A baseline study of metal contamination along the Namibian coastline for Perna perna and Choromytilus meridionalis.

The use of bivalves such as the brown mussel (Perna perna) and the black mussel (Choromytilus meridionalis) is common in the study of marine pollution and the effect of these pollutants on ecosystems and are important in both economic and ecological roles. Namibian marine ecosystems are threatened by pollution from mining, commercial fishing and population growth. The aims of this study were to determine baseline metal concentrations, spatial variation and variation between species. Metal levels in C. meridionalis from Guano Platform (GP) are the lowest of all the sites. The most polluted sites are Rocky Point (RP), Halifax Island (HIL) and between Walvis Bay and Swakopmund (WS). The bioaccumulation of metals between P. perna and C. meridionalis were not uniform for all metals. Overall the study indicates the condition of the coastline to be mostly normal, with Cd and Pb levels being of concern

Allozyme variation in two populations of the Mopane worm, Imbrasia belina (Saturniidae), and the effect of developmental stage and staggered generations

Imbrasia belina is utilised as a food item by certain ethnic groups of southern Africa, but little is known of the genetic structure of this resource. The aims of this study were to determine whether the limited flight ability of moths has an effect on gene flow between two geographically distant I. belina populations, whether there are gene expression differences between moths, worms and pupae and whether staggered generations have different genotypic expressions. Gene products of 19 protein-coding loci from moths collected at two locations, one of which included two staggered generations, were analysed by horizontal starch gel electrophoresis. High levels of polymorphism (42% and 47%) and heterozygosity (0.182 to 0.210) were present in all groups. There were developmental constraints on the expression of the phosphoglucomutase enzyme coding locus, and only allozyme and not isozyme differences between individuals from the various developmental stages were found at other loci. Although the groups displayed a large amount of variation, little differentiation and a large amount of gene flow were observed between them. Results indicate that the genetic diversity of I. belina populations is relatively high. The February-hatching Messina group is recommended for commercial utilisation due to the large amount of genetic variation in this population. (South African Journal of Animal Science, 2001, 31(1): 15-24

Genetic relationships between three indigenous cattle breeds in Mozambique

This study provides the first account of genetic relationships between three indigenous cattle breeds from Mozambique. Forty-two blood group factors and six blood proteins revealed genetic variation of 84% (Angone), 88% (Bovine de Tete) and 90% (Landim) at the loci studied. Average heterozygosity values ranged from 33% for Angone and Bovine de Tete to 35% for the Landim. The genetic distance was greatest between the Landim and both the Bovine de Tete and the Angone breeds, whereas the smallest genetic distance was observed between the Bovine de Tete and the Angone. These results show the intermediate relationship of Bovine de Tete with the Angone and Landim breeds and show that the Bovine de Tete is an admixture of taurine and indicus genes. (South African Journal of Animal Science, 2000, 30(2): 92-97

Phylogenetic relationships, based on allozyme data, between six cycad taxa indigenous to South Africa

Phylogenetic relationships between Encephalartos altensteinii Lehmann, E. friderici-guilielmii Lehmann, E. lehmannii Lehmann, E. natalensis Dyer and Verdoorn, E. transvenosus Stapf and Burtt Davy and E. villosus Lemaire were studied, using Cycas revoluta Thunberg as outgroup. Three continuous and one discontinuous buffer systems were used and gene products of 21 enzyme coding loci were examined by horizontal starch gel-electrophoresis. A biochemical key, based on fixed allele differences, is presented. Fixed allele differences at one locus between E. altensteinii and E. natalensis may confirm that these species do not share the same gene pool. However, the genetic distance is the least (0.042) between these two species, compared to the mean genetic distance value of 0.222 for the other ingroup taxa. The results are discussed with reference to affinities based on morphology and distribution.Articl

Selected mineral and heavy metal concentrations in blood and tissues of vultures in different regions of South Africa

