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

A qualitative view of the HIV epidemic in coastal Ecuador

In 2013 approximately 37,000 people were living with HIV in Ecuador (prevalence 0.4%), representing a generalized epidemic where most new infections arise from sexual interactions in the general population. Studies that examine attitudes towards people living with HIV (PLWH), individual risk perception of acquiring HIV amongst Ecuadorians, and the ways in which levels of risk perception may affect risk behaviors are lacking. This qualitative study aimed to fill this gap in the literature by investigating these issues in the rural, coastal community of Manglaralto, Ecuador, which has among the highest incidence of HIV in Ecuador. We conducted interviews with 15 patients at Manglaralto Hospital. Analysis of interview transcripts revealed widespread negative attitudes towards PLWH, prevalent risk behaviors such as multiple sex partners and lack of condom use, and low individual risk-perception of contracting HIV. These findings underscore the need for increased efforts to prevent further growth of the HIV epidemic in Ecuador

Local adaptation with gene flow in a highly dispersive shark

Abstract Adaptive divergence in response to environmental clines are expected to be common in species occupying heterogeneous environments. Despite numerous advances in techniques appropriate for non‐model species, gene–environment association studies in elasmobranchs are still scarce. The bronze whaler or copper shark (Carcharhinus brachyurus) is a large coastal shark with a wide distribution and one of the most exploited elasmobranchs in southern Africa. Here, we assessed the distribution of neutral and adaptive genomic diversity in C. brachyurus across a highly heterogeneous environment in southern Africa based on genome‐wide SNPs obtained through a restriction site‐associated DNA method (3RAD). A combination of differentiation‐based genome‐scan (outflank) and genotype–environment analyses (redundancy analysis, latent factor mixed models) identified a total of 234 differentiation‐based outlier and candidate SNPs associated with bioclimatic variables. Analysis of 26,299 putatively neutral SNPs revealed moderate and evenly distributed levels of genomic diversity across sites from the east coast of South Africa to Angola. Multivariate and clustering analyses demonstrated a high degree of gene flow with no significant population structuring among or within ocean basins. In contrast, the putatively adaptive SNPs demonstrated the presence of two clusters and deep divergence between Angola and all other individuals from Namibia and South Africa. These results provide evidence for adaptive divergence in response to a heterogeneous seascape in a large, mobile shark despite high levels of gene flow. These results are expected to inform management strategies and policy at the national and regional level for conservation of C. brachyurus populations