Finding the nearest relatives of nasonia hymenoptera pteromalidae
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Finding the nearest relatives of Nasonia (Hymenoptera: Pteromalidae). Roger Burks University of California, Riverside Department of Entomology. What is Nasonia ?. Gregarious puparial parasitoids of calyptrate flies in bird nests and refuse

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Finding the nearest relatives of Nasonia (Hymenoptera: Pteromalidae)

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Finding the nearest relatives of Nasonia (Hymenoptera: Pteromalidae)

Roger Burks

University of California, Riverside

Department of Entomology


What is Nasonia?

  • Gregarious puparial parasitoids of calyptrate flies in bird nests and refuse

  • Model system, better known than any other species of Chalcidoidea—genome project ongoing

  • Three species, each infected by two unique strains of Wolbachia


The three species of Nasonia

  • Females almost identical (Darling & Werren 1990)

  • Males differ in degree of wing reduction

  • Nasonia vitripennis worldwide, synanthropic

  • N. giraulti in eastern North America, N. longicornis in western North America

    • specialized on flies in bird nests


Wolbachia basic background

  • Bacteria infecting arthropods and filarial nematodes

  • Transmitted vertically from mother to offspring (Binnington & Hoffmann 1989)

  • Cause crossing incompatibility in Nasonia (Breeuwer & Werren 1990)

  • Phylogenetic congruence between bacteria and host usually absent– horizontal transmission?

  • May cause rapid speciation in arthropods (Laven 1959, 1967; Breeuwer & Werren 1990)


How Wolbachia affects Nasonia

  • Cytoplasmic Incompatibility (Breeuwer & Werren 1990)

    • Causes death of offspring of mothers that do not have same Wolbachia strains as the father

  • Incompatible crosses:

    • Uninfected female x infected male

    • Infected female x male infected by at least one different strain

  • Infection rate near 100% in wild Nasonia

    • “Cured” colonies used to study Wolbachia effects in lab


Why Nasonia’srelationships still need studying

  • Nasonia is a model system for evolutionary biology studies, yet…

  • Ancestral states cannot be inferred with only three analyzed species!

  • No agreement in classification of wasps in its family (Pteromalidae)

  • Needed: means to reject some pteromalids as close Nasonia relatives


Pteromalidae is a scary taxon

  • 587 genera in 31 subfamilies

  • Pteromalinae with only 283 genera

  • Parasitoids of various terrestrial arthropods

  • No previous phylogenetic analysis using more than 10 pteromaline genera

  • Previous analyses with either morphology only or 28S ribosomal sequences only


Pteromalinae molecular vs. morphological rates of evolution

  • 283 genera of Pteromalinae, but...

  • 28S D2 sequence divergence equal to that of the genus Aphelinus (Heraty 2004)

  • Rapid morphological evolution or ribosomal constraints?

  • Rapid evolution due to Wolbachia?


Tools for the search

  • Morphology

    • 105 morphological characters (work in progress)

  • 28S D2-D5 ribosomal DNA, Wingless

    • Secondary structure alignment for 28S (Gillespie et al. 2005) to be compared with POY results

  • Analysis with parsimony (PAUP, TNT, POY), maximum likelihood, Mr. Bayes

  • Hypothesis testing with ML using CONSEL


Outgroup selection

  • Based on Heraty lab matrix of Chalcidoidea

    • 28S D2-D5, 18S E17-E35 ribosomal DNA

    • 471 taxa (including outgroups)

    • All families, 84 total subfamilies represented

  • Subfamilies Diparinae, Ormocerinae are legitimate outgroups for Pteromalinae


Combined 28S and Wingless molecular results, Parsimony (PAUP)

black = Pteromalinae

red = other Pteromalids

* = Wolbachia positive

Numbers indicate

bootstrap support

(1000 replicates)

Agrees with simple POY

run in topology

1176 steps in PAUP

rci = 0.209

ri = 0.403


Combined 28S and Wingless molecular results, Mr. Bayes 3.1

black = Pteromalinae

red = other Pteromalids

* = Wolbachia positive

6 parameters, 4 chains, partitioned

by gene region, 1 million

generations

Numbers indicate

posterior probability


Combined 28S and Wingless molecular results, Likelihood

black = Pteromalinae

red = other Pteromalids

* = Wolbachia positive

model: GTR+I+G

program: PAUP


Testing hypotheses not present in the optimum maximum likelihood tree (500 total sampled trees for test)

au = approximately unbiased test (Shimodaira 2002)

sh = Shimodaira-Hasegawa test (Shimodaira & Hasegawa 1999)


Problem: Not enough variation to have statistical power

Solution: Add a more rapidly evolving gene

Candidates:

Long-wavelength Rhodopsin—multiple copies?

Pten—contains intron, but short

Cytochrome Oxidase I & II—AT richness


Perspective

  • Trichomalopsis sarcophagae 28S sequence (>1100 base pairs) differs from that of Nasonia vitripennis by only 1 base pair

  • Sampling remains incomplete

    • Nasonia not well-surveyed in Palearctic region

    • Trichomalopsis with 54 species!

Trichomalopsis microptera male


They differ by only one base pair in 28S??

Trichomalopsis sarcophagae

Nasonia vitripennis


Further goals

  • Sequence from more species of Trichomalopsis, other genera near Nasonia (>120 specimens to be sequenced)

  • Finish morphological analysis

  • Wolbachia survey across Pteromalinae, comparing bacteria and wasp phylogenies


Acknowledgments

Heraty lab:

Dave Hawks

Johan Liljeblad

James Munro

Jeremiah George

Jason Mottern

Chrissy Romero

Adena Why

Jutta Burger

Matt Buffington

Funded by: NSF FIBR: 0328363

Advisory committee:

John Heraty

Richard Stouthamer

Bob Luck

Cheryl Hayashi

Jack Werren

Matt Yoder

Doug Yanega

Serguei Triapitsyn

Lara Baldo

James Russell

Genet Tulgetske

Danel Vickerman


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