Systematics and Biogeography of Burrowing Bryozoans

Current investigations of the three principal families of ectoproctbryozoan burrowers has shown that while two of the families,the Terebriporidae and the Immergentiidae, belong to the minorOrder Ctenostomata, the third family, Penetrantiidae, previouslyconsidered a ctenostome, actually belongs to the major OrderCheilostomata. The implications of this are important; we haveconsidered the burrowing bryozoans to be a small obscure group,specialized for the burrowing mode of existence. We must nowconsider the possibility that there may be many more speciesof burrowing bryozoans as yet undiscovered, that they occurin at least two of the three bryozoan orders, and that burrowingconstitutes an important ecological niche or mode of adaptationfor the bryozoans. While such a change may seem to be merelya taxonomic maneuver, itmay also serve to emphasize the diversityof the ectoproct bryozoan groups which do burrow, and perhapsencourage research on them. At present we are making progressdescribing the living species, their anatomy and histology.We still know almost nothing about how they penetrate the substrate,nothing about possible effects upon the host organism, and nothingabout their means of geographical distribution, although theyseem to occur worldwide, burrowing primarily in molluscan shells.     

Myxomycetes:Biology,Systematics,Biogeography,and Ecology

正黏菌是丰富多彩的生物多样性世界提供给人类的一个独特类群。Myxomycetes:Biology,Systematics,Biogeography,and Ecology是迄今为止全方位、多视角展示黏菌生物学的第一本巨著。由美国阿肯色大学Steven L.Stephenson教授等活跃在当今黏菌各研究领域的,以及来自全球11个国家的29位国际知名黏菌学者共同完成。全书按照领域和专题分为13章,由不同作者分别编写,中国工程院院士、《菌物研究》主编、吉林农业大学李玉教授及其团队成员工琦教授和刘朴教授是"第六章黏菌生理学和生物化学"的作者。     

Systematics and Biogeography of Scaled Woodcreepers (Aves: Dendrocolaptidae)

The geographical variation of three qualitative plumage characters and three body measurements of populations of the Scaled Woodcreeper (Lepidocolaptes squamatus), a species whose range is centered in eastern Brazil, is analyzed. Three distinctive populations are recognized (wagleri, squamatus, and falcinellus). Under the biological species concept (BSC), two species are recognized (L. squamatus, including squamatus and wagleri as subspecies; and L. falcinellus). Under either the phylogenetic species concept (PSC) or under the evolutionary species concept (ESC), the three distinctive populations should be regarded as independent species. Based on plumage similarities, we suggest that squamatus and wagleri form a monophyletic group, with falcinellus as its sister-group. Geological changes (tectonism and formation of river courses) are suggested as causal factors that promoted speciation in Scaled Woodcreepers.     

Molecular Systematics of Tanagers (Thraupinae): Evolution and Biogeography of a Diverse Radiation of Neotropical Birds

The tanagers (Passeriformes: Emberizidae: Thraupinae) are a diverse group of mostly Neotropical birds with a wide range of feeding morphologies, behaviors, plumage patterns and colors, and habitat preferences. Phylogenetic relationships of genera in this lineage were investigated using cytochromebsequence data. This study indicates that the generaEuphoniaandChlorophonia(traditionally considered part of Thraupinae) do not form a monophyletic group with the other tanagers. Within the rest of Thraupinae, several monophyletic groups are identified that agree with traditional sequential taxonomies. Other monophyletic groups provide novel interpretations of biogeographic patterns and morphological evolution within tanagers. In several lineages, plumage patterns and colors persist despite dramatic changes in bill morphology. Phylogenetic structure and estimated timings of divergence events indicate that tanagers probably originated on Caribbean islands and later diversified throughout Central and South America during the mid-Tertiary.     

