Showing papers on "Diversity index published in 1990"

Comparison of phenotypic diversity and DNA heterogeneity in a population of soil bacteria.

Abstract: The phenotypic diversity of about 200 bacterial strains isolated from soil was compared with the genotypic diversity of the same population. The strains were phenotypically characterized by the API 20B test system. The results of these tests were subjected to cluster analysis, which revealed 41 biotypes at 80% similarity. The five dominating biotypes contained 43% of the strains. The phenotypic diversity as determined by the Shannon index, equitability, rarefaction, and cumulative differences was high, but indicated some dominant biotypes. The genetic diversity was measured by reassociation of mixtures of denatured DNA isolated from the bacterial strains (C0t plots). The observed genetic diversity was high. Reassociation of DNA from all bacterial strains together revealed that the population contained heterologous DNA equivalent to 20 totally different bacterial genomes (i.e., genomes that have no homology). This study showed that reassociation of DNA isolated from a collection of bacteria gave a good estimate of the diversity of the collection and that there was good agreement with different phenotypic diversity measures. The Shannon index in particular has features in common with the genetic diversity measure presented here.

Sample-size dependence of diversity indices and the determination of sufficient sample size in a high-diversity deep-sea environment

Abstract: Diversity indices, although designed for comparative purposes, often cannot be used as such, due to their sample-size dependence. I t is argued here that this dependence is more pronounced in h~gh divers~ty than in low diversity assemblages and that indices more sensitive to rarer species require larger sample sizes to estimate diversity with reasonable precision than indices which put more weight on commoner species. This was tested for Hill's diversity numbers No to N, (Hill 1973) and some other commonly used diversity indices for a high-diversity nematode assemblage in the Mediterranean deep sea. Although diversity indices were introduced into the ecological literature more than 20 yr ago and have very often been criticized since, their use in applied ecological research, mainly in pollution impact studies, is still very popular ( e . g . Heip et al. 1988a). A fundamental drawback of many diversity indices is their sample-size dependence (Sanders 1968 and references therein), making comparison between studies difficult. Yet, the main purpose of quantifying diversity by a numerical index is to provide means for comparison between different communities. One way of avoiding incomparability of measurements resulting from different-sized samples was provided by the rarefaction method of Sanders (1968). In this method, one calculates the number of species expected from each sample if sampling size is standardized. Hurlbert (1971) showed that the rarefaction method generally overestimates the expected number of species present and h e introduced an exact computational formula for this index: the expected number of species in a sample with size n , drawn from a population of size N which had S species, is given by i' Inter-Research/Printed in F. R. Germany where Ni represents the number of individuals in the i th species in the full sample (Hurlbert 1971). This index was used by Heck et al. (1975) to estimate sufficient sample size for the calculation of the number of species in a sample. However, a mere species count, like ES (n), does not cover all information present in the community as it is not related to the way the individuals are divided among the species. Thus other diversity measures should be considered as well. Sample size dependence of diversity indices. Intuitively, one expects that not all diversity indices are equally influenced by sample size, and that also the type of community (with high or low diversity) plays a role. Let us consider the influence of sample size on Hill's diversity numbers (N,) of various orders (Hill 1973). Hill's diversity number of order a is given by: S Na = I C Pia I("l-al

Diversity in the American States: Updating the Sullivan Index

Abstract: The index of socioeconomic and cultural diversity among the American states formulated by John L. Sullivan for 1960 is recreated for 1980. Comparisons are made between the index for the two time periods, and changes among the states are examined over time. Significant differences continue to exist between northern and southern states, mainly because of cultural rather than socioeconomic factors. The diversity index remains a relatively powerful predictor of policy variation among the states and, as such, might be considered as a substitute for geographic region in comparative state policy research.

Effects of changes in sewage pollution on soft-botiom macrofauna communities in the inner Oslofjord, Norway

Abstract: The macrobenthic fauna of Vestfjorden, inner Oslofjord was sampled in 1980 and 1985 at 19 stations. The aim of this study was to detect possible faunal changc:s following the start of a sewage treatment plant in 1982. The faunal data were analyzed by a variety of methods including diversity indices, log-normal distribution of individuals among species and classification and ordination analysis. The results show a decline in species number and abundance which may be related to increased pollution. However, the diversity and the evenness have increased. The area within a radius of 2-3 km from the outlet of the treatment plant shows clear pollution effects while the marginal areas show improved conditions.

Changes in the diversity of New Zealand forest birds

Abstract: Shannon diversity indices for several subfossil assemblages of New Zealand birds are compared with estimates for living communities today. As expected, bird species diversity was higher in the pre-human environment, but it was also greater than that predicted from studies of living communities. Previous estimates of the number of terrestrial bird species in the pre-human avifauna are too low, and many of these were incorrectly interpreted as being open-country species. The pre-human fauna was deficient in open-country birds. A prediction based on biogeographic (species-area) theory that this deficiency in open-country species was filled by half the species of moa (Dinornithiformes) is not supported by palaeoecological evidence. The major fall in bird species diversity in New Zealand is linked to the type of forest removed in Polynesian times, as well as the area.

Statistical analysis and trends in biomass and diversity of North Sea macrofauna.

Abstract: Total biomass and biomass of large taxonomic groups (polychaetes, mollusks, crustaceans, echinoderms) and species diversity of the macrofauna were determined for 200 North Sea stations sampled synoptically by seven vessels during Spring 1986 and for 120 additional stations sampled in earlier years by the Marine Laboratory of MAFF in Aberdeen. There exists a clear and significant decreasing trend in biomass with latitude, both in total biomass and for the different taxonomic groups. Apart from latitude also sediment composition and chlorophyll a content of the sediment influence total biomass and biomass of most groups significantly. Biomass increases consistently in finer sediments and sediments with a higher chlorophyll a content. The same trends are found for the results within laboratories. Some interaction exists, indicating weak laboratory and zonal effects. Diversity, as measured by Hill's diversity index N1 = exp H' shows a clear and significant trend with latitude. Towards the north of the North Sea diversity increases considerably. The trend is also found for laboratories separately and is everywhere equally strong. Environmental variables had no clear influence on diversity. Other diversity measures show the same trend but are more variable than N,.