Gradients of life-history variation: an intercontinental comparison of fishes

Multivariate analysis identified atwo-dimensional continuum of life-historyvariation among 301 fish species from Europe,North America, South America and the Atlanticand Pacific coasts of North America. The firstaxis was associated with larger body size,higher fecundity, delayed maturation, fewerreproductive events, and shorter breedingseason on one end and small size, lowfecundity, early maturity, multiplereproductive events per year, and prolongedbreeding season on the other. The second axiscontrasted fishes having larger eggs and moreparental care against fishes with the oppositesuite of traits.Phylogenetic affiliations of species wereapparent in the general patterns of ordinationof species within orders, indicatingevolutionary divergences in life-historypatterns. In fact, partitioning the variance oflife-history traits showed that taxonomic orderand latitude were the most important factorsand geographic region and habitat the least.Despite phylogenetic constraints, basiclife-history patterns showed consistencybetween distantly geographical regions,latitudinal ranges and basic adult habitats,indicating convergences in life-historypatterns. Although the basic life-historypatterns seemed repeatable among distantlyrelated taxa, geographical and latitudinalaffiliations were apparent. Species from SouthAmerica are skewed toward the opportunisticendpoint, whereas North American marine speciesare skewed toward the periodic endpoint of thetrilateral continuum model. Most of the fishspecies from South American data set came fromfluctuating environments, so an opportunisticstrategy of early maturation and continuousspawning permits efficient recolonization ofhabitats over small spatial scales. Incontrast, most species in the North Americanand European data sets came from seasonalhabitats that are nonetheless more hydrologicalstable, so a periodic strategy of delayingmaturation to attain large clutches enhancesadult survivorship during suboptimalenvironmental conditions and recruitment whenearly life stages encounter suitableenvironmental conditions. Similarly,latitudinal affiliations were also observed:opportunistic strategists more common intropical latitudes and periodic strategistsmore common in temperate and Arctic latitudes.     

Risk assessment for nonindigenous pests: 1. Mapping the outputs of phenology models to assess the likelihood of establishment

This paper demonstrates the use of phenology models mapped over the landscape as a tool in support of risk assessments for nonindigenous plant pests. Drawing on the relationship between pest development and temperature, the approach uses gridded sequential interpolated temperatures at a resolution of 1 km, linked with phenology models, to predict the potential for a pest to develop throughout the landscape. The potential for establishment of Colorado beetle (Leptinotarsa decemlineata) in England and Wales was used as an illustration. The likelihood of the pest completing a single generation during a 30‐year period (1961–90) was computed. Summaries of phenology, based firstly upon point temperature series from weather stations and secondly upon temperatures interpolated across the landscape, were compared. The results revealed that the use of point data led to a 70% likelihood of over‐estimating the area at risk from year to year. In the case of average long‐term risk however, the point‐based and landscape‐wide distributions of establishment potential were similar. We demonstrate how the use of phenology models running on a daily time scale provides date based results, so allowing outputs to be tied in with periods in the cropping cycle. The application of daily data in computing the phenological results, unlike the main body of published work on pest risk assessment which uses averaged monthly data, reflects more fully the underlying variability and degrees of sensitivity of the pest to changes in weather.     

广东内伶仃岛植物区系的研究

通过对广东内伶仃岛的维管植物区系进行全面考察、采集、鉴定和研究,结果表明,（1）共有野生维管植物127科367属551种,其中蕨类植物20科25属38种,种子植物107科342属513种,12种为广东新记录;（2）种子植物区系的表征科主要有：樟科、茜草科、夹竹桃科,番茄枝科,大戟科、桑科、冬青科,芸香科、葡萄科、五加科、紫金牛科、荨麻科、防己科、天南星科、棕榈科等;（3）属的地理成分以泛热带分布为主,其次为旧世界热带及东亚分砷;（3）通过与邻近地区植物区 的比较,发现内伶仃岛与香港植物区系相似性最高,与古田、古兜山的相似性次之,而与南昆山的相似性较低,它们均属于华夏植物区系界的华南省。     

