Coevolution

Coevolution

• Between plants and animals

• A relationship develops between two organisms such that, as they interact with each other over time, each exerts a selection pressure on the other.

• Evolution of each becomes interdependent on that interaction

Coevolution

• “a reciprocally induced evolutionary change over time between two organisms”

Types of relationships...

A B

Neutral 0 0 Neither population

exerts influence on the

other

Mutualism + + Both populations

benefit

Commensalism + 0 One population

benefits, other neutral

Predation + - Predator benefits, prey

does not

Parasitism + - One benefits, host is

affected negatively

Symbiotic relationshipAnts and Acacia tress

Beltian bodiesthorns

nectaries

Ants, caterpillars and acacia

How is it a mutual relationship?

• Ants provide tree services too! Attack herbivores, chew up nearby trees so Acacias aren’t in shadows.

• Tree provides ants- nectar for food, thorns for nest, protein rich Beltian bodies (on leaf tips)

Example #2- Figs and Wasps

synconium

Why is it mutually beneficial?

• Reproductive system of both are tied together.

• Fig benefits from pollination

• Wasps benefit by having a food source for larva

Some primate examples

• Mutualism– Seed dispersal– Pollination

• Predation– Seed predation

• Parasitism– Strangling fig– Polyspecific associations

Plants and Seed Dispersal

•Processing techniques•Dispersal location•Seeds’ Mechanical properties •Shape- Oval seeds•Size- large seeds•Color?

Processing technique

Damage seedMolars used

Undamaged seedIncisor used

brown lemur Sifaka

Dispersal location

• Not under the tree- tree shadow (why?)

• Lemurs have short gut passage rate (less than 30 minutes)

• So there must be some travel away from parent tree.

Seeds fate?

• Not get eaten by secondary predator (rats)

• Buried or in enough feces to germinate

• Seedling survival (limited- 1 out of 4000 seeds)

Seed properties

• Should be resistent to chewing

• Oval shape facilitates swallowing whole

• Color attractive to primate (bright?)

• Large to prevent damage

Pollination

• Morphological adaptations

• Flower size, color, smell

• Number of plants visited

• Flower handling

Morphology

• Muzzle length• Tongue (lemur

picture)

Ruffed lemur

Mouse lemur

Flower morphology

• Large flowers• Tough petals• Produce copious

nectar• Brightly colored• Smell strongly

Traveler’s palm

Visits and handling

• Must visit more than one tree with flowers to transfer pollen

• Need to handle flowers carefully so don’t destroy reproductive parts.

Seed PredationSeed Predation

Fruit and seeds

Eats seeds

protects seeds

Fruits simultaneously

Still eats seeds but not all seeds

Thwarts protection

Parasitism

Strangling fig Polyspecific associations- not trueCoevolved relationships

Summary tableSummary tablePollination Seed-Disp Seed- Pred.

Target Nectar Fruit, Seeds Seeds

Cues smell, color size, color,smell

size, color,smell

Adv. to plant

pollentransfer

Move seedsaway

None

Adv. to primate

Food Foodalthoughseeds notuseful(heavy)

Food

Are these really examples of Coevolution?

??

Seed Dispersal: Not a tight relationship

• Seeds fate once on the ground?

• Seedling survival?• Not dependent on

one organism for dispersal- secondary dispersers

Dung beetle

Agouti

Pollination: not a tight relationship

• Flowers can rely on many different pollinators (insects, bats, birds, mammals)

• BUT- Madagascar- limited pollinators (few bats, birds)

Once upon a time...

• In general, a hard relationship to document- a bit of “story” telling

• Evolutionary Story Telling- the Angiosperm hypothesis (Handout in coursepack)