Frequency Distribution Of Species Research Articles

A Variance Test for Detecting Species Associations, with Some Example Applications

A little—used measure of species association is provided by the ratio of the variance in total species number (or total density of individuals) in samples to the sum of the variances of the individual species. Use of this ratio allows a test of the null hypothesis that species do not covary among samples. As the test is simultaneous it is preferable to pairwise 2 X 2 contingency table analysis and pairwise correlation analysis when the number of species is large. Simulation reveals that this test is also more powerful than Pearson's g2 test for comparing observed and expected frequency distributions of species in samples. The variance test was applied to a selection of data from the literature. Results reveal that positive associations are the rule in nature and negative associations are uncommon. Invertebrate species tend to be more positively associated among samples than are vertebrates, although the difference is not significant. Examples of biological processes, especially interspecific interactions, that might produce associations among species are suggested. However one must be cautious not to infer the importance or unimportance of a specific process from the result of the test alone.

Avicennia canopy effects on mangrove algal communities in Spencer Gulf, South Australia

Studies of mangrove algal communities at eight localities in Spencer Gulf, South Australia, provide evidence that the presence or absence of an Avicennia tree canopy may influence the frequency distribution of algal species on pneumatophores. Certain algae occurred with significantly higher frequencies on pneumatophores. Certain canopy, while other species were significantly more frequent on pneumatophores beyond the canopy. The distribution of total algal cover, total algal biomass, and total species diversity, however, does not appear to be correlated with the presence or absence of a tree canopy.

Effects of Depth and Marine Reserve Fishing Restrictions on the Structure of a Rocky Reef Fish Assemblage in the North-Western Mediterranean Sea

SUMMARY (1) A visual scuba diving census, in which abundance and size class structure of conspicuous fish species were determined, was used to assess the effects of depth and marine reserve fishing restrictions on the structure of a Mediterranean rocky reef fish assemblage by comparing communities at sites from two depth ranges inside and outside a marine reserve. (2) The total assemblage had thirty-five conspicuous species and was dominated by Labridae (thirteen spp.) and Sparidae (nine spp.). (3) Mean species richness (number of species) and diversity (Shannon) did not differ significantly between sites. (4) Ordination of abundance data showed that occurrence and relative abundance of species was affected by depth (deep samples separated completely from shallow samples) and marine reserve status (samples from the marine reserve were significantly separated from those taken at the same depth outside the reserve). (5) Samples from the same depth were similar, because the majority of species showed a preference for either deep or shallow areas. The known biology of several species indicated that feeding requirements may be responsible for depth preferences. (6) Samples from reserve sites had signficantly higher densities of fish species sought after and/or vulnerable to local fishing methods, than those from non-reserve sites of similar depth. (7) Size frequency distributions of vulnerable species at reserve sites generally had a larger modal size class than distributions from non-reserve sites. (8) The data suggest that reduced fishing pressure in the reserve has provided effective protection for species vulnerable to fishing.

Mitochondrial-catalyzed ATP hydrolysis in highly enriched [ 18O]H 2O. : Frequency distributions of 18O-labelled P i species

1. 1. The 2,4-dinitrophenol-resistant intermediate phosphate ⇌ water oxygen exchange reaction which accompanies the hydrolysis of ATP catalyzed by heart submitochondrial vesicles was studied in highly enriched 18O-labelled water. The phosphate formed was converted into the tris(trimethylsilyl) phosphate derivative which was analyzed by chemical ionization mass spectrometry. The amount of exchange relative to that of ATP hydrolysis, and the ATP dependence of the exchange on the ATP concentration were measured. The results were in good agreement with previous studies carried out on water of low enrichment. However, the new procedure enabled the determination of the relative frequency distributions of phosphate species with 1, 2, 3, or 4 oxygen atoms derived from water. Oxygen from water was not found only in singly or quadruply 18O-labelled species. This finding further helps to exclude the possibility that the vesicles contain two separate ATPases, one non-exchanging, the other highly exchanging. 2. 2. The frequency distributions of 18O-labelled P i species were measured at high (6 mM) and low (0.01 mM) ATP, as well as at three intermediate ATP concentrations. Regression analysis was carried out to see if the frequency distributions found with the intermediate ATP concentrations were simple composites of the patterns obtained at the high and low ATP levels. The analysis did not support the idea that the phosphate formed at the intermediate ATP levels was a binary mixture of phosphate produced by the hydrolysis of ATP at a high and a low affinity ATP site. This finding excluded models involving two independent Michaelis-Menten ATPases, as well as simple two-site negatively cooperative models. 3. 3. Oxygen from water was incorporated into all four oxygens of phosphate, and the extra oxygen (i.e., that incorporated over and above the single oxygen needed for the hydrolytic step) was distributed approximately binomially. This implies that the four oxygen atoms of P i were equivalent during the time enzyme-bound P i underwent exchange. Thus a pseudorotation mechanism in which one oxygen was strongly liganded to a group on the enzyme does not appear likely. The exchange may thus reflect the dynamic reaction, ATP + H 2O ⇌ ADP + P i on the enzyme surface. The effect of ATP concentration upon exchange may thus reflect the extent of hydrolysis and reesterification which occurs prior to P i release from the enzyme.

