A NEW SEMLIKIICHTHYS FISH (TELEOSTEI, PERCIFORMES) FROM THE UPPER MIOCENE OF CHAD: FOSSIL RECORD AND PALAEOBIOGEOGRAPHICAL IMPLICATIONS

Abstract:  Semlikiichthys is a fossil genus of perciform fish from the Neogene continental deposits of Africa. Until now, it was known in Mio-Pliocene sites of the Great Lake Region and of the River Nile by a single species, S. rhachirhinchus . Here, we describe new Semlikiichthys material recovered from Central Africa (Upper Miocene of Toros-Menalla, western Djurab, Chad), and compare it to S. rhachirhinchus , which is the only known species of the genus, and also with Lates niloticus , which is the fish in African Neogene deposits that most closely resembles it. We attribute the Chadian material to Semlikiichthys darsao sp. nov., based on ten osteological characters of the neurocranium, the maxilla, the dentary and the first vertebra. Our comparative anatomical study also enables us to provide a revised diagnosis for the genus and to reconsider the taxonomic attribution of the fossils assigned to it. Furthermore, the fossil record of Semlikiichthys supports a connection between sub-basins of the Nilo-Sudanese region during the Miocene, and a disruption between the Great Lake and the Nile Basin on the one hand and the Chadian Basin on the other before 7 Ma.     

Enhanced CH4 emission from a wetland soil exposed to Elevated CO2

Methane emissions from wetland soils are generally a positive function ofplant size and primary productivity, and may be expected to increase dueto enhanced rates of plant growth in a future atmosphere of elevatedCO₂. We performed two experiments with Orontium aquaticum, acommon emergent aquatic macrophyte in temperate and sub-tropical wetlands, todetermine if enhanced rates of photosynthesis in elevated CO₂atmospheres would increase CH₄ emissions from wetland soils.O. aquaticum was grown from seed in soil cores under ambient and elevated(ca. 2-times ambient) concentrations of CO₂ in an initialglasshouse study lasting 3 months and then a growth chamber study lasting 6months. Photosynthetic rates were 54 to 71% higher underelevated CO₂ than ambient CO₂, but plantbiomass was not significantly different at the end of the experiment. Ineach case, CH₄ emissions were higher under elevated thanambient CO₂ levels after 2 to 4 months of treatment, suggestinga close coupling between photosynthesis and methanogenesis in our plant-soilsystem. Methane emissions in the growth chamber study increased by 136%. We observed a significant decrease in transpirationrates under elevated CO₂ in the growth chamber study, andspeculate that elevated CO₂ may also stimulate CH₄ emissions by increasing the extent and duration offlooding in some wetland ecosystems. Elevated CO₂ maydramatically increase CH₄ emissions from wetlands, a sourcethat currently accounts for 40% of global emissions.     

Revision of the 'nudidrosophila' and 'ateledrosophila' species groups of Hawaiian Drosophila (Diptera: Drosophilidae), with descriptions of twenty-two new species

Abstract.  The 'nudidrosophila' and 'ateledrosophila' species groups, formerly described as genera, are a relatively small and understudied part of the enormous Hawaiian Drosophila radiation. Only nine species were described previously. Here we revise the two groups, provide a key to males and females, and describe fully all species. The 'ateledrosophila' group now contains three species, D. diamphidia Hardy, D. papala sp.n. , and D. preapicula Hardy. The 28 species of the 'nudidrosophila' group are separated into five subgroups: 'hirtitibia' ( D. hirtitibia Hardy, D. konaensis sp.n. , D. mawaena sp.n. , and D. papaalai sp.n. ); 'kahania' ( D. kahania sp.n. and D. longipalpus sp.n. ); 'nudidrosophila' ( D. aenicta Hardy, D. amita Hardy, D. canavalia sp.n. , D. eximia Hardy, D. gemmula Hardy, D. kualapa sp.n. , D. lepidobregma Hardy, D. mahui sp.n. , D. malele sp.n. , D. panoanoa sp.n. , and D. poonia sp.n. ); 'okala' ( D. akoko sp.n. , D. kuhao sp.n. , D. makawao sp.n. , D. okala sp.n. , and D. panina sp.n. ); and 'velata' ( D. halapepe sp.n. , D. kauaiensis sp.n. , D. lauoho sp.n. , D. milolii sp.n. , D. pohaka sp.n. , and D. velata Hardy).     

