Ecophenotypic strategies of dalmanellid brachiopods

General ecophenotypic patterns, of particular interest when they apply to all, or most, taxa of the group concerned, can never be demonstrated until after monophyletic taxa have been recognized, that is, until after the initial stages of phylogeny construction have been carried out. In criticizing certain dalmanellid phylogenies, and based in large part on a study of five 'species subgroups'. Hurst & Watkins (1978; Geologica et Palaeontologica 12 ) postulate ecophenotypic patterns for Isorthis , and Hurst (1978; Palaeontology 21 ) postulates general patterns of ecophenotypic variation for dalmanellid brachiopods. These patterns may be invalid for four reasons: (1) Univariate and 'bivariate' statistical analysis of the samples used to define the five subgroups reveals no significant differences between subgroups, or vertical trends, for the very morphological characters claimed to exhibit the ecophenotypic patterns; (2) Hurst & Watkins' discriminant function analysis contains procedural errors and its results are ambiguous; (3) several of the five subgroups represent mixtures of unrelated taxa; (4) in recognizing the alleged patterns, Hurst & Watkins ignored contrary evidence from many taxa (and from many dalmanellid studies). □ Brachiopoda, Dalmanellidae, Silurian, ecology, evolution, systematics.     

The macro-invertebrate fauna of a small Andean stream

SUMMARY. The benthic fauna of a small headwater stream in the Amazon drainage in Ecuador was studied from August 1976 to July 1977. The sampling station was at an altitude of 3300 m in a typical paramo habitat of constant and cool temperatures. The fauna is dominated numerically by Hydracarina, Insecta, Copepoda and Oligochaeta, The major insect groups are Ephemeroptera, Plecoptera, Trichoptera, Elmidae (Coleoptera) and Chironomidae (Diptera). Benthos densities followed a bimodal pattern of rapid decreases and intervening gradual recoveries; similar patterns occur in most taxa, but are more pronounced in smaller animals such as Copepoda and Hydracarina. An analysis of the size-frequency distribution of three species of mayfly, two of stonefly and six of caddisfly suggest non-seasonal life-cycles except for Anacroneuria sp. Spates are thought to be the major factor regulating benthic densities in such non-seasonal environments.     

Effects of Nitrate Level on Nitrogen Metabolism in Winged Bean and Soya Bean

The effects of high (15 mM) and low (0.75 mM) solution nitratelevels on nitrogen metabolism in three genotypes (IL 7A, IL13 and IL 21) of winged beans [Psophocarpus tetragonolobus (L.)DC.] and one genotype (Williams) of soya bean [Glycine max (L.)Merrill] were investigated. Plants were grown for 42 days ina greenhouse in solution culture prior to sampling. The 15 mM nitrate treatment resulted in greater growth of allplant parts except roots. Growth of soya beans was more responsiveto nitrate level than was growth of winged beans. The high nitratelevel inhibited nodulation in all plants. The IL 13 and IL 21winged bean genotypes had similar nitrogenase activity (acetylenereduction per plant) as the soya bean and IL 7A winged beangenotype had lower activity. However, the IL 13 winged beangenotype had higher nitrogenase activity (acetylene reductionper unit nodule mass) than the other three genotypes which allhad similar activity. The 15 mM solution nitrate level stimulatedleaf and root nitrate reductase (NR) activity for all plants.All winged bean genotypes had higher leaf NR activity and higherpercentage reduced- and nitrate-nitrogen contents of leavesand stems compared with soya beans. However, total protein (reducednitrogen) was greater in soya beans when sampled indicatingthat more nitrate had been metabolized by soya beans than bywinged beans during the 42-day growth period. Psophocarpus tetragonolobus (L.) DC., winged bean, Glycine max (L.) Merrill, Soya bean, nitrate reductase, nitrogen fixation, nitrogenase activity, nodulation