Mitochondrial DNA sequence variation among populations and host races of Lambdina fiscellaria (Gn.) (Lepidoptera: Geometridae)

Abstract

The hemlock looper, Lambdina fiscellaria (Gn.), is a recurring major forest pest that is widely distributed in North America. Three subspecies (L. f. fiscellaria, L. f. lugubrosa (Hulst) and L. f. somniaria (Hulst)) have been recognized based on larval host or adult pheromone differences, but no consistent morphological differences have been reported. To clarify their taxonomic status, we surveyed mitochondrial DNA (mtDNA) sequence and restriction site variation in two protein coding genes, cytochrome oxidase I and II (COI and COII), in populations across the range of L. fiscellaria. In addition to variation in COI and COII, we found an intergenic spacer region of 20-23 bp located between the tRNA tyrosine gene and the start of COI. Of the 141 specimens of L. fiscellaria assayed, 137 were grouped into two distinct mtDNA lineages, one of which was disproportionately associated with eastern populations and one with western populations. However, single specimens and two populations in eastern Canada had mtDNA resembling that of western populations. Three divergent and rare haplotypes had basal affinities to the two common lineages. The two major lineages of L. fiscellaria were diverged by approximately 2% from each other, as well as from the mtDNA of two outgroup species, L. athasaria (Walker) and L. pellucidaria(G. & R.). The two outgroup species had essentially the same mtDNA and may be conspecific. We interpret the pattern of mtDNA variation within L. fiscellaria as indicating genetic polymorphism within a single species without clear subspecific divisions, rather than evidence of multiple cryptic species.

Evolutionary Assembly of the Milkweed Fauna: Cytochrome Oxidase I and the Age of TetraopesBeetles

“…Because milkweed herbivores, including these beetles, are thus likely to be of young to moderate geological age, I chose to sequence a mitochondrial gene of ostensibly suitable rate in these insects, the locus encoding subunit I of the terminal electron transport enzyme cytochrome oxidase (COI). COI has proved useful in resolving relationships among closely related species and genera of insects and other arthropods (Juan et al, 1995;Sperling et al, 1995Sperling et al, , 1996Sperling et al, , 1999Lunt et al, 1996;Willett et al, 1997;Knowlton and Weigt, 1998;Sandoval et al, 1998;Wells and Sperling, 1999;Caterino and Sperling, 1999;Dobler and Farrell, 1999;Funk, 1999;Harrison and Crespi, 1999;Moran et al, 1999). As the largest and most conservative proteincoding mitochondrial gene in insects (Crozier and Crozier, 1993), COI is potentially well suited to establishing a temporal framework for comparative studies of at least Cenozoic insect faunas, including the insects that attack Tertiary-originating lineages such as milkweeds (Dobler and Farrell, 1999), yuccas (Pellmyr and Leebens-Mack, 1999), and Asteraceace .…”

Contemporary Patterns in a Historical Context: Phylogeographic History of the Pipevine Swallowtail, Battus Philenor (Papilionidae)

“…These results are in contrast to many other phylogeographic studies of Lepidoptera in North America, which have found some genetic structure on a continental scale. Sperling et al (1998) found that mtDNA sequence variation of the hemlock looper, Lambdina fiscellaria (Geometridae), revealed two major lineages that were associated with either eastern or western populations. Similarly, Sperling and Harrison (1994) found geographic structure for mtDNA variation in Papilio zelicaon.…”

Evidence for two genetically and chemically defined host races of Tyria jacobaeae (Arctiidae, Lepidoptera)

“…lineages of insects within a species, which are confined to a single host plant. A number of genetic studies have already shown that some host races can be recognised by distinct mitochondrial haplotypes (Brown et al 1996;Dobler & Farrell 1999;Shufran et al 2000;Sperling et al 1999). This finding indicates that the specific insect-plant relationship must have evolved some time ago because the occurrence of nucleotide substitutions, which characterise the haplotypes, is time dependent.…”

“…But also the alternative has been documented: Boulding (1998) found no evidence for phylogenetically distinct host races in the pea aphid (Acyrthosiphon pisum) indicating a more recent or no consistent host plant selection. It is a matter of debate whether the genetically defined host races should be considered as an indication of genetic polymorphism within a single species without clear subspecific divisions, or as evidence for sibling or multiple cryptic species (Sperling et al 1999;Adams & Funk 1997).…”

“…16S rDNA and ND1 from the alpine population and from PA sequestering lowland populations in order to understand whether these populations might represent genetically differentiated host races. Nucleotide sequences from 16S rDNA, (Aubert et al 1999;Brown et al 1996;Dobler & Farrell 1999;Schneider et al 1999;Shufran et al 2000;Simon et al 1994;Sperling et al 1999;Von NickischRosenegk & Wink 1993).…”