Mitochondrial phylogeny of the endemic mouthbrooding lineages of cichlid fishes from Lake Tanganyika in eastern Africa

Of the three cichlid species flocks in eastern Africa, Lake Tanganyika harbors the oldest species assemblage, which is also the most diverse morphologically and behaviorally. For 12 species (20 individuals) of 12 genera of the tribe Ectodini, 852 bp from two segments (cytochrome b and control region) of the mitochondrial genome were sequenced. In addition, orthologous sequences were obtained from eight species (11 individuals) representing other mouthbrooding lineages from Lake Tanganyika. Comparisons of sequence divergences revealed that the single Tanganyikan tribe Ectodini appears to be approximately five times older than the whole Lake Malawi cichlid species flock, suggesting that the radiation of the Tanganyikan mouthbrooding lineages took place long before the species flocks of Lakes Malawi and Victoria evolved. Seven of nine surveyed tribes of Tanganyikan cichlids appear to be approximately equally divergent, and this seems to corroborate the hypothesis of a rapid simultaneous formation of lineages at an early stage in the history of the Lake Tanganyika species flock. The close genetic relationship between the endemic Tropheus lineage and a nonendemic "Haplochromine," Astatotilapia burtoni, indicates that members of the tribe Tropheini may be the sister group of the cichlid flocks of Lakes Malawi and Victoria. The phylogenetic analyses demonstrate the monophyly of the Ectodini and identify the Cyprichromini as their sister group among the Tanganyikan cichlids. Within the tribe Ectodini the molecular data suggest both a branching pattern different than that previously proposed and a subdivision of the Ectodini into four clades, instead of the two originally described. The previously postulated model of morphological transformations believed to be responsible for the drastically different types of ecological specialization found among the Ectodini might therefore be in need of reinterpretation. Characters immediately related to foraging and nutrition seem to be particularly prone to homoplasy, even among members of a single lineage of cichlid fishes.      

Mitochondrial diversity in linguistic isolates of the Alps: a reappraisal

In Stenico et al. (1996) we reported unusually high levels of mitochondrial diversity in the Alps. In particular, two communities of Ladin speakers appeared the most extreme European mitochondrial outliers at that time. Recently, it has been observed that some rare nucleotide substitutions occur repeatedly among those sequences, raising the possibility of systematic sequencing errors. No biological material was left from the previous study, and hence we had to sample new individuals from the same communities. Here, we present the HVSI sequence variation, along with haplogroup assignment based on restriction fragment length polymorphism (RFLP), in 20 Ladin speakers of Colle Santa Lucia. None of the new sequences displays substitutions at the sites viewed as problematic. However, Ladins still show high levels of mtDNA diversity, both within their community and with respect to other Europeans, and they can still be considered one of the main European mitochondrial outliers.     

Mitochondrial genetic analyses suggest selection against maternal lineages in bipolar affective disorder.

Previous reports of preferential transmission of bipolar affective disorder (BP) from the maternal versus the paternal lines in families suggested that this disorder may be caused by mitochondrial DNA mutations. We have sequenced the mitochondrial genome in 25 BP patients with family histories of psychiatric disorder that suggest matrilineal inheritance. No polymorphism identified more than once in this sequencing showed any significant association with BP in association studies using 94 cases and 94 controls. To determine whether our BP sample showed evidence of selection against the maternal lineage, we determined genetic distances between all possible pairwise comparisons within the BP and control groups, based on multilocus mitochondrial polymorphism haplotypes. These analyses revealed fewer closely related haplotypes in the BP group than in the matched control group, suggesting selection against maternal lineages in this disease. Such selection is compatible with recurrent mitochondrial mutations, which are associated with slightly decreased fitness. Although such mismatch distribution comparisons have been used previously for analyses of population histories, this is, as far as we are aware, the first report of this method being used to study disease.     

Plant communities of mountain grasslands in a broad cross-section of the Eastern Alps

