sand dune speciation: exploring the evolutionary history of trogloderus leconte
TRANSCRIPT
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Sand Dune Speciation:Exploring the Evolutionary History of
Trogloderus LeConte
(Coleoptera: Tenebrionidae)M. Andrew Johnston
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Trogloderus LeConte 1879
• Erected as a monotypic genus– 1 specimen from SW Idaho
• Flightless• Psammophilic
– Eolian sand formations
• Western U.S. distribution
Trogloderus costatus LeConte
Dumont Dunes, CA
Olancha Dunes, CA
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Trogloderus LeConte 1879
Tribe Amphidorini LeConte 1862
• North American distribution• 6 genera, ~ 250 species• Most in Eleodes Eschscholtz
Eleodes armatus LeConte
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Taxonomic History
Revised by La Rivers, 1946
– 4 species subspecies– 2 more described later
Trogloderus
costatus LeConte tuberculatus Blaisdell nevadus La Rivers vandykei La Rivers
costatus
ssp. ssp. ssp. ssp.
syn. mayhewi Pappsyn. pappi Kulzer
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Taxonomic History
Revised by La Rivers, 1946
• Invoked orthogenetic evolution• Hypothesized Trogloderus to be ancient
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Research Questions
• Does the current taxonomy capture actual diversity?
• When and where did Trogloderus originate?• What are the patterns and processes of
diversification across sand dunes?
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Research Methods
• Morphological analysis– 1,860 Trogloderus specimens– Evaluated morphotypes and their distributions
• Molecular analysis– Phylogenetic reconstruction of Amphidorini
• 77 taxa, 7 gene fragments– 3 nuclear, 4 mitochondrial
• Aligned in MUSCLE• Partitioned by PartitionFinder• Analyzed by RAxML, MrBayes and BEAST
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Amphidorini Phylogeny
• All analyses highly congruent
• Eleodes paraphyletic– Trogloderus LeConte
– Lariversius Blaisdell
ML ReconstructionShowing Bootstrap Support
Photo by Kojun Kanda
Lariversius tibialis Blaisdell
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Amphidorini Phylogeny
• Dune specialization is common– Found in at least 7 lineages– Ancestral state unclear
ML ReconstructionShowing Bootstrap Support
Photo by Kojun Kanda
Lariversius tibialis Blaisdell
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Trogloderus Diversification
• Trogloderus recovered as monophyletic
• Parent clade supported• Sister relationship not well
supported
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Trogloderus Diversification
Close outgroups• Mainly Eleodes (Blapylis)• Dune Specialists• High elevation species
– AZ, CA, Pacific NW– Under-sampled
Photo by Kojun Kanda
Eleodes barbatus Whickham Lariversius tibialis BlaisdellEleodes snowii Blaisdell
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Trogloderus Diversification
• Molecular phylogeny supports and explains the 7 identified morphotypes
• Pronotal Sculpturing
tube
rcul
ate
reti
cula
teSympatric
5% sequence divergence
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Trogloderus Distribution
0.1% within-group,2% between-group sequence divergence
T. “warneri” sp nov
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Trogloderus Distribution
T. “warneri” sp nov
Great Basin Colorado Plateau
Costae tuberculateRugose intervals
Costae and intervals smooth
Transitional population found along Northern bank of Lake Powell
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Trogloderus Distribution
T. “warneri” sp nov• Gene flow inhibited by geographic barriers– Wasatch Mountains– Colorado River
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Trogloderus Distribution
Overlapping ranges,4% sequence divergenceDifferent male genitalia
T. nevadus nevadus La RiversT. vandykei La RiversT. nevadus “aalbui” sp nov
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Trogloderus Distribution
T. nevadus nevadus La RiversT. vandykei La RiversT. nevadus “aalbui” sp nov
Great Basin dune formation• Late pleistocene 1-3 ma• Sand derived from dried
pluvial lakes
Owens Valley• Sand from Owens river• 10-35 ka
Mojave Desert sand dunes• Sand from Mojave river• 10-35 ka
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Trogloderus DistributionUnplaced Species
• T. costatus LeConte
• T. tuberculatus Blaisdell
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Results
• Does current taxonomy capture known diversity?– 5 species, 1 currently undescribed– 2 undescribed subspecies
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Results
• Does current taxonomy capture known diversity?
• When and where did Trogloderus originate?– Likely a young lineage, perhaps with roots in
Pleistocene– Area of origin unclear, perhaps in the Great Basin
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Results
• Does current taxonomy capture known diversity?
• When and where did Trogloderus originate?• What are the patterns and processes of
diversification?– Following recent sand formations, 10,000-35,000
years ago– Mountains and rivers that stop sand, stop gene
flow
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Future Directions
• Finalize taxonomic revision of the genus• Increase taxon and geographic sampling for
phylogenetic analyses• Develop calibrated dating analyses• Compare Trogloderus to other dune specialist
groups
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Acknowledgements
Funding
NSF ARTS award DEB-1258154
Specimens and Expertise
Bill Warner Phoenix, AZRolf Aalbu CASCWarren Steiner USNMLee Herman AMNHKojun Kanda OSU
Research Group
Nico FranzAaron Smith
Sangmi Lee Sal AnzaldoGuanyang Zhang Chris HennyAndrew JansenOmron BlauoRebecca Livingston
Photo CreditsKojun Kanda, Bugguide.netAaron Smith, tenebrioniDBase.orgETOPO1, NOAA