover data from 1687 United Kingdom 10 km national grid squares were used to assess the relationship between species pool and cover data in Great Britain using fuzzy classification and constrained ordination.

ResultsGround beetle species pools classified into nine groups which were related to land cover variables using constrained ordination. There was a strong relationship between upland land cover and three ground beetle groups. Deciduous woodland, coastal and tilled land were associated with three other groups. Three further groups did not appear to be strongly associated with any particular cover, but differed in geographical position.

ConclusionThe distribution of species pools derived from the British national recording scheme at the 10 km scale was strongly related to satellite‐derived land cover data. There appears to be considerable potential for the use of a synthesis of land cover and ground beetle data in the monitoring of environmental change over a large, countrywide, area.
Influence of climate on Bonelli's eagle's (Hieraaetus fasciatus V. 1822) breeding success through the Western Mediterranean
Authors: Ontiveros Diego , Pleguezuelos Juan M.
Published: May 2003

Aim  To assess the impact of certain climatic variables on the breeding success of some populations of Bonelli's eagle (Hieraaetus fasciatus V. 1822) throughout its latitudinal distribution range, in order to account for recent and differential declines in populations.

Location  Western Mediterranean, from southern Morocco to southern France.

Methods  Seven populations were considered for the latitudinal distribution range of the species. Data from 1052 breeding attempts were taken from the literature and, for each population, breeding success was measured as the mean number of fledglings per pair per year. Breeding success, as a dependent variable, was related to five geographical and climatic variables (latitude, mean annual temperature, mean minimum temperature of the coldest month, mean maximum temperature of the hottest month and mean annual precipitation) as independent variables, through some regression models, which take into account the multicolinearity of the variables.

Results  All the analyses agreed that average annual temperature was an important factor associated with the breeding success of the species in each region, and accounted for up to 97% of the variance of the breeding success throughout a latitudinal gradient in the study area.

Main conclusions  The low breeding success of the northern populations (probably because of climatic constraints) and the tendency of juveniles to disperse southwards, diminishes recruitment in those populations. Therefore, as human pressure and habitat destruction causes high adult and pre‐adult mortality of the species throughout its entire latitudinal range, disturbances in the northern populations have more profound effects, thereby explaining observed population declines.
Regional differences in responses of chinook salmon populations to large‐scale climatic patterns
Authors: Levin Phillip S.
Published: May 2003

Aim  To quantitatively explore the extent to which many different populations of the same species (chinook salmon, Oncorhynchus tshawytscha) respond cohesively to a common large‐scale climatic trend.

Location  The Columbia River basin of the northwestern US.

Methods  I used regression analyses to describe the downward trend in population growth (number of recruits per spawning adult) for thirteen populations of chinook salmon distributed among three geographical regions: Snake River, Upper Columbia River and Middle Columbia River. I then used residuals from these regressions to characterize per capita productivity for each brood year. Positive residuals indicated productivity higher than that predicted by the time series, while negative residuals revealed years in which productivity was lower than predicted. I next used analysis of covariance (ancova) to test the null hypothesis that associations between ocean/climate conditions and deviations from predicted population growth did not vary among geographical regions. All ancovas used residuals generated from the regressions as the response variable, geographical region as the main effect, and climatic condition [characterized by the Pacific Decadal Oscillation index (PDO)] as the covariate. A major climate shift occurred in 1977, and because the association of the PDO with salmon productivity varied between the pre‐ and post‐1977 climate regimes, I analysed data from the two regimes separately.

Results  There were marked impacts of climate on salmon production that varied among geographical regions and between decade‐scale climate regimes. During the pre‐1977 climate regime, productivity of salmon populations from the Snake River tended to exceed expectations (i.e. residuals were positive) when values of the PDO were negative. In contrast, this pattern was not evident in populations from the upper or middle Columbia Rivers. During the post‐1977 regime when ocean productivity was generally lower, the association of the PDO with salmon productivity changed – productivity tended to fall short of expectations (i.e. residuals were negative) when values of the PDO were negative.

Main conclusions  Understanding the linkages between salmon populations and climate is critical as managers attempt to preserve threatened salmon populations in the face of both natural or human‐induced climate variation and the litany of human activities affecting salmon. An important step in this understanding is the recognition that the response to ocean/climate change by salmon populations of the same species and river basin is not necessarily homogeneous.