Ticks, ivermectin, and experimental Chagas disease

Following an infestation of dogticks in kennels housing dogs used for long-term studies of the pathogenesis of Chagas disease, we examined the effect of ivermectin treatment on the dogs, ticks, trypanosome parasites, and also on triatomine vectors of Chagas disease. Ivermectin treatment was highly effective in eliminating the ticks, but showed no apparent effect on the dogs nor on their trypanosome infection. Triatominae fed on the dogs soon after ivermectin treatment showed high mortality, but this effect quickly declined for bugs fed at successive intervals after treatment. In conclusion, although ivermectin treatment may have a transient effect on peridomestic populations of Triatominae, it is not the treatment of choice for this situation. The study also showed that although the dogticks could become infected with Trypanosoma cruzi, this only occurred when feeding on dogs in the acute phase of infection, and there was no evidence of subsequent parasite development in the ticks.     

Endemicity,Biogeography, Composition,and Community Structure On a Northeast Pacific Seamount

The deep ocean greater than 1 km covers the majority of the earth''s surface. Interspersed on the abyssal plains and continental slope are an estimated 14000 seamounts, topographic features extending 1000 m off the seafloor. A variety of hypotheses are posited that suggest the ecological, evolutionary, and oceanographic processes on seamounts differ from those governing the surrounding deep sea. The most prominent and oldest of these hypotheses, the seamount endemicity hypothesis (SMEH), states that seamounts possess a set of isolating mechanisms that produce highly endemic faunas. Here, we constructed a faunal inventory for Davidson Seamount, the first bathymetric feature to be characterized as a ‘seamount’, residing 120 km off the central California coast in approximately 3600 m of water (Fig 1). We find little support for the SMEH among megafauna of a Northeast Pacific seamount; instead, finding an assemblage of species that also occurs on adjacent continental margins. A large percentage of these species are also cosmopolitan with ranges extending over much of the Pacific Ocean Basin. Despite the similarity in composition between the seamount and non-seamount communities, we provide preliminary evidence that seamount communities may be structured differently and potentially serve as source of larvae for suboptimal, non-seamount habitats.Open in a separate windowFigure 1Bathymetric map of the Central California Coast with Monterey Canyon and Davidson Seamount.     

Systematics,conservation and sustainable development

The contribution of systematics to conservation and sustainable use of species is discussed. An adequate inventory of species is required for both areas and recent field work shows that the inventory is far from complete. This supports the first mission of Agenda 2000 which is to discover described and inventory global species diversity. The importance of making these data available in data base format is stressed. Sound systematics is a necessity for conservation legislation where control depends on the ability to identify organisms correctly. The establishment of reserves is also dependent upon data from systematics about centres of diversity and endemism and examples of this are given. Molecular systematics has made new tools available to conservation such as genetic fingerprinting which is useful both to breeding programmes of rare species and for identification for legal proceedings.Systematics is also one of the foundations for programmes of sustainable development especially in the search for new crops, non-timber forest plants from extraction forests and the identification of wild relatives of crop species. Examples of the role of systematics in a fuelwood programme in Zimbabwe, a sustainable development programme in northeast Brazil and in the search for a chemical component with medicinal properties for curing AIDS are given. The more predictive a classification we can develop using modern cladistic and molecular techniques the more useful systematics will be for both conservation and sustainable development. The goal of Agenda 2000 to organize the information derived from the programme in an efficiently retrievable form that best meets the needs of science and society is a laudable target that is crucial for conservation and the sustainable use of the plant resources of the world.     

Systematics, biogeography and conservation of Lactoridaceae

Lactoridaceae are a monotypic family confined to the Juan Fernandez (= Robinson Crusoe) Islands, Chile, an archipelago four million years old. Interest in the lone species, Lactoris fernandeziana, has increased in recent years due to its suspected role in early angiosperm evolution, as well as its endangered conservation status. Reports of fossil pollen of Lactoris (as Lactoripollenites) from deep sea sediments of Cretaceous age off the western coast of South Africa provide evidence for southern hemisphere occurrence of the family 70–90 million years ago. This age, plus trimerous symmetry and simple morphology of the flower with three tepals, six stamens and three nearly free carpels with laminar placentation, involve the family with hypotheses regarding evolution of early angiosperms, especially paleoherb and monocot divergences. Based on cladistic analyses with morphological and nucleotide data, recommended taxonomic placement of Lactoris is as a monotypic order, Lactoridales, allied most closely to Aristolochiales, and also near Piperales. Approximately 1000 individuals of Lactoris are believed to exist, and genetic variation within and among populations as measured by isozymes and RAPDs is low. This, in part, could be due to the self-compatibility and geitonogamous breeding system of this wind-pollinated species. More efforts at ex situ conservation should be attempted so that this important angiosperm family is maintained for future evolutionary studies.     