Manipulation of dietary lipids, fatty acids and vitamins in zooplankton cultures

1. A wide range of species that are cultivated in commercial mariculture are planktonic during at least part of their life cycle; for example, the larval stages of shellfish (shrimp and molluscs) and the live feeds (rotifers, brine shrimp, copepods) used in the larviculture of marine fish and shellfish. Over the last decades various techniques have been developed to deliver nutrients to these zooplanktonic organisms either through artificial diets or by manipulating the composition of the live prey fed to the carnivorous stages. This paper reviews the methodology that has allowed aquaculturists to gain knowledge of nutritional requirements and may offer interesting opportunities for ecologists to verify the importance of key nutrients in the natural food chain of marine as well as freshwater ecosystems.
2. Live micro-algae can be replaced partially or completely in the diet of filter-feeders such as rotifers, Artemia , shrimp larvae and bivalves, by various types of preserved algae, micro-encapsulated diets and yeast-based diets, whereas lipid emulsions and liposomes may be utilized to supplement specific lipid-and water-soluble nutrients, respectively. Microbound and micro-encapsulated diets have been designed to supplement live feed in the culture of micro-predators such as fish and shrimp larvae.
3. Live prey organisms, in particular rotifers and Artemia , can be 'bio-encapsulated' with a variety of enrichment diets to manipulate their content in certain nutrients, including ω3 highly unsaturated fatty acids (FA) and the vitamins C, A and E. Nevertheless, the enrichment techniques are not applicable for all nutrients and prey organisms. Phospholipid composition is difficult to manipulate through the diet of live feed and the enrichment of the essential FA docosahexaenoic acid (DHA) is hampered in most Artemia species due to the catabolism of this FA following enrichment.     

Tetrataxis: a loosely attached limpet-like foraminifer from the Upper Palaeozoic

Associations of Tetrataxis preserved in situ and attached to a varicty of biogenic substrates are described from the Carboniferous of northern and central England. Environmental changes considered unsuitable for foraminiferal activity initially caused the tetrataxids to cling to their substrates of attachment in a similar way that limpets do when disturbed. Before conditions conducive to foraminiferal activity returned, the development of encapsulating fabrics (of either organic. cement or sediment origin) effected their preservation in life position. Comparisons made with Recent foraminifera. together with an appreciation of distributional data and the development of hard and soft tissue morphologies. provides strong evidence to suggest that Tetrataxis was primarily a loosely adherent, but mobile, phytal form which grazed upon benthic algae and a variety of marine invertebrates in search of food and shelter. *** Tetrataxis, Carboniferous, foraminifera, mode of life.     

Auxin-Promoted Transport of Metabolites in Stems of Phaseolus vulgaris L.: Auxin Dose-Response Curves and Effects of Inhibitors of Polar Auxin Transport

Transport of ¹⁴C-photosynthate in decapitated stems of Phaseolusvulgaris explants was dependent on the concentration of indole-3-aceticacid (IAA) applied to the cut surfaces of the stem stumps. Thephysiological age of the stem influenced the nature of the transportresponse to IAA with stems that had ceased elongation exhibitinga more pronounced response with a distinct optimum. Increasednutrient status of the explants had little influence on theshape of the IAA dose-response curve but increased, by two ordersof magnitude, the IAA concentration that elicited the optimalresponse. Applications of the inhibitor of polar auxin transport,1-(2-carboxyphenyl)-3-phenylpropane-1, 3-dione (CPD), affectedIAA-promoted transport of ¹⁴C-photosynthates. At sub-optimalIAA concentrations, CPD inhibited transport, whereas at supra-optimalIAA concentrations, ¹⁴C-photosynthate transport was marginallystimulated by CPD. Treatment with CPD resulted in a significantreduction in stem levels of [¹⁴C]IAA below the site of inhibitorapplication, while above this point, levels of [¹⁴C]1AA remainedunaltered. The divergent responses of auxin-promoted transportto CPD treatment are most consistent with a remote action ofIAA on photosynthate transport in the decapitated stems. Key words: Auxin, photosynthate, transport     

Effects of current and historic habitat fragmentation on the genetic structure of the sand goby Pomatoschistus minutus (Osteichthys,Gobiidae)

Habitat fragmentation is a major force that will influence the evolution of a species and its distribution range. Pomatoschistus minutus, the sand goby, has a North Atlantic–Mediterranean distribution and shows various level of habitat fragmentation along its geographic repartition. The use of mitochondrial sequences of the cytochrome b (cyt b) gene and two co‐dominant sets of nuclear markers (introns and microsatellites) allowed us to describe the relationships between P. minutus populations belonging to several different geographical regions of Europe and to assess the structure of populations inhabiting the Golfe du Lion, along the French Mediterranean coast. The present study confirms that the taxon located in the Adriatic Sea (Venice) should be considered as a distinct species, separated approximately 1.75 Mya. The comparison of P. minutus between the Atlantic and western Mediterranean coasts using polymorphic co‐dominant markers revealed that they belong to two demographically independent units, and thus could be considered as well as distinct species, more recently separated (0.3 Mya). The Pleistocene glaciations seem therefore to have played an important role in the diversification of this complex. Finally, at a regional scale in the Golfe du Lion, P. minutus appears to form a single huge homogeneous population. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 175–198.