Lecture 9 Pollination and Seed Dispersal

Perfect flower

mega and microsporangia in the same flower

Imperfect flower

Either megasporangia or microsporangia

Monoecious

Mega and microsporangia in the same plant

Dioecious

Mega and microsporangia on different plants

Costs of selfing

Inbreeding depression: Reduction in fitness due to the unmasking of deleterious recessive mutations

Genetic mechanisms to prevent selfing

-Self-incompatibility

-Heterostyly (structural self-incompatibility)

Benefits of selfing

Reproductive assurance, pass on advantageous traits, more common in invasive plants

Chasmogamous vs. cleistogamous flowers

Chasmogamous flowers: Open, showy, and fragrant for insect cross-pollination

Cleistogamous flowers: Smaller, green, bud-like flowers that never open; guaranteed reproduction

How is pollination mutualistic?

Food for pollinators, pollination for plant

Bee pollination

-Bilateral or radial symmetry

-Blue, purple, yellow, UV reflective

-Broad tube sometimes with nectar guides

Fly pollination

-Pale flower with musky odor

-Colored and strongly scented like decaying fish

Moth pollination

-Bloom in the evening

-Pale in color

-Rich fragrance

Hummingbird pollination

-Bright colors (often red)

-Tubular with copious nectar

-No fragrance

Many insect pollinators…

codiversified with flowering plants.

Wind pollination

-Inconspicuous, scentless, nectarless

-Large quantities of small, lightweight pollen

-Causes allergies

Fruit

Mature ovary containing seeds

Function of fruit

Protects developing seeds and aids in dispersal

Berry

Single carpel or multiple fused carpels

Aggregate fruit

Multiple pistils and carpels fused or unfused

Multiple fruit

Fused mass of many individual flowers

Examples of abiotic dispersal

Wind, water

Examples of biotic dispersal

Animals

Possible outcomes of plant-pollinator coevolution

Specialization, generalization, pollinator adaptations, floral specialization

E

B