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.     

Systematics and Biogeography of Hard Ticks, a Total Evidence Approach

Systematic relationships among the basal Ixodidae are examined using one morphological and three molecular data sets, 18S and 28S nuclear and 16S mitochondrial rDNA. Although different combinations of partitions are incompatible in a partition homogeneity test, combining them produces similar or better support for most major lineages through both additive and complementary effects. The different data sets are not complete for all taxa, but inclusion or exclusion of taxa with missing data for one or more data sets (8 of 29 ingroup taxa) does not influence overall tree topology and only weakly affects support levels. The only notable effect was based on gap treatment in the 28S data set. Gap treatment completely changes the arrangement and support levels for one basal node. The combined analyses show strong support for the Metastriata, a lineage including most endemic Australian Ixodes , and a lineage including the remaining Ixodes , but not for the Prostriata (= Ixodes s.l.). The distribution pattern of endemic Australian taxa (nearly all included in three exclusively Australian basal lineages) suggests that these lineages, and by extension the Ixodidae, originated after the isolation of Australia in the late Cretaceous, much more recently than previously indicated.     

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.     

Chironomids from Southern Alpine Running Waters: Ecology, Biogeography*

The chironomid fauna living in running waters in the Southern Alps was investigated from an ecological and biogeographical point of view: 202 species were identified (not including terrestrial species). It must be emphasised that species identification is tentative within some genera, especially those awaiting revision (e.g., Boreoheptagyia, Chaetocladius). Although much taxonomic work was done in the past on the chironomid Alpine fauna, there are still many unsolved problems. Most of the species found are widespread in the Palearctic Region, with no evidence of bio-geographical barriers separating different Alpine sectors. Really a relatively high number of species reported from the northern and western side (France, Switzerland, Austria) of the Alps was not captured on the southern side (Italy), whereas most species found on the southern side are also present on the northern one. Very few species are reported from southern side only. Lack of sampling, imperfect taxonomic knowledge and different environmental conditions between the northern and southern sides may be responsible of this result. A comparison of the fauna of the southern Alps with the fauna of the Apennines suggests that the differences are probably more related to ecological conditions (lack of glaciers in the Apennines) than to biogeographical barriers. Different chironomid assemblages colonise manifold habitat types: strict cold-stenothermal species tolerating high current velocity (e.g., Diamesa latitarsis – steinboecki group) are almost the sole inhabitants of kryal biotopes, while other cold-stenothermal species are restricted to cold springs (Diamesa dampfi, D. incallida, Tokunagaia rectangularis, T. tonollii), there are also species characteristic of hygropetric habitats (Syndiamesa edwardsi, S. nigra) or restricted to lacustrine habitats (Corynoneura lacustris, Paratanytarsus austriacus). It must be emphasised that different responses to environmental factors can be observed between species belonging to the same genus (e.g., Diamesa, Eukiefferiella, Orthocladius , Paratrichocladius), so species identification is really needed for a good ecological work. Water temperature, current velocity, substrate type are the most critical factors, sometime chironomid species appear to be rather opportunistic and their presence or absence cannot be clearly related to a well defined range of values of environmental variables: be it a lack of knowledge or a real datum will be the task of future studies. The waters of the Alps are still relatively unpolluted, but hydraulic stress due to river damming and canalization is a serious problem for macrofauna conservation, and as the glaciers retreat, the species confined to the glacial snouts are at risk of extinction, some of them possibly even before their existence be discovered. *The complete database with detailed taxonomical, ecological and biogeographical information can be obtained by the senior author to request (e-mail: bruno.rossaro@unimi.it). A table with species response to environmental variables is also available at the web site: http://users.unimi.it/~roma1999/rossaro.html, downloading file CHIRDB.)     

Phylogenetic Systematics and Biogeography of the Neoephemeridae (Ephemeroptera: Pannota)

A revision of species of the pannote Holarctic and Oriental mayfly family Neoephemeridae is presented. Three genera are recognized in a strictly phylogenetic classification. Potamanthellus [=Neoephemeropsis Ulmer syn. n.] includes P. caenoides (Ulmer) comb. n., P. amabilis (Eaton) [=N. cuaraoensis Dang syn. n.], P. ganges sp. n., P. chinensis (Hsu) [=P. rarus (Tiunova and Levanidova) syn. n.], P. edmundsi sp. n., and the Oligocene fossil Potamanthellus rubiensis Lewis. Neoephemera [=Leucorhoenanthus Lestage syn. n.] includes N. maxima (Joly), N. purpurea (Traver), N. youngi Berner, N. bicolor McDunnough, and N. compressa Berner. Ochernova gen. n., includes O. tshernovae (Kazlauskas) comb. n. Taxa are described, illustrated and keyed. Species cladistics and biogeography are presented.     

Biogeography: An Emerging Cornerstone for Understanding Prokaryotic Diversity,Ecology, and Evolution

New questions about microbial ecology and diversity combined with significant improvement in the resolving power of molecular tools have helped the reemergence of the field of prokaryotic biogeography. Here, we show that biogeography may constitute a cornerstone approach to study diversity patterns at different taxonomic levels in the prokaryotic world. Fundamental processes leading to the formation of biogeographic patterns are examined in an evolutionary and ecological context. Based on different evolutionary scenarios, biogeographic patterns are thus posited to consist of dramatic range expansion or regression events that would be the results of evolutionary and ecological forces at play at the genotype level. The deterministic or random nature of those underlying processes is, however, questioned in light of recent surveys. Such scenarios led us to predict the existence of particular genes whose presence or polymorphism would be associated with cosmopolitan taxa. Furthermore, several conceptual and methodological pitfalls that could hamper future developments of the field are identified, and future approaches and new lines of investigation are suggested.