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In this study, population genetic and demographic parameters were inferred using sequence data from 151 individuals of Anguilla mossambica originating from continental south and south-east Africa and Madagascar. The analyses were based on a 532 bp segment of the mitochondrial cytochrome b gene. The absence of genetic structuring was observed thereby supporting the hypothesis of panmixia for the endemic A. mossambica. The overall nucleotide diversity π = 0.002 and the haplotype diversity reached h = 0.691. Significant negative values from several tests of neutrality and mismatch analysis pointed to fluctuating historical population sizes. Bayesian averaging resulted in higher support for population growth models vs. a constant population-size model. Population decline and subsequent growth most likely predated the last glacial and were probably related to extended periods of extreme drought followed by wetter and more stable hydroclimate between 150 and 75,000 years before present (kBP). According to this scenario the female effective population size has increased since 110 kBP by c. two orders of magnitude to a recent level of about 650,000 (219,317-2,292,000)., (© 2019 The Fisheries Society of the British Isles.)

We examined innate responses to conspecific and heterospecific alarm cues in a small cyprinid minnow, the Eastern Cape redfin Pseudobarbus afer. We found that redfins respond to conspecific skin extract, which contains alarm chemicals, and showed that their preferred response is to hide in refugia. Redfins also respond to skin extract from an allopatric, distantly related minnow species, the chubbyhead barb Enteromius anoplus indicating that neither sympatry nor close phylogenetic relationships are necessary for recognition of heterospecific alarm cues. Although both conspecific and heterospecific alarm cues induced similar responses, the response to heterospecific cues was less intense. This may be explained by a trade-off between selection to maximise threat recognition and selection to avoid the costs of responding to irrelevant cues, or by differences in chemical structures of alarm cues between species. These findings have implications for the conservation of this Endangered fish species and for freshwater fishes throughout Africa., (© 2019 The Fisheries Society of the British Isles.)