Preliminary analysis for genetic structure and interspecific relationships within genus Chrysichthys in Lake Nasser, Egypt

Abstract

A key goal for African Union 2063 Agenda is the acceleration of aquatic resources economic growth through promoting blue economy. Being autochthonous to Africa, Family clarotidae catfishes are very popular for fisheries, owing to their, abundance, population resilience, and reasonable economic value. To identify the status of genetic diversity of Chrysichthys species in Lake Nasser,Egypt, i.e. C. auratus and C. rueppelli specimens were collected from different side extensions (Khors or Fjords) of the Lake, that were Ghazal, Garf Hussein, Hamedo, Shenyara, Amada and Toshka. Mitochondrial Cytochrome oxidase subunit I gene (COI) hypervariable 5′ region was sequenced in all samples. The sequences were subjected to several genetic, phylogenetic, and population genetic analyses. Both DNA barcoding and COI-based phylogenies revealed that both C. auratus and C. rueppelli have the same mitochondrial genome sequence. Furthermore, the level of haplotype diversity of Chrysichthys in Lake Nasser was higher than that known for most Nile fishes. All sites showed high haplotype diversities, especially in the Northernmost parts of the Lake, the nearest to the high dam. Samples from all Khors showed signs of recent population expansion, non-significant raggedness, and mismatch curves with either unimodal or skewed unimodal patterns. All Lake Nasser Chrysichthys populations appeared to be completely mixed. The current study provided three key novelties over all previous works. The first was the identical mitochondrial barcode sequences between C. auratus and C. rueppelli. The second was the high genetic diversity within the sampled individuals. The third was the mitochondrial genetic dysconnectivity between North and West African C. auratus. These results should be strongly considered upon providing fisheries statistics about genus Chrysichthys from Lake Nasser and Africa in general. Moreover, more investigation at the level of nuclear barcode identities within genus Chrysichthys can reveal more information about those hypothetically two species, C. auratus and C. rueppelli.