Exploring data interaction and nucleotide alignment in a multiple gene analysis of Ips (Coleoptera: Scolytinae)

The possibility of gene tree incongruence in a species-level phylogenetic analysis of the genus Ips (Coleoptera: Scolytidae) was investigated based on mitochondrial 16S rRNA and nuclear Elongation factor-1α sequences, and existing Cytochrome Oxidase I and non-molecular data sets. Separate cladistic analyses of the data partitions resulted in partially discordant most-parsimonious trees but revealed only low conflict of the phylogenetic signal. Interactions among data partitions, which differed in the level of sequence divergence (COI > 16S > EF-1α), base composition, and homoplasy, revealed that much of the branch support only emerges in the simultaneous analysis, in particular for deeper nodes in the tree which are almost entirely supported due to \"hidden support\" (sensu Gatesy et al., 1999). Apparent incongruence between data partitions is in part due to suboptimal alignments and bias of character transformations, but there is little evidence to invoke incongruent phylogenetic h...