Jerry A. Powell

Synchronized, mass-emergences of a yucca moth, Prodoxus Y-inversus (Lepidoptera: Prodoxidae), after 16 and 17 years in diapause

SummaryIn 1985 and 1986, more than 180 adults of Prodoxus y-inversus Riley eclosed from cocoons of the 1969 generation in Yucca baccata, after prepupal larvae spent 16 and 17 years in diapause, intervals prior to mass emergence that are unmatched by any other insect on record. The emergences, which occurred during 15- to 16-day periods, followed many years of virtually no maturation by other individuals of the colony, and the size of the moths was not diminished by the long wait. Successful delay of development and synchronous emergence by many individuals indicates that whole populations can postpone activities through long periods of conditions that would be adverse for adult activity.

Lepidoptera: Moths, Butterflies

Publisher Summary This chapter deals with the order Lepidoptera that includes moths and butterfly. The Lepidoptera is defined as a monophyletic lineage by a suite of more than 20 derived features, the most obvious of which are the scales and proboscis. The scales are modified, flattened hairs that cover the body and wings, shingle-like, and are the source of the extraordinary variety of color patterns typical of these insects. In all but the most primitive forms, feeding by adults is accomplished by pumping in liquid via a tubular proboscis (haustellum), which usually is elongate and coiled under the head. The sister group of Lepidoptera, the Trichoptera (caddisflies), lack this development of mouthparts and the covering of scales and possess caudal cerci on the abdomen, which are not present in Lepidoptera. A widely accepted phylogenetic hypothesis of relationships among lepidopteran evolutionary lineages is based on morphological characteristics in living forms, primarily of the adults. The problem in such analysis is that we do not know what kinds of species might have preceded and interceded with the primitive extant lineages, each of which is now represented by one or a few relict genera that have divergent larval features not shared with other Lepidoptera. Moreover, the fossil record is of little use in revealing clues to “missing links,” and the preservation usually fails to provide information on critical characteristics, particularly those of the larvae and pupae.

Genome-wide SNPs resolve phylogenetic relationships in the North American spruce budworm (Choristoneura fumiferana) species complex

High throughput sequencing technologies have revolutionized the potential to reconcile incongruence between gene and species trees, and numerous approaches have been developed to take advantage of these advances. Genotyping-by-sequencing is becoming a regular tool for gathering phylogenetic data, yet comprehensive evaluations of phylogenetic methods using these data are sparse. Here we use multiple phylogenetic and population genetic methods for genotyping-by-sequencing data to assess species relationships in a group of forest insect pests, the spruce budworm (Choristoneura fumiferana) species complex. With few exceptions, all methods agree on the same relationships, most notably placing C. pinus as basal to the remainder of the group, rather than C. fumiferana as previously suggested. We found strong support for the monophyly of C. pinus, C. fumiferana, and C. retiniana, but more ambiguous relationships and signatures of introgression in a clade of western lineages, including C. carnana, C. lambertiana, C. occidentalis occidentalis, C. occidentalis biennis, and C. orae. This represents the most taxonomically comprehensive genomic treatment of the spruce budworm species group, which is further supported by the broad agreement among multiple methodologies.

Geographic Proximity Not a Prerequisite for Invasion: Hawaii Not the Source of California Invasion by Light Brown Apple Moth (Epiphyas postvittana)