Species Diversity, Biogeography, and the Evolution of Biotas

SYNOPSIS. A central scientific problem for ecologists and systematistshas been to explain spatiotemporal patterns of species diversity.One aspect of this question is how to understand the taxonomicassembly of biotas and their included ecosystems and communities.Four processes add or subtract species from a region: speciation,extinction, biotic dispersion, and long-distance dispersal.Speciation and biotic dispersion are postulated to result inhistorically structured (hierarchical) species assemblages,whereas long-distance dispersal results in assemblages thatwould be expected to be historically unstructured (nonhierarchical).Continental biotas, as exemplified by the Australian avifauna,are historically structured: they are segregated into areasof endemism having hierarchical relationships that presumablyarose as a result of their history being dominated by cyclesof biotic dispersion and vicariance. It is also proposed thatthese latter two processes are necessary, and in many casesprobably sufficient, to explain the taxonomic composition ofcommunities within these areas of endemism. Long-distance dispersalappears to play a much more minor role in the assembly of eithercontinental biotas or their communities than current ecologicaltheory would predict.     

Biogeography of Dwarf Lemurs: Genetic Evidence for Unexpected Patterns in Southeastern Madagascar

Seven species of dwarf lemurs (Cheirogaleus spp.) are currently recognized after a recent revision of the genus. During a field study in southeastern Madagascar, we observed 3 distinct morphotypes of Cheirogaleus resembling Cheirogaleus medius, C. major and C. crossleyi. In particular, for Cheirogaleus crossleyi southeastern Madagascar was far away from the known distribution range of the species when referring to the recent revision of the genus. In order to clarify the taxonomic status of the 3 morphotypes, we compared field samples from southeastern Madagascar to museum specimens from several locations in Madagascar and to field samples from Kirindy/CFPF, western Madagascar by genetic analyses using the mitochondrial cytochrome b gene. Genetic data yield strong support for 2 of the 3 morphotypes to represent Cheirogaleus medius and C. major. The third morphotype is genetically closely related to Cheirogaleus crossleyi, albeit more distantly than the other 2 morphotypes to the respective reference samples. The genetic distance is related to a considerable geographic distance between the location of our field study and the origin of the respective reference specimen, because Cheirogaleus crossleyi had been reported only from northern Madagascar. Our field observations indicate an isolated population in southeastern Madagascar. We propose to identify them as Cheirogaleus crossleyi and discuss the population genetic and biogeographic considerations supporting this conclusion.     

Systematics,biological knowledge and environmental conservation

Systematics and taxonomy are essential: they respectively elucidate life's history, and organize and verify biological knowledge. This knowledge is built of interrelated concepts which are ultimately accounted for by biological specimens. Such knowledge is essential to decide how much and what biodiversity survives human onslaughts. The preservation of specimens in natural history collections is the essential part of the process which builds and maintains biological knowledge. These collections and the human expertise essential to interpret specimens are the taxonomic resources which maintain accurate and verifiable concepts of biological entities. Present and future knowledge of the complexities and diversity of the biosphere depends on the integrity of taxonomic resources, vet widespread ignorance and disregard for their fundamental value has created a global crisis. Preservation of specimens in natural history collections is chronically neglected and support to study and manage collections is very insufficient. The knowledge held by experienced taxonomists is not being passed on to younger recruits. Neglect of collections has destroyed countless specimens and threatens millions more. These threats to taxonomic resources not only impinge on systematics but all biology: this tragedy jeopardizes the integrity of biological knowledge. The consequences for environmental conservation and therefore humanity are also of dire severity and the biodiversity crisis adds unprecedented weight to the barely recognized crisis in taxonomy and systematics.Where correspondence should     

