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Biodiversity Notes

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

Description
Biodiversity – Oct. 31/12 - Order Lepidoptera – Moths: Lep means scale and ptera means wing, so these are scale-winged insects. - Insects in the Order Lepidoptera undergo complete metamorphosis with the stages egg, larva (caterpillar), pupa, and adult. They have two pairs of membranous wings covered in scales (synapomorphy). There are 200,000 described species worldwide. Most species are commonly called moths. Butterflies are a derived group of day-flying moths (is a monophyletic group). - Lepidopteran phylogeny: Most lepidopterans are moths – all basal groups and some derived groups are moths. Butterflies are a monophyletic derived group of moths. They are day-flying fancy moths with clubbed antennae. The most diversity is in the macrolepidoptera. - Lepidopterans have two pairs of membranous wings covered in scales. They hold their wings in a variety of positions. All four wings are used in flying. A close-up picture of a lepidopteran wing shows the scales. The scales are flattened, plate-like hairs. Under the scales is a membranous wing, similar to a fly wing. The scales come off like dust on one’s finger when a lepidopteran is handled. Colour – The scales are pigmented, or they have a microstructure that reflects incoming light causing physical colour, such as iridescence. The Genus Morpho is abundant in Central and South America. It shows iridescence of its wings (physical colour). Some species have clear patches on their wings, which is a part of crypsis (camouflage), and they would most likely rest on trees with white bark. - Most caterpillars are phytophagous/herbivorous, which means they feed on the leaves of plants (leaf-feeding). A few larvae are serious pests for crops, stored grains, and fabrics. Silk for our silk fabrics comes from the caterpillar of the silk moth. Adults are beautiful and are symbols of the environmental movement. They are highly sought after by collectors. - Lepidopterans have co-evolved with angiosperms (flowering plants): Most caterpillars feed on the leaves of flowering plants. Most caterpillars are specialized feeders, meaning they feed on only one or a few species or genera of flowering plants. Adults are pollinators. Adult mouthparts – most have a long siphoning tube that is coiled at rest, and it is called a proboscis. Proboscis is a modified mouthpart for specialized feeding, such as drinking the nectar of flowers. The proboscis is coiled at resting position. Most adults are important pollinators and some are specialized on certain types of flowers. In the process of eating, they are pollinating. Many caterpillars are exposed-feeders, which means they feed on leaves while exposed on vegetation. Other caterpillars feed on leaves in a concealed position, such as in a leaf roll. It is important for them to be camouflaged/concealed. Caterpillars have a well-developed head, strong chewing mouthparts for munching and crunching leaves, and silks glands in their mouth. All caterpillars spin silk from their silk glands and they spin silk on vegetation as they feed. - Lep/Angiosperm co-evolution: Caterpillars have three pairs of legs on their thoracic segments and five pairs of prolegs, with crochets, on their abdominal segments. Prolegs are an adaptation to holding onto vegetation. Crochets are a synapomorphy of larvae (caterpillars). As they walk along the vegetation, they lay down a silk layer on which they walk. They have crochets (tiny hooks) on their prolegs, which help them to cling to the silk, and therefore to their host plant. The silk and the crochets help them to stay on their host plant. - Lep/Angiosperm co-evolution: Many plants produce toxic secondary metabolites in their leaves. These toxic substances are meant to deter herbivores. Many caterpillars (and other insects) have evolved the ability to not only eat these toxic leaves, but to sequester the chemicals in their body and use them for their own purp
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