Think About It …

Why would a symbiotic relationship be

beneficial to an organism?

Let’s explore some

symbiotic

relationships …

By: Kristine Ann B. de Jesus

Ecology of

interactions

I. Terms and concepts

A. Symbiosis

B. Mutualism

C. Degree of dependence: Obligate vs. facultative

D. Types of Mutualism

E. What is a Niche

F. Co-Evolution

G. Neutralism

H. Commensalism

I. Ammensalism

Biological interactions are the effects

organisms in a community have on one

another. An organism's interactions with

its environment are fundamental to the

survival of that organism and the

functioning of the ecosystem as a whole

In ecology, it can involve individuals of the same species or individuals of different species. Species may interact once in a generation (pollination) or live completely within another (endosymbiosis).

Effects range from consumption of another individual (predation, herbivory, or cannibalism), to mutual benefit (mutualism).

Interactions need not be direct; individuals may affect each other indirectly through intermediaries such as shared resources or common enemies.

Sym: From the greek/latin meaning “with”

Bio: from the greek/latin meaning “to live” or “living”

Symbiosis: A relationship where two organisms live together where at least one of the organisms benefits from the relationship.

Symbiosis: “sym” = together, “biosis”= living; close physical association (e.g., host and internal symbiont). Could be beneficial or parasitic.

Symbiosis is the close interaction between different species of animals. Interactions vary from one creature living on another to one creature living inside another.

The fundamental mystery of mutualism is why

one species has apparently evolved to help

another…

“for such could not have been produced through

natural selection”

– Charles Darwin

The answer, of course, is that each species “helps the other” only for the sake of

benefits that it itself accrues.

Most mutualisms probably evolved from originally parasitic interactions

Mutualism is an interspecific interaction

between two species that benefits both

members.

Populations of each species grow, survive

and/or reproduce at a higher rate in the

presence of the other species.

Mutualisms are widespread in nature, and

occur among many different types of

organisms.

Mutualistic Symbiosis is a type of mutualism in which individuals interact physically, or even live within the body of the other mutualist. Frequently, the relationship is essential for the survival of at least one member.

Example: Lichens are a fungal-algal symbiosis (that frequently includes a third member, a cyanobacterium.) The mass of fungal hyphaeprovides a protected habitat for the algae, and takes up water and nutrients for the algae. In return, the algae (and cynaobacteria) provide carbohydrates as a source of energy for the fungus.

Bees fly from

flower to flower

gathering nectar,

which they make

into food,

benefiting the

bees. When they

land in a flower, the

bees get some

pollen on their hairy

bodies, and when

they land in the

next flower, some

of the pollen from

the first one rubs

off, pollinating the

plant.

The bee and the flower

Spider crabs live in shallow areas of the ocean floor, and greenish-brown algae lives on the crabs' backs, making the crabs blend in with their environment, and unnoticeable to predators. The algae gets a good place to live, and the crab gets camouflage.

The spider crab and the algae.

A certain kind of bacteria lives in the intestines of humans and many other animals. The human cannot digest all of the food that it eats. The bacteria eat the food that the human cannot digest and partially digest it, allowing the human to finish the job.

The bacteria and the

human

Black-eyed Susan gets pollinated by

Green lacewing.

Both

benefit…lacewing

gets food (nectar)

and Black-eyed

Susan gets

pollinated.

Racoon and Poison Ivy

› The raccoon

eats the berries

of the poison ivy

and disperses

the seeds as it

poops.

› Both benefit.

Mushroom and fly› Fly lands on and

eats mushroom.

Some of the spores

will adhere to the fly.

› When the fly dies,

(of natural causes)

the spores will be on

new ground and will

allow the mushroom

to grow in a new

area.

Obligate: at least one species could not grow and reproduce without the other

-The species involved are in close proximity and interdependent with one another in a way that one cannot survive without the other.

Facultative: Mutualisms are not essential for the survival of either species. Individuals of each species engage in mutualism when the other species is present.

- both organisms do better with their mutualist, but can survive and reproduce without it.

