Genetic relationships among Merluccius species

Genetic data from nine species of Merluccius (Euro-African species merlucci us, capensis, paradoxus, polli, senegalensis; American species bilinearis, productus, hubbsi, australis) from 21 informative allozyme loci provided in sights into the phylogenetic and biogeographical relationships within the g enus. The highest values of polymorphic loci and mean heterozygosity occur in the four American species. These values are consistent with large popula tion sizes during speciation (through vicariant processes), and continuing through to the present. Conversely, the lower values of Euro-African specie s are consistent with bottlenecks occurring during or subsequent to speciat ion. Euro-African and American species formed two distinct clades. In the f ormer group, merluccius, capensis and senegalensis clustered together as th e most derived species, with distinct relationships between polli and parad oxus from an earlier divergence. Similarly, productus, australis and hubbsi clustered closely as the most derived American species, clearly diverging from the more ancestral bilinear is. Analyses including comparative data pr eviously published for M. gayi indicated a close pairing to hubbsi. The dat a support a north-west Atlantic origin of the genus with unsampled M, albid us of broad Caribbean distribution proposed as the most primitive extant sp ecies.