Systematics, similarity and Acanthaceae pollen morphology

SCOTLAND, R. W., 1992. Systematics, similarity and Acanthaceae pollen morphology. A brief discussion of the history of Acanthaceae classifications is provided. It is argued that several approaches utilizing pollen morphological data for the classification of the family can be identified. The Lindau pollen types are shown to have an indirect relationship to Lindau's own classification. Pollen morphological similarity is explored within the context of cladistic methodology. It is shown that some of the Lindau pollen types are analogous. It is demonstrated that shared similarities can be of three types: conflicting (homoplasious), plesiomorphic and apomorphic.     

Biogeography, Evolution, and Diversity of Epibionts in Phototrophic Consortia

Motile phototrophic consortia are highly regular associations in which numerous cells of green sulfur bacteria surround a flagellated colorless β-proteobacterium in the center. To date, seven different morphological types of such consortia have been described. In addition, two immotile associations involving green sulfur bacteria are known. By employing a culture-independent approach, different types of phototrophic consortia were mechanically isolated by micromanipulation from 14 freshwater environments, and partial 16S rRNA gene sequences of the green sulfur bacterial epibionts were determined. In the majority of the lakes investigated, different types of phototrophic consortia were found to co-occur. In all cases, phototrophic consortia with the same morphology from the same habitat contained only a single epibiont phylotype. However, morphologically indistinguishable phototrophic consortia collected from different lakes contained different epibionts. Overall, 19 different types of epibionts were detected in the present study. Whereas the epibionts within one geographic region were very similar (Dice coefficient, 0.582), only two types of epibionts were found to occur on both the European and North American continents (Dice coefficient, 0.190). None of the epibiont 16S rRNA gene sequences have been detected so far in free-living green sulfur bacteria, suggesting that the interaction between epibionts and chemotrophic bacteria in the phototrophic consortia is an obligate interaction. Based on our phylogenetic analysis, the epibiont sequences are not monophyletic. Thus, the ability to form symbiotic associations either arose independently from different ancestors or was present in a common ancestor prior to the radiation of green sulfur bacteria and the transition to the free-living state in independent lineages. The present study thus demonstrates that there is great diversity and nonrandom geographical distribution of phototrophic consortia in the natural environment.     

Biogeography, evolution, and diversity of epibionts in phototrophic consortia

Motile phototrophic consortia are highly regular associations in which numerous cells of green sulfur bacteria surround a flagellated colorless beta-proteobacterium in the center. To date, seven different morphological types of such consortia have been described. In addition, two immotile associations involving green sulfur bacteria are known. By employing a culture-independent approach, different types of phototrophic consortia were mechanically isolated by micromanipulation from 14 freshwater environments, and partial 16S rRNA gene sequences of the green sulfur bacterial epibionts were determined. In the majority of the lakes investigated, different types of phototrophic consortia were found to co-occur. In all cases, phototrophic consortia with the same morphology from the same habitat contained only a single epibiont phylotype. However, morphologically indistinguishable phototrophic consortia collected from different lakes contained different epibionts. Overall, 19 different types of epibionts were detected in the present study. Whereas the epibionts within one geographic region were very similar (Dice coefficient, 0.582), only two types of epibionts were found to occur on both the European and North American continents (Dice coefficient, 0.190). None of the epibiont 16S rRNA gene sequences have been detected so far in free-living green sulfur bacteria, suggesting that the interaction between epibionts and chemotrophic bacteria in the phototrophic consortia is an obligate interaction. Based on our phylogenetic analysis, the epibiont sequences are not monophyletic. Thus, the ability to form symbiotic associations either arose independently from different ancestors or was present in a common ancestor prior to the radiation of green sulfur bacteria and the transition to the free-living state in independent lineages. The present study thus demonstrates that there is great diversity and nonrandom geographical distribution of phototrophic consortia in the natural environment.