HEXAPODS AND ANGIOSPERMS INSECT EVOLUTION: HEXAPODS AND ANGIOSPERMS

Most modern families radiated (50%+) Most modern orders First winged insects First hexapods

PANGAEA

Cretaceous-Tertiary Extinction

Gnetales - Ancestors of Angiosperms?

Fossil Pollen

Animal Pollination Advantages 1. Precision of transfer 2. Gene flow 3. Reproduction in sparse populations 4. Speciation

Orchid Pollination

Fossil Evidence for Insect Pollination 1. Pollen in guts of fossilized insects 2. Structure of flowers 3. Specialized insect structures

Fossil Evidence for Insect Pollination 1. Pollen in guts of fossilized insects 2. Structure of flowers 3. Specialized insect structures

Fossil Evidence for Insect Pollination 1. Pollen in guts of fossilized insects 2. Structure of flowers 3. Specialized insect structures 4. Ability to hover

Orchids and Hawkmoths (Lepidoptera: Sphingidae)

Orchids and Hawkmoths (Lepidoptera: Sphingidae) Anther cap

Orchids and Hawkmoths (Lepidoptera: Sphingidae) nectary

Red Queen Hypothesis "Well, in our country," said Alice, still panting a little, "you'd generally get to somewhere else — if you run very fast for a long time, as we've been doing." "A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!" For an evolutionary system, continuing change is needed just so that one species can maintain its fitness relative to the species with which it is co-evolving.

Orchid lengthens nectary to draw moth closer to pollen Orchids and Hawkmoths (Lepidoptera: Sphingidae) Moth lengthens proboscis to reach nectar Orchid lengthens nectary to draw moth closer to pollen

Figs and Fig Wasps Pleistodontes froggatti

Figs and Fig Wasps Ficus macrophylla

Figs and Fig Wasps

Figs and Fig Wasps