Interspecific Associations in a Woodland Stream

1981 ◽  
Vol 38 (10) ◽  
pp. 1271-1280 ◽  
Author(s):  
Seth R. Reice
Keyword(s):  
Community Structure ◽  
Benthic Macroinvertebrates ◽  
Community Organization ◽  
Common Species ◽  
Interspecific Association ◽  
Chi Square ◽  
Leaf Pack ◽  
Leaf Packs ◽  
Species Pairs ◽  
Associated Species

Patterns of association of benthic macroinvertebrates were examined within a riffle of New Hope Creek, North Carolina, USA. The 16 most common species were tested for cooccurrences. Chi-square contingency tests on simultaneous presence and absence of two species at a time were performed. The strength of the association and its direction were determined for significantly associated species pairs using the V statistic. The patterns of association among 120 species pairs are presented for each of three mineral substrate types (cobbles, pebbles, and gravel) and leaf packs (5 g of Cornus florida leaves) attached to them. These data were collected over a 3-mo period.The results show that significant interspecific association on a given substrate was found for 18.3% or less of the species pairs. The species which strongly associated on one substrate type differed from those associating on another substrate. The presence or absence of leaf packs on a mineral substrate patch, which did not affect most species densities, did affect the cooccurrence patterns among species. The presence of leaf packs reduced the number of significantly associated species pairs on all substrates. In all cases in mineral substrates, negative associations were rare. The proportion of negative associations approximated what one would predict by chance alone. This suggests that competition may not be an important factor in stream communities.This work presents a different approach to the analysis of lotic communities. It suggests several hypotheses about community structure in streams. It reaffirms that substratum type is a major governing factor in stream community structure and dynamics.Key words: benthic macroinvertebrates, community organization, competition, interspecific association, leaf pack, patchiness, predation, stream, substrate

A survey of the ecology and composition of submerged aquatic snail–plant communities

1978 ◽  
Vol 56 (11) ◽  
pp. 2263-2279 ◽  
Author(s):  
Eva Pip
Keyword(s):  
Water Chemistry ◽  
Plant Communities ◽  
Submerged Macrophytes ◽  
Environmental Parameters ◽  
Common Species ◽  
Gastropod Species ◽  
Chi Square ◽  
Environmental Preferences ◽  
Species Pairs ◽  
Major Grouping

A total of 305 sites were surveyed in southern Manitoba and adjacent areas for the presence of aquatic gastropods and submerged macrophytes with respect to eight water chemistry parameters. Many of the 41 gastropod species found within the study area showed significant preferences for certain parameters. Chi-square tests revealed 68 significant positive and 4 negative interspecific gastropod associations, many of which could not be correlated with net similarities or dissimilarities in significant preferences for the environmental parameters examined. The most common species did not form the most highly significant associations. Members of possible species pairs were compared with respect to their similarities in significant positive associations with other gastropods. The major groupings that emerged reflected characteristics of the habitats within which the species occurred most frequently.Chi-square tests were also conducted for possible snail–plant pairs, resulting in 161 significant positive and 31 negative associations. Many of these could not be correlated with environmental preferences. Members of possible gastropod pairs were compared with respect to their similarities in significant associations with macrophytes. The major grouping that emerged consisted of gastropods which also formed the most highly significant positive associations with macrophytes.

scholarly journals Diversity and Community Structure of Oribatid Mites (Acari, Oribatei) at Memorial Complexes of a Megapolis

2013 ◽  
Vol 47 (4) ◽  
pp. 291-297
Author(s):  
L. A. Kolodochka ◽  
O. S. Shevchenko
Keyword(s):  
Community Structure ◽  
Species Diversity ◽  
Species Complex ◽  
Common Species ◽  
Oribatid Mites ◽  
Direct Relation ◽  
City Center ◽  
Degree Of Dominance ◽  
Different Types ◽  
The City

Abstract In different types of substrate (soil, litter, lichens and mosses) collected at three memorial complexes (cemeteries) of Kyiv (Ukraine), 70 species from 57 genera, 34 families of oribatid mites were found. A few eurytopic species capable of tolerance to different types of pollution make up an essential part in each species complex. The species diversity and complexity of oribatid community structure at researched areas increased with distance from the city center. There was no direct relation between the degree of dominance of most common species and the cemetery’s relative remoteness from the center of the city.

scholarly journals Modelling community structure and species co-occurrence using fishery observer data

2016 ◽  
Vol 73 (7) ◽  
pp. 1750-1763 ◽  
Author(s):  
Jeffrey Robert Pulver ◽  
Hui Liu ◽  
Elizabeth Scott-Denton
Keyword(s):  
Cluster Analysis ◽  
Community Structure ◽  
Gulf Of Mexico ◽  
Reef Fish ◽  
Efficient Method ◽  
Probabilistic Models ◽  
Distinct Species ◽  
Common Species ◽  
Species Relationships ◽  
Correlation Measure

Abstract In this study, we modelled fishery observer data to compare methods of identifying community structure using cluster analyses to determine stratifications and probabilistic models for examining species co-occurrence in the Gulf of Mexico deepwater reef fish fishery. Comparing cluster analysis methods, the correlation measure of dissimilarity in combination with average agglomerative linkage was the most efficient method for determining species relationships using simulated random species as a comparison tool. Cluster analysis revealed distinct species stratifications and in combination with multiscale bootstrapping generated probabilities indicating the strength of stratifications in the fishery. A more parsimonious approach with probabilistic models was also developed to quantify pairwise species co-occurrence as random, positive, or negative based on the observed vs. expected fishing sets with co-occurrence. For the most common species captured, the probabilistic models predicted positive or negative co-occurrence between 84.2% of the pairwise combinations examined. These methods provide fishery managers tools for determining multispecies quota allocations and offer insights into other bycatch species of interest.

