The influence of man-made fires on large wild herbivores in Lake Burungi area in northern Tanzania

The effect of fire on the distribution of large wild herbivores during the late dry season was studied in northern Tanzania during October 1987. All species were attracted to burnt-over areas with 1–10 cm regrowth of grass. Recently burnt areas with no regrowth and areas not burnt during the dry season were avoided.
By the end of the dry season the study area was left as a fire mosaic, with different areas burnt at different times during the dry season. Thirty two percent was unburnt. The fires were mainly man-made but for purposes other than wildlife management. Such a fire mosaic has a positive effect on the larger herbivores by supplying protein-rich food during the dry season.

Résumé

On a étudié en octobre 1987, durant la deuxième saison sèche l'effet du feu sur la distribution de grands herbivores dans le nord de la Tanzanie.
Toutes les espèces sont attirées par les surfaces brûlées où les repousses sont de 1 à 10 cm. Les surfaces sans repousses et les zones non brúéees sont évitées. A la fin de la saison sèche, la zone étudiée ressemblait à une mosaïque due au feu, avec des endroits brûlés a des moments différents durant la saison sèche. Trente-deux pour-cents n'avaient pas brûlé. La plupart des feux avaient été allumes par l'homme, mais dans d'autres buts que la gestion de la faune. Une telle mosaïque a un effet positif sur les grands herbivores car elle fournit un complément de nourriture riche en protéines au cours de la saison sèche.     

Outline of phylogeny and character evolution in Rhizocarpon (Rhizocarpaceae, lichenized Ascomycota) based on nuclear ITS and mitochondrial SSU ribosomal DNA sequences

The phylogeny of the lichen genus Rhizocarpon (Rhizocarpaceae, lichenized Ascomycota) was investigated using nucleotide sequences from the ITS region of the nuclear ribosomal DNA and the SSU region of the mitochondrial ribosomal DNA from 13 species of Rhizocarpon , Catolechia wahlenbergii and Poeltinula cerebrina . Phylogenetic estimations were performed using maximum parsimony and Bayesian MCMC tree sampling. Twelve phylogenetic null hypotheses were tested using MCMC tree sampling. The evolution of five morphological characters was assessed by mapping them onto MCMC tree samples. The results indicate that Rhizocarpon in its current sense is polyphyletic and can only be made monophyletic if R. hochstetteri is excluded or Poeltinula , and possibly also Catolechia , are included. The root placement in the Rhizocarpaceae is ambiguous, either Catolechia or Poeltinula + R. hochstetteri being the sistergroup to the rest of the family. Previously suggested infrageneric arrangements based on presence or absence of the yellow substance rhizocarpic acid in the thallus or the septation of the ascospores are unnatural. Some species with grey or brown thallus may have evolved from a yellow ancestor. Spore septation and colour, amyloidity of the thalline medulla, and the presence of stictic acid complex and rhizocarpic acid are shown to have changed multiple times during the course of evolution.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 535–546.     

Phylogeny and cladistic classification of terrestrial nemerteans: the genera Pantinonemertes Moore & Gibson and Geonemertes Semper

Evolutionary relationships among seven species from two genera ( Pantinonemertes and Geonemertes ) of terrestrial nemerteans (phylum Nemertea) were estimated by a Wagner analysis of 27 morphological, ecological and life history characters. Pantinonemertes was found to be a paraphyletic taxon, and it is suggested that this genus should be combined with Geonemertes to form a monophyletic group. A previous hypothesis for how terrestrial nemerteans evolved is discussed and compared to the results of the cladistic analysis. This suggests that terrestrial and semi-terrestrial species evolved from a marine ancestor; the upper littoral and marine environments have been recolonized by descendants from a terrestrial ancestor.     