Concentrations of eight essential elements (Ca, Co, Cr, Cu, Fe, Mn, Ni and Zn) and three toxic metals (Al, Pb and Sr) were measured in various tissue samples from African whitebacked (Pseudogyps africanus), Cape griffon (Gyps coprotheres) and Lappetfaced (Torgos tracheliotos) vultures in different regions of South Africa. Blood samples from live African whitebacked vultures were taken from nestlings from two breeding populations, adults from a wildlife reserve and immature birds held in captivity. With the exception of Sr and Mn, concentrations of the majority of metals differed between two or more of the sampling localities and between captive and wild individuals. Birds from Moholoholo had the highest overall blood metal concentrations, while concentrations in birds from Dronfield were the lowest, as can be expected for nestlings and adults respectively. Fatty tissues and bones had the highest values of metal accumulation, especially Sr, and this is congruent with results from previous studies. It was concluded that most concentrations compared well with those reported for other avian species, but concentrations of Cr, Ni and Pb in the dead vultures were generally above values characteristic of heavy metal poisoning. The values reported for each of two wild populations of P. africanus nestlings and adults, and for two other vulture species could serve as base-line data for future comparative studies. (South African Journal of Animal Science, 2001, 31(2): 57-64

Biochemical genetic markers to identify hybrids between Aloe arborescens and A. ferox (Aloaceae)

Two populations of Aloe arborescens, six A. ferox populations, and a population of natural hybrids between A. arborescens and A. ferox were examined by horizontal starch gel-electrophoresis to assess levels of genetic variation and differentiation at 23 enzyme coding loci. Gene products revealed polymorphism in all of the populations studied, except for the four western populations of A. ferox. This indicates that the latter are founder populations from few parents, displaying only the dominant alleles, and with a possible migration route from east to west (as was also found for other plant taxa in South Africa). Biochemical genetic markers to identify A. arborescens×A. ferox hybrids were found at the DDH-2 and MNR-2 enzyme coding loci. Unique alleles were found in pure A. arborescens and A. ferox populations at these loci, which is an important result because it was not always possible to identify individuals correctly from their morphological characters. Genetic distance (Nei 1978) values between conspecific populations ranged from zero, between the western A. ferox populations, to 0.007 (A. arborescens) and to 0.01 (A. ferox, eastern populations), and it averaged 0.174 between the pure species

Determining the most suitable method of otolith preparation for estimating the age of tigerfish, hydrocynus vittatus in the Pongolapoort Dam, South Africa

The growth, morphology and relative age estimates of the lapillus and asteriscus otoliths were studied to gain a better understanding of the development and ageing of tigerfish otoliths. Asteriscus and lapillus growth showed good to excellent linear relationships for thickness (r2 = 0.547), length (r2 = 0.741), diameter (r2 = 0.799) and mass (r2 = 0.929). Otolith vs. somatic growth showed the highest correlations between lapillus and standard lengths (r2 = 0.659) as well as asteriscus mass and standard length (61%). Subject to further testing, it is believed that these near-linear relationships show promise for future use in tigerfish ageing studies. The possibility of using otolith morphometrics in tigerfish ageing studies will not only be cheaper, faster and easier but also more precise by avoiding reader error and bias. Indices of bias and precision showed sectioned lapilli to be the most precise ageing technique in terms of between-reader (CV = 7.85%; APE = 5.55%) and between-structure (CV = 6.20; APE = 4.20%) analyses.http://africanzoology.journals.ac.za/pub/article/view/631/883http://africanzoology.journals.ac.za/pu

Is caudal fin colour in tigerfish Hydrocynus vittatus a sex or population trait?

Tigerfish caudal fin colours vary from yellow to red, with distinct dissimilarities previously noted. To understand these colour differences, tigerfish were collected during 2008 to 2010 from four southern African populations in the Upper Zambezi River (ZAM), Okavango Delta (OKA), Pongolapoort Dam (POD) and Phongolo River (POR), and caudal fin colouration was classified according to pattern and sex. Muscle and liver tissue were assayed by starch electrophoresis. Caudal fin colour in OKA, ZAM and POD showed significant differences between sexes. Genetics revealed closer relationships between OKA and ZAM, substantiated by their recurrent and historical links, and between POD and POR, as expected for a dam and associated river. There is an association between the genetic and geographical distance of tigerfish populations, but variation in caudal colour in this species can most likely be attributed to their environment, territorial dominance and sexual behaviour.http://www.ajol.info/index.php/aja

Population Genetics and Biosystematics

Exam paper for second semester: Population Genetics and Biosystematic