Biology Notes 4-18-08 - Biology Notes How did insects...

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Biology Notes April 18, 2008 How did insects evolve? -1,000,000 species -flight connected with diversity Patterns in HOX genes: -genes in each segment -mutation that prevents legs from forming in wrong segments - Crustaceans are most closely related to insects through HOX research -Molecular data: insect and crustacean lineages separated about 450 million years ago, same as first land plants -no vertebrates, some snails and spiders -ancestral hexapods invaded a terrestrial environmental that lack and similar organisms -wings contributed to their success. Wings: -homologous genes control developed of insect wings and crustacean appendages -insect wings may have evolved from a dorsal branch of a crustacean gill-like structure Insects: -external mouthparts -paired antennae with a sensory organ called Johnston’s organ (sense smell) -gills in aquatic evolved into tracheae on land -terrestrial insects have a unique gas exchange system -tracheae: air sacs and tubular channels extend from external openings (spiracles) into tissues 1
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