Gyrodactylus spp. diversity on African Clarias gariepinus (Burchell, 1822): the result of co-evolutionary strategy?
|Year of publication||2015|
|MU Faculty or unit|
|Description||Sharptooth catfish, Clarias gariepinus (Burchell, 1822), is widely distributed in Africa with the exception of Maghreb, Upper Guinea and Cape provinces of South Africa. This species was introduced into many countries mainly for aquaculture purposes. On the African continent, C. gariepinus is currently known to be a host to seven species of the genus Gyrodactylus von Nordmann, 1832 (Gyrodactylidae). During the period August 2011 – November 2014, several localities were sampled to establish gyrodactylid parasite diversity in the southern African region. In total 31 specimens of C. gariepinus were collected on several spots in South Africa (Flag-Boshielo Dam, Loskop Dam, Sand and Barota River in Limpopo Province; Mooi River and Barberspan Dam, North- West Prov.) and Zimbabwe (Zambezi River and Lake Kariba). The Gyrodactylus prevalence was noted to be 45%. Species identification based on haptoral sclerites morphometry and nuclear rDNA ITS sequences identified the presence of 9 different Gyrodactylus species, of which four are currently known, i.e. G. alekosi Přikrylová, Blažek & Vanhove, 2012; G. gelnari Přikrylová, Blažek & Vanhove, 2012; G. rysavyi Ergens, 1973 and G. transvaalensis Prudhoe & Hussey, 1977. Present finding reveals unexpected Gyrodactylus species diversity and their wide distribution across different regions. Detailed morphological analyses revealed clear differences in the shape and size of taxonomically important structures between the species examined. Phylogenetic analyses based on the ITS rDNA sequences assisted in revealing interspecific relationships. Analysis of 18S rDNA revealed identical sequences for four species with distant geographical origin and which differ substantially in morpho-metrical characters. The observed species richness among one host seems to be an evident signal that co-evolution occurred in this host-parasite system; however the host-switching is regarded as a main evolutionary strategy at gyrodactylid parasites.|