Forces Driving Diversification I

Forces acting on early angiosperms

1. Biotic: other plants - interactions. Animal interactions - Insects and Herbivorous Dinosaurs.

2. Abiotic Conditions.

Animal interactions

Two way selective process known as co-evolution (refers to any situation in which a pair of organisms act as selective agents for each other)

Co-evolution with insects

The fossil records show a distinct correlation between the radiation of plant groups and insect groups.

Insect interactions.

1. Herbivores (predatory interactions)

2. Pollination (symbiotic interaction)

Herbivory

Prevent being eaten- invest and evolve defenses or evolve ways to grow despite being eaten. Morphological, anatomical and chemical deterrents. Oleanane (defense against insect, fungal and bacterial attack. Has been found in fossils of Bennettitales and Gigantopterids).

Pollination

Angiosperms predominantly insect pollinated. Their emergence and divergence may be primarily insect driven. Primary insect pollinating lineages: Coleoptera (beetles). Lepidoptera (butterflies and moths). Diptera (flies). Hymenoptera (bees, wasps and ants).

Increased aperture

Offers selective advantages because it increases the number of prespective germination sites. Thus facilitating contact between at least one aperture and the stigmatic surface.

Occurred at the base of the eudicot clade.

Triporate pollen could represent a key innovation for eudicot success and subsequent radiations.

Beetle pollination

Were plentiful in the early mesozoic (252-66 MYA). Both angiosperms and beetles diversified since Cretaceous. Still assist with pollination of primitive angiosperms

To encourage insect visitors

Flowers produced

1. Edible flower parts

2. Protein rich pollen

3. Nectar

4. Oils and waxes

5. Bright colours

6. Marking and guides

7. Scents and perfumes

8. Pheromones

9. Landing platforms

Pollination syndrome

The sum of all the factors and features that play a part in pollination.