Species number, species abundance and body length of arboreal arthropods associated with an Australian rainforest tree

Abstract.

• 1 The species number, the abundance per species and the body length of arthropods foraging within the crowns of an over-storey rainforest tree from Australia, Argyrodendron actinophyllum (Sterculiaceae), were investigated by interception trap sampling and restricted canopy fogging. Emphasis was placed upon the interpretation of trap data. Arthropods were trapped continuously day and night, over a 2-year period and the final analyses examined the attributes of 759 species which represented 20,500 individuals.
• 2 The proportion of‘rare’species (Le. collected once) intercepted was high (35.7%), although lower than in other similar rainforest surveys. Neither the α log-series nor the log-normal distribution could be fitted to the relationship between number of species and number of individuals, since the number of rare species was much higher than predicted and the mode of the distribution could not be identified. The proportion of rare species was higher in fogging collections (452%) than in trap collections.
• 3 The data are compared with a study of Bornean arboreal beetles, obtained by fogging trees during a single sampling event. Several patterns were common to both data sets. However, the three-dimensional plot of the variables describing the structure of the arthropod community showed a notably rougher surface than in the case of Bornean beetles.
• 4 Although several factors may complicate the interpretation of the three-dimensional plots, long-term and continuous sampling may alter our perception of complex arthropod communities. This methodology is imperative for a proper understanding of arthropod community structure in rain forests.

     

Diversity of extinct and living actinistian fishes (Sarcopterygii)

Synopsis A total of 121 actinistian species belonging to 47 genera and 17 undetermined actinistians is reported from the literature. There are 69 valid species with fair assessment of their phylogenetic position; 21 valid species with poor assessment of their phylogenetic position; 31 actinistian incertae sedis; and 18 taxa that had been identified incorrectly as actinistians or are nomen nuda. The fossil record of the actinistians covers a history of approximately 380 million years. The greatest diversity occurred during the Scythian (Early Triassic).     

Clonal diversity, population structure, and dispersal in the parthenogenetic moth Ectoedemia argyropeza

Populations of the parthenogenetic moth Ectoedemia argyropeza (Lepidoptera, Nepticulidae) were studied for their clonal composition. Clones were characterized by 6 polymorphic enzyme loci. In a geographic survey 32 clones were observed among 812 individuals. Two clones were predominant, together they explained over 75% of the total variation. Relationships among clones hinted at a monophyletic origin of the species. Analysis of the life cycle and population structure indicated that E. argyropeza is a very sedentary species, with bottlenecks, drift, and passive migration as important population genetical factors moulding the variation.     

Factors influencing species diversity in saline waters of Death Valley,USA

Salinity is a major factor influencing the distributions and abundances of aquatic macroinvertebrates of saline waters in Death Valley, California, USA. A general pattern of declining numbers of species with increasing salinity is seen in Death Valley waters. Some species are restricted to low salinities, others are found only in highly saline pools, and still others are widely distributed over a broad range of salinities.Salinity alone cannot explain distributions seen in the field. Distributions and abundances of species such as the caddisfly Limnephilus assimilis Banks are broader than would be predicted on the basis of laboratory studies of salinity and temperature. I present evidence that for such species, biotic factors such as reduced predation at high salinities may compensate for increased physiological stress.     

Spatial distribution of species diversity indices and their correlation with plot size

In a physiognomically uniform Leucobryo-Pineteum phytocoenose the spatial pattern of point diversity was determined and the effect of quadrat size on the assessment of alpha diversity (in Whittaker's, 1977, sense) was analysed. In both cases the Shannon index of total species diversity and the evenness index were used to measure diversity. A contagious spatial pattern of point diversity and a high variation of point diversity values, as well as a strong non-linear dependence of H and J values on quadrat size, and also a decrease in H and J variation with an increase in quadrat size were found.Nomenclature follows Ehrendorfer (1973). Liste der Gefässpflanzen Mitteleuropas.     

Biomass: Is it a useful tool in paleocommunity reconstruction?

In general, more of the biomass of the community is preserved than is its numerical abundance. Thus, the paleontologist, on the average, works with more of the community when biomass is used. Community characteristics such as taxon dominance and habitat proportions are at least as accurately derived from biomass as numerical abundance. The use of biomass is clearly more appropriate in describing energy flow and trophic proportions. Whenever possible, biomass should be used as a complement to numerical abundance in future paleoecologic reconstructions.     

Influence of the surface microlayer on nutrients,chlorophyll and algal diversity of a small eutrophic bog pond

Nutrients, chlorophyll, phaeophytin and algal abundances were investigated in the surface microlayer and at subsurface depths in a small eutrophic bog pond. Nutrient levels were consistently higher in the microlayer while algal abundance was sometimes higher but sometimes lower in the microlayer than at near subsurface depths. Algal diversity values were strongly influenced by the depth of flagellate blooms, and in contrast to previous studies, diversity in the microlayer was higher than at near subsurface depths. These results are discussed in terms of weather parameters, affinity of algal species for the surface and differences between microlayer ecology in shallow and deep water systems.     

Selection of diverse genotypes for heterosis in yield and response in toria (Brassica campestris L.)

Summary Thirty-one genotypes of toria (Brassica campestris L.) were grown in twelve environments and subsequently analysed in order to select potential parents which expressed diversity for both 12 different characters (estimated by Mahalanobis' D² technique) and response to the environments (estimated on the basis of negative correlation between deviations in seed yield of a pair of genotypes from their respective environmental means). Coefficients of determination (r²) were also used to measure the reliability of correlation, which is the basis of diversity of response. Stability parameters (b and S²d) and mean seed yield were also considered in selecting potential parents. On the basis of these criteria, three pairs of genotypes (ITSA and TCSU-1, TCSU-7 and TH-8 and Ludhiana Composite-1 and TH-4) are recommended to be used as parents for hybridization programmes so that heterosis both in seed yield and response may be exploited.     

An experimental evaluation of diversity indices as environmental discriminators

Seven diversity indices were calculated for each of fifty-eight microcosm communities. All fifty-eight communities were initiated from equal density inoculations of fourteen algal species. Each microcosm developed in one of six controlled experimental environments; the environments differing only in their temporal patterns of disturbance. Five linear discriminating techniques were used to evaluate the diversity index most useful for discriminating between these environments. The Shannon-Wiener index was best according to two of the discriminating methodologies and second best using the other techniques. Evenness was best when the Shannon-Wiener index was second best and vice versa.