Patterns of Alpha-Diversity and Abundance in Breeding Bird Communities across North America

Community diversity can be examined by noting the number of species within a single habitat of known area (alpha-diversity), the changes in species composition along a series of habitats (beta-diversity), or the total species richness of a large geographic region (gamma-diversity; Whittaker 1960, 1972). The diversity of breeding birds in a community is closely related to the structure of the vegetation (MacArthur and MacArthur 1961, MacArthur et al. 1962, 1966, Tramer 1969, Karr and Roth 1971, Peterson 1975, Roth 1976). Studies of beta-diversity in birds have focused on species composition or rates of species turnover between adjacent habitats (Cody 1970, 1975, Tramer 1974a, Karr 1976). Gamma-diversity patterns have been examined for breeding birds (MacArthur and Wilson 1967, Cook 1969, Bock and Lepthien 1975) and wintering birds (Bock and Lepthien 1974, 1976, Tramer 1974a, b) but these studies based their comparisons on extensive areas which obscured fine patterns of diversity. Since birds respond to the proximate releasers of their habitat (James 1971), not arbitrary geographic blocks, an analysis of local avian communities could provide insights into diversity pertaining to the structure of breeding bird populations. Cook (1969), Tramer (1974a), and Bock and Lepthien (1974, 1975, 1976) have traced the diversity of North American birds to changes in earth history and its subsequent effects on climate, vegetation, and resource availability. These analyses considered relative species richness and disregarded the effects of relative species abundance, or species equitability. My objectives here are to describe and interpret patterns of species frequency distribution within breeding bird communities in North America.

The association between larval parasitic water mites (Hydracarina) and Anopheles implexus (Theobald) (Diptera, Culicidae)

AbstractThe parasitic larvae of two species of water mites were studied on resting and biting Anopheles implexus (Theo.) from the Zika Forest near Entebbe, Uganda. Details are given of the mites' morphology, positions of attachment, growth stages and visible effects on hosts. Living larvae of the more numerous mite species (designated as species F, Limnesiidae) were only moderately reliable indicators of the nulliparous state of female hosts, whereas those of the other species (species G, Arrenuridae) were more reliable nullipar indicators, evidently owing to their far more rapid development. The presence of living larvae of either species not completely full-grown denoted the nulliparous state of female hosts with certainty. Male mosquitoes showed consistently lower infestation rates than females from the same resting samples, but the incidence of the different growth classes of species F indicated that these mites departed from hosts of either sex with equal facility and therefore regardless of whether the hosts returned to oviposition sites or not. Frequency distributions of species F on each host sex fitted most closely to highly clumped negative binomials, and biological interpretation of patterns of decline in mite numbers on females in successive Sella's stage groups, and other data, provided evidence of there being at most a negligible amount of mite-mediated host mortality.The study confirms the usefulness as well as the limitations of the presence of parasitic water mites as a rapid means of age-grading female mosquitoes, and suggests several new applications.

Interpretation of Quaternary paleoecology from Cladocera and midges, and prognosis regarding usability of other organisms

Sedimentary remains of chydorid Cladocera are abundant and can be identified precisely to species. Their percentage composition by species in sediments is integrated over habitats and seasons. Under stable conditions the relative frequency distribution of species corresponds to the MacArthur broken-stick model, so that marked departures from the predicted distributions indicate perturbations in the system. Lakes differ greatly in their capacity to buffer the effects of external changes. Cladocera can also indicate fluctuations in lake level, the changing effectiveness over time of size-selective predation, and broad patterns of climatic change through invasion and extinction of species. The remains of dipterous larvae (chiefly Chironomidae) are not only much less abundant than Cladocera but also have a much greater taxonomic uncertainty. Nevertheless, the profundal taxa provide clear insight into changing conditions in the hypolimnion over time and of the long-term readjustments and changes in the total fauna and their environmental correlates. Rhizopods, neorhabdocoeles, and rotifers, although barely studied to date, give promise in helping interpret past conditions.

Gibberellic Acid-induced Phase Change in Hedera helix as Studied by Deoxyribonucleic Acid-Ribonucleic Acid Hybridization

Applications of gibberellic acid to the mature form of Hedera helix induce morphological reversions to the juvenile form of growth. The juvenile forms produced are stable with time and differ dramatically from the mature in phenotype. DNA-RNA hybridization techniques have been used to study the RNA populations of juvenile, mature and gibberellic acid-treated mature apices. Hybridization competition experiments using RNA extracted by a hot phenol technique and uniformly labeled in vitro with (3)H dimethylsulfate show no qualitative differences between the species of RNA present in juvenile and mature apices. However, differences are observed in the frequency distribution of RNA species using both uniformly labeled or pulse-labeled RNA as a reference. RNA extracted from gibberellic acid-treated mature buds was a less effective competitor than control mature RNA and the difference observed was comparable to that observed between mature and juvenile RNA. These results indicate that at least part of the molecular basis of phase change and gibberellic acid action may involve an alteration in the rate of transcription of certain genes in the apices of the mature form.RNA extracted using the hot phenol procedure contained a fraction of rapidly labeled RNA which was not extractable with cold phenol. When RNA extracted only with cold phenol was used in competition experiments sequences unique to the juvenile were detected and sequences unique to the mature were not detected. Implications of these results in relation to possible post-transcriptional control mechanisms are discussed.

