BIOCHEMICAL DIVERGENCE AND BIOGEOGRAPHY OF ANGLERFISH OF THE GENUS LOPHIUS (LOPHIIFORMES)

We used an allozyme phylogeny (with Lophiomus setigerus as an outgroup ) and the geologic and oceanographic history of the Atlantic Ocean to construct an historical biogeographical hypothesis for the seven speci es of Lophius. Nei's modified genetic distances based on 32 loci range d from 0.418 between L, piscatorius (Europe) and L. litulon (Japan), t o 1.05 between L,. piscatorius and L. vaillanti (West Africa). The top ologies of the phenetic trees were incongruent with the cladistic tree s of polarized character-state changes. The cladistic analyses show th at L. piscatorius and L. litulon are sister taxa, but it is not clear whether L. budegassa (Mediterranean Sea) and L. vomerinus (southern Af rica) are sister taxa or whether the latter taxon lies outside L. pisc atorius, L. litulon and L. budegassa. The branch leading to L. america nus (North America) lies just outside these taxa, and L. vaillanti is the most primitive species of Lophius. The allozyme phylogeny suggests the following scenario of vicariances and dispersals. Ancestral Lophi us arose as a vicariant split with a common ancestor to Lophiomus by t he collision of the African Plate with Eurasia in the Neogene. The rif ting of Africa from South America led to the appearance of Lophius gas trophysus (Brazil) and L. vaillanti. Lophius americanus appeared by a northward range expansion along the:Americas and climatic vicariance o r by dispersal from ancestral South American populations. An ancestral European Lophius arose by range expansion or dispersal across the Nor th Atlantic of an ancestral North American Lophius, and L. budegassa a rose in the Mediterranean Sea following the Messinian Crisis in the Pl iocene. Lophius vomerinus arose through dispersal along West Africa an d appears to be a sister taxon of L. budegassa. Lophius piscatorius an d L. litulon are sister taxa, and L. litulon arose by long-distance di spersal through the Arctic Ocean after the Bering Strait opened. These results suggest that dispersal has been as important as vicariance in driving speciation in Lophius.