Flower-fruit size allometry at three taxonomic levels in Crepis (Asteraceae)

The present investigation utilizes the major axis technique to examine the allometric relationship between flower and fruit size, two developmentally related characters. Regression of log (corolla length) on log (fruit length) using data from 188 species of Crepis , 52 populations of C. tectorum and 40 sibships from a population of C. tectorum demonstrated that flower size shows a decelerating increase with increasing fruit size at all taxonomic levels, with the allometric slope varying from 0.53 to 0.69. The null hypothesis of isometry was rejected in analyses using species or sibships as observations, while the comparison of populations revealed a slope significantly different from 1 only if two outliers were excluded from the analysis. Numerous species and populations have escaped the constraint linking flower and fruit size, including C. tectorum (which has a high ratio of flower to fruit size within the genus) and C. tectorum subsp. pumila (which has a high ratio of flower to fruit size within the species).     

Assessing the use of sediment organic,carbonate and biogenic silica content as indicators of environmental conditions in Arctic lakes

The objective of this paper is to examine three sediment parameters used in paleolimnological studies, sediment organic, carbonate and biogenic silica (BSi) content, and to quantify the relationship among these parameters and modern environmental conditions for a series of Canadian Arctic lakes. Sediment samples from 63 lakes were analysed for organic, carbonate and BSi content. The environmental and physical parameters of these lakes were recorded. Bedrock composition exerted a very strong influence on sediment organic, BSi and carbonate content, and differences in lake production accounted for much of the remaining variance. The strongest relationships existed among sediment carbonate content, BSi content and water pH. A statistical model developed for predicting water pH provides a new tool for reconstructing past environmental conditions for Arctic aquatic ecosystems. A positive relationship between mean July air temperature and sediment organic and BSi content was detected, but was confounded by effects of bedrock on these parameters. However, the relationship between mean July air temperature and sediment organic and BSi could be even more significant in the context of constant bedrock composition, as is the case in paleolimnological studies.     

The use of the central raphe endings as a taxonomic character

The use of the central raphe endings as a key character in the classification ofNitzschia is argued to be of doubtful validity. Some aspects of the evolution of the raphe are discussed in relation to variation in raphe structure within fibulate genera.Notes for a monograph of theBacillariaceae (Bacillariophyta) 1.     

Impacts of logging and rehabilitation on invertebrate communities in tropical rainforests of northern Borneo

The inclusion of carbon stock enhancements under the REDD+ framework is likely to drive a rapid increase in biosequestration projects that seek to remove carbon from the atmosphere through rehabilitation of degraded rainforests. Concern has recently been expressed, however, that management interventions to increase carbon stocks may conflict with biodiversity conservation. Focusing on a large-scale rainforest rehabilitation project in northern Borneo, we examine the broad impacts of selective logging and subsequent carbon enhancement across a wide range of invertebrate fauna by comparing the abundance of 28 higher-level taxa within two separate rainforest strata (leaf-litter and understorey) across unlogged, naturally-regenerating and rehabilitated forest. We additionally assess changes in functional composition by examining responses of different feeding guilds. Responses of individual taxa to forest management were idiosyncratic but logging resulted in more than a 20% increase in total invertebrate abundance, with fewer than 20% of taxa in either stratum having significantly lower abundance in logged forest. Rehabilitation resulted in a marked reduction in abundance, particularly among leaf-litter detritivores, but overall, there were much smaller differences between unlogged and rehabilitated forest than between unlogged and naturally regenerating forest in both total invertebrate abundance and the abundances of different feeding guilds. This applied to both strata with the exception of understorey herbivores, which were more abundant in rehabilitated forest than elsewhere. These results support previous data for birds suggesting that carbon stock enhancement in these forests has only limited adverse effects on biodiversity, but with some impacts on abundance within particular guilds.     

The effect of reduced-impact logging on fruit-feeding butterflies in Central Amazon, Brazil

The Amazon region represents more than a half of all tropical forests in the world, and has been threatened by many anthropogenic activities, including several kinds of timber harvesting. The reduced-impact logging (RIL) is considered a less destructive method of timber harvesting, but there is a general lack of information about the effects on Amazonian invertebrates, including butterflies. We investigated the effect of RIL on fruit-feeding butterflies by comparing canopy and understory between an area under RIL and a control area without RIL. The canopy fauna is different and significantly richer than the understory fauna, showing that sampling only the lower strata underestimates the diversity of fruit-feeding butterflies. The effects of RIL were mainly detected in the understory butterfly assemblage, as significant differences were observed in species composition within this stratum. Effects of the RIL regime, which include tree cutting, skid trails and roads openings, are stronger in the understory than in the canopy, explaining the reported differences. Despite the detectable effects of RIL on the composition of fruit-feeding butterfly assemblages, the overall diversity was not affected. A similar pattern has been detected in many other groups, indicating that a noticeable part of the diversity of many taxa could be preserved in areas under RIL management. Therefore, in view of the problems of creating protected areas in the Amazon, RIL is a good alternative to preserve fruit-feeding butterflies and surely many other taxa, and it might be a desirable economic alternative for the region.     

