A Preliminary Assessment of Skin Microbiome Diversity of Zebrafish (Danio rerio): South African Pet Shop Fish.

The zebrafish (Danio rerio) is a well-known model organism used in an array of scientific research fields. Many microbiome studies conducted on fishes have focused on gut microbiome diversity. To our knowledge, no investigations into the skin microbiome diversity of pet shop zebrafish have been performed. In this pilot study we aimed to assess the microbiome diversity composition of different groups of zebrafish housed at the Department of Genetics, University of the Free State, South Africa. These fish originated from pet shops located in Bloemfontein, South Africa. We investigated the skin microbiome diversity between wild-type zebrafish and the well-known leopard colour morph. The microbiome compositions between zebrafish sexes were also assessed. No significant differences were observed between colour morphs. A core microbiome was identified for the zebrafish housed at our laboratories. Cetobacterium was significantly more abundant in females compared to males, with Limnobacter more abundant in males. Both these genera are known components of fish microbiomes, including zebrafish. The precise reason for this link should be further investigated. This research adds to the growing knowledge base linked to aquatic microbiome structure in different habitats.

High genetic diversity and population differentiation in Clarias gariepinus of Yala Swamp: evidence from mitochondrial DNA sequences.

In order to improve the conservation and sustainable utilization of the African catfish Clarias gariepinus of the Yala Swamp in Kenya, genetic diversity and population structure of Lakes Kanyaboli and Namboyo populations of the species were studied using DNA sequences of the mitochondrial D-loop control region. Genetic diversity inferred as haplotype and nucleotide diversities and number of singletons and shared haplotypes was higher in the Lake Kanyaboli population (LKG) than the Lake Namboyo population (LNG) of C. gariepinus. Thirty-one haplotypes were inferred, of which 25 (80·6%) were private or singletons, while only six (19·4%) haplotypes were shared between LKG and LNG. Both populations were differentiated, with FST value that was significantly different from zero (P < 0·05). Two clusters were inferred both from the maximum likelihood tree and the spanning networks of phylogenetic relationships of haplotypes. Mismatch distribution for total sample was multi-modal but individually, distributions were uni-modal in LKG, but multimodal in LNG. The mean ± s.d. raggedness index for both populations was 0·085 ± 0·098 and not significantly different from zero (P > 0·05). Individual raggedness indices were 0·015 and 0·154 for LKG and LNG respectively. Fu's Fs was negative for both populations, with LKG recording -14·871, while LNG had -2·565, significantly different from zero for LKG (P < 0·05), but the value for LNG was not significant (P > 0·05). Tajima's D was negative for both populations, with LKG recording -1·734, while LNG had -1·136. Standardized square differences (SSD) were 0·001 for LKG and 0·048 for LNG and non-significant between them (P > 0·05). Values between all populations were also not significantly different (P > 0·05), mean ± s.d. SSD 0·025 ± 0·033.

Adult age confounds estimates of static allometric slopes in a vertebrate.

In many animal groups, the size of male genitalia scales shallowly with individual body size. This widespread pattern appears to admit some exceptions. For instance, steep allometries have been reported for vertebrate genitalia. This exception, however, may be due to a confounding effect arising from the continued growth of some structures during adulthood in vertebrates. Consider the possibility that genitalia continue to grow in adults while body size does not. If so, taking measurements from adults of different ages could yield steeper allometries than would be obtained from measurements of adults of the same age. We used vervet monkeys to test this hypothesis. We found that all body parts continued to grow in adult vervet monkeys, with sexual traits (including genitalia) showing faster growth rates. Traits with faster growth rates over adult ages had steeper allometries. And accounting for variation in adult age yielded shallower allometries, bringing vervet monkey genitalia in line with the predominant pattern observed in other animal groups. These results suggest that steep allometric slope estimates reported for other vertebrates may be due in part to mixing of adult ages, and reinforces one of the most consistent patterns yet detected in the study of static allometry.

Allozyme divergence among four representatives of the subfamily Alcelaphinae (family: Bovidae).

We used protein gel electrophoresis to study genetic diversity within and between blue wildebeest (Connochaetes taurinus), black wildebeest (C. gnou), red hartebeest (Alcelaphus buselaphus caama) and blesbok (Damaliscus dorcas phillipsi). Twenty-nine protein encoding loci were resolved, average heterozygosity ranged from 3.25-5.36% and between population gene diversity accounted for the major share of the total relative gene diversity (69.34%). Genetic distance values ranged from 0.021 to 0.132 and 0.029 to 0.136, with closest identity between the two wildebeest species (as expected for congeneric species). The results are discussed with specific reference to taxonomic relationships between species within the subfamily where interbreeding is known to have occurred.

Genetic variability in South African blue wildebeest (Connochaetes oaurinus).

1. We use protein gel-electrophoresis to investigate genetic heterogeneity at 33 protein coding loci in a total of 46 blue wildebeest (C. taurinus) kept under different management regimes. 2. Average heterozygosity ranged from 2.14 to 4.3% and within-population differences accounted for 97.2% of total relative gene diversity. 3. Comparatively little divergence was found between animals sampled from populations with very diverse population sizes and management histories, with the largest genetic distance estimated between any two populations being only 0.0021. 4. We discuss our results with particular emphasis on the influence of management history on genetic diversity and divergence in C. taurinus.