AFLPs RESOLVE PHYLOGENY AND REVEAL MITOCHONDRIAL INTROGRESSION WITHIN A SPECIES FLOCK OF AFRICAN ELECTRIC FISH (MORMYROIDEA: TELEOSTEI)

Abstract

Estimating species phylogeny from a single gene tree can be especially problematic for studies of species flocks in which diversification has been rapid. Here we compare a phylogenetic hypothesis derived from cytochrome b (cyt b) sequences with another based on amplified fragment length polymorphisms (AFLP) for 60 specimens of a monophyletic riverine species flock of mormyrid electric fishes collected in Gabon, west-central Africa. We analyze the aligned cyt b sequences by Wagner parsimony and AFLP data generated from 10 primer combinations using neighbor-joining from a Nei-Li distance matrix, Wagner parsimony, and Dollo parsimony. The different analysis methods yield AFLP tree topologies with few conflicting nodes. Recovered basal relationships in the group are similar between cyt b and AFLP analyses, but differ substantially at many of the more derived nodes. More of the clades recovered with the AFLP characters are consistent with the morphological characters used to designate operational taxonomic units in this group. These results support our hypothesis that the mitochondrial gene tree differs from the overall species phylogeny due at least in part to mitochondrial introgession among lineages. Mapping the two forms of electric organ found in this group onto the AFLP tree suggests that posteriorly innervated electrocytes with nonpenetrating stalks have independently evolved from anteriorly innervated, penetrating-stalk electrocytes at least three times.

Genetic drift does not sufficiently explain patterns of electric signal variation among populations of the mormyrid electric fishParamormyrops kingsleyae

“…The ability for fine-scale discrimination is consistent with profound and rapid diversification of temporal features of Paramormyrops EODs (Sullivan et al 2002;Sullivan et al 2004), as well as behavioral studies that indicate Paramormyrops highly prefer species-specific EOD waveforms (Hopkins and Bass 1981;Arnegard et al 2006). …”

“…There are at least two species radiations of African mormyrids, one in the genus Campylomormyrus (Feulner et al 2007;Feulner et al 2008) and a second in the genus Paramormyrops (Sullivan et al 2002;Sullivan et al 2004). There are more than 20 nominal Paramormyrops species, which have rapidly diverged in the geographically restricted drainage basins of West-Central Africa.…”

Adaptive radiation and hybridization in Wallace's Dreamponds: evidence from sailfin silversides in the Malili Lakes of Sulawesi

“…Although these systems have served for decades as natural laboratories for the study of speciation processes, it is only recently that hybridization has been proposed as a major explanatory factor for the generation of diversity (Seehausen 2004). Indeed, recent molecular phylogenetic evidence shows that introgression and hybrid speciation has occurred within species flocks (Barrier et al 1999;Salzburger et al 2002;Shaw 2002;Smith et al 2003;Schliewen & Klee 2004;Sullivan et al 2004;Joyce et al 2005). However, unequivocal evidence for large scale hybridization events that are related to the evolution of megadiversity is still lacking.…”

“…However, the amplified fragment length polymorphism (AFLP) technique (Vos et al 1995) constitutes a powerful tool to investigate phylogenetic relationships within species flocks (Albertson et al 1999;Allender et al 2003;Schliewen & Klee 2004;Sullivan et al 2004) with the advantage to provide numerous unlinked nuclear loci. These can be used to test hypotheses of hybridization by screening for homoplastic effects in phylogenetic trees (Seehausen 2004;see §2d ).…”

Snails in the desert: Species diversification of Theba (Gastropoda: Helicidae) along the Atlantic coast of NW Africa

“…chudeaui (Figure 2a). As the AFLP method allows a genome‐wide investigation of numerous markers, individual effects related to the particular evolutionary history of single loci are more likely to be compensated (Koblmüller et al., 2007; Sullivan, Lavoué, Arnegard, & Hopkins, 2004). We therefore expect that the AFLP NJ tree (Figure 2a) draws a more reliable picture of the evolutionary history of T .…”