Inventories of ground herbs at three altitudes on Bukit Belalong,Brunei, Borneo

Ground herbs (including pteridophytes) were studied in three 0.25 ha plots at each of three altitudes at Bukit Belalong, Brunei (913 m). At c. 200 m and c. 500 m there was evergreen lowland rain forest and at c. 850 m there was lower montane rain forest. In each plot all species of ground herb and the number of individuals and their cover were recorded. Ground herb cover, density and species-richness were higher in the lower montane forest plots. A total of 121 species were recorded, and of these 47% were restricted to the lower montane forest and 15% were restricted to the plots at 200 m. Phytosociological analyses indicate that the three altitudes have distinct ground herb communities. It is believed that the increase in herb growth is primarily due to the moister environment at higher altitudes, but higher light levels in the lower montane forest may also have an effect.     

Limitations to the use of arthropods as temperate forests indicators

Because arthropods dominate terrestrial ecosystems in species number and biomass, they can potentially play a major role as environmental indicators in applied ecology and nature conservation. We tested the suitability of arthropods as indicators for particular forest types based on a comprehensive standardized sampling of various taxa by different trap types in 93 mature temperate forest sites in three regions of Germany. We tested whether indicator species (1) can be derived for different forest types across regions, (2) are more widespread and more abundant than non-indicator ones, (3) belong to a particular taxon or trophic guild, and (4) are consistent between regions and years. Among 2041 sampled arthropod species, only four were significant indicator species for the same forest type in all region, and no single taxon or guild performed better than other groups. Indicators were generally more abundant and more widespread than non-indicators, but both abundance and distribution varied widely between species. When the analysis was repeated using data from the next year, indicator values of species significantly correlated between years, but the identity of more than 50 % of significant indicators changed, suggesting high among-year variability. We conclude that overall, arthropods did not turn out to be reliable indicators, at least at the scale of Germany. If anything, arthropod indicator species should be defined at the regional scale. Furthermore, indicators should be selected across taxa and trophic levels. Future evaluation of indicator species among arthropods should be conducted over several years based on standardized sampling protocols to develop a reliable definition of indicator species despite the high fluctuations in abundance of species among arthropods, which might either mask or overestimate the indicator value of particular species.     

The use of grasses as indicators of environmental pollution

Summary An exploratory examination of the use of rye grass as an indicator of environmental accumulation of minor elements confirmed that natural grass is contaminated by soil or airborne dust, and that this contamination cannot be washed off sampled grass with water without also removing elements from within the leaves, to an extent that varies with the age and/or environment of the grass. This reduces the suitability of natural grasses as indicators of pollution, and alternative procedures are required and proposed.     

Fruit size and shape: Allometry at different taxonomic levels in bird-dispersed plants

Summary The likelihood that a plant's seeds will be dispersed by fruit-eating birds may depend upon the size and shape of its fruits. Assuming that elongate fruits can be swallowed more easily than spherical fruits of equal volume and that plant fitness is enhanced by seed dispersal by many individuals and species of birds, natural selection should favour increasing fruit elongation with increasing fruit size in bird-dispersed plants. According to this view, this allometric pattern would be adaptive. Alternatively, fruit shape in bird-dispersed plants may be constrained by development or phylogeny. To determine whether there was any evidence to support the adaptive allometry hypothesis, we examined allometric relationships between length and diameter in fruits and seeds in a group of neotropical bird-dispersed plant species. Using the major axis technique, we regressed ln(diameter) on ln(length) for fruits and seeds at various taxonomic levels: (1) within individual trees ofOcotea tenera (Lauraceae) (2) among 19 trees within a population ofO. tenera, as well as among pooled fruits from multiple trees within 20 other species in the Lauraceae, (3) among 25 sympatric species within a plant family (Lauraceae) and (4) among 167 species representing 63 angiosperm families within a plant community in Monteverde, Costa Rica. At most taxonomic levels, a tendency for fruit length to increase more rapidly than fruit diameter among fruits (negative allometry) occurred more frequently than expected by chance. Estimated slopes of the regressions of fruit length on fruit diameter were < 1 within 15 of the 19 individualO. tenera trees, among tree means withinO. tenera, among pooled fruits within 16 of the 20 other species in the Lauraceae, among species means within the Lauraceae and among means of all bird-dispersed species in the lower montane forests of Monteverde. Seed allometry showed similar patterns, although for both fruits and seeds the broad confidence intervals of the slopes estimated by major axis regression overlapped 1 in many cases. Among the 63 Monteverde family means, fruit length and diameter scaled isometrically. Based on measurements of ontogenetic changes in fruit shape in a single species,O. viridifolia, we found no evidence that negative allometry in fruit shape within the Lauraceae was an inevitable consequence of developmental constraints. Instead, increasing elongation of fruits and seeds in certain plant taxa is consistent with adaptation to gape-limited avian seed dispersers. Contrary results from vertebrate-dispersed species from Malawi and Spain may reflect differences between the New and Old World in plant taxa, seed dispersers or evolutionary history.     