Phylogenetic relationships and genetic distances between some monostiliferous interstitial nemerteans (Ototyphlonemertes, Hoplonemertea, Nemertea) indicated from the 16s rRNA gene

Part of the 16s rRNA mitochondrial gene is used to reconstruct the relationships within five populations (representing three currently recognized species) of interstitial nemerteans ( Ototyphlonemertes , Hoplonemertea, Nemertea), and to assess genetic divergence between representatives of these populations. The non-helicophoran individuals form a monophyletic sister-group to the helicophoran taxon, which further resolves a previous hypothesis based on morphological characters. The small nucleotide differences between some of the populations are within levels expected for panmictic populations and fail to distinguish them genetically; without applying a phylogenic perspective, some of the populations may be allocated into paraphyletic species assemblages.     

Cyanobiont specificity in some Nostoc-containing lichens and in a Peltigera aphthosa photosymbiodeme

The cyanobacterial symbionts in some Nostoc -containing lichens were investigated using the nucleotide sequence of the highly variable cyanobacterial tRNA^Leu (UAA) intron. When comparing different Nostoc -containing lichens, identical intron sequences were found in different samples of the same lichen species collected from two remote areas. This was true for all species where this comparison was made ( Peltigera aphthosa (L.) Willd., P. canina (L.) Willd. and Nephroma arcticum (L.) Torss.). With one exception, a specific intron sequence was never found in more than one lichen species. However, for two of the species, Peltigera aphthosa and Nephroma arcticum , two different cyanobionts were found in different samples. By examining a P. aphthosa photosymbiodeme it could be shown that the same Nostoc is present in both bipartite and tripartite lobes of this lichen. It is thus possible for one cyanobiont/ Nostoc to form the physiologically different symbioses that are found in bipartite and tripartite lichens. The connection between photobiont identity and secondary chemistry is discussed, as a correlation between differences in secondary chemistry and different cyanobionts/ Nostoc s in the species Peltigera neopolydactyla (Gyeln.) Gyeln. was observed. It is concluded that more knowledge concerning the photobiont will give us valuable information on many aspects of lichen biology.     

Phagotrophic Mechanisms and Prey Selection in Free-living Dinoflagellates1

Three types of feeding mechanisms are known in dinoflagellates: pallium feeding, tube feeding, and direct engulfment. Pallium feeding has only been described for heterotrophic thecate species (Protoperidinium, Diplopsalis group). Tube feeding is commonly found among both naked and thecate species of mixotrophic and heterotrophic dinoflagellates (e.g. Amphidinium, Dinophysis, Gyrodinium, Peridiniopsis). Direct engulfment is mainly found among naked species (e.g. Gymnodinium, Gyrodinium, Noctiluca): recently, however, some thecate species have been shown to use this feeding mechanism as well. Feeding behavior in dinoflagellates involves several steps prior to actual ingestion, including precapture, capture, and prey manipulation. As feeding mechanisms allow the ingestion of relatively large prey or parts thereof, dinoflagellates are regarded as raptorial feeders. While prey size plays an important role in the ability of dinoflagellates to ingest food, this alone cannot explain observed prey preferences. Some dinoflagellate species can be very selective in their choice of prey, while others show a remarkable versatility.     

Cryptic speciation at organic‐rich marine habitats: a new bacteriovore annelid from whale‐fall and fish farms in the North‐East Atlantic

Vigtorniella ardabilia sp. nov. , a new chrysopetalid annelid, is described from a whale‐fall in Sweden and from sediment samples collected beneath fish farms in Norway. The new Vigtorniella species is morphologically almost identical to Vigtorniella flokati from whale‐falls in the Pacific Ocean, although molecular evidence from four genes shows that they are different species. Population genetic structure and phylogenetic relationships of V. ardabilia sp. nov. were assessed using molecular data from the nuclear genes 18S and 28S, and the mitochondrial 16S and cytochrome c oxidase subunit I (COI). High levels of gene flow are reported between contrasting organic‐rich environments in the North Atlantic (fish farms and whale‐fall). Observations of feeding biology and habitat suggest that V. ardabilia specializes on bacterial mats, rather than on whale‐falls, although the two species of Vigtorniella for which data were available show very different feeding behaviours. Our results further showed an unexpectedly low divergence rate in Vigtorniella for the mitochondrial markers, suggesting stabilizing selection. Analyses carried out with parsimony, maximum likelihood, and MrBayes all placed the genus Vigtorniella as sister group to Dysponetus, suggesting a close evolutionary link to sediment‐dwelling fauna. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 774–785.     

