Chlorophyllb-containing oxygenic photosynthetic prokaryotes: Oxychlorobacteria (Prochlorophytes)

The major ultrastructural and pigment characteristics of three chlorophyllb-containing photosynthetic prokaryote genera,Prochloron, Prochlorothrix, andProchlorococcus, are summarized. Aspects of their ecology are reviewed, as are also the major findings of comparisons among the three genera, and between them and the cyanobacteria, based on analyses of nucleotide sequences. The information summarized is discussed to assess how closely the three genera are related and whether they form a natural taxonomic grouping within the cyanobacteria. It is concluded that, although much of the evidence points to substantial differences among the three genera, the convenience of keeping them together as a group, namely, Oxychlorobacteria (formerly Prochlorophyta), outweighs certain inconsistencies revealed by analysis of a range of objective criteria. Current views on the possible significance of the group to considerations of the evolution of green chloroplasts are also presented.     

Craniometric variability in two populations of roe deer (Capreolus capreolus) from Spain

Two populations of roe deer from Spain, approximately 300 km apart from each other and currently recognized as separate subspecies. were studied to analyse the nature of the morphological differences between these populations and to assess the validity of its taxonomic division. Sixty-one skulls of roc deer from the Occidental Cantabric Mountains (OCM) and 17 from the Northern lberic Mountains (NIM) were used. No significant sexual dimorphism allowed pooling of male and female samples, on which a large set of 53 measurements was taken. Skulls from the OCM population are, on average, 1·9% larger than those from the NIM population. Twenty-five out of the 53 characters showed some degree of significant differences between means of both populations, though only four showed highly significant differences. Mandible characters were the most variable traits, showing also significant differences between populations. Eight principal factors were extracted. explaining a total of 84·7% of the sample variance. An ANOVA of factor scores from each population revealed significant differences in PF 1 and PF 3. Interpretation of these two factors suggests that morphological differences between both populations can be summarized as specimens from OCM having larger mandibles and broader neurocranium than specimens from NIM. Mandible differences might reflect morphological adaptations to favour the consumption of ligneous plants, which are more frequently eaten by the OCM roe deer population, whereas a broader neurocranium might be related to antler size. It is concluded that biometric differences observed in skulls from these two populations only reflect minor morphological adaptations to different habitats, thus. there is a lack of morphological data to support the taxonomic distinction of the OCM population as a separate subspecies.     

Understanding microbial community diversity metrics derived from metagenomes: performance evaluation using simulated data sets

Metagenomics holds the promise of greatly advancing the study of diversity in natural communities, but novel theoretical and methodological approaches must first be developed and adjusted for these data sets. We evaluated widely used macroecological metrics of taxonomic diversity on a simulated set of metagenomic samples, using phylogenetically meaningful protein-coding genes as ecological proxies. To our knowledge, this is the first approach of this kind to evaluate taxonomic diversity metrics derived from metagenomic data sets. We demonstrate that abundance matrices derived from protein-coding marker genes reproduce more faithfully the structure of the original community than those derived from SSU-rRNA gene. We also found that the most commonly used diversity metrics are biased estimators of community structure and differ significantly from their corresponding real parameters and that these biases are most likely caused by insufficient sampling and differences in community phylogenetic composition. Our results suggest that the ranking of samples using multidimensional metrics makes a good qualitative alternative for contrasting community structure and that these comparisons can be greatly improved with the incorporation of metrics for both community structure and phylogenetic diversity. These findings will help to achieve a standardized framework for community diversity comparisons derived from metagenomic data sets.     

Population history in social spiders repeated: colony structure and lineage evolution in Stegodyphus mimosarum (Eresidae)

Social cooperative spiders from diverse taxonomic families share life-history and demographic traits, including highly inbred colony structure. The combination of traits suggests constrained pathways for social evolution in spiders. The genus Stegodyphus has three independently evolved social species, which can be used as replicate samples to analyse population constraints in evolutionary time. We tested colony structure and population history of the social S. mimosarum from South and East Africa using mitochondrial DNA variation, and we compared the results to published data for the independently evolved social congener S. dumicola . S. mimosarum had many and diverse haplotypes (5–7% sequence divergence for ND1) but colonies were monomorphic and genealogically similar haplotypes occurred in abutting regions. These findings are nearly identical to results for S. dumicola and imply similar colony-level processes over evolutionary time in independently evolved social species. These population dynamics are discussed with respect to the apparent lack of cladogenesis in social spiders.     

