Bark beetles (Scolytinae) are ideal models for the study of herbivore host breadth evolution. These beetle feed on a variety of hosts but they are all categorized as either generalists or specialists. Exceptions to these generalized feeding habits present opportunities to address the evolutionary and ecological factors that influence host breadth. For example, many specialist species are recorded as feeding rarely or occasionally on non-hosts. It remains untested whether or not these observations represent a polyphyletic lineage of individuals. If this hypothesis is rejected then phylogenetic canalization of non-host feeding is supported. This finding would suggest that natural selection pressures of non-host feeding are evolutionarily significant. Recent collections of Ips confusus (LeConte), a pinyon pine tree specialist, on non-host trees offers an opportunity to address the above questions. Ten I. confusus individuals were collected from blue spruce in Greenlee County, AZ. Mitochondrial cytochrome oxidase I (mtDNA COI) DNA sequence variation among these individuals were compared in parsimony and nested clade analyses with a total of 75 pine feeding individuals from populations throughout the species range. These analyses indicate that the phylogenetic patterns are associated with geographic separation and that the beetles collected from spruce did not form a monophyletic group.
Species 1: Coleoptera Scolytidae Ips confusus (pinyon pine engraver)
Keywords: molecular, nested clade analysis
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