Apart from forests, the landscape of the Alps is dominated by grasslands, where they account for up to 40% of the agricultural area. This study focuses on the main man-made grassland plant communities of the Eastern Alps, shows their current spatial distribution and examines how strongly the influence of land use and site factors determines the communities. Discriminant analysis was used to harmonize the phytosociological classification of 1502 vegetation relevés from the literature and 375 own recorded inventories from Western Austria and Northern Italy. Land-use intensity, altitude, slope and pH were also recorded, in order to assess the impact of the factors to plant communities, as calculated in nonmetric multidimensional scaling. We identified 39 plant communities and generated a table with the main ecological and floristic parameters as well as a map showing their present spatial distribution. Contrary to the literature, the pasture communities Crepido-Festucetum commutatae, Deschampsio cespitosae-Poetum alpinae and Rumicetum alpini occur also in fertilized meadows. On the other hand we found meadow communities occurring in pastures, such as the Angelico-Cirsietum oleracei, the Pastinaco-Arrhenatheretum, the Ranunculo repentis-Alopecuretum pratensis and the Trisetetum flavescentis. The most species-rich communities - the Caricetum ferruginei and the Seslerio-Caricetum sempervirentis - occur in unfertilized meadows above calcareous bedrock. Further species-rich communities - the Campanulo scheuchzeri-Festucetum noricae, the Gentianello anisodontae-Festucetum variae, the Pulsatillo alpinae-Festucetum noricae, the Trifolio thallii-Festucetum nigricantis and the Hypochoerido uniflorae-Festucetum paniculatae - are endangered: they are regionally restricted and depend on the absence of fertilizer and on mowing once annually or every second or third year. Therefore agri-environmental measures should focus on unfertilized mountain meadows, in order to conserve these rare grassland communities.     

Macroinvertebrate communities of karst springs of two river catchments in the Southern Limestone Alps (the Julian Alps, NW Slovenia)

The macroinvertebrate communities of 16 karst springs in the Southern Limestone Alps (Slovenia, SE Europe), were studied from May to September 1999, together with the major chemical parameters of the water and selected physical characteristics of the springs. The springs are located in an area of 800 km², between 410 and 955 m a.s.l., and drain into two rivers whose catchments are separated by mountain ranges up to 2864 m. The Soča river drains into the Adriatic Sea and the Sava into the Black Sea. Springs showed relatively large fluctuations in discharge and small variations in temperature (normally about 1 °C) during the period of study. Seventy macroinvertebrate taxa were collected. Chironomidae (Diptera), Limnephilidae (Trichoptera), Enchytraeidae (Oligochaeta), Tricladida (Turbellaria) and Belgrandiella kuesteri (Gastropoda) were the most widespread taxa, collected from the majority of sampling sites. The environmental characteristics showed a great heterogeneity, and there was a large variation in the taxonomic composition and relative abundance of taxa between springs and during seasons. The coexistence of taxa with highly divergent ecological requirements is characteristic of the spring communities studied. They range from stygobionts and spring-restricted species to ubiquitous species. The differences observed in spring fauna in the two river catchments were probably dictated by differences in local environmental parameters and not by the geographical location in the different river catchments.     

Estuarine fish communities of the eastern James-Hudson Bay coast

Synopsis Sampling in six estuaries of the east coast of James and Hudson Bays between 1973 and 1977 has revealed latitudinal differences in the composition of fish communities. Arctic and subarctic marine species are more prominent in estuaries of Hudson Bay. Fewer species are found northwards with 35 species in lower rivers and estuaries of James Bay and only 24 in those of Hudson Bay, for a total of 38 species. Climate, postglacial dispersion and restricted space are proposed as causes of the observed distribution of fishes. Send reprint request to this address     

Mitochondrial lineages in Notochthamalus scabrosus as indicators of coastal recruitment and interactions

A significant genetic cline has previously been identified along the Chilean coast in the barnacle Notochthamalus scabrosus. Samples from the previous study, spanning 800 km, were not able to show whether the southern lineage ultimately goes to fixation at higher latitudes. In addition to expanding the geographic sampling of this species, locations that were sampled approximately four to five generations ago were resampled for this study, enabling a temporal comparison of the location and strength of the observed cline. Here, we show that although the cline persists as expected, the tremendous changes in observed lineage frequencies near the clinal boundary are indicative of source-sink dynamics that may be associated with a codistributed biogeographic transition zone. We also find that the southern lineage does not increase in frequency in more southern populations, suggesting that this lineage is maintained through a combination of density-dependent interactions and a coastal fitness gradient.     

