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1.
ANDERS MARTINSSON 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1969,2(2):153-161
The procedure of first defining a time boundary between the Silurian and Devonian Systems and postponing the designation of a stratotype leaves stratigraphers without guidance as to which series the Silurian should be divided into and which corresponding epochs would be practicable for reference in international work. The situation in Europe is reviewed with respect to established usage, and it is found that with present concepts Silurian series based on the succession in the Welsh Borderland and in the Barrandian can be made compatible in the critical part of the succession. A natural consequence of the establishment of a system boundary at the base of the zone with Monograptus uniformis would be the redefinition of the Downtonian as proposed by Allen & Tarlo 1963, to be used subsynonymously with the Pridolian. 相似文献
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A new species of Monoplacophora, redescription of the genera Veleropilina and Rokopella, and new information on three species of the class 总被引:1,自引:0,他引:1
Vema levinae Warén, sp. n. is described from a submarine volcano off western Mexico. The type species of Rokopella and Veleropilina are redescribed, the usage of the names is discussed and Rokopella and Veleropilina are recognized as valid genera in Neopilinidae. Rokopella euglypta (Dautzenberg & Fischer, 1897) is redescribed from shells and a single live specimen taken from seamounts south of the Azores, from a depth of 1200–1600 m. Tectura reticulata Seguenza, 1876 (Gastropoda, 'Acmaeidae', southern Italy, Upper Pliocene/Lower Pleistocene) is considered to have been based on the monoplacophoran species previously known as Neopilina zografi from the Mediterranean, and is classified in the genus Veleropilina. Veleropilina zografi (Dautzenberg & Fischer, 1896) is redescribed based on shells from several seamounts south of the Azores. It is considered distinct from Rokopella euglypta and classified in the genus Veleropilina. An undescribed species of Veleropilina from a seamount off southern Baja California is reported, figured and discussed but not formally described. 相似文献
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ANDERS FORSMAN RICHARD SHINE 《Biological journal of the Linnean Society. Linnean Society of London》1995,55(4):273-291
Females of Lampropholis delicata are dimorphic for colour pattern, the difference between morphs being the presence or absence of a distinct white mid-lateral stripe. A less distinct striped morph occurs also in males. We evaluated alternative hypotheses for the maintenance of this polymorphism by examining temporal and spatial variation in morph frequency, testing for differential selection among morphs using data on body size and reproductive traits from preserved specimens, and experimentally manipulating colour pattern in free-ranging lizards of both sexes, to assess the influence of the lateral stripe on survival rates. We found that the relative frequency of striped individuals varied among populations and decreased from north to south in both sexes, coincident with an increasing incidence of regenerated tails. Morph frequencies did not change through time within a population. Striped gravid females appeared to survive better and produced larger clutches than did non-striped females. In our experimental study, the relationship between survival and colour morph differed between the two sexes; males painted with a white lateral stripe had lower survival than control (brown stripe) males, but survival did not differ between striped and control females. The different response in the two sexes may be due partly to differences in temperature and microhabitat selection. We propose that the white lateral stripe decreases susceptibility to predators in gravid females but increases risk of predation in males, especially in combination with low temperatures. The polymorphism might be maintained by: (1) opposing fitness consequences of the stripe in males and females; (2) sex-specific habitat selection; and (3) gene flow in combination with spatial variation in relative fitness of the two morphs. 相似文献
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ANDERS WAREN 《Zoologica scripta》1980,9(1-4):187-210
All species that have been described of the genera mentioned in the title are listed and their systematic position given. The species of Stilifer (with 11 species, including S. inflatus sp.n. and 5. concavus sp.n.) are parasites of starfishes. Scalenostoma (3 species) are parasites of stone corals. Thyca (with 8 species) is removed from Capulidae, and included in Eulimidae. T. hawaiiensis sp.n. is described. The species of Thyca are parasites of starfishes. The species of Mucronalia (including M. trilineata sp.n.) are probably parasites of ophiuroids and Echineulima (with 4–6 species, including E. ponderi sp.n.) are parasites of echinoids. All species are figured, their characteristics are given and their host species and distributions are listed. Keys are given to the species of each genus, except Mucronalia. The genera Stilimella Laseron and Hyperlia Pilsbry are synonymized with Scalenostoma and the genera Kiramodulus Kuroda, Granulithyca Habe and Bessomia Berry are considered subgenera of Thyca. 相似文献
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ALICE NICOLLE PER HALLGREN JESSICA
Von EINEM EMMA SOFIA KRITZBERG WILHELM GRANÉLI ANDERS PERSSON CHRISTER BRÖNMARK LARS‐ANDERS HANSSON 《Freshwater Biology》2012,57(4):684-695
1. Aquatic ecosystems in Northern Europe are expected to face increases in temperature and water colour (TB) in future. While effects of these factors have been studied separately, it is unknown whether and how a combination of them might affect phenological events and trophic interactions. 2. In a mesocosm study, we combined both factors to create conditions expected to arise during the coming century. We focused on quantifying effects on timing and magnitude of plankton spring phenological events and identifying possible mismatches between resources (phytoplankton) and consumers (zooplankton). 3. We found that the increases in TB had important effects on timing and abundance of different plankton groups. While increased temperature led to an earlier peak in phytoplankton and zooplankton and a change in the relative timing of different zooplankton groups, increased water colour reduced chlorophyll‐a concentrations. 4. Increased TB together benefitted cladocerans and calanoid copepods and led to stronger top‐down control of algae by zooplankton. There was no sign of a mismatch between primary producers and grazers as reported from other studies. 5. Our results point towards an earlier onset of plankton spring growth in shallow lakes in future with a stronger top‐down control of phytoplankton by zooplankton grazers. 相似文献