Background The light brown apple moth (LBAM), Epiphyas postvittana (Walker), is native to Australia but invaded England, New Zealand, and Hawaii more than 100 years ago. In temperate climates, LBAM can be a major agricultural pest. In 2006 LBAM was discovered in California, instigating eradication efforts and quarantine against Hawaiian agriculture, the assumption being that Hawaii was the source of the California infestation. Genetic relationships among populations in Hawaii, California, and New Zealand are crucial to understanding LBAM invasion dynamics across the Pacific. Methodology/Principal Findings We sequenced mitochondrial DNA (mtDNA) from 1293 LBAM individuals from California (695), Hawaii (448), New Zealand (147), and Australia (3) to examine haplotype diversity and structure among introduced populations, and evaluate the null hypothesis that invasive populations are from a single panmictic source. However, invasive populations in California and New Zealand harbor deep genetic diversity, whereas Hawaii shows low level, shallow diversity. Conclusions/Significance LBAM recently has established itself in California, but was in Hawaii and New Zealand for hundreds of generations, yet California and New Zealand show similar levels of genetic diversity relative to Hawaii. Thus, there is no clear relationship between duration of invasion and genetic structure. Demographic statistics suggest rapid expansion occurring in California and past expansions in New Zealand; multiple introductions of diverse, genetically fragmented lineages could contribute to these patterns. Hawaii and California share no haplotypes, therefore, Hawaii is not the source of the California introduction. Paradoxically, Hawaii and California share multiple haplotypes with New Zealand. New Zealand may be the source for the California and Hawaii infestations, but the introductions were independent, and Hawaii was invaded only once. This has significant implications for quarantine, and suggests that probability of invasion is not directly related to geographic distance. Surprisingly, Hawaiian LBAM populations have much lower genetic diversity than California, despite being older.

Genetic evaluation of the evolutionary distinctness of a federally endangered butterfly, Lange’s Metalmark

BackgroundThe Mormon Metalmark (Apodemia mormo) species complex occurs as isolated and phenotypically variable colonies in dryland areas across western North America. Lange’s Metalmark, A. m. langei, one of the 17 subspecies taxonomically recognized in the complex, is federally listed under the U.S. Endangered Species Act of 1973. Metalmark taxa have traditionally been described based on phenotypic and ecological characteristics, and it is unknown how well this nomenclature reflects their genetic and evolutionary distinctiveness. Genetic variation in six microsatellite loci and mitochondrial cytochrome oxidase subunit I sequence was used to assess the population structure of the A. mormo species complex across 69 localities, and to evaluate A. m. langei’s qualifications as an Evolutionarily Significant Unit.ResultsWe discovered substantial genetic divergence within the species complex, especially across the Continental Divide, with population genetic structure corresponding more closely with geographic proximity and local isolation than with taxonomic divisions originally based on wing color and pattern characters. Lange’s Metalmark was as genetically divergent as several other locally isolated populations in California, and even the unique phenotype that warranted subspecific and conservation status is reminiscent of the morphological variation found in some other populations.ConclusionsThis study is the first genetic treatment of the A. mormo complex across western North America and potentially provides a foundation for reassessing the taxonomy of the group. Furthermore, these results illustrate the utility of molecular markers to aid in demarcation of biological units below the species level. From a conservation point of view, Apodemia mormo langei’s diagnostic taxonomic characteristics may, by themselves, not support its evolutionary significance, which has implications for its formal listing as an Endangered Species.

Sex-biased secondary contact obscures ancient speciation onto relictual host trees in central California moths (Syndemis: Tortricidae)

The tortricid moth genus Syndemis has ten described species, with two polyphagous species in Europe and North America respectively. We sequenced five nuclear and four mitochondrial genes for Syndemis samples across both continents and discovered unexpected, extensive diversification restricted to California. DNA evidence supports five new, undescribed, species endemic to California, while the rest of North America and Europe have only one species each. Further, the nuclear genes are less variable and yield contrasting phylogenetic signal compared to mitochondrial DNA for basal relationships between taxa across the genus. Such conflict strongly suggests that male and female moths exhibit radically different levels of philopatry. Our results highlight the importance of sex-specific behavior, and the need for inclusion of multiple genes to fully understand species boundaries, their causes, and the process of speciation. While mtDNA introgression often is invoked to explain incongruous haplotype distributions, our study shows that nuclear DNA selective sweeps, or swamping, can occur while mtDNA and ecology preserve an ancient divergence that is not discernable in nuclear DNA. This study further demonstrates that diversification of herbivores may occur on relictual, declining hostplants, which contrasts with the dominant co-speciation model.