黑河流域浮游植物及其地理分布特征研究

1997年5至8月对黑河（中）流域河道、湖泊、沼泽的10站位的调查中,共鉴定浮游植物8门109种（未鉴定到种的按1种计）,其中蓝藻（Cyanophyta）16tkhh,bqvnaiks(Cryptophyta)2种,甲藻（Pyrrophyta)3种,金藻（Chrysophyta)4种,黄藻（Xanthophyta)4种,裸藻（Euglenophyta)8种,绿藻（Chlorophyta)38种,硅藻（Bacillariophyta)34种。南部祁连山山区的浮游植物种类很贫乏。中下游诸点有黑河流域浮游植物全部属、种,故可以认为黑河流域浮游植物地理分布具有与河流水文分带相对应的垂直地理性分异。     

Trophic diversity of the otter (Lutra lutra L.) in temperate and Mediterranean freshwater habitats

Aim To analyse the geographical patterns in the composition and diversity of otter's (Lutra lutra L.) diet and their relationship with climatic characteristics. Location European freshwater habitats under Mediterranean and temperate climatic regimes. Methods Thirty‐seven otter diet studies were reviewed, twenty‐one from temperate and sixteen from Mediterranean areas. All studies were based on spraint analysis and their results expressed as relative frequency of occurrence of seven main prey categories. Principal Component Analysis was performed to extract the main gradients of diet composition. Pearson's correlation and t‐tests were used to assess the relationship between diet characteristics (composition, diversity and taxonomic richness) and geographical and climatic variables. Results A clear latitudinal gradient in diet composition was observed. Otter diet was more diverse and featured more prey classes in southern localities, while the species was more piscivorous towards the north, where it predated upon a higher number of fish families. This pattern was similar when temperate and Mediterranean localities of Europe were compared. Mediterranean otters behaved as more generalist predators than temperate ones, relying less on fish, and more on aquatic invertebrates and reptiles. Main conclusions Geographical differences in otter feeding ecology in Europe seem to be related with the two contrasted climatic conditions affecting prey populations. The otter can act as a highly specialized piscivorous predator in temperate freshwater ecosystems, which do not suffer a dry season and have a comparatively stable water regime compared to Mediterranean ones. However, the unpredictable prey availability in Mediterranean areas, affected by strong spatial and temporal water shortages, favours a diversification of the otter's diet.     

Geographical distributions,relative abundance and coexistence of Drosophila aldrichi and Drosophila buzzatii in Australia

Abstract Climatic data and collection records for the cactophilic Drosophila aldrichi and Drosophila buzzatii for 97 localities were used to examine the effects of geographical location, season, host plant species and climatic factors on their range and relative abundance. Temporal variation in relative abundance was assessed from monthly collections over 4 years at one locality. Effects of weather variables over the 28 days before each collection were examined. A generalized linear model of the spatial data showed significant geographical variation in relative abundance, and significant climatic effects, with the proportion of D. aldrichi higher in the warm season, and increasing as temperature variation decreased and moisture indices increased. The temporal data gave generally concordant results, as D. aldrichi proportion was higher in summer and autumn, and increased as maximum and minimum temperatures increased, and as variation in maximum temperature decreased. In a laboratory competition experiment, D. aldrichi eliminated D. buzzatii at 31°C, but was itself eliminated at 18°C and 25°C. The range of D. buzzatii is constrained only by availability of its host plant, Opuntia species, although its relative abundance is reduced in the northern part of its distribution. The range of D. aldrichi, from central Queensland to northern NSW, Australia, is entirely within that of D. buzzatii, and its relative abundance decreases from north to south. Both climate and weather, particularly temperature variability, have direct effects on the relative abundances of the two species, and both likely act indirectly by influencing the outcome of interspecific competition.     

