Sand Dune Speciation: Exploring the Evolutionary History of Trogloderus LeConte

Sand Dune Speciation:Exploring the Evolutionary History of

Trogloderus LeConte

(Coleoptera: Tenebrionidae)M. Andrew Johnston

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

Trogloderus LeConte 1879

Tribe Amphidorini LeConte 1862

• North American distribution• 6 genera, ~ 250 species• Most in Eleodes Eschscholtz

Eleodes armatus LeConte

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

Taxonomic History

Revised by La Rivers, 1946

• Invoked orthogenetic evolution• Hypothesized Trogloderus to be ancient

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?

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

Amphidorini Phylogeny

• All analyses highly congruent

• Eleodes paraphyletic– Trogloderus LeConte

– Lariversius Blaisdell

ML ReconstructionShowing Bootstrap Support

Photo by Kojun Kanda

Lariversius tibialis Blaisdell

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

Trogloderus Diversification

• Trogloderus recovered as monophyletic

• Parent clade supported• Sister relationship not well

supported

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

Trogloderus Diversification

• Molecular phylogeny supports and explains the 7 identified morphotypes

• Pronotal Sculpturing

tube

rcul

ate

reti

cula

teSympatric

5% sequence divergence

Trogloderus Distribution

0.1% within-group,2% between-group sequence divergence

T. “warneri” sp nov

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

Trogloderus Distribution

T. “warneri” sp nov• Gene flow inhibited by geographic barriers– Wasatch Mountains– Colorado River

Trogloderus Distribution

Overlapping ranges,4% sequence divergenceDifferent male genitalia

T. nevadus nevadus La RiversT. vandykei La RiversT. nevadus “aalbui” sp nov

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

Trogloderus DistributionUnplaced Species

• T. costatus LeConte

• T. tuberculatus Blaisdell

Results

• Does current taxonomy capture known diversity?– 5 species, 1 currently undescribed– 2 undescribed subspecies

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

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

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

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