1. Facultative mutualisms: Each species gains a benefit from the

presence of the other, but each

can still survive without the other.

“Generalist” mutualisms.

2. Obligate mutualisms: Each species can only live in the

presence of the other. “Exclusive”

mutualisms

Termites and their Flagellates

Neither organism can survive without

the other

The plant provides food for the ant, as well

as shelter. In return, the ants defend the

plant from other herbivores, or organisms

that eat plants, as well as remove other

plants from the vicinity of their plant so it

can grow better.

Acacia ants

live in acacia

trees.

The tree

provides big

hollow thorns

as a home for

the ants.

The tree also

provides food

for the ants in

yellow

swellings on

the leaves

(red oval).

The ants defend the tree against herbivores, both large and small.

They attack insects and large grazing herbivores.

Resource-resource mutualism-A relationship where one resource is

traded for another.

corals and the symbiotic algae

The algae get

inorganic nutrients

from the corals, and

the corals get sugars

that are by-products

of photosynthesis from

the algae. When a

coral 'bleaches' it is

actually kicking out

the zooxanthellae

that live in it, so all you

see is the coral's

skeleton, which is

white.

Service-resource mutualismThis relationship occurs between two

organisms where one gets a resource,

and the other gets a service.The honeybee gets

pollen from the flower

(the resource), and

the flower gets its

pollen spread to other

areas (the service)

honeybees and flowers

Flowering plants and pollinators. (both facultative and obligate)

Parasitoid wasps and polydna viruses. (obligate)

Ants and aphids. (facultative)

Termites and endosymbiotic protozoa. (obligate)

Humans and domestic animals. (mostly facultative, some obligate)

Lichens (fungus and Algae)

Lichens, little non-descript

patches of stuff you see

growing on rocks and tree

bark. This is a symbiosis,

consisting of a fungus and

an alga. The fungus provides

a protective home for the

algae, and gathers mineral

nutrients from rainwater and

from dissolving the rock

underneath. The alga gathers

energy from the sun.

Lichen is really two organisms: algae and fungus.

The fungus needs food but cannot make it. The

algae makes food but needs some way to keep

moist. The fungus forms a crust around the algae

which holds in moisture. Both organisms benefit.

The otters help

the kelp by

eating the sea

urchins which

endanger it. The

kelp provides

and anchor for

the otters while

they sleep.

Otters and Kelp

The cleaner fish eats parasites and food bits out of the inside of this moray eel. It gets a meal and is protected from predators by the fierce eel.

Each type of Yucca plant

can only be pollinated by a

specific kind of Yucca

moth.

That moth can only live on

that kind of Yucca.

Mutualisms are pervasive

1. Pollination mutualisms

2. Dispersal mutualisms

3. Protection mutualisms

4. Nutrient acquisition mutualisms

Pollination mutualisms

Hawkmoth

•Plants get ovules fertilized

•Animals get pollen or nectar as food

Angraecum arachnites

(Madagascan orchid)

Pollination mutualisms

Pollination mutualisms

Marcgravia evenia has leaves that act

like satellite dishes.

A) Because there are so many different species, they are able to

pollinate a greater variety of flowering plants.

B) Because they have short life cycles, short generation times,

and many offspring.

C) Because they have small brains and therefore cannot learn to

recognize many different plant species.

D) Because they can move quickly from plant to plant and

therefore can remember the last species visited.

•Plant gets its seeds

dispersed

•Animal gets food

Seed dispersal mutualisms

Epomophorous wahlbergi

Whalberg's Epauletted Fruit Bat

Virola surinamensis

(Wild nutmeg)

ramphastos swainsonii

(Toucan)

Seed dispersal mutualisms

Pseudomyrmex ferruginea

Acacia cornigera

(Swollen Thorn Acacia)

•Plants provide ants with nectar

and other resources.

•Ants protect plants from

herbivores.

Protection mutualisms

Protection mutualisms: lycaenid butterflies

Butterfly larvae

produce ‘honeydew’ that

the ants eat.

The ants protect