Osteology and ecology of Megantereon cultridens SE311 (Mammalia; Felidae; Machairodontinae), a sabrecat from the Late Pliocene – Early Pleistocene of Senéze, France

Megantereon cultridens was a derived, Late Pliocene to Early Pleistocene sabrecat, and although fossils of animals referred to the genus and species have been found at several locations throughout Eurasia, most are fragmentary. However, the specimen SE311 from Senéze in France represents an almost complete and well-preserved skeleton, and this is only known from very few other sabrecats, thus providing a rare glimpse into the full anatomy of an unusual and derived sabrecat. In this monograph, we provide a complete overview of the anatomy of Megantereon cultridens SE311, and compare it with extant large felids, and the few other derived sabrecats from which ample fossil material is known, although most frequently representing several specimens. SE311 was a large specimen of M. cultridens and would have had a body mass of 100–110 kg and a head–body length or around 160 cm, which is similar to a small lioness or large male jaguar. Megantereon sp. were sexually dimorphic, and the size of SE311 suggests that it was a male. As with several other derived sabrecats, it was powerfully built, and had particularly robust forequarters with very well-developed muscle attachment sites, indicating a powerful forelimb and shoulder musculature. The neck was proportionally much longer than in extant felids, and the thoracic and particularly lumbar region was proportionally shorter, mimicking the condition in other derived sabrecats from which large parts of the vertebral column is known. Megantereon probably lived in open-forest environments and preyed on cervids, which were dispatched with a shearing bite from the hypertrophied and blade-like upper canines to the throat of the prey, while the prey was held immobile with the massive forelimbs, thus minimizing the risk of damage to the fangs.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 833–884.     

Nitrate leaching from three afforestation chronosequences on former arable land in Denmark

In regions dominated by agricultural activities, nitrogen (N) is recognized as a major pollutant in aquatic environments. In north‐western Europe, afforestation of agricultural land is part of a strategy to improve water quality. In Denmark, former arable land has been afforested during the past 40–50 years. This study evaluated the effect of afforestation of former arable land on nitrate leaching, based on three afforestation chronosequences. Precipitation, canopy throughfall and soil water were collected and soil moisture was monitored at two Danish locations, Vestskoven (nutrient‐rich, medium deposition) and Gejlvang (nutrient‐poor, high deposition). Afforestation was performed using Norway spruce [Picea abies (Karst.) L.] and common oak (Quercus robur L.) at Vestskoven and Norway spruce at Gejlvang. The results suggest that afforestation of former arable land initially leads to lower nitrate leaching than that occurring under the former agricultural land use, and largely below the standard of 50 mg NO⁻₃ L⁻¹ for groundwater to be utilized as drinking water. Nitrate concentrations became almost negligible in forest stands of 5–20 years of age. However, after canopy closure (>20 years) nitrate concentrations below the root zone and nitrate leaching tended to increase. This was attributed to increased N deposition with increasing canopy development and decreased N demand once the most N‐rich biomass compartments had been built up. Nitrate leaching started to increase at a throughfall deposition level of about 10 kg N ha⁻¹ yr⁻¹. Compared with nutrient‐poor sandy soils, nutrient‐rich clayey soils appeared more vulnerable to disturbance of the N cycle and to increased N deposition, leading to N saturation and enhanced nitrate leaching. In approximately the first 35 years after afforestation, nitrate leaching below the root zone was generally higher below oak than below Norway spruce.