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Biodiversity Notes

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Department
Biology
Course
Biology 3484A/B
Professor
Nina Zitani
Semester
Fall

Description
Biodiversity – Oct. 24/12 - In incomplete metamorphosis, wings develop externally in nymphs and wing pads are clearly visible. - Type 2 – complete metamorphosis: The stages are egg, larva, pupa, and adult. These stages occur in all insects that undergo complete metamorphosis. There is drastic change in form from egg to adult. The egg becomes a larva and the larva becomes different instars. It then becomes a pupa and then an adult. The wings of larval instars developed internally. Most larvae have basic chewing mouthparts regardless of the mouthpart type in the adult. The larval stage is a feeding stage. The pupal stage usually does not feed and is inactive or quiet. Adults are capable of reproduction and have wings. Sexual reproduction occurs in most groups of insects. Larvae (and nymphs in incomplete metamorphosis) can be called immatures. Larvae and adults often live in different habitats. Larval stages are the feeding stages. Adults often don’t feed, or feed very little (ex. drink nectar from flowers). Their main function is to reproduce. Adults are the winged form of the insect (in both incomplete and complete metamorphosis). An evolutionary advantage is that larvae and adults are not in competition with one another. The adults are pollinators. - In complete metamorphosis, wings develop internally in larvae and no wing pads are visible externally. - Endopterygota: Arthropoda – Hexapoda – Insecta – Pterygota – Neoptera – Endopterygota. Is a monophyletic group of insects that undergo complete metamorphosis (wings develop internally) and there are 11 orders. The synapomorphy for the Endopterygota group is complete metamorphosis. The 11 orders are: Megaloptera (dobsonflies), Rhaphidioptera (snakeflies), Neuroptera (lacewings), Coleoptera (beetles), Strepsiptera (twisted-winged insects), Diptera (flies), Mecoptera (scorpionflies), Siphonaptera (fleas), Trichoptera (caddisflies), Lepidoptera (moths), Hymenoptera (wasps). - The big four insect orders: Coleoptera (beetles), Diptera (flies), Lepidoptera (moths), Hymenoptera (wasps). The big four do not represent a clade (not a monophyletic group). Each order separately is a clade, but together they do not form a clade. They are the most speciose groups, the most abundant, and the most ecologically important of the insects. Each order in the big four is hyperdiverse. There are thousands, maybe millions, of species in the big four order that are unknown, especially in the tropics. - Order Coleoptera – Beetles: Coleo means sheath and ptera means wing, so these are sheath-winged insects. - What is a beetle?: Beetle larvae are commonly grubs and they feed on rotting wood. Adult beetles have a front pair of wings called elytra and a hind pair of wings that are membranous. The front pair of wings, the elytra, are thickened and leathery, or hard and brittle. The hind wings are membranous (membrane-like, thin and transparent with distinct veins). Elytra are generally not used in flying. The hind wings power flight. When the beetle is at rest, the elytra lay overtop of the folded hind wings and meet in a straight line down the middle of the back. The elytra serve as protection for the hind wings. Elytra are a synapomorphy for this group. Beetle larvae are scavengers, predators, herbivores, decomposers, and parasites. Most (not all) larvae feed concealed in substrate (ex. dead wood, leaf litter, mushrooms, fruits). Many also pupate concealed in substrate. This results in conservation implications – Deadwood is a habitat for beetles, so we must keep deadwood around because beetles are a food source for many birds and other animals. Many adult beetles are day-active (diurnal), but most are nocturnal. There are 300,000 described species of beetles, and thousands of species are still unknown and undescribed. Plants also have 300,000 described species. There are larger families with 30,000–40,000 described species. The smallest species is less than 1mm and the largest tropical species is up to 12.5cm. Beetles are found in most habitats, except marine. - Pronunciation of insect family names: All end in idae, which is pronounced i-dee. Ex. Carabidae
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