TAXONOMIC STATUS AND PHYLOGENETIC-RELATIONSHIPS OF SOME SPECIES OF THE GENUS GAMMARUS (CRUSTACEA, AMPHIPODA) DEDUCED FROM MITOCHONDRIAL-DNASEQUENCES

Mitochondrial DNA nucleotide sequence analysis was used to determine t he extent of genetic differentiation among six species of the genus Ga mmarus (Crustacea, Amphipoda) common in France (G. fossarum, G. pulex, G. Lacustris, G. wautieri, G. roeseli, G. marinus). From 23 different populations, 104 specimens were compared to examine their taxonomic s tatus and their phylogenetic relationships. Nucleotide sequences for a 376-base segment of the cytochrome c oxidase subunit I (COI) gene wer e obtained through direct sequencing of amplified DNA. The strong sequ ence variability found at the interspecific level, generally masked by morphological or ecological similarities, is consistent with that obs erved for other crustaceans and supports existing species classificati ons. A high level of genetic variation was observed at the intraspecif ic level, suggesting that the COI gene will be a powerful marker for a mphipod population biology. Based on the mitochondrial DNA results, we propose a phylogenetic hypothesis of the relationships among the six studied species, which is discussed in biogeographic and evolutionary terms. (C) 1997 Academic Press.