Unformatted text preview: Unit Two - Insect Evolution
By the end of the unit you should be able to: Describe the four successive stages of insect evolution
Define ametabolous, hemimetabolous and holometabolous, and the similar terms
regarding wing development
Describe the two theories of insect wing evolution and why it is difficult to explain
how insects evolved their wings. Introduction
Differentiate between ametabolous, hemimetabolous, and holometabolous.
Type of metamorphosis
holometabolous Definition Insects that do this lacking metamorphosis, no change in
body form development to adult
immature stages lack genitelia
body form gradually changes at each
wing buds grow at each molt
body form abruptly changes at pupal
molt Evolutionary Stages
What does "apterygote" mean? without wings Describe this stage and which insects represent this group.
insects- archaeognatha, zygentoma Paleopterous
What does "paleopterous" mean? wings What is another term used to describe this stage? Pterygota Describe this stage and which insects represent this group.
ephemeroptera, odonata lepidopter What are some of the advantages wings and flight provide?
disperse greater distances, locate isolated food sources, ﬁnd mates more easily, avoid predators Wing Flexon
What does "neopterous" mean?
new wing, abilty to bend at the base Describe this stage and which insects represent this group.
insects: crickets, roaches,
grasshoppers, thrips, earwigs How was this stage an advantage over the previous stages?
insects with wing ﬂexon could now crawl into crevices or under rocks to hide form predators Complete Metamorphosis
Describe this stage and which insects represent this group.
insects: wasps, bees, ﬂies, beetles, ﬂeas, moths, butterﬂies Why are insects in this group so successful?
holometabolous insects' larval form can be more specialized Wing Evolution/ Adaptation ASSIGNMENT Write a brief essay for your journal (no more than one-page) supporting one hypothesis over the
others. Title your journal entry, "Wing Evolution Project."
View Full Document
- Summer '08
- holometabolous insects, body form, insect wing evolution, Wing Flexon, insects- archaeognatha