R. Edward DeWalt

A DNA Barcode Library for North American Ephemeroptera: Progress and Prospects

DNA barcoding of aquatic macroinvertebrates holds much promise as a tool for taxonomic research and for providing the reliable identifications needed for water quality assessment programs. A prerequisite for identification using barcodes is a reliable reference library. We gathered 4165 sequences from the barcode region of the mitochondrial cytochrome c oxidase subunit I gene representing 264 nominal and 90 provisional species of mayflies (Insecta: Ephemeroptera) from Canada, Mexico, and the United States. No species shared barcode sequences and all can be identified with barcodes with the possible exception of some Caenis. Minimum interspecific distances ranged from 0.3–24.7% (mean: 12.5%), while the average intraspecific divergence was 1.97%. The latter value was inflated by the presence of very high divergences in some taxa. In fact, nearly 20% of the species included two or three haplotype clusters showing greater than 5.0% sequence divergence and some values are as high as 26.7%. Many of the species with high divergences are polyphyletic and likely represent species complexes. Indeed, many of these polyphyletic species have numerous synonyms and individuals in some barcode clusters show morphological attributes characteristic of the synonymized species. In light of our findings, it is imperative that type or topotype specimens be sequenced to correctly associate barcode clusters with morphological species concepts and to determine the status of currently synonymized species.

Ephemeroptera, Plecoptera, and Trichoptera fauna of Churchill (Manitoba, Canada): insights into biodiversity patterns from DNA barcoding

Abstract The insect orders Ephemeroptera, Plecoptera, and Trichoptera (EPT) are particularly important for freshwater ecological and biomonitoring studies, but difficulties in their identification to species level impede research. DNA barcoding provides a solution to this problem by linking newly collected specimens to a reference library of authoritatively identified specimens. Here, we consider the ways in which patterns of intraspecific and interspecific genetic divergences in the barcode region can provide rapid insights into the taxonomic identity, morphological features, and geographical distributions of species. Our study led to a >5× increase in the EPT fauna, including 68 caddisfly, 37 mayfly, and 7 stonefly species, recorded from Churchill. DNA barcoding also aided detection of rare taxa, allowed identification of otherwise unidentifiable life stages, revealed several potentially new species of caddisflies and mayflies, and suggested the presence of cryptic species. The new insights into this fauna and the strong congruence between morphological and molecular characters affirm the utility of DNA barcoding for rapid characterization of the diversity of EPT faunas. We also explore the phenology and habitat preferences of Churchills trichopterans and demonstrate that comprehensive sampling is important for documenting biodiversity through DNA barcoding.

Accelerated construction of a regional DNA-barcode reference library: caddisflies (Trichoptera) in the Great Smoky Mountains National Park

Abstract Deoxyribonucleic acid (DNA) barcoding is an effective tool for species identification and life-stage association in a wide range of animal taxa. We developed a strategy for rapid construction of a regional DNA-barcode reference library and used the caddisflies (Trichoptera) of the Great Smoky Mountains National Park (GSMNP) as a model. Nearly 1000 cytochrome c oxidase subunit I (COI) sequences, representing 209 caddisfly species previously recorded from GSMNP, were obtained from the global Trichoptera Barcode of Life campaign. Most of these sequences were collected from outside the GSMNP area. Another 645 COI sequences, representing 80 species, were obtained from specimens collected in a 3-d bioblitz (short-term, intense sampling program) in GSMNP. The joint collections provided barcode coverage for 212 species, 91% of the GSMNP fauna. Inclusion of samples from other localities greatly expedited construction of the regional DNA-barcode reference library. This strategy increased intraspecific divergence and decreased average distances to nearest neighboring species, but the DNA-barcode library was able to differentiate 93% of the GSMNP Trichoptera species examined. Global barcoding projects will aid construction of regional DNA-barcode libraries, but local surveys make crucial contributions to progress by contributing rare or endemic species and full-length barcodes generated from high-quality DNA. DNA taxonomy is not a goal of our present work, but the investigation of COI divergence patterns in caddisflies is providing new insights into broader biodiversity patterns in this group and has directed attention to various issues, ranging from the need to re-evaluate species taxonomy with integrated morphological and molecular evidence to the necessity of an appropriate interpretation of barcode analyses and its implications in understanding species diversity (in contrast to a simple claim for barcoding failure).

Just How Imperiled Are Aquatic Insects? A Case Study of Stoneflies (Plecoptera) in Illinois

Abstract Nearly 5,000 historical and contemporary specimen records of stoneflies (Plecoptera) from Illinois demonstrated that this fauna is highly imperiled, boding poorly for aquatic insect communities in North America and elsewhere. Losses include two extinctions of endemics and 20 extirpations of 77 total species, a rate of loss that is higher than for either mussels or fish in Illinois. Another 19 species (24.7%) were designated as critically imperiled, being known from five or fewer locations. Two families, Perlidae and Perlodidae, experienced the greatest number of losses. Species lost were mostly those with longer life cycles and direct egg hatch. Three historically hyperdiverse regions were identified and losses in all 14 natural divisions were documented. Large river habitats and historically prairie regions have experienced the greatest proportional losses of species. This scenario probably follows for Ephemeroptera, Trichoptera, and Odonata in the Midwest and in other areas with similar glacial and cultural histories.

