Phylogenetics of Parapanteles (Braconidae: Microgastrinae) wasps, an underused tool for their identification, and an exploration of the evolution of their symbiotic viruses

Parks, Kyle Stephen

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Description

Title

Phylogenetics of Parapanteles (Braconidae: Microgastrinae) wasps, an underused tool for their identification, and an exploration of the evolution of their symbiotic viruses

Author(s)

Parks, Kyle Stephen

Issue Date

2018-07-09

Director of Research (if dissertation) or Advisor (if thesis)

Whitfield, James

Doctoral Committee Chair(s)

Whitfield, James

Committee Member(s)

• Robertson, Hugh M.
• Berlocker, Stewart H
• Johnson, Kevin

Department of Study

Entomology

Discipline

Entomology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Braconidae, Microgastrinae, Polydnavirus, Systematics, Wing Interference Patterns

Abstract

Microgastrinae is the most diverse subfamily of Braconidae, one of the largest families of parasitoid wasps. Microgastrines parasitize nearly all families of Lepidoptera, but the majority of species are only known to attack one or two Lepidoptera species. Microgastrinae is diverse and much of this diversity arose during a still poorly-understood ancient rapid radiation, causing many short branches deep in the microgastrine phylogeny that are difficult to reconstruct. Due to these difficulties, many microgastrine genera, especially the more specious genera, may not be monophyletic and their placements within the microgastrine phylogeny are ambiguous. In Chapter 2, I constructed a 5-gene molecular phylogeny to assess the monophyly of the genus Parapanteles Ashmead (Braconidae: Microgastrinae), a medium-sized genus of microgastrine wasps that was first defined over a century ago, lacks a unique synapomorphic character, and its monophyly has not been adequately tested. Parapanteles larvae parasitize large, unconcealed caterpillars (macrolepidoptera) and have been reared from an unusually large diversity of hosts for a relatively small parasitoid genus. I used the extensive existing Cytochrome Oxidase I sequences plus four additional genes (wingless, elongation factor 1-alpha, ribosomal subunit 28s, and NADH dehydrogenase subunit 1) to construct individual gene trees and concatenated Bayesian and maximum-likelihood phylogenies of Parapanteles species and several species from other microgastrine genera. In these phylogenies, a plurality of Parapanteles species were recovered as a monophyletic group within another genus, Dolichogenidea, while the remaining Parapanteles species were highly polyphyletic. In Chapter 3, I describe and assess the usefulness of the wing interference patterns of a monophyletic clade of Parapanteles wasps discovered in Chapter 2 for aiding in species identification. Wing interference patterns (WIPs) are color patterns of insect wings caused by thin film interference. We were able to detect consistent WIP differences between Parapanteles species. In some cases, WIPs can be used to diagnose sibling species that would otherwise require SEM images. The species-specific patterns of WIPs are diagnostically valuable but of uncertain evolutionary significance. In Chapter 4 I used an anchored phylogenomics approach to address intergeneric relationships in Microgastrinae more broadly. Previous molecular phylogenies of this taxon have consistently recovered many short and poorly supported basal internal nodes, supporting the hypothesis that Microgastrinae coevolved with their hosts in an ancient rapid speciation event. The systematics of the 64 currently recognized extant genera are still poorly resolved and the monophyly of many of these genera is questionable. To address these challenges, I selected 89 species, broadly from within and across several microgastrine genera, and Drs. Emily and Alan Lemmon at Florida State University performed anchored hybrid enrichment to generate 370 gene fragment sequences for each. Drs. Emily and Alan Lemmon made a concatenated maximum-likelihood analysis of this dataset with RAxML which resolved nearly all nodes with high bootstrap support. This phylogeny supports several larger genera (Apanteles, Cotesia, Dolihcogenidea, and Glyptapanteles) as mostly monophyletic, although taxa from smaller, rarer genera are recovered within each. It also corroborates previous results that Parapanteles is a polyphyletic genus composed of several subclades of disparate genera, although most are within Dolichogenidea. Microgastrinae wasps have symbiotic viruses, known as polydnaviruses, encoded within their nuclear genomes that females produce and inject, along with eggs, into their host caterpillars. In Chapter 5 I sequenced the genomes of 16 microgastrine species from a monophyletic clade of Parapanteles Ashmead with extensive host-use records, and annotated polydnavirus genes in each genome. I found that probable duplications, pseudogenes, and rearrangements are common, especially in the protein-tyrosine-phosphatase polydnavirus gene family. These results support the model that frequent gene births and deaths are a major factor in polydnavirus genome evolution, and extend our knowledge of polydnaviruses to a major previously unexplored segment of the microgastrine phylogeny.

Graduation Semester

2018-08

Type of Resource

text

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http://hdl.handle.net/2142/101686

Copyright and License Information

Copyright 2018 Kyle Parks

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