Equitability Of Distribution Research Articles

Pathological Mitosis and Mixoploidy in the Meristematic Tissues of Grape Plant

The emergence of cells with pathological mitosis and the deviation from diploidity in the meristematic tissue of experimental plants of the genus Vitis (Tournef.) Linn. obtained from stenospermocarpic seeds was evaluated. The grape plants obtained from crossing seedless varieties with seedless and seed pollinators were the material for cytogenetic research. A total of 11 crosses were made. The cytogenetic analysis was carried out according to the recommended methods for fruit crops and grape. A total of 11 039 cells were examined. The pathology of mitosis in the cells of grape plants in vitro was observed, in particular, a hollow metaphase, a three-group metaphase and a metaphase with polar chromosomes as well as haploid, triploid, and tetraploid cells. The total frequency of abnormal cells was 0.15. The pathology of mitosis is observed in meristematic tissue of grape varieties as well. The evaluation of emergence of mitotic anomalies in the meristematic tissue of plants was carried out. The correspondence between the actual distribution of the anomalies in experimental populations and the theoretical distribution, as well as the degree of their relative habit to populations, the indices of absolute, relative, and intrapopulation diversity, was determined. As a result of the study of the polyembrionic hybrid offspring of grapes, differentiation in the equitability of distribution and habit of five mitotic anomalies to 11 populations was revealed, and differences between experimental populations by diversity were detected. The maximum degree of relative diversity of populations reached a value of 0.503. In general, the low relative diversity indicates a lack of complete equalization of anomalies by the presence in the populations.

Phenotypic cluster and diversity analysis of native chickens in Western Visayas, Philippines

Western Visayas has largest population of native chickens in the Philippines; however, data on the phenotypic and genetic diversity is limited. Eight hundred and ten chickens from 270 different flocks, from six provinces within the region were chosen for characterization. Data collected includes farmer selection practices, means of identifying genetic groups and information on phenotypic traits of native chickens. This information was analysed using statistical tools suggested by FAO. Phenotypic diversity and equitability of distribution were analysed using Simpson's diversity index and equality of distribution. Results showed that native chicken genetic resources are comprised of two types, the Jolo and Bisaya; the latter was further divided into Bisaya–Cluster I and Bisaya–Cluster II. Jolo chickens were the heaviest (P < 0.01) but comparable with Bisaya–Cluster II in terms of egg weight, head shape and phenotypic distance. They all had higher diversity and equitability of distribution in their plumage colour and pattern, though the iris and shank colour had higher diversity but had limited distributions. Bisaya–Cluster II and Jolo chickens had higher diversity and above average distribution in liveweight. They were also homogenous in feather morphology and distribution; head and breast shape, and skeletal variants. Thus, the observed diversities and distributions can be used in identifying genetic materials for any breeding undertakings.

Estuaries of Contrasting Trophic Status in KwaZulu-Natal, South Africa

The aim of the present investigation was to assess the feasibility of using sediment diatom communities to monitor pollution levels in the estuaries of KwaZulu-Natal. To this end, benthic diatom communities were examined along the length of two morphometrically similar estuaries of contrasting trophic status; the eutrophic Manzimtoti and oligotrophic Mhlabatshane. It was observed that: (1) the total number of diatoms was significantly higher in the Manzimtoti estuary than in the Mhlabatshane; and (2) species composition, rather than community structure, correlated well with nutrient levels of the water. In this regard, the benthos of the Manzimtoti was dominated byNitzschiaspp. andNaviculaspp. whileDiploneisspp. andAchnanthidiumspp. were common in the Mhlabatshane estuary. Furthermore, variations in the diatom communities were recorded along the length of the estuaries, in that: (1) species richness, diversity, equitability of distribution and number of individuals tended to decrease downstream; and (2) the brackish and freshwater assemblages were similar within each estuary but differed markedly from saline sites located at the estuary mouths. As a result, these observations indicated that any attempt to use benthic diatoms to monitor the nutrient loading of estuaries in KwaZulu-Natal must make use of species composition data from sediments sampled at comparable sites along the length of the estuary.

Fish community structure response to major habitat changes within the littoral zone of an estuarine coastal lake

The littoral environment and fish fauna of Swartvlei, an estuarine lake, was monitored for four years during which major habitat changes occurred. Initially (1979) the zone was dominated by the submerged macrophytes Potamogeton pectinatus, Chara globularis and Lamprothamnium papulosum. This plant community was replaced by filamentous algal mats during 1980 and with the disappearance of these mats in 1981 the littoral zone was transformed into a sandy habitat. There was a highly significant decline in the numbers of fishes in the littoral zone between the macrophyte and sand phases but no significant decrease in fish biomass between the two phases. Analysis of gill net catches revealed an increase in the CPUE of the family Mugilidae between the macrophyte and sand phases but a decline in the CPUE of vegetation associated species such as Monodactylus falciformis and Rhabdosargus holubi over the same period. The increase in mullet stocks during the sand phase was attributed to epipsammic micro-algal production and the input of allochthonous detritus during the 1981 floods. The three fish species diversity indices used in this study showed minor fluctuations between the habitat phases and these variations were related to changes in the equitability of distribution between the individual species within each habitat type. The numbers of fish species recorded during the macrophyte, algal mat and sand phases varied by less than 20%. The resilience of estuarine fishes to major alterations in their environment was illustrated by the fact that all fish species recorded at the beginning of 1979 were present at the end of 1982, despite major habitat and food resource changes.

Warbler Ecology: Diversity, Similarity, and Seasonal Differences in Habitat Segregation

Parnell (1969) gathered data on foliage type and habitat zone preferences of warbler species during spring migration and the immediate postmigratory period. Occurrences of species were recorded in four data sets: (i) foliage type, spring migration; (ii) foliage type, postmigration; (iii) habitat zone, spring migration; and (iv) habitat zone, postmigration. The present study is a re—analysis of Parnell's data by a number of statistical methods. The species that are most broadly distributed within the habitat have indices of ecological diversity (H) or niche breadth, of from 3 to 5 times greater than the most narrowly distributed forms. There is no correlation between H in foliage types and H in habitat zones within seasons, but there are significant correlations for H between spring migration and post—migration samples within vegetational subdivisions. Average H is not significantly different between seasons for either foliage type or habitat zone data. The dominant component of H is the number of vegetational subdivisions occupied, rather than the equitability of distribution within subdivisions. Ecological similarity (S = complements of average Euclidian distance in hyperspaces defined by vegetational subdivisions) among species is assessed by cluster analysis of each data set. S among species is not correlated between foliage type and habitat zone occurrences within seasons, but is correlated between spring migration and postmigration samples within vegetational subdivisions. Average ecological distance among species is greater in the reproductive season than during spring migration for both foliage type and habitat zone data. Increased segregation among species in the breeding season may be due to the reduction in the number of warbler species in the study area during that time, seasonal shifts in behavior as regards interaction of species, or simple population differences.