Lack of between- and within-species isoenzyme variability in Aquila eagles (Aves: Accipitriformes)

Isoenzyme analysis is a fast and inexpensive method for taxonomic and population genetic analyses. Variation of eight enzymes and two non-specific blood proteins among five species of eagles in genus Aquila was analysed with the aim of detecting species-specific markers and intraspecies variation for population genetic studies. However, no isoenzyme variability was detected. We conclude that isoenzyme analysis of blood samples has limited value for taxonomic, population and hybridization studies among eagles.     

Intraspecific Variation in the Vocalizations and Hand Pad Morphology of Southern Lesser Bush Babies (Galago moholi): A Comparison with G. senegalensis

Previous studies have shown the taxonomic value of vocal repertoires and hand (volar) pad characteristics in the classification of cryptic nocturnal primates such as bush babies. However, no study included quantitative comparisons within the geographical range of any one species. We investigated levels of intraspecific variation in calls and hand pad characteristics of the southern lesser bush baby (Galago moholi), using the northern lesser bush baby (Galago senegalensis) for interspecific comparisons. Examination of calls recorded from different regions along a transect of 1500 km across southern Africa revealed low levels of intraspecific variation in Galago moholi, whereas comparisons with homologous call-types in G. senegalensis revealed them to be significantly different. Volar pad measurements across the ranges of both species also showed low levels of intraspecific variation and relatively high interspecific variation. These findings demonstrate that vocal and volar pad characteristics can be used as consistent measures of difference between species that look almost identical. These methods provide a practical means of distinguishing between cryptic species, whether in the field, in captivity, or, in the case of volar pads, of preserved specimens.     

A population genetic analysis of migration: the case of the noctule bat (Nyctalus noctula)

Although rarely assessed, the population genetics of hibernating colonies can help to understand some aspects of population structure, even when samples from nursery or mating colonies are not available, or in studies of migration when both types of samples are available and can be compared. Here we illustrate both points in a survey of mitochondrial DNA (mtDNA) control region sequences used to study the population genetics of hibernating colonies of a migrating species, the noctule bat (Nyctalus noctula). Lacking samples from Scandinavian nursery colonies, we use a North European hibernacula to suggest that Scandinavian populations are isolated from Central and East European colonies. Then, we compare genetic diversities of nursery and hibernating colonies. We find a significantly higher haplotype diversity in hibernacula, confirming that they consist of individuals from different nursery colonies. Finally, we show that pairwise comparisons of the haplotype frequencies of nursery and hibernating colonies contain some information on the migration direction of the noctule bat.     

Delimitation difficulties in species splits: a morphometric case study on the Euxoa tritici complex (Lepidoptera, Noctuidae)

Abstract. Genital characteristics tend to vary greatly between Lepidoptera species, providing helpful features for species delimitation. The differences between species are usually remarkable and suspicions about species identity never arise. However, fairly often, and possibly increasingly, taxa are elevated to species rank on the basis of very slight morphological differences, often without quantitative support. Euxoa tritici (Linnaeus) is a typical example of a variable species split into several morphologically similar species. The present study tested whether the diagnostic genital characters of the current classification, based on nonquantitative methodology, provide safe identification of species. Both traditional distance morphometrics as well as modern geometric morphometrics, which also enables quantitative shape exploration, were used. Moreover, whether the study specimens can be unambiguously categorized into several species with visual comparisons was tested independently using four specialist entomologists. Genital types of several named species as well as considerable variation in genitalia were found, but no support was found for the presence of several morphologically distinguishable species with quantitative morphometric analyses. Neither were study specimens categorized unambiguously by specialists. The results suggest that pure visual comparisons may lead to unsound taxonomic conclusions and that a quantitative approach in critical cases should be used more frequently.     

A multivariate approach to host plant associated morphological variation in the polyphagous leafhopper, Alnetoidia alneti (Dahlbom)

Canonical variate analysis (CVA) on morphological distance measurements shows that differences exist among adult samples of A. alneti taken from a number of host plant species in South Wales. This variation is also correlated with variation in the degree of yellow pigmentation. Adults taken from alder and hazel form extremes in a continuum of variation, those from alder being larger and more pigmented. The variation between these two populations is greater than host-independent variation among samples of each population taken from a number of individual trees at different localities in Britain in different years. Ordination shows that the variation between the alder and hazel populations is along different axes to that among samples in these populations. Different axes of variation are also found among adults from different pairs of host plant species. Multiple-group principal component analysis (MGPCA) suggests that much of the variation between adults from alder and hazel may be interpreted as allometry-free 'shape' that is uncorrelated with variation in overall size within each population. Transfer experiments showed that the differences in both size and shape may have little genetic basis and are probably host plant induced> The taxonomic and ecological implications of these results are discussed.     