Life history parameters as indicators of growth rate in three salp populations

A strong correlation exists between individual growth rate andfive life history parameters in the fast growing salp Thaliademocratica. The five parameters are number of aggregate budsper chain; body size of reproductive solitaries; the ratio ofaggregate offspring to their solitary parents; the solitaryto aggregate ratio; and the relative proportions of juvenilesand adults in the solitary generation. Correlation coefficientsaveraging 0.68 and ranging up to 0.85 were found between theestimates of these parameters in 37 samples of salp blooms takenover 15 years in the western Pacific and eastern Indian oceans.Growth rate, estimated previously in 12 of these samples, alsocorrelated strongly with each of the five parameters with coefficientsranging from 0.88 to 0.96. After analysis of partial correlationswe selected parameters to form regression equations with growth.These equations are excellent indicators of growth in the sequentiallysampled salp populations. Because of the significant correlationbetween the parameters in a wider range of samples, they arealso likely to be indicators of growth in general salp populations.     

An examination of scale of assessment,logging and ENSO-induced fires on butterfly diversity in Borneo

The impact of disturbance on species diversity may be related to the spatial scales over which it occurs. Here I assess the impact of logging and ENSO (El Niño Southern Oscillation) -induced burning and forest isolation on the species richness (477 species out of more than 28,000 individuals) and community composition of butterflies and butterfly guilds using small (0.9 ha) plots nested within large (450 ha) landscapes. The landscapes were located in three habitat classes: (1) continuous, unburned forest; (2) unburned isolates surrounded by burned forest; and (3) burned forest. Plots with different logging histories were sampled within the two unburned habitat classes, allowing for independent assessment of the two disturbance factors (logging and burning). Disturbance within habitat classes (logging) had a very different impact on butterfly diversity than disturbance among habitat classes (due to ENSO-induced burning and isolation). Logging increased species richness, increased evenness, and lowered dominance. Among guilds based on larval food plants, the species richness of tree and herb specialists was higher in logged areas but their abundance was lower. Both generalist species richness and abundance was higher in logged areas. Among habitat classes, species richness was lower in burned forest and isolates than continuous forest but there was no overall difference in evenness or dominance. Among guilds, generalist species richness was significantly lower in burned forest and isolates than continuous forest. Generalist abundance was also very low in the isolates. There was no difference among disturbance classes in herb specialist species richness but abundance was significantly higher in the isolates and burned forest than in continuous forest. Tree specialist species richness was lower in burned forest than continuous forest but did not differ between continuous forest and isolates.The scale of assessment proved important in estimating the impact of disturbance on species richness. Within disturbance classes, the difference in species richness between primary and logged forest was more pronounced at the smaller spatial scale. Among disturbance classes, the difference in species richness between continuous forest and isolates or burned forest was more pronounced at the larger spatial scale. The lower levels of species richness in ENSO-affected areas and at the larger (landscape) spatial scale indicate that future severe ENSO events may prove one of the most serious threats to extant biodiversity.     

Cope's Rule in the Pterosauria, and differing perceptions of Cope's Rule at different taxonomic levels

The remarkable extinct flying reptiles, the pterosaurs, show increasing body size over 100 million years of the Late Jurassic and Cretaceous, and this seems to be a rare example of a driven trend to large size (Cope's Rule). The size increases continue throughout the long time span, and small forms disappear as larger pterosaurs evolve. Mean wingspan increases through time. Examining for Cope's Rule at a variety of taxonomic levels reveals varying trends within the Pterosauria as a whole, as pterodactyloid pterosaurs increase in size at all levels of examination, but rhamphorhynchoid pterosaurs show both size increase and size decrease in different analyses. These results suggest that analyses testing for Cope's Rule at a single taxonomic level may give misleading results.     

Assessing the vulnerability of European butterflies to climate change using multiple criteria

Vulnerability of 100 European butterfly species to climate change was assessed using 13 different criteria and data on species distributions, climate, land cover and topography from 1,608 grid squares 30′ × 60′ in size, and species characteristics increasing the susceptibility to climate change. Four bioclimatic model-based criteria were developed for each species by comparing the present-day distribution and climatic suitability of the occupied grid cells with projected distribution and suitability in the future using the HadCM3-A2 climate scenario for 2051–2080. The proportions of disadvantageous land cover types (bare areas, water, snow and ice, artificial surfaces) and cultivated and managed land in the occupied grid squares and their surroundings were measured to indicate the amount of unfavourable land cover and dispersal barriers for butterflies, and topographical heterogeneity to indicate the availability of potential climatic refugia. Vulnerability was also assessed based on species dispersal ability, geographical localization and habitat specialization. Northern European species appeared to be amongst the most vulnerable European butterflies. However, there is much species-to-species variation, and species appear to be threatened due to different combinations of critical characteristics. Inclusion of additional criteria, such as life-history species characteristics, topography and land cover to complement the bioclimatic model-based species vulnerability measures can significantly deepen the assessments of species susceptibility to climate change.     

Early embryogenesis in discoglossoid frogs: a study of heterochrony at different taxonomic levels

We studied the timing of the early development of the cranial neural crest, neural tube differentiation, somite formation and body elongation in the closely related frog species Discoglossus montalenti , Discoglossus galganoi , Discoglossus pictus , Bombina orientalis , Bombina variegata and Bombina maxima . Despite their different egg and embryo sizes, event pairing shows that there are only very few heterochronies among the three Bombina species and the three Discoglossus species in early developmental events. Instead, differences become apparent at the genus level (interpreted as phylogenetic signal). For example, the separation into a mandibular and a hyoid portion of cranial neural crest could be seen earlier in the Discoglossus than in the Bombina species when compared with the development of the neural tube. The development of the cranial neural crest streams also shifts (relatively) forward in time when compared with body elongation and somite formation in the Discoglossus species in contrast to the Bombina species. Comparisons with other species show that attempts to correlate heterochronies in early development with life history changes should take into account the possibility of a rather high evolvability, i.e. a high probability of convergence in the timing of these early events.     

An investigation into the use of hypertext as a user interface to taxonomic keys

In an attempt to overcome some of the drawbacks of existingtaxonomic keys, we have experimented with a computerized versionof a key, changing the interface to the key, but leaving theinformation contained in the key essentially unchanged. Thisis in contrast to most previous work on the use of computersin taxonomy, where work has concentrated on alternative identificationtechniques and techniques for manipulating taxonomic data. Hopkin's(1991) Key to the Woodlice of Britain and Ireland was converted(including the diagrams and colour photographs), into a hypertextdocument using the Unix Guide hypertext system. An experimentwas conducted where test subjects with a wide range of experienceof taxonomic keys and computing skills were asked to identifywoodlouse specimens using the paper and hypertext forms of thekeys. The results showed that test subjects were more likelyto obtain an identification with the hypertext version of thekey. they found it easier to use and preferred using it to thepaper version of the key. However, there were indications thattest subjects were more likely to obtain a misidentificationusing the hypertext key than the paper version of the key. Furtherwork is needed to discover the possible causes of the increasedfrequency of misidentifications, and ways in which the usabilityof hypertext keys can be further enhanced     

基于COⅠ基因对三种大黑鳃金龟分类地位的研究

本试验将江南大黑鳃金龟Holotrichia gebleri Faldermann分别与东北大黑鳃金龟Holotrichia diomphalia Bates、华北大黑鳃金龟Holotrichia oblita Faldermann进行了杂交试验,得到了F1代成虫,自交得到了F2代,表明F1代的雌雄虫具有正常的生殖力,3种金龟子之间不存在生殖隔离。对这3种大黑鳃金龟的COⅠ基因进行了扩增与测序并构建了系统进化树,结果显示:江南大黑、华北大黑和东北大黑3种鳃金龟的遗传距离相近,分类地差别不显著,与外类群的暗黑鳃金龟Holotrichia parallela Motschulsky在遗传距离和分类地位上差异显著。以上结果表明,江南大黑鳃金龟、东北大黑鳃金龟和华北大黑鳃金龟应为同一个物种的不同地理类群。