Genetic and Morphological Characterization of Freshwater Shrimps (Caridina africana Kingsley, 1882) Reveals the Presence of Alien Shrimps in the Cape Floristic Region, South Africa.

Abstract

Morphological identification and molecular data (mtDNA COI) were used to resolve the taxonomic identity of a non-native freshwater shrimp in the Cape Floristic Region (CFR) of South Africa and to evaluate levels of genetic diversity and differentiation in the species' core natural distribution. The species was morphologically and genetically identified as Caridina africana Kingsley, 1882, whose main natural distribution is in the KwaZulu-Natal (KZN) Province, more than 1200 km from the point of new discovery. Subsequently, sequence data from natural populations occurring in seven rivers throughout KZN showed the presence of nuclear copies of the mtDNA COI gene (NUMTs) in 46 out of 140 individuals. Upon removal of sequences containing NUMTs, levels of genetic diversity were low in the alien population (possibly as a consequence of a bottleneck event), while varying levels of genetic diversity and differentiation were found in natural populations, indicating habitat heterogeneity, fragmentation and restricted gene flow between rivers. Following the present study, the alien shrimp has survived the Western Cape's winter and dispersed into a nearby tributary of the Eerste River System, hence posing an additional potential threat to endangered endemics. Understanding the biology of this alien species will aid detection and eradication procedures.