Morphological stasis and phylogenetic relationships in Tadpole shrimps, Triops (Crustacea: Notostraca)

The tadpole shrimp (Triops) is a well-known 'living fossil' whose fundamental morphology has been unchanged for over 170 million years. Thus, tadpole shrimps are suitable subjects for the study of morphological stasis. We were able to obtain samples of three species of Triops (T. granarius, T longicaudatus and T. cancriformis) from four regions in Japan. Taxonomic species were identified by diagnostic morphology. We inferred phylogenetic relationships between individual samples using mitochondrial 16S rRNA. Carapace shapes were compared among populations using shape coordinate methods. The phylogeny inferred from mtDNA shows that T. granarius is phylogenetically more similar to T. longicaudatus than to T. cancriformis. mtDNA sequences did not differ among the populations of T granarius. However, there were two distinct phylogenetic species within T. longicaudatus. In spite of the similarity in fundamental morphological characteristics among Triops species, mtDNA sequences of Triops showed marked differences among the four phylogenetic species. Among the populations of T. granarius , the carapace shape of the Fukuoka population was significantly different from those of other populations of T. granarius. The carapace shape of the Kagawa population of T. longicaudatus was more similar to those of the Shizuoka and Kagawa populations of T. granarius. The shape of the carapace of T. cancriformis was significantly different from those of T. granarius and T longicaudatus. Thus, taxonomic species, phylogenetic species and populations with similar carapace morphology did not correspond with each other. The present results indicate that most of the morphological change did not occur at the time of speciation (lineage separation) and that morphological stases are important evolutionary patterns, but they are not species-level properties.     

Molecular and phenotypic evidence of a new species of genus Esox (Esocidae, Esociformes, Actinopterygii): the southern pike, Esox flaviae

We address the taxonomic position of the southern European individuals of pike, performing a series of tests and comparisons from morphology, DNA taxonomy and population genetics parameters, in order to support the hypothesis that two species of pike, and not only one, exist in Europe. A strong relationship emerged between a northern genotype supported by COI, Cytb, AFLP and specific fragments, and a phenotype with round spot skin colour pattern and a large number of scales in the lateral line, clearly separated from a southern genotype with other skin colour pattern and a low number of scales in the lateral line. DNA taxonomy, based on a coalescent approach (GMYC) from phylogenetic reconstructions on COI and Cytb together with AFLP admixture analysis, supported the existence of two independently evolving entities. Such differences are not simply due to geographic distances, as northern European samples are more similar to Canadian and Chinese samples than the southern Europe ones. Thus, given that the differences between the two groups of European pike are significant at the phenotypic, genotypic and geographical levels, we propose the identification of two pike species: the already known northern pike (Esox lucius) and the southern pike (E. flaviae n.sp.). The correct identification of these two lineages as independent species should give rise to a ban on the introduction of northern pikes in southern Europe for recreational fishing, due to potential problems of hybridisation.     

The taxonomic distinctness of coastal bottom-dwelling fish communities of the North-east Atlantic

1. New techniques for identifying the average taxonomic range of species assemblages were applied to an extensive dataset of bottom-dwelling fish in the coastal waters of NW Europe. These taxonomic distinctness indices provided much greater resolution than traditional diversity indices as they incorporated information on taxonomic relationships into an index which measures species dominance. Unlike standard measures of species richness and diversity, the mean value of these statistics is independent of sampling effort, and this allows objective comparisons to be made between samples from studies where sampling effort is not standardized.
2. A reduction in the average taxonomic range between the fauna of western waters of the UK and that of the southern North Sea was consistent with the general decline in species richness observed between these regions, and suggests that these two factors may be spatially positively correlated. Indices calculated for individual samples of fish on a local scale, however, did not all fit this trend.
3. Much of the variability in taxonomic diversity within the coastal waters of NW Europe was caused by the variable geographical distribution of the elasmobranchs. Of all the families which comprise the fish communities, this group has life-history characteristics which make it most susceptible to impact by commercial trawl fisheries.
4. The use of taxonomic distinctness measures provided additional insights, of relevance to biodiversity assessment, suggesting that they might usefully be applied to other aquatic and terrestrial fauna.     

