Evidence of hybridisation within the genus Chrysoblephus and conserved nuclear sequences of South African sparids (Teleostei: Sparidae)

Abstract

Several hybridisation events have been recorded in marine fish, yet there is little information for southern African species. Here we present evidence for hybridisation within the genus Chrysoblephus (Sparidae), by analysing a fish caught off KwaZulu-Natal, off the east coast of South Africa. We utilise three mitochondrial (16S, COI and Cyt b) and four nuclear markers (1st intron of the S7 ribosomal protein gene, Tmo-4C4, Histone 3 and 18S rRNA) to resolve the hybrid parentage. MtDNA analyses support C. anglicus as the maternal lineage. Analyses of the Tmo-4C4 gene and the first intron of the S7 gene show six and four heterozygous positions for the hybrid fish respectively. The heterozygous positions are shared by C. anglicus and C. puniceus, which suggests C. puniceus to be the paternal lineage, with the hybrid being a first generation cross. Morphologically, the hybrid mostly resembles C. puniceus, with some meristic counts overlapping with other sparid species. Interestingly, only two of the four nuclear markers show variation within the sparids sampled in this study; 1 160 bp of 18S rRNA and Histone 3 were invariable even between the genera Chrysoblephus, Gymnocrotaphus, Petrus and Pachymetopon, suggesting conserved nuclear evolution or a rapid speciation within this group of endemic fishes.

Keywords:

• 1st generation hybrid
• heterozygous
• mitochondrial DNA
• nuclear DNA
• rapid speciation