On species frequency models

SUMMARY An extension of the negative binomial model as a species frequency distribution is given by allowing the shape parameter k to take values between -1 and 0. Different estimation methods are assessed for this extended negative binomial model and the logarithmic series model. Tables for standard errors are given. Many successful attempts have been made to fit mathematical models to populations of many species. Fisher's logarithmic series model (Fisher, Corbet & Williams, 1943), Preston's log normal model (Preston, 1948), the negative binomial model (Brian, 1953) and McArthur's broken stick model (McArthur, 1957) have all proved useful, giving a reasonably good fit to biological data. The purpose of this paper is to give an extension of the negative binomial model by allowing the parameter, usually symbolized by k, to take values between - 1 and 0, and to assess different estimation methods for this extended negative binomial model and the logarithmic series model. The extended model seems to fit well in situations where the negative binomial fails and has usually been substituted by the log normal model, which is more complicated to handle mathematically.

Toward a definition of a mineral sample in geology

Any rock may be regarded as an “aggregate” of mineral species frequency distributions, thus opening up a new method of analyzing the problems of the nature of these discrete distributions.

Species frequency distributions

This paper deals with the branch of statistical ecology which studies the pattern of variation in the abundances of the different species present in a habitat, as distinct from the actual abundances of a fixed set of species. Much of the work in this field has been done by ecologists, the leading contributor being C. B. Williams, who has published a monograph on the subject (Williams, 1964). A consequence is that while the practical phenomena which stimulated the development of the theory are well documented, the mathematical reasoning behind the results is sometimes left implicit or unclear. For instance the empirical observation that in a random collection of insects the numbers of species represented by 1, ..., s specimens are often approximately of the form

An analysis of vegetation–environment relationships in Saskatchewan sloughs

This study examined the relationships between the distribution of herbaceous species and some of the major environmental factors in sloughs. Frequency distribution of species was studied in 64 stands. Environmental data, collected in 40 of these, included weekly readings of water level, fortnightly readings of pH and total dissolved solids in water, and texture and organic matter content of topsoil and subsoil. An association table of 24 leading dominants, arranged so that strongly associated species were close together, corresponded closely to their observed order along a moisture gradient. Environmental scalars were constructed to combine data on pH and total dissolved solids, as well as initial water depth and rate of water loss. The soil data showed very little association with species distribution. Synthetic scalars for water regime and for water chemistry were plotted against one another to obtain an arrangement of stands. Plotting the frequency distribution of the leading dominant species over the environmental arrangement of stands showed most of the species to be strongly affected by the water regime and somewhat less affected by salinity. A few were restricted to a very narrow range of one of these factors, while others flourished in all segments of the environment. The relationships suggested by this analysis are largely in agreement with those suggested by the vegetation analysis alone.

A Pre-impoundment Survey of the Helminth and Copepod Parasites of Micropterus spp. of Beaver Reservoir in Northwest Arkansas

A total of 489 bass were examined and 21 species of parasites were recovered, as follows: nine species of trematodes representing six families; one cestode; two acanthocephalans representing two families; four nematodes representing three families; two leeches representing one family; and three copepods representing three families. From 410 fish specimens taken from 25 collection sites along the White River drainage, 18 species of parasites were recovered; of these specimens all but one was parasitized by at least one species of parasite. Seventy-nine Micropterus salmoides were examined from three state fish hatcheries presently stocking Beaver Reservoir to determine if the preventative measures used were effective in eliminating ectoparasites. Of these, all but four were parasitized by one or more species of parasite for an overall infection rate of 95%. Eleven species of parasites were recovered from the hatchery fish, three of which were not present in the White River drainage. Posthodiplostomum minimum and Neoechinorhynchus cylindratus, respectively, were the most prevalent parasite species in all three of the hosts studied. Twenty-one selected surveys were compared with the present pre-impoundment survey to determine the frequency and geographical distribution of the parasite species recovered. A comparison made between the 1962 and 1963 collections revealed pronounced fluctuations in the percentage of infection of many parasite species. The distribution, prevalency, and host specificity of parasites, and the control of fish parasites with relationship to this study are discussed.

The Application of the Logarithmic Series to the Frequency of Occurrence of Plant Species in Quadrats

The Application of the Logarithmic Series to the Frequency of Occurrence of Plant Species in Quadrats