Population Structure and the Colonization Route of One of the Oldest North American Invasive Insects: Stories from the Worn Road of the Hessian Fly, Mayetiola destructor (Say).

An integral part to understanding the biology of an invasive species is determining its origin, particularly in pest species. As one of the oldest known invasive species, the goals of this study were to evaluate the evidence of a westward expansion of Hessian fly into North America, from a potential singular introduction event, and the population genetic structure of current populations. Levels of genetic diversity and population structure in the Hessian fly were compared across North America, Europe, North Africa, Western Asia, and New Zealand. Furthermore, Old World populations were evaluated as possible sources of introduction. We tested diversity and population structure by examining 18 microsatellite loci with coverage across all four Hessian fly chromosomes. Neither genetic diversity nor population genetic structure provided evidence of a westward movement from a single introduction in North America. Introduced populations in North America did not show identity or assignment to any Old World population, likely indicating a multiple introduction scenario with subsequent gene flow between populations. Diversity and selection were assessed on a chromosomal level, with no differences in diversity or selection between chromosomes or between native and introduced populations

The Uniform Soybean Tests: Northern Region 2015

United States Department of Agriculture Agricultural Research Service, West Lafayette, Indiana, Cooperating with State Agricultural Experiment Stations, Northern States

The Uniform Soybean Tests: Northern Region 2016

United States Department of Agriculture Agricultural Research Service, West Lafayette, Indiana, Cooperating with State Agricultural Experiment Stations, Northern States

A BAC-based physical map of the Hessian fly genome anchored to polytene chromosomes

<p>Abstract</p> <p>Background</p> <p>The Hessian fly (<it>Mayetiola destructor</it>) is an important insect pest of wheat. It has tractable genetics, polytene chromosomes, and a small genome (158 Mb). Investigation of the Hessian fly presents excellent opportunities to study plant-insect interactions and the molecular mechanisms underlying genome imprinting and chromosome elimination. A physical map is needed to improve the ability to perform both positional cloning and comparative genomic analyses with the fully sequenced genomes of other dipteran species.</p> <p>Results</p> <p>An FPC-based genome wide physical map of the Hessian fly was constructed and anchored to the insect's polytene chromosomes. Bacterial artificial chromosome (BAC) clones corresponding to 12-fold coverage of the Hessian fly genome were fingerprinted, using high information content fingerprinting (HIFC) methodology, and end-sequenced. Fluorescence <it>in situ </it>hybridization (FISH) co-localized two BAC clones from each of the 196 longest contigs on the polytene chromosomes. An additional 70 contigs were positioned using a single FISH probe. The 266 FISH mapped contigs were evenly distributed and covered 60% of the genome (95,668 kb). The ends of the fingerprinted BACs were then sequenced to develop the capacity to create sequenced tagged site (STS) markers on the BACs in the map. Only 3.64% of the BAC-end sequence was composed of transposable elements, helicases, ribosomal repeats, simple sequence repeats, and sequences of low complexity. A relatively large fraction (14.27%) of the BES was comprised of multi-copy gene sequences. Nearly 1% of the end sequence was composed of simple sequence repeats (SSRs).</p> <p>Conclusion</p> <p>This physical map provides the foundation for high-resolution genetic mapping, map-based cloning, and assembly of complete genome sequencing data. The results indicate that restriction fragment length heterogeneity in BAC libraries used to construct physical maps lower the length and the depth of the contigs, but is not an absolute barrier to the successful application of the technology. This map will serve as a genomic resource for accelerating gene discovery, genome sequencing, and the assembly of BAC sequences. The Hessian fly BAC-clone assembly, and the names and positions of the BAC clones used in the FISH experiments are publically available at <url>http://genome.purdue.edu/WebAGCoL/Hfly/WebFPC/</url>.</p

Bar plots of admixture assignments for the entire data set, spanning North America, Old World, and New Zealand collections, based on Bayesian clustering implemented in Tess, showing K = 13–16.

<p>Each bar represents a single individual with the colors indicating the likelihood assignment of the individual to an inferred genetic cluster. Location abbreviations are the same as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059833#pone-0059833-t001" target="_blank">Table 1</a>.</p

Bar plots of admixture assignments for Old World collections, based on Bayesian clustering implemented in Tess, showing K = 5–7.

<p>Bars and abbreviations are representative as stated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059833#pone-0059833-g001" target="_blank">Figure 1</a>.</p

Deviance Information Criterion (DIC) plots.

<p>Plot of DIC values against K to estimate an inverse “plateau” that is representative of the actual K for each of the three independent Tess runs: (a) the entire data set, (b) North American collections only, and (c) Old World collections only.</p

Bar plots of admixture assignments for North American collections, based on Bayesian clustering implemented in Tess, showing K = 6–9.

<p>Bars and abbreviations are representative as stated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059833#pone-0059833-g001" target="_blank">Figure 1</a>.</p

Motif, cytological location, and null allele frequency for each microsatellite locus.

<p>Motif, cytological location, and null allele frequency for each microsatellite locus.</p

Summary statistics for each collection and population.

<p>Each population is listed along with the collection(s) that make up the population. North American populations are based on Tess analysis at K = 7 (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059833#pone-0059833-g002" target="_blank">Figure 2</a> and text), and includes the identifier code for each population/collection (ID Code), number of individuals (n), observed heterozygosity (H_O), expected heterozygosity (H_E), Nei’s unbiased gene diversity (D), mean number of alleles per locus (N_A), number of effective alleles (N_ea), number of private alleles (N_P), the value <i>M</i>, from a M-ratio test, and inbreeding coefficient (F_IS), *denotes p-values<0.05 and **<0.0001.</p