Spatial pattern in dry grassland communities of the Central Alps and its ecophysiological significance

The spatial pattern of species and microhabitats in a dry grassland mosaic in a Central Alpine valley was studied by a variance/mean analysis. In addition, the water-usage strategies of the dominant species were investigated. A significant correlation between species pattern and microhabitat pattern was found for the grass species. Grasses, with their homorhizal root system, are unable to exploit sources of water in deep rock crevices, and are therefore dependent on the water-storage capacity of the particular soil layer. Dwarf shrubs and succulents (with one exception) are independent of this latter water source. The common chamaephytes exhibit contradictory types of stomatal behaviour.Artemisia alba is characterized by a water-conservation strategy, whereasHelianthemum nummularium spp.obscurum andTeucrium chamaedrys are not. The careful usage of the water reserves byArtemisia alba would seem to represent an adaptation to dry grassland conditions. The other dwarf shrubs, in contrast, with their ‘water-wasting’ strategy, have a root system like that ofArtemisia and are unable to compensate for the higher rate of water loss. Thus, the observed ecophysiological differences cannot be interpreted as being ‘different solutions to the same problem’, as a result of divergent evolution. Two alternative interpretations are: a) the stomatal behaviour of the chamaephytes is a characteristic of their respective genera and which is not particularly adaptive here; b) the dry grasslands studied are the remnants of a former vegetation type, which had a low level of competition.     

Nitrogen relations of ruderal communities (Rumicion alpini) in the Northern Calcareous Alps

Summary The total nitrogen and nitrate turnovers of three plots of plant communities typical of cattle resting sites in the Bavarian Alps were investigated. Annual net N mineralisation of the soil and N content of the above-ground phytomass at maximum development are low in the Senecio cordatus dominated community W at 1,450 m altitude (80 and 57 kg N/ha respectively) and highest in the nearly pure Rumex alpinus stand K (1,240 m) (156 and 148 kg N/ha). The subalpine mixed Rumex alpinus community S (1,790 m) is intermediate with low mineralisation but high N content in the aboveground parts (69 and 128 kg N/ha). In general the mineralisation values are below those from other comparable plant communities. The main component of N mineralisation is nitrification in all three plots.The nitrate content in the phytomass at full development increases from 0.1 g/m² in W to 0.3 g/m² in S and to 1.0 g/m² in K. With one exception (Adenostyles alliariae) no species showed a real nitrate accumulation in the leaf laminae towards the end of the growing season.     

Comparative analysis of the floristic richness of alpine communities in the Caucasus and the Central Alps

Abstract. Species richness of selected alpine plant communities in the Teberda Biosphere Reserve (Northwestern Caucasus) and the Davos area (Central Alps) was compared in series of plots from 0.0025 to 100 m². Communities developing under similar ecological conditions and with similar syntaxonomic positions were compared in order to estimate the role of recent environment versus regional historical factors in determining plant community structure and diversity. The floristic richness of the Caucasian and Alpic fens was very similar. The Grasslands and Meadows were quite similar as to floristic richness for plots > 25 cm × 25 cm, but the Caucasian communities had fewer species in smaller plots. The Lichen heath at Teberda was richer than the Caricetum curvulae cetrarietosum for all plot sizes, except the two smallest ones. On the other hand, the plots of the Salix Snowbed community were richer in species than the Caucasian snowbeds for all plot sizes. The Rhododendron Shrubland plots were very similar as to floristic richness in larger plots (4 — 100 m²). Generally, most Alpic communities near Davos were richer in species at small plot sizes than the corresponding communities from Teberda. Caucasian communities were floristically less similar to each other — and thus more discrete — than the Alpic ones. The possible role of different factors controlling floristic richness of the communities is discussed. Our results suggest that recent ecological conditions have a big influence on local floristic diversity and may lead to high similarities between ecologically similar communities from different regions. In addition, the general floristic richness of a regions as well as island effects should be taken into account.     

Novel soil lineages of Archaea are present in semi-arid soils of eastern Australia

The diversity of Archaea was studied in vertisolic and loam soils of a semi-arid region in Australia. Sampling was undertaken at an agricultural site, two grassland environments, and a brigalow (Acacia harpophylla) woodland. Archaeal community structure was profiled using amplified ribosomal DNA restriction analysis (ARDRA) combined with rDNA sequencing of an example of each restriction fragment length polymorphism type. Sequence comparison and phylogenetic analysis demonstrated that both crenarchaeotal and euryarchaeotal Archaea were present at oxic depths in the soil at all field sites. Along with previously described soil archaeal lineages, novel soil lineages and the deeply divergent Pendant-33 group of Euryarchaeota were also detected. A novel statistical method for comparing ARDRA derived data was demonstrated and implemented using the archaeal communities from the four field sites. Archaeal diversity, as measured by this method, was significantly higher in the agricultural site than at either of the grassland sites or the brigalow woodland.     