Diversity and Classification of Insects and Collembola

Publisher Summary This chapter describes classification, anatomy, morphology, physiology, reproduction, life history, phylogeny, evolution, ecology, and taxonomy of orders and families in which one or more life stages are truly aquatic and adapted for survival under or on the water surface. It also briefly mentions another arthropod group, the semiaquatic springtails (class Entognatha, order Collembola). A total of 10 orders of insects contain aquatic species. Five of them (Ephemeroptera, Odonata, Plecoptera, Trichoptera, and Megaloptera) are aquatic orders in which almost all species have aquatic larvae. The remaining five orders (Heteroptera, Coleoptera, Diptera, Lepidoptera, and Neuroptera) are partially aquatic orders in which most species are terrestrial. However, these orders contain species or entire families that have one or more life stages adapted for living in an aquatic environment. Three aquatic orders (Ephemeroptera, Odonata, and Plecoptera) have a hemimetabolous life cycle, which includes three developmental stages: egg, larva, and adult. The other two aquatic orders (Trichoptera and Megaloptera) have a holometabolous life cycle, which includes four developmental stages: egg, larva, pupa, and adult. Four of the five partially aquatic orders (Coleoptera, Diptera, Lepidoptera, and Neuroptera) also have holometabolous life cycles. The fifth order, Heteroptera (Hemiptera), has a paurometabolous life cycle, which includes three developmental stages: egg, larva, and adult.

DNA barcoding: a taxonomic point of view

Abstract A taxonomic perspective of deoxyribonucleic acid (DNA) barcoding is presented here with respect to its use within the freshwater science community. The goals and methods of DNA barcoding and the criticisms leveled at the procedure by the taxonomic community are explained. The major goal of DNA-barcoding efforts is to aid identification of specimens by matching sequences to a sequence library. This goal is achievable, but barcoding efforts must be coupled with a much wider sampling regime and should be done with the full cooperation and collaboration of the taxonomic community. Through collaborative efforts, taxonomists and barcode advocates can build capacity for taxonomy and sequence the vast number of specimens needed to build a truly comprehensive barcode library for use by benthic scientists. Other barcoding goals, such as species diagnosis and biodiversity surveys, are more problematic, but solutions are possible.

Chapter 36 – Order Plecoptera

Plecoptera, or stoneflies, are an ancient insect order. The order name refers to the ability to fold their wings horizontally. Sixteen extant families and nearly 3,500 valid species are currently known. The nymphs of the vast majority of species are aquatic and most feed in two general categories, as shredders of leaves and as predators of other invertebrates. Adults are terrestrial, inhabiting vegetation near the stream or lake from which they emerged. In this chapter we present the morphology of stoneflies and cover aspects of their ecology and behavior. We also discuss sampling, rearing, and preservation of stonefly specimens. The conservation status of stoneflies is also discussed.

Refugia and Postglacial Expansion of Acroneuria frisoni Stark & Brown (Plecoptera:Perlidae) in North America

Abstract: We used mitochondrial cytochrome c oxidase subunit I to infer the demographic history of Acroneuria frisoni Stark & Brown, a widespread eastern North American stonefly. We sequenced 1510 base pairs from 348 individuals from 36 populations, obtained 160 haplotypes, and tested 3 major hypotheses: 1) Wisconsinan and Illinoian glaciations were vicariant events that separated western and eastern populations; 2) the Mississippi River floodplain was a postglacial barrier to dispersal of eastern and western populations; and 3) at least 2 genetically distinct glacial refugia existed, east and west of the Mississippi River. We also investigated other barriers, pathways to dispersal, and the relative importance of refugia to repopulation of northern areas. Species-distribution modeling of its Wisconsinan-glacial-age distribution placed A. frisoni at the far southern end of the current distribution and in other areas further south and west than it is currently known, and separated western and eastern populations. Eastern and western populations accounted for 70% of the variation in the data set (analysis of molecular variance), and the Mississippi River was a major barrier to gene flow (Bayesian phylogenetic analysis). We identified a western, Ozark Mountains clade (OZK), a Midwest clade (MDW) in central and western Tennessee, and an Appalachian Mountains clade (APP) in Tennessee and Pennsylvania. Members of the MDW clade recolonized once-glaciated and glacially influenced areas north of the Ohio River. Members of the APP clade appear to be confined to the Tennessee River valley and the Ridge and Valley province of the Appalachian Mountains. The Mississippi River floodplain prevented members of the OZK clade from recolonizing northern areas, except in southern Illinois. Comparison to other species with similar distributions points to refuge use and recolonization similar to that of a megalopteran. Our data will guide reintroduction of A. frisoni into areas of the Midwest from which it has been extirpated.

Modelling of historical stonefly distributions using museum specimens

Stoneflies are imperiled in many regions of the world, but it is often difficult to determine their relative imperilment because of the absence of reliable data. Natural history collections, such as those at the Illinois Natural History Survey (INHS), are sources for such data. We have used Random Forests models of the historical distributions of Illinois stoneflies to better understand their natural range. We have also determined which of 58 georeferenced reach, watershed, and climate summary data appear to explain these distributions. Four species were modelled with relative success, suggesting that this approach has merit and that it may be useful for determining the extent of loss and to informing future conservation efforts for Plecoptera in Illinois and surrounding areas. Expanding the range of this analysis to include adjacent states will improve the models and allow us to model rare species for which enough data were not present from Illinois alone.

Perlesta ouabache, a new species of stonefly (Plecoptera: Perlidae) from Indiana, USA

Perlesta ouabache sp. n. is described from Indiana, USA. Perlesta ouabache is distinguished from Nearctic congeners by characteristics of the male paraprocts and eggs.