Coevolution of Insects and (Flowering) Plants

Photographs in this presentation © Pearson Education or Fred M. Rhoades unless otherwise listed in notes.

Coevolution

• • • Mutual evolutionary influence between two species Insects and flowering plants are coevolved Which group “led” is in contention

Characteristics of Insects

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Segments fused:

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Head

• •

Compound eyes Mouth parts: sucking, chewing, laping

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Other paired appendages

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Thorax

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3 pairs of legs

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Wings: none, 1 or 2 pairs

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Abdomen

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“Visera” (reproduction, digestion, etc.)

Fig 33.33, part Nature of wings used to define insect orders

Characteristics of Insects, cont.

• • •

Like all arthropods, insects molt Complete metamorphism

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Larva (feeding)

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Pupa (metamorph)

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Adult (reproduction) Incomplete metamorphism

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Immature look like small adults

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Gradual increase in size from molt to molt

Excellent web site on evolution of insect flight (and other insect facts) at the Hooper Virtual Micropaleontological Museum

Insect diversity

• Some 30 Orders

Insect evolution

• • • • • • • Arthropods followed plants onto land Insects evolved on land First insect in Mid Paleozoic (springtail) Insect diversity explosion in Late Paleozoic Plants used for food and shelter Early seed plant pollen a food source?

Further coevolution with plants in Mesozoic and Cenozoic

Plant spores and pollen are wind dispersed

• • Spores: * Bryophytes * Ferns, etc.

Pollen: * Gymnosperms (conifers, etc.) • Exceptions (past and present): * A few, unusual mosses –

Splachnum

* Several cycads * Several Gnetophyta * Most flowering plants (but not all)

Splachnum moss grows on dung and spores are dispersed by flies.

All that is seen here is the end of the sporophytes.

Gymnosperms

• •

Cycads Gnetophytes

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Some are pollinated by beetles

Cycads in Univ. of Georgia Botany Dept. Greenhouse Pollination of Dioon (cycad) by beetles

Flower evolution

• • • • Gymnosperm pollen or ovule predation by beetles Some pollination occurred First flowers * Pistils hold ovules * Numerous, generalized parts * Lots of pollen Later flowers * Fusion of parts * Tubular * Bilateral symmetry * More colors

Benefits to the plants

• • Efficient pollen transfer More outcrossing Salmonberry flowers are hummingbird pollinated

Benefits to the pollinators.

• • • 70% of flowers pollinated by insects 30% of flowers pollinated by wind, bats, birds Benefits * Pollen • rich food source * Nectar • average ~ 40% sugar * No benefit? - Trickery • pseudocopulation Bee

Ophrys

– diagram from Charles Darwin

Important pollinating Insect Orders

• • • • Coleoptera – Beetles Diptera – Flies Hymenoptera – Bees, Wasps & Ants Lepidoptera – Moths & Butterflies

Coleoptera = “sheath-wings”

• • • • Beetles (not Beatles) 250,000+ named species Chewing mouthparts Beetle flowers * Dull, light color * Strong odors: fruity, spicy or fetid * Pollen, nectar, other flower parts Phratora beetle head SEM by Alfred Köpf - Sonoma State University

Magnolia

Amborella

Skunk Cabbage, Lysichticum

• • • • •

Diptera = “two-wings”

Flies 85,000+ named species Most attack animals Lapping, sucking or sawing mouthparts Fly flowers (carrion flies) * Dull, dark colors * Fetid odors (dead meat) * Few pollen or nectar rewards Blowfly SEMs - “tongue” ↑ ← head

Stapelia

– “Carrion Flower” or “Starfish Flower”

Hymenoptera = “membrane-wings”

• • • • • • Bees, Wasps, and Ants 110,000+ named species Chewing & lapping mouthparts Hairy bodies Complex social behavior “Bee” flowers * bilaterally symmetrical * short fused petal tubes * yellows and blues * patterns visible in UV * nectar guides Honey bee head SEM - University of Bath Bumble bee stealing nectar from a Comfrey flower

Collinsia

Viola

• • • •

Lepidoptera = “scaly-wings”

Moths (nocturnal) & Butterflies (diurnal) 150,000+ named species Sucking mouthparts Butterfly & moth flowers * Like bee flowers, but with: * Long fused petal tubes * Butterfly colors: yellow, red * Moth colors: white or pale, fragrant Cabbage Butterfly head SEM - University of Bath

Butterfly on Oregano flowers

Convolvulus

“Morning Glory”

Odonata

• • • Grasshoppers, etc.

Not pollinating insects But eat a lot of plant biomass with chewing mouthpart

There are dangers to being a pollinator Unsuspecting “bee fly” pollinator gets nabbed for visiting marigold