Insect Classification & Phylogenetics Non-insect hexapods and lower insects

1. Insect Classification & PhylogeneticsNon-insect hexapods and lower insects Lecture2

2. Basic terms to know • Taxonomy – theory and practice of describing, naming, and classifying organisms • Phylogenetics– study of the evolutionary relationships among organisms • Systematics– science of biological classification (taxonomy + phylogenetics) • Classification – process of establishing, defining and ranking taxa into a hierarchical series of groups

3. Honey bee (Apismellifera, Linneaus 1758) genus species publication year for original description original describer Apini, Apinae, Apidae, Apoidea, Aculeata, Hymenoptera

4. Honey bee (Apismellifera, Linneaus 1758) genus species publication year for original description original describer Phylogeny of Apis Lo et al. (2010) Systematic Entomology

5. Honey bee (Apismellifera, Linneaus 1758) genus species publication year for original description original describer Phylogeny of Apinae Noll (2002) Cladistics

6. Phylogenetics • Apomorphy – derived character • Synapomorphy – shared derived character • Plesiomorphy – ancestral character • Symplesiomorphy – shared ancestral character • Autapomorphy – uniquely derived character • Homology – similar feature as a result of common evolutionary origin • Homoplasy – character that evolved convergently

7. Phylogenetics • Monophyly – a group that includes all descendants of a single common ancestor joined by synapomorphy • Paraphyly – a group descended from a single common ancestor joined by synapomorphy but does not include all descendants • Polyphyly – a group derived from more than one ancestor joined by homoplasy

8. Arthropoda • Most successful animals on the planet • Cuticle made largely of chitin and proteins • Exoskeleton • Segmented body and tagmosis

9. Phylogeny of Metazoa (based on DNA) • Arthropoda belongs to Protostomia (mouth first) • Arthropoda belongs to Ecdysozoa (ecdysis) • Relationships within Arthropoda have been contentious (Dunn et al. 2008 Nature)

10. Classical (and outdated) view on the relationships within Arthropoda Crustacea Hexapoda Chelicerata Myriapoda Atelocerata (Trachea) Mandibulata (Mandibles)

11. New (and increasingly accepted) view on the relationships within Arthropoda Myriapoda Crustacea Hexapoda Chelicerata Pancrustacea (DNA, neurogenesis, eye development) Mandibulata (Mandibles)

12. Phylogeny of Arthropoda (based on DNA) Hexapods are land crustaceans. (Regier et al. 2010 Nature)

13. Phylogeny of Arthropoda (based on genome, morphology) Hexapods are land crustaceans. (Rota-Stabelli et al. 2010 PRS)

14. Some major characteristics of Hexapoda: • Maxillary plate present • 3 body parts (head, thorax, abdomen) • 3 thoracic segments each bearing a pair of legs • Legs composed of 6 segments • 11 maximum abdominal segments • Trachea • Some major characteristics of Insecta: • External mouthparts • Malpighian tubules • Annulated antennae • 2 pretarsal claws articulated with tarsus • Johnston’s organ • Ovipositor • Posterior tentorial arms fused

15. Non-insect hexapods • Class Entognatha: Protura, Collembola, Diplura • Entognathous mouthparts: enclosed in folds of head that form a gnathal pouch

16. Collembola • Springtails • ~6000 species • 4-segmented legs • 6-segmented abdomen with a jumping organ (furcula and retinaculum) • Leaf litter (detritivores) • One of the most abundant animals in the world (~100,000 per cubic meter)

17. Diplura • ~800 species worldwide • No eyes, no tentorium, two prominent cerci (either long and filiform or short and forcep-like), moniliform antennae • Herbivorous or predaceous

18. Protura • ~500 species worldwide • No eyes, no antennae, no tentorium, no cerci • Front legs enlarged, with many sensilla (serve role of antennae) • Anamorphic development – segments added posteriorly during development

19. Some major characteristics of Hexapoda: • Maxillary plate present • 3 body parts (head, thorax, abdomen) • 3 thoracic segments each bearing a pair of legs • Legs composed of 6 segments • 11 maximum abdominal segments • Trachea • Some major characteristics of Insecta: • External mouthparts • Malpighian tubules • Annulated antennae • 2 pretarsal claws articulated with tarsus • Johnston’s organ • Ovipositor • Posterior tentorial arms fused

20. Archaeognatha • Bristletails • ~350 species worldwide • Two extant families: Machilidae and Meinertellidae • Large compound eyes that are in contact medially • Monocondylic mandibles • Abdominal segments bear small appendages moveable by muscles • Under bark, in litter, and in rock crevices, • Feed on algae, lichens, and vegetable debris

21. Zygentoma • Silverfish or firebrat • ~400 species worldwide • Five extant families • Eyes and ocelli present, reduced or absent • Body flattened, long cerci and median filament • Dicondylic mandibles • Sister to Pterygota • Omnivorous