Interstitial Dorvilleidae (Annelida, Polychaeta) from Europe, Australia and New Zealand

Four dorvilleid species new to science are described from intertidal and subtidal sandy sediments. For three of them new genera are erected: Coralliotrocha natans gen. et sp.n., Microdorvillea otagensis gen. et sp.n. and Pusillotrocha Åkessoni gen. et sp.n. One species represents the first record of the genus Pettiboneia from Australia, P. australiensis sp.n. Ophryotrocha minuta Levi, 1954 redescribed from Helgoland is transferred to a different genus, Arenotrocha gen.n. The present taxa belong to a morphological series of species with an increasing degree of neoteny in the family Dorvilleidae.     

Reproductive ecology of the endemic Lecocarpus pinnatifidus (Asteraceae) in an isolated population in the Galápagos Islands

Lecocarpus pinnatifidus is an endemic member of the Asteraceae occurring on only one island in the Galápagos archipelago. The capitula are large with female ray florets and male disc florets. They are self-compatible but this study suggests fruit set is pollen limited. Visits from Xylocopa darwini and other larger insect pollinators are rare, and small insects seem to be the main pollinators. Small insects carry few pollen grains and most likely mediate self-pollinations. Self-compatibility and seed set after selfing are the most common reproductive strategy in the Galápagos Islands and L. pinnatifidus seemingly fits well into this group.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 171–180.     

Coelenterate Neuropeptides: Structure, Action and Biosynthesis

Evolutionary "old" nervous systems such as those of coelenteratesare peptidergic: Using various radioimmunoassays we have nowisolated 13 novel neuropeptides from sea anemones and severalothers from hydrozoan polyps and medusae. These peptides areall structurally related and contain the C-terminal sequenceArg-X-NH₂ or Lys-X-NH₂, where X is Ala, Asn, Ile, Phe, Pro orTrp. Three neuropeptides have a novel N-terminal L-3-phenyllactylresidue, which protects against degradation by nonspecific aminopeptidases.The neuropeptides from sea anemones are produced by differentsets of neurones and have excitatory or inhibitory actions onisolated muscle preparations, suggesting that they are neurotransmittersor neuromodulators. We have also cloned the precursor proteinfor the sea-anemone neuropeptide Antho-RFamide (<Glu-Gly-Arg-Phe-NH₂).In Calliactis parasitica this precursor harbours 19 copies ofimmature Antho-RFamide (Gln-Gly-Arg-Phe-Gly) together with 7other, putative neuropeptide sequences. The precursor of Anthopleuraelegantissima contains 14 copies of Antho-RFamide and 19 other,putative neuropeptides. This shows that the biosynthetic machineryfor neuropeptides in coelenterates, the lowest animal grouphaving a nervous system, is already very efficient and similarto that of higher invertebrates, such as molluscs and insects,and vertebrates.     

Sculpture and vascularization of dermal bones,and the implications for the physiology of basal tetrapods

Sculpture of dermal bones and their vascularization in basal tetrapods are closely connected. Ontogenetic data suggest that the large vessels that coursed to the superficial bone surface induced the formation of sculptural ridges and tubercles around their openings. Imprints show that the vessels continued on the bone surface and coursed within furrows or pits, where they were protected by the sculpture from mechanical damage. Dermal bone histology indicates a consolidation of the integument in basal tetrapods by strong, mineralized Sharpey's fibres in the sculptural ridges and tubercles, and by the presence of metaplastic tissue in several taxa. Because of the tight integration of bone and dermis, the large vessels were not able to spread over the sculptural elements, but instead had to pass interosseously. The diverse sculptural morphologies depend on the variation in height and width of the ‘nodal points’ and their connecting ridges, and in the size and shape of the enclosed cells and furrows. A principal component analysis (PCA) and discriminant function analysis (DFA) of 47 basal tetrapod taxa with 12 discrete characters shows that dermal sculpture is suited for distinguishing some main basal tetrapod lineages. Taxa that are interpreted as being largely aquatic have generally a more regular sculpture than presumably terrestrial ones. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 302–340.     

