Observations on the distribution of meroplankton during a downwelling event and associated intrusion of the Chesapeake Bay estuarine plume

MA Bostrom
BB Collette
BE Luckhurst
KS Reece
JE Graves

Abstract

Intergeneric hybridization between the epinepheline serranids Cephalopholis fulva and Paranthias furcifer in waters off Bermuda was investigated by using morphological and molecular characters. Putative hybrids, as well as members of each presumed parent species, were analyzed for 44 morphological characters and screened for genetic variation at 16 nuclear allozyme loci, two nuclear WDNA loci, and three mitochondrial (mt)DNA gene regions. Four of 16 allozyme loci, creatine kinase (CK-B*), fumarase (FH*), isocitrate dehydrogenase (ICDH-S*), and lactate dehydrogenase (LDH-B*), were unique in C. fulva and R furcifer. Restriction fragments of two nuclear DNA intron regions, an actin gene intron and the second intron in the S7 ribosomal protein gene, also exhibited consistent differences between the two presumed parent species. Restriction fragments of three mtDNA regions-ND4, ATPase 6, and 12S/16S ribosomal RNA-were analyzed to identify maternal parentage of putative hybrids. Both morphological data and nuclear genetic data were found to be consistent with the hypothesis that the putative hybrids were the result of interbreeding between C. fulva and R furcifer. Mean values of 38 morphological characters were different between presumed parent species, and putative hybrids were intermediate to presumed parent species for 33 of these characters. A principal component analysis of the morphological and meristic data was also consistent with hybridization between C fulva and R furcifer. Thirteen of 15 putative hybrids were heterozygous at all diagnostic nuclear loci, consistent with F, hybrids. Two putative hybrids were identified as post-F(1) hybrids based on homozygosity at one nuclear locus each. Mitochondrial DNA analysis showed that the maternal parent of all putative hybrid individuals was C. fulva. A survey of nuclear and mitochondrial loci of 57 C fulva and 37 R furcifer from Bermuda revealed no evidence of introgression between the parent species mediated by hybridization.