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 species of Lophius. Nei's modified genetic distances based on 32 loci ranged from 0.418 between L, piscatorius (Europe) and L. litulon (Japan), to 1.05 between L,. piscatorius and L. vaillanti (West Africa). The topologies of the phenetic trees were incongruent with the cladistic trees of polarized character-state changes. The cladistic analyses show that L. piscatorius and L. litulon are sister taxa, but it is not clear whether L. budegassa (Mediterranean Sea) and L. vomerinus (southern Africa) are sister taxa or whether the latter taxon lies outside L. piscatorius, L. litulon and L. budegassa. The branch leading to L. americanus (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 Lophius arose as a vicariant split with a common ancestor to Lophiomus by the collision of the African Plate with Eurasia in the Neogene. The rifting of Africa from South America led to the appearance of Lophius gastrophysus (Brazil) and L. vaillanti. Lophius americanus appeared by a northward range expansion along the:Americas and climatic vicariance or by dispersal from ancestral South American populations. An ancestral European Lophius arose by range expansion or dispersal across the North Atlantic of an ancestral North American Lophius, and L. budegassa arose in the Mediterranean Sea following the Messinian Crisis in the Pliocene. Lophius vomerinus arose through dispersal along West Africa and appears to be a sister taxon of L. budegassa. Lophius piscatorius and L. litulon are sister taxa, and L. litulon arose by long-distance dispersal 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.