Diet and habitat use of moulting Greylag Geese Anser anser on the Danish island of Saltholm

The diet and habitat use of moulting Greylag Geese Anser anser were studied at the recently established moulting site on the island of Saltholm, between Denmark and Sweden. Classification of the vegetation in the area most used by Greylag Geese during their moult showed that the geese selected low saltmarsh habitats which were richest in Common Saltmarsh- grass Puccinellia maritima and that dropping density was highly correlated with Puccinellia cover. Geese showed slowest step rates and highest peck rates in vegetation types rich in Puccinellia. Examination of faecal material confirmed that the geese fed almost exclusively on PuccineEia during the main moult period, despite its limited spatial distribution. Puccinellia maritima exhibited the highest levels of protein of any of the graminoid species present except for the belowground lower stem base of Sea Club-rush Scirpus maritimus, which offers a nongrowing food resource which is difficult to extract and consume. The results of this study suggest that the statement that the "limited data available for moulting waterfowl indicate no active selection for proteinaceous foods; i.e., birds are selecting foods in proportion to their availability" does not hold for Greylag Geese moulting on Saltholm.     

Reloading the revolver – male fitness as a simple explanation for complex reward partitioning in Nasa macrothyrsa (Loasaceae,Cornales)

Reward partitioning and replenishment and specific mechanisms for pollen presentation are all geared towards the maximization of the number of effective pollinator visits to individual flowers. An extreme case of an apparently highly specialized plant–pollinator interaction with thigmonastic pollen presentation has been described for the morphologically complex tilt‐revolver flowers of Caiophora arechavaletae (Loasaceae) pollinated by oligolectic Bicolletes pampeana (Colletidae, Hymenoptera). We studied the floral biology of Nasa macrothyrsa (Loasaceae) in the field and in the glasshouse, which has very similar floral morphology, but is pollinated by polylectic Neoxylocopa bees (Apidae, Hymenoptera). We investigated the presence of thigmonastic anther presentation, visitor behaviour (pollinators and nectar robbers), co‐ordination of pollinator visits with flower behaviour and the presence of nectar replenishment. The aim of this study was to understand whether complex flower morphology and behaviour can be explained by a specialized pollination syndrome, or whether alternative explanations can be offered. The results showed that Nasa macrothyrsa has thigmonastic pollen presentation, i.e. new pollen is rapidly (<< 10 min) presented after a pollinator visit. Nectar secretion is independent of removal and averages 7–14 µL h^–1. The complex flowers, however, fail to exclude either native (hummingbirds) or introduced (honeybees) nectar robbers, nor does polylectic Neoxylocopa actively collect the pollen presented. The findings do not support a causal link between complex flower morphology and functionality in Loasaceae and a highly specialized pollination. Rapid pollen presentation is best explained by the pollen presentation theory: the large proportion of pollinators coming shortly after a previous visit find little nectar and are more likely to move on to a different plant. The rapid presentation of pollen ensures that all these valuable ‘hungry pollinators’ are dusted with small pollen loads, thus increasing the male fitness of the plant by increasing the likelihood of siring outcrossed offspring. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 124–131.     

Rapid changes in fish community structure and habitat distribution following the precipitation of lake phosphorus with aluminium

1. Fish community structure and habitat distribution of the abundant species roach, perch and ruffe were studied in Lake Nordborg (Denmark) before (August 2006) and after (August 2007) aluminium treatment to reduce internal phosphorus loading. 2. Rapid changes in fish community structure, abundance and habitat distribution occurred following a decline in in‐lake phosphorus concentrations from 280 to 37 μg P L^?1 and an increase in Secchi depth transparency from 1.1 to 1.9 m (August). The proportion of perch in overnight gill net catches increased, whilst roach decreased, and the average weight of all key species increased. 3. The habitat distribution of perch and roach changed from a high proportion in the upper pelagic and littoral zones in 2006, towards enhanced proportions in the deeper pelagic and profundal zone in 2007. The abundance of large‐bodied zooplankton increased and the abundance of benthic invertebrates decreased in the same period, suggesting that the habitat shift was not induced by food limitation. 4. Ruffe shifted from the littoral and upper profundal zones towards the deep profundal zone, likely reflecting an increased predation risk in the littoral zone and better oxygen conditions in the deep profundal. 5. Our results indicate that enhanced risk of predation in the upper pelagic and the littoral zones and perhaps improved oxygen concentrations in the deeper profundal zone at decreasing turbidity are responsible for the observed habitat shift. The results indicate that fish respond rapidly to changes in nutrient state, both in terms of community structure and habitat use.