Hexapoda Origins: Monophyletic, Paraphyletic or Polyphyletic? Rob King and Matt Kretz
Outline Review Hexapod Origins Response to Hexapod Origins How the same data = different trees Arthropod Origins The Enigmatic Insect
Phylogenetics Seeks to explain relatedness in terms of evolutionary history Darwin s Modern Trees of of Life
Taxonomy Review Monophyletic Paraphyletic Polyphyletic Apomorphies Autapomorphies Synapomorphies Plesiomorphies
Taxonomy Review Kingdom Phylum Subphylum Superclass Class
Taxonomy Review Animalia Phylum Subphylum Superclass Class
Taxonomy Review Animalia Arthropoda Subphylum Superclass Class
Taxonomy Review Animalia Arthropoda Mandibulata Superclass Class
Taxonomy Review Animalia Arthropoda Mandibulata Hexapoda Class
Taxonomy Review Animalia Arthropoda Mandibulata Hexapoda Insecta
Methods of Reconstructing Relationships Paleontology Morphology Developmental Biology Comparative Morphology Molecular Phylogenetics
Hexapod Origins 4 mitochondrial protein sequences: Tricholepidion gertschi (Zygentoma) Gomphiocephalus hodgsoni (Collembolan) Other Arthropods Results: Collembola (springtails) separate evolutionary lineage that adapted independently to life on land polyphyletic
Implications Hexapoda now polyphyletic Collembolans outside of Crustaceans and Insecta clade Supports Pancrustacea (Hexapods + Crustaceans)
Interesting Outcomes What s odd about this tree? Artifacts: Apis mellifera (Honey Bees) Heterodoxus (Dog Louse)
Long Branch Attraction A phenomenon that occurs when rapidly evolving lineages are inferred to be closely related, regardless of true evolutionary relationships How are the results interpreted? Homoplasy seen as Synapomorphy?
Reduced Data Set What s the costs & benefits of a reduced data set? 15 vs. 35 taxa?
Technical Comment on Hexapod Origins Same mitochondrial protein sequences Different tree What s new? * 0.46 0.1 Katharina Loligo Albinaria Lumbricus Platynereis 0.89 Narceus * Thyropygus MYRIAPODA * Lithobius 0.72 0.61 Limulus 0.84 * Ixodes CHELICERATA Rhipicephalus Artemia 0.75 Daphnia ARTHROPODA CRUSTACEA 0.91 1.00 Pagurus * Penaeus Gomphiocephalus * PANCRUSTACEA Tetrodontophora COLLEMBOLA 0.96 HEXAPODA 0.57 Tricholepidion Locusta 0.40 Triatoma Zygentoma Orthoptera Hemiptera Crioceris INSECTA * 0.87 Tribolium 0.70 Coleoptera Apis Hymenoptera * PTERYGOTA Heterodoxus Phthiraptera 0.86 0.68 * Bombyx mandarina Bombyx mori Lepidoptera * Ostrinia furnacalis Ostrinia nubilalis 0.76 Anopheles quadrimaculatus Anopheles gambiae * * * * * * Chrysomya Cochliomyia Diptera Ceratitis Drosophila yakuba Drosophila melanogaster
Technical Comment on Hexapod Origins 25 taxon: reduced data set: 91 / 1.00 Katharina Loligo MOLLUSCA Why is this tree better then then Nardi s 15 taxon tree? 99 / 1.00 95 / 1.00 100 / 1.00 Lumbricus ANNELIDA Platynereis Limulus Chelicerata Narceus Myriapoda Thyropygus Pagurus 100 / 1.00 ARTHROPODA 100 / 1.00 51 / 1.00 45 / 0.92 Penaeus Daphnia Artemia Crustacea PANCRUSTACEA 63 / 1.00 HEXAPODA 100 / 1.00 Tricholepidion Triatoma Gomphiocephalus Tetrodontophora 56 / 0.99 INSECTA 100 / 1.00 Tribolium Crioceris 77 / 0.98 PTERYGOTA 49 / 0.88 54 / 0.76 66 / 0.98 71 / 0.98 77 / 0.99 100 / 1.00 70 / 0.91 Locusta Ostrinia 100 / 1.00 Bombyx Anopheles Drosophila Ceratitis Chrysomya 0.1 100 / 1.00 Cochliomyia
Nardi vs. Delsuc How did Delsuc get a different tree from Nardi using the same data? What are the implications of phylogenetic analysis of amino acids? Empirically deduced matrices from mammalian dominated sequence databases Does not model the variation of rate across sites Bias in nucleotide composition
Variation and Position in Codon Sites RY recoding is simply when a computer program recodes the third codon position for a purine or a pyrimidine depending on the bias. Why the third codon position?
Nardi vs. Delsuc How did Delsuc get a different tree from Nardi using the same data? What are the implications of phylogenetic analysis of amino acids? Empirically deduced matrices from mammalian dominated sequence databases Does not model the variation of rate across sites Bias in nucleotide composition
Bias in Nucleotide Composition Some taxa share a high AT bias Apis (84%) Rhipicephalus (78%) Heterodoxus (79%) Why would there be a high AT nucleotide concentration within the mitochondrial genome?
Arthropod Relationships Revealed Used 41 kilobases of DNA from 62 single copy nuclearprotein coding genes (wow) 75 Arthropods Mandibulata (Myriapoda + Hexapoda + Crustacea) Subphylum Results: Hexapods rest within Mandibulata and are monophyletic Pancrustacea is monophyletic Crustacea is paraphyletic Recover the Entognatha as sister group to Ectognatha
Hexapoda in Mandibulata
Monophyly & Paraphyly Hexapoda = monophyletic Pancrustacea = monophyletic Crustacea = paraphyletic
Entognatha - Ectognatha
The Enigmatic Insect
Strepsiptera strepsi = twisted, ptera = wing twisted winged parasites 10 families with 600 species Endoparasitic in bees, wasps, leafhoppers, silverfish, and cockroaches
Classifying the Enigma
Possibility 1 Neuoptera Megaloptera Raphidoptera Coleoptera Diptera Mecoptera Siphonaptera Trichoptera Lepidoptera Hymenoptera
Possibility 2 Neuoptera Megaloptera Raphidoptera Coleoptera Diptera Mecoptera Siphonaptera Trichoptera Lepidoptera Hymenoptera
Possibility 3 Neoptera Endopterygota Paraneoptera Pscopotera Phthiraptera Thysanoptera Hempitera Neuroptera Megaloptera Raphidioptera Coleoptera Diptera Mecoptera Siphonaptera Trichoptera Lepidoptera Hymenoptera
What the scientists think Whiting et al. 1997
What the scientists think Wiegmann et al. 2009
Possibility1 Possibility2 Possibility3
Characters: Possibility1 SistergrouptoColeoptera SimilarCharacteristics 1.Absenceofthoracicnotopleuralsuture(grooveonsideofprothorax) 2.Modificationofforewingsintoelytra 3.Posteromotorism(hindwingpoweredflight) Possibility2 SistergrouptoDiptera SimilarCharacteristics 1.18SrDNAsupportplacementofhalteresonforewingaspossible homeoticmutation 2.Modificationofforewingsintohalteres Possibility3 SistergrouptoHolometabolous SimilarCharacteristics 1.Exopterygotadevelopment(externalwingbudformation) 2.Possessionoflarvalstomata(lateralocelli)