THE PERILS OF SINGLE-GENE TREES - MITOCHONDRIAL VERSUS SINGLE-COPY NUCLEAR-DNA VARIATION IN WHITE-EYES (AVES, ZOSTEROPIDAE)

Phylogenetic relationships among animal populations and species common ly have been inferred from patterns of variation observed within a sin gle gene system, most often the mitochondrial genome. Analysis of rest riction site variation in the mitochondrial DNA of two species of whit e-eye (Zosterops lateralis and Z. lutea) in Australia produced a singl e gene tree that does not accurately represent the organismal tree. In contrast, patterns of variation at two anonymous, single-copy nuclear DNA loci revealed a phylogeography consistent with traditional classi fication of the species. Discordance between mitochondrial DNA and sin gle-copy nuclear DNA variation is probably the result of past hybridiz ation between Z. lateralis and Z. lutea, evidence of which has been lo st from the nuclear genome by recombination. This study provides a cle ar empirical demonstration that single gene genealogies cannot be assu med to accurately represent the true phylogenies, and emphasizes the n eed for composite genetic analyses.