Intraspecific Genetic Diversity in the Marine Shrimp Penaeus vannamei: Multiple Polymorphic Elongation Factor-1α Loci Revealed by Intron Sequencing

Intron sequences from the elongation factor-1α (EF1α) gene from the marine shrimp Penaeus vannamei reveal extensive variation even among inbred populations of hatchery-raised shrimp. Among 44 individuals analyzed, we found 13 alleles varying by up to 7.5% sequence differences, and including several allele-diagnostic insertions and deletions. High heterozygosity contrasts with low genetic variation at allozyme loci, but we observed up to four alleles per individual, suggesting that we have identified two separate, polymorphic loci. We partitioned the observed alleles into two groups representing hypothetical duplicated loci. However, the alleles are so similar to one another that a phylogenetic analysis does not cluster them into monophyletic groupings. A possible explanation is that concerted evolution is acting to homogenize genetic variation among these two putative loci.