The combined role of glaciation and hybridization in shaping the distribution of genetic variation in a Patagonian southern beech

Aim The distribution of the genetic variation in long‐lived species is a combination of both, historical and current processes. In Nothofagus nervosa (Phil.) Dim. et Mil., the possible existence of multiple glacial refugia, the unidirectional gene flow along fragmented areas and the natural hybridization with the related species Nothofagus obliqua (Mirb.) Oerst. highlights as the most important factors responsible for modelling its genetic structure. The present study aims to find out the relative importance of these evolutionary processes in determining the distribution pattern of the genetic variation in N. nervosa. Location The study was carried out in north‐western Patagonia, Argentina. Twenty populations covering the entire distribution range of N. nervosa in Argentina were analysed. For comparison purposes, three populations from Chile were also included. Methods Genetic variation was detected using isozyme gene markers; diversity and differentiation parameters were calculated. A cluster analysis was performed and the correlation between genetic and geographical distances was tested. Results Levels of genetic variation were relatively high given the small distribution range of the species in Argentina. Genetic and geographical distances were not correlated and a longitudinal trend in the genetic variation was evident. Hotspots of diversity with rare and private alleles were observed among western populations, while hybrid seeds were found almost exclusively among eastern populations. Main conclusions The higher level of diversity observed in western populations could be related with the location of glacial refugia. Furthermore, it should also reflect low levels of gene flow given the eastward unidirectional winds. On the contrary, ancient and current interspecific hybridization processes would mainly cause the particular genetic constitution of the eastern populations. Evidence is presented supporting that glaciations and hybridization were the main factors shaping the distribution of the genetic variation in N. nervosa.     

Application of common predictive habitat techniques for post-border weed risk management

Weed risk assessment has become an accepted methodology for examining the likelihood and consequence of a plant species becoming invasive outside of its native range. Weed risk assessment draws upon biological and ecological information to estimate the likelihood and magnitude of the threats posed by introducing non-indigenous plants. In geographical terms, this has traditionally been understood as within a new country following importation of plant material. However, recent risk assessment development has focused more specifically on intracountry risk posed by already-present invasive plants and is referred to as post-border weed risk management. This form of assessment calls for fine-scale predictions of invasive species habitat suitability. This study applies some of the more popular and widely available habitat prediction models that represent a variety of different statistical approaches (linear regression, logistic regression, Bayesian probability, Classification and Regression Trees, Genetic Algorithm for Rule-set Production) to a single invasive plant, the vertebrate-dispersed, fleshy fruited European olive ( Olea europaea L.) in southern Australia. The relationships between the dependant ( O. europaea distribution) and independent (soil and climate) variables are used in the models to produce predictive maps for each model. Accuracy was calculated for each model output as well as a combined surface to examine whether recent calls for ensemble modelling of distributions produces improved predictions. Overall, the combined prediction demonstrated superior accuracy compared to any individual model outputs. The combined outputs can be likened to mapped gradations of predicted habitat suitability. The type of output produced in this study should form a critical component of post-border weed risk management but more importantly, the methodology will add to this important discipline.     

Proof of geographical origin of Albanian sage by essential oil analysis

Salvia officinalis L. and the closely related Salvia fruticosa Mill. (Lamiaceae) are amongst the economically most important medicinal and aromatic plants. Both species are rich in essential oil, which can vary significantly and is partly responsible for their bioactivity and sensorial properties. Therefore we studied its variability within Albania, one of the main exporters of both species. In S. officinalis a clear geographical gradient could be observed from North to South, based mainly on a trade-off between the thujones (α- and β-thujone) and camphor. The differences between the provinces were so pronounced that the essential oil profile could be used to identify the origin of unknown samples from within Albania to a high degree of certainty. The variability within S. fruticosa was not as pronounced due to its restricted distribution to coastal regions in the South–West only. No hybrids between the two species could be found in the overlapping distribution areas.