Intraspecific diversification and mitonuclear discordance in the monogenean parasite Dolicirroplectanum lacustre, co-introduced with the invasive Nile perch

Abstract

Parasites typically speciate faster, and become more species-rich than their hosts. This especially holds in large and long-lived hosts. Most African lates perches (Latidae), some of the largest freshwater fishes, host only a single monogenean flatworm: Dolicirroplectanum lacustre. This parasite has 'failed to diverge', but displays high morphological variability, with two morphotypes identified.

The Nile perch (Lates niloticus) is a notorious invasive species. The introductions of Nile perch from lakes Albert and Turkana into lakes and rivers in the Lake Victoria region led to the impoverishment of the trophic food webs, particularly well documented in Lake Victoria. Along with the introductions of the Nile perch, its parasites were co-introduced.

To investigate the pattern of parasite co-introduction, we studied the intraspecific diversity of <i>D. lacustre</i> from Nile perch in Lake Albert and Lake Victoria by assessing morphological and genetic differentiation. A single morphotype is suggested to be co-introduced in Lake Victoria. Based on our results, we reported reduced genetic and morphological diversity in Lake Victoria, resulting from a founder effect. The diversification in the COI mitochondrial gene portion was directly linked with the morphotypes, while the nuclear gene portions indicated conspecificity. Mitonuclear discordance within the morphotypes of D. lacustre indicates an incomplete reproductive barrier between the morphotypes.