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Chemical defense
Figure from Les Insectes, Hachette, Paris, 1883
The evolution of geadephagan chemical defense: A phylogenetic - - PowerPoint PPT Presentation
The evolution of geadephagan chemical defense: A phylogenetic - - PowerPoint PPT Presentation
The evolution of geadephagan chemical defense: A phylogenetic understanding of the diversity and stasis of compounds and gland structures in carabid beetles Kipling Will, Aman Gill - University of California, Berkeley Athula Attygalle - Stevens
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Formica sp., Mt. Diablo, CA
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Chemically defended Promecognathus laevissimus drives away Formica sp. ants, Mt. Diablo, CA
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Thomas Eisner
Pherosophus image courtesy of the Institute of Physics
The bombardier beetle. Dramatic carabid beetle chemical defense made famous by Tom Eisner.
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Images courtesy of (1) Thomas Eisner; (2,4) Alex Wild, & (3) Carabidae.Org
Diversity of quinone producers
- 1. Pherosophus sp
- 2. Metrius contractus
- 3. Clivina fossor
- 4. Chlaenius tricolor
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The NSF funded Carabid Q project team
Aman Gill UC Berkeley Wendy Moore
- U. of AZ
Tanya Renner San Diego State
Athula Attygalle Stevens Inst. of Technol. Hoboken
The evolution of Geadephagan chemical defense: Molecular evolution and functional validation of genes essential to quinone production in two bombardier beetle species using RNAi. Dr. Aman Gill The Paussus L. (Carabidae: Paussinae) of Madagascar: An explosive adaptive radiation of myrmecophilous beetles. Dr. James Robertson and
- Dr. Wendy Moore
Molecular phylogeny of the flanged bombardier beetles (Carabidae: Paussinae). Dr. Wendy Moore
Related talks at ICE
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- 1. Genetic basis of chemical production
- 2. Biosynthetic pathways leading to final
products
- 3. Evolutionary transitions of compounds,
pathways, and genes.
- 4. Environmental and selective correlates
Project objectives: Telling the story of chemical defense of carabid beetles
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Talk Outline
- Brief background carabid beetle chemical
defense
- Structure of the gland system
- Summary of knowledge and sampling for
defensive chemicals in carabids
- Phylogenetic distribution of selected chemical
classes
- Implications of a 2-phase system
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Carabidae
Worldwide 37,000 described species. All are thought to be chemically defended
Random images from Google search
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Replete defensive gland reservoirs
Open abdomen, dorsal view of Platynus brunneomarginatus
All Adephagan beetles have a pair of pygidial glands. Gland reservoirs may
- ccupy 20-30% of the
space in the abdomen.
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The system of cells and ducts in P. brunneomarginatus
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Close up of secretory cells from the formic acid producing P. brunneomarginatus
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- 545 species from across the family
- covering 59 of the ~75 tribes
- Approximately 250+ compounds
- 18 classes of compounds
Current understanding of carabid defensive gland products
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Carabidae Chemical Classes [species/tribes]
I: Hydrocarbons [105/33] II: Ketones and non-Aromatic Aldehydes [66/14] III: Aliphatic Alcohols [10/9] IV: Esters [34/18] V: Formic Acid [161/27] VI: Higher Saturated Carboxylic Acids [183/34] VII: Unsaturated Carboxylic Acids [168/26] VIII: Phenols [33/3] IX: Aromatic Aldehydes [102/6] X: Aromatic Alcohols [2/2] XI: Aromatic Esters [13/12] XII: Aromatic Acids [2/2] XIII: Quinones [37/7] XIV: Sulfur Compounds [2/1] XV: Terpenes [6/4] XVI: Aromatic Ethers [1/1] XVII: Nitrogen Heterocyclic [2/2] XVIII: Cyanides [1/1]
Classes in black from Moore (1979), in red newly recognized Nomius pygmaeus Psydrus piceus
Image, Joyce Gross
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Unsaturated Carboxylic Acids Hydrocarbons Higher Saturated Carboxylic Acids
Complementary distribution of Hydrocarbons and Carboxylic Acids
present absent Unk/Amb
Adephaga ML tree from 6 gene analysis, D.R. Maddison, et al. unpubl. BToL data
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Formic Acid Quinone
Correlated distribution
- f Hydrocarbons with
Formic Acid and Quinone
present absent Unk/Amb
Hydrocarbons Adephaga ML tree from 6 gene analysis, D.R. Maddison, et al. unpubl. BToL data
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Agra sp., Carabidae Maquipucuna reserve, Pichincha, Ecuador. Image by Alex Wild
- A huge diversity of “ground
beetles” are arboreal.
- Arboreal habitat exposes
them to predation.
- Most arboreal species
produce formic acid & hydrocarbons.
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One gland reservoir per gland the produce the same compounds Two phases occur together (aqueous/hydrophobic) Formic acid/Hydrocarbons Beetles live in a three dimensional habitat with lots of potential predators
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(Hydrocarbons) (Formic Acid) (Hydrocarbons Formic Acid)
The 2-phases are not miscible, but must be sprayed together
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Anterior Dorsal Image of Platynus angustatus courtesy Igor Sokolov, LSU
(Formic Acid) (Hydrocarbons)
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If the lipid phase floated to the top a climbing beetle would be disadvantaged Anterior Dorsal
(Formic Acid) (Hydrocarbons)
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Tests suggest that Carabids spray a mix regardless
- f body orientation.
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If the lipid phase floated to the top a climbing beetle would be disadvantaged Anterior Dorsal
(Formic Acid) (Hydrocarbons)
This does not happen!
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Formic Acid Hydrocarbons A dorsal lobe on the reservoir in some taxa and at least one
- ther mechanism in
- ther taxa holds the
lipid phase near the efferent duct. We don’t know how the second case works, yet.
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Conclusions
- 1. Using formic acid with hydrocarbons as a defensive
chemical mix was probably key for carabids to move into the canopy habitat, a factor driving the Harpalinae radiation.
- 2. In addition to these chemicals, there needs to be an
effective storage and delivery system for a 2-phase
- admix. Carabids have evolved the dorsal lobe and at
least one other undetermined mechanism to do this.
- 3. Our telling of the detailed story of chemical defense
- f carabid beetles is just beginning.
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