How did this mutualism evolve? What are the origins? · Scarlet gilia : an example of selection...

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Mutualism

Mutualism: Inter-specific relationship from which both species benefit

Mutualism

Symbiosis: Intimate (generally obligate) inter-specific relationships from which both partners benefit

Mutualism

Pollination by animals (ie birds, bees, moths, butterflies, beetles, ants, mammals)Pollinators receive food rewards (nectar and pollen), plants have pollen moved to

other flowersHow did this mutualism evolve? What are the origins?

1. Antagonistic origin in a predator/prey relationship

How did this mutualism evolve? What are the origins?1. Antagonistic origin in a predator/prey relationship

Early plants were probably

wind pollinated and insects

were predators feeding on

spores, pollen or ovules

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How did this mutualism evolve? What are the origins?1. Antagonistic origin in a predator/prey relationship

Early plants were probably wind pollinatedand insects were predators feeding on

spores, pollen or ovules

By chance, some floral visitors were

less damaging and perhaps evenbeneficial in moving pollen between

plants, thus selecting for traits inplants that would minimize damage

and cost and maximize pollen transfer

How did this mutualism evolve? What are the origins?2. Evolution of plant traits that minimize negative impact of insects

a) protect ovules and pollen

Closed carpel to protect ovules

Defend pollen

with chemical or

physical defenses


a) protect ovules and pollen

Bees are sophisticated pollen

predators

Bilateral symmetry in flowers

minimizes pollen predation by bees

Pollen is an

expensive reward,

but nectar is cheaper


b) minimize cost of rewards

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How did this mutualism evolve? What are the origins?3. Evolution of traits that attract beneficial insect pollinators

Visual attraction

Visual attraction with UV patterns

Olfactory attraction

(nocturnal pollinators)

How did this mutualism evolve? What are the origins?4. Evolution of traits that increase specialization

By restricting access to only the mostefficient pollinators, pollen will more

likely be transferred to a conspecific(same species) rather than wastingpollen on the wrong species

Long corollas require

long tongues


Evolution of syndromes for a subset of pollinators, e.g. humming bird

flowers are red, tubular, easy access for hovering birds, high amounts

of nectar, low concentrations


Evolution of syndromes for a subset of pollinators, e.g. bat-pollinated

flowers are white, open for easy access, high amounts of nectar at night,

lots of pollen to compensate for high nectar costs

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Orchids have very specialized coevolvedrelationships with male orchid bees which visit

flowers to collect chemicals to incorporate intotheir sexual pheromones (perfumes)


Fly pollinated

flowers smell like

rotten flesh, are

often purple or

brown, can heat

up and give no

reward (faking out

the carrion flies)


This orchid smells

and looks like a

female fly, so

male flies visit the

flower, try to

“copulate” with the

flower, and in the

process transfer

pollen (another

example of faking

out the flies

How did this mutualism evolve? What are the origins?5. Animals will be under selection to maximize rewards and avoid defenses

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Scarlet gilia : an example of selection between pollinator and plant

Common in mountain meadows throughout the west.Polymorphism for flower color (white and red)

Red preferred by humming birds, white by hawkmoths

Scarlet gilia : an example of selection between pollinator and plant

Seasonal shift selection for flower color: ref favored early and white favored late

Pe

rce

nta

ge

se

ed

se

t

July August

white

red

Pe

rce

nta

ge

of

tota

l p

olli

na

tors

Pe

rce

nta

ge

of

tota

l p

lan

ts

July August

Fruit dispersal by wind, water, gravity and animals

1. Origin in seed predation

Scatter hoarding by seedpredators (storing seeds for

later consumption), but someseeds escape and germinate

Seed predators/dispersers influence seed

establishment and plant composition

Jaguars Jaguars

Mammals Mammals

Large <==> Small Large <==> Small

Seeds Seeds Seeds Seeds

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Fruit dispersal by animals

2. Seeds are expensive and valuable, so plants evolve mechanisms to

defend the seed (usually with toxins).

3. Plants evolve a cheaper reward to attract dispersers (fleshy fruits).

4. And attractive displays (color).

Acacia seeds with fleshy aril for dispersay by birds and ants


2. Seeds are expensive and valuable, so plants evolve mechanisms to

defend the seed (usually with toxins).

3. Plants evolve a cheaper reward to attract dispersers.

4. And attractive displays (color).

Evolution of edible fruit parts and inedible seeds (offspring) minimizes seeddestruction and maximizes dispersal


Advantages to the animals - food supply

Resplendant Quetzaland wild Avocado

(Lauraceae)


Advantages to the animals - food supply

Some plants haveadaptations for specificdispersers

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Advantages to the plants

1. Reduces competition between seedlings and parent plant



2. Gets seeds deposited with package of nutrients



3. Targeted dispersal to specific specialized sites

mistletoe plant mistletoe seeds stuck to bark



4. Avoid specialized herbivores and

seed predators that are

concentrated on the parent tree

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Distance from parent

Number of seeds

dispersed

Number of seedlings surviving

from Janzen and Connell

Greatest

success ofseedlings

If all seeds landed under the parent plant, there would be no successfulrecruitment of seedlings due to specialized herbivores and seed predators

This will prohibit the establishment of single species stands and increaseforest diversity


Advantages to the plants: an example from wild nutmeg (Virola)

All seeds

killed byweevils

Increased seedsurvival fartherfrom parent

How did this mutualism evolve? What are the origins? · Scarlet gilia : an example of selection...

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