Population genetic structure of Conophthorus ponderosae Hopkins (Coleoptera: Scolytidae) inferred from mitochondrial DNA haplotypes
Menard, Katrina Louise
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Pine cone beetles (Conophthorus sp.) are serious pests of many forest ecosystems since they burrow into pine cone tissues for egg deposition, causing the death of the seeds. Management of these beetles in natural and commercial stands of pines has been problematic due to lack of understanding about species limits and distribution. This study was conducted to investigate the phylogeography and phylogenetics of the genus. Several species represented by disjunct populations appear to be monophyletic including Conophthorus edulis, C. mexicanus, C. coniperda, and C. conicollens, whereas C. ponderosae is polyphyletic with many distinct clades isolated by geography. This study explored whether host use or geography has played a greater role in the diversification of this genus, focusing on the polyphyletic C. ponderosae and the monophyletic C. edulis. In the first study, 751bp of the mtDNA CO1 gene were sequenced to reconstruct a phylogeny of the genus, and the distribution and host use were compared to investigate whether these factors were significantly associated. The second study addressed population structure and possible historical influences on the C. edulis and C. ponderosae populations using a nested clade analysis of the mtDNA haplotypes. Despite potential limitations due to sampling, several conclusions could be drawn. Three separate haplotype networks were found for the C. ponderosae haplotypes, indicating that there have been at least three lineages that have associated with P. ponderosa. Geography was significantly associated with the phylogeny at greater distances (>900km), but host use was not significant. At the species level, association with geography is variable. Population structure for C. ponderosae at the species level is minimal, and suggests that there has not been much time for lineage sorting of the haplotypes based on the nested clade analysis as compared to C. edulis.