Cryptic Diversity of African Tigerfish (Genus Hydrocynus) Reveals Palaeogeographic Signatures of Linked Neogene Geotectonic Events

Abstract

The geobiotic history of landscapes can exhibit controls by tectonics over biotic evolution. This causal relationship positions ecologically specialized species as biotic indicators to decipher details of landscape evolution. Phylogeographic statistics that reconstruct spatio-temporal details of evolutionary histories of aquatic species, including fishes, can reveal key events of drainage evolution, notably where geochronological resolution is insufficient. Where geochronological resolution is insufficient, phylogeographic statistics that reconstruct spatio-temporal details of evolutionary histories of aquatic species, notably fishes, can reveal key events of drainage evolution. This study evaluates paleo-environmental causes of mitochondrial DNA (mtDNA) based phylogeographic records of tigerfishes, genus Hydrocynus, in order to reconstruct their evolutionary history in relation to landscape evolution across Africa. Strong geographical structuring in a cytochrome b (cyt-b) gene phylogeny confirms the established morphological diversity of Hydrocynus and reveals the existence of five previously unknown lineages, with Hydrocynus tanzaniae sister to a clade comprising three previously unknown lineages (Groups B, C and D) and H. vittatus. The dated phylogeny constrains the principal cladogenic events that have structured Hydrocynus diversity from the late Miocene to the Plio-Pleistocene (ca. 0–16 Ma). Phylogeographic tests reveal that the diversity and distribution of Hydrocynus reflects a complex history of vicariance and dispersals, whereby range expansions in particular species testify to changes to drainage basins. Principal divergence events in Hydrocynus have interfaced closely with evolving drainage systems across tropical Africa. Tigerfish evolution is attributed to dominant control by pulses of geotectonism across the African plate. Phylogenetic relationships and divergence estimates among the ten mtDNA lineages illustrates where and when local tectonic events modified Africa's Neogene drainage. Haplotypes shared amongst extant Hydrocynus populations across northern Africa testify to recent dispersals that were facilitated by late Neogene connections across the Nilo-Sahelian drainage. These events in tigerfish evolution concur broadly with available geological evidence and reveal prominent control by the African Rift System, evident in the formative events archived in phylogeographic records of tigerfish.

Morphometry and DNA barcoding reveal cryptic diversity in the genus Enteromius (Cypriniformes: Cyprinidae) from the Congo basin, Africa

“…Molecular techniques like DNA barcoding have already proven to be powerful for the identification of both marine and freshwater fish taxa Pereira et al 2013), and to detect cryptic species diversity or taxonomic inconsistencies (Goodier et al 2011;Collins & Cruickshank 2012;Decru et al 2016). However, the uncritical use of molecular tools to identify species, especially using only a single molecular locus (mt genome), is unwarranted (DeSalle et al 2011), and traditional morphology has proven its value as a suitable technique to assess the diversity in many taxa.…”

Evolutionary history of Nile perch Lates sp. inferred from mitochondrial DNA variation analyses

“…Construction of spatio-temporal details of the evolutionary histories of fishes can reveal key events of drainage evolution Goodier et al 2011). This is because the biogeography of extant freshwater fishes represents responses to landscape evolution.…”

“…Therefore, the evolutionary history of each aquatic species is characterized by a distinct pattern of genetic variation, which includes persisting relics of drainage evolution (Craw et al 2007). Goodier et al (2011) studied the phylogeography of the African tigerfish of the genus Hydrocynus and found that the diversity and distribution of Hydrocynus reflect a complex history of vicariance and dispersal. Moreover, range expansions in this particular species testify to changes in drainage basins, and the principal divergence events in Hydrocynus have closely interfaced with evolving drainage systems across tropical Africa.…”

Ichthyofauna of the Itimbiri, Aruwimi, and Lindi/Tshopo rivers (Congo basin): Diversity and distribution patterns

“…Recently, a cytochrome b gene study (Goodier et al 2011) suggested possible cryptic diversity in the species, with possibly five separate species in the Congo basin. Although no samples of H. vittatus from the Nile basin were included in their analyses, their results highlight the need of a taxonomic revision and the possibility of detecting additional species in areas outside their study region.…”