Copepod communities in karstic mediterranean lakes along the eastern Adriatic coast

The copepod communities of karstic lakes along the eastern Adriatic coast were studied. Lakes were divided in several groups according to their morphology (deep, shallow, barrage and reservoirs), production (oligotrophic, mesotophic and eutrophic), and salinity of water: freshwater and brackish. Copidodiaptomus steueri, Eucyclops serrulatusand Macrocyclops albidus belong to the group that inhabited most of the lakes under the study, regardless of lake type. The shallow karstic lakes are usually inhabited by Thermocyclops dybowskii, T. oithonoides, Cyclops vicinus and Eudiaptomus padanus etruscus in freshwater biotopes, and Calanipedia aquaedulcis and Copidodiaptomus steueri in brackish biotopes. The last two species can also be found in deep karstic lakes with brackish water (Bacina lakes in the Neretva River delta). Species like Cyclops abyssorumcan be found in most deep freshwater lakes. Some Calanoida were recorded in only one lake, like Eudiaptomus transsylvanicusin the deep Lake Vrana on the island of Cres, or Eudiaptomus hadzici in the barrage Lake Visovac. Production of the lakes, expressed as copepod biomass, depends on lake trophy, and in some lakes also on hydrology and salinity. Most of the meso-eutrophic lakes in the study area had Calanoida dominating, while Cyclopoida dominated in some oligotrophic and eutrophic lakes as well.     

Fish communities in the eastern,seasonal-floodplain of the Sudd,Southern Sudan

Annual flooding of the permanent Sudd swamps innundates large areas of Oryza longistaminata grasslands. Fish migration into a southeast section of the seasonal floodplain was led by Clarias gariepinus, Polypterus senegalus and several small species which were intent on spawning. Channa obscura and juveniles of Oreochromis niloticus were prominent among later entrants. From a total of 23 species caught in seasonal habitats, 7 contributed over 97% of total estimated numerical and biomass densities. The latter ranged from 435–580 kg ha^–1. In the 1982–83 flood-season entry to the floodplain was essentially restricted to species tolerant of oxygen-deficient waters and thereby able to penetrate the papyrus and Typha swamps of the permanent wetland. Migrants became stranded in temporary pools and subject to heavy cropping by birds.     

Microbial communities in saline lakes of the Vestfold Hills (eastern Antarctica)

A detailed survey was undertaken of the microbial communities of 16 saline lakes in the Vestfold Hills (Princess Elizabeth Land, eastern Antarctica), which ranged in salinity from slightly brackish (4–5‰) to hypersaline (maximum: 174‰). Temperatures at comparable sampling depths in the lakes ranged from −12.2°C to +10.5°C. Ranges in the abundances of bacteria, heterotrophic nanoflagellates (HNAN) and phototrophic nanoflagellates (PNAN) were 1.40 × 10⁷ l⁻¹–1.58 × 10¹⁰ l⁻¹, 4.83 × 10⁴ l⁻¹–1.70 × 10⁷ l⁻¹ and 0–1.02 × 10⁷ l⁻¹, respectively. There was considerable variation across the salinity spectrum, though in the case of bacteria and PNAN significantly higher concentrations of cells were seen in two of the most saline lakes. The autotrophic ciliate Mesodinium rubrum occurred in all but five of the lakes and was found at salinity levels up to 108‰. Heterotrophic ciliates were generally scarce. Dinoflagellates, particularly Gonyaulax c.f. tamarensis, Gyrodinium lachryma and Gymnodinium sp., occurred in the majority of the lakes. On the basis of chlorophyll a concentrations, nutrient levels and microplankton concentrations the lakes spanned the spectrum from ultra-oligotrophic to oligo/mesotrophic. The most saline lakes had much reduced species diversity compared with the less saline environments. Isolation from the marine environment has led to nutrient depletion, simplification and a truncated trophic structure. Received: 19 September 1996 / Accepted: 13 January 1997     

Phylogenetic alpha and beta diversities of butterfly communities correlate with climate in the western Swiss Alps

The observation of non‐random phylogenetic distribution of traits in communities provides evidence for niche‐based community assembly. Environment may influence the phylogenetic structure of communities because traits determining how species respond to prevailing conditions can be phylogenetically conserved. In this study, we investigate the variation of butterfly species richness and of phylogenetic α‐ and β‐diversities along temperature and plant species richness gradients. Our study indicates that butterfly richness is independently positively correlated to temperature and plant species richness in the study area. However, the variation of phylogenetic α‐ and β‐diversities is only correlated to temperature. The significant phylogenetic clustering at high elevation suggests that cold temperature filters butterfly lineages, leading to communities mostly composed of closely related species adapted to those climatic conditions. These results suggest that in colder and more severe conditions at high elevations deterministic processes and not purely stochastic events drive the assemblage of butterfly communities.