A taxonomic reappraisal of the Daphnia hyalina complex (Crustacea: Cladocera): an experimental and ecological approach

The paper is a taxonomic study of the limnetic Daphnia populations of the English Lake District, the populations upon which the most popular taxonomic scheme is based (Johnson, 1952).
Johnson treats these populations as three varieties of the species D. hyalina, namely D. hyalina s. str., D.h. var. galeata and D.h. var. lacustris .
Careful examination of the populations of Esthwaite reveals that what has previously been regarded as a population of a single variety of D. hyalina. includes three distinct forms. Experimental work confirms that these are genetically distinct. One of these forms corresponds to D. hyalina var. galeata , whilst the other two are designated the "toothed" and "round-headed" forms.
The first part of the paper is concerned with the taxonomic status of var. galeata . Brooks (1957) and some later workers treat this as a separate species (D. galeata) on morphological grounds. This is fully supported by the present work. Differences between var. galeata and co-existing forms in incidence of sexual reproduction, in vertical distribution and in seasonal abundance and average brood-size provide further support for the separation of D. galeata.
The second part of the paper is concerned with D. hyalina s.str. which, on the basis of morphology, ecology and reproductive behaviour, is shown to be at least as distinct from other members of the complex as is D. galeata . It is argued that other forms should therefore to be removed from D. hyalina . The taxonomic status and affinities of the remaining "toothed" and "round-headed" forms are discussed.     

Chromosomes of thecercopithecus aethiops species group:C. aethiops (Linnaeus, 1758),C. cynosurus (Scopoli, 1786),C. pygerythrus (Cuvier, 1821), andC. sabaeus (Linnaeus, 1766)

The banded karyotypes of 34 monkeys of known geographic origin and belonging to the Cercopithecus aethiops group of species (C. aethiops, C. pygerythrus, C. cynosurus, C. sabaeus) show that chromosome evolution in this group is highly conservative. All species have 2n =60 chromosomes with very similar chromosome banding. However, differences were found both within and between species. A polymorphism of the NOR area of the “marked” chromosome pairs was found in all taxa (9 of 34 animals). All individuals referred to C. sabaeus,from both West Africa and the Barbados, are characterized by having highly positive G- and C- banded terminal sequences on chromosomes 7,10,12, and 14. Outgroup comparisons with other primates and a parsimony analysis suggest that these terminal bands are derived and are probably good taxonomic and phylogenetic indicators. Moreover, chromosome 18 is variable both between and within species in G banding and in short-arm length. The existence of within-species variation in karyotypes suggests that karyological comparisons must be based on adequate samples that include specimens coming from all the major geographic populations of the species concerned.     

Modelling potential wildlife-vehicle collisions (WVC) locations using environmental factors and human population density: A case-study from 3 state highways in Central California

Roads can exert direct and indirect impacts on ecosystems and organisms. In particular, wildlife-vehicle collisions (WVC) may be a considerable threat for populations of certain wildlife species. Despite such threat, there is still incomplete understanding of the factors responsible for high road mortality. Only a few empirical studies have tested the idea that spatial variation of roadkill is affected by environmental characteristics and socio-demographic factors. This study examines the relationships between WVC involving different taxonomic groups (i.e. ungulate, avian, medium mammal, small mammal) and physical and human population characteristics of landscapes by adapting the ecological model, Maxent, to distribution modelling of carcasses resulting from WVC. We used observations from the California Roadkill Observation System of four taxonomic groups recorded along highways in northern California. Our results indicated that current carcass-observation locations were explained primarily by total forest area (cells) within 500 m buffer and road density within a 500 m neighborhood. Our results found that current carcass-observation locations are modelled well using environmental variables and human population density together. Moreover, a comparison of projected potential roadkill locations based on environmental factors and human population density among different taxonomic groups revealed substantially different distributions. These results indicate potential areas where wildlife populations are at increased risk of coming into contact with traffic and the potential utility of this methodology for modelling current and future distributions of wildlife across landscapes using the Maxent approach.     

Morphometric divergence in populations of Anastrepha obliqua (Diptera,Tephritidae) from Colombia and some Neotropical locations

The West Indian fruit fly, Anastrepha obliqua, is one of seven species of quarantine importance of its genus and is one of the most economically important fruit fly pests in Colombia. The taxonomic status of this species is a key issue for further implementation of any pest management program. Several molecular studies have shown enough variability within Anastrepha obliqua to suggest its taxonomic status could be revised; however, there are no morphological studies supporting this hypothesis. The aim of this work was to describe the morphological variability of Colombian populations of Anastrepha obliqua, comparing this variability with that of other samples from the Neotropics. Measurements were performed on individuals from 11 populations collected from different geographic Colombian localities and were compared with populations from Mexico (2), Dominica Island (1), Peru (1) and Brazil (2). Linear morphometric analyses were performed using 23 female morphological traits, including seven variables of the aculeus, three of the thorax, and six of the wing; seven ratios among them were also considered. Discriminant function analyses showed significant morphological differentiation among the Colombian populations, separating them into two groups. Furthermore, in the comparisons between Colombian samples with those from other countries, three clusters were observed. The possibility of finding more than one species within the nominal Anastrepha obliqua population is discussed.