Sampling and Sample Size in Ecological Analyses of Fossil Mammals

Paleobiology ◽  
1975 ◽  
Vol 1 (2) ◽  
pp. 195-204 ◽  
Author(s):  
Ronald G. Wolff
Keyword(s):  
Community Structure ◽  
Sample Size ◽  
Late Pleistocene ◽  
Sediment Sample ◽  
Quantitative Data ◽  
Community Organization ◽  
Minimum Sample Size ◽  
Bulk Sediment ◽  
Adequate Sampling ◽  
Biased Samples

Analysis of several thousand mammalian fossils from late Pleistocene sediments in California provide data on sampling in mammalian paleoecology. Recovery of bones and teeth from the screenwashed bulk sediment sample residue is considered nearly total. Neither surface collecting alone, nor small bulk samples provide satisfactory quantitative data on original community structure or postmortem alterations in community organization. Minimum sample size for the analysis of diversity is discussed. Diversity and size-trophic ratios of the total identifiable mammalian component of this fauna (N = 1222) are similar to those expected in living communities, and therefore suggest adequate sampling, and minimally biased samples.

scholarly journals Impact of Dilution on Microbial Community Structure and Functional Potential: Comparison of Numerical Simulations and Batch Culture Experiments

2001 ◽  
Vol 67 (2) ◽  
pp. 702-712 ◽  
Author(s):  
Rima B. Franklin ◽  
Jay L. Garland ◽  
Carl H. Bolster ◽  
Aaron L. Mills
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Numerical Simulations ◽  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Community Organization ◽  
Colony Morphology ◽  
Community Size ◽  
And Function

ABSTRACT A series of microcosm experiments was performed using serial dilutions of a sewage microbial community to inoculate a set of batch cultures in sterile sewage. After inoculation, the dilution-defined communities were allowed to regrow for several days and a number of community attributes were measured in the regrown assemblages. Based upon a set of numerical simulations, community structure was expected to differ along the dilution gradient; the greatest differences in structure were anticipated between the undiluted–low-dilution communities and the communities regrown from the very dilute (more than 10−4) inocula. Furthermore, some differences were expected among the lower-dilution treatments (e.g., between undiluted and 10−1) depending upon the evenness of the original community. In general, each of the procedures used to examine the experimental community structures separated the communities into at least two, often three, distinct groups. The groupings were consistent with the simulated dilution of a mixture of organisms with a very uneven distribution. Significant differences in community structure were detected with genetic (amplified fragment length polymorphism and terminal restriction fragment length polymorphism), physiological (community level physiological profiling), and culture-based (colony morphology on R2A agar) measurements. Along with differences in community structure, differences in community size (acridine orange direct counting), composition (ratio of sewage medium counts to R2A counts, monitoring of each colony morphology across the treatments), and metabolic redundancy (i.e., generalist versus specialist) were also observed, suggesting that the differences in structure and diversity of communities maintained in the same environment can be manifested as differences in community organization and function.

scholarly journals Identification ofCandidaSpecies Associated with Vulvovaginal Candidiasis by Multiplex PCR

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Mahnaz Mahmoudi Rad ◽  
Ameneh Sh Zafarghandi ◽  
Maryam Amel Zabihi ◽  
Mahkam Tavallaee ◽  
Yasaman Mirdamadi
Keyword(s):  
Multiplex Pcr ◽  
Fungal Infections ◽  
Positive Association ◽  
Common Species ◽  
Vaginal Swab ◽  
Vulvovaginal Candidiasis ◽  
Rrna Genes ◽  
Its2 Region ◽  
Chi Square ◽  
Significant Positive Association

Background. Vulvovaginal candidiasis is a common infection. The aim of this study was to identify the species of vaginalCandidaisolates by using multiplex PCR technique.Methods. 191 isolates from patients admitted to Mahdieh hospital were identified. The vaginal swab specimens were cultured on Sabouraud Dextrose Agar. The ITS1 region between the 18S and 5.8S rRNA genes and a specific DNA fragment within the ITS2 region were amplified. The multiplex PCR products were separated by electrophoresis in 2% agarose gel, visualized by staining with ethidium bromide, and photographed. Descriptive statistics, Chi-square test, and Spearman correlation were used to summarize the findings.Results.C. albicansandC. glabratawere the most common species isolated from the specimens. A mix ofC. glabrataandC. albicanswas the most common mixed infection isolated from the samples. The analysis revealed a significant positive association between older age and infection withC. glabrataisolates (Spearman’s rho = 0.89,P=0.015).Conclusion. Multiplex PCR is a fast, yet reliable method to identifyCandidaspecies.C. albicansand thenC. glabrataare the two most common causes of vulvovaginal candidiasis. The number of mixed fungal infections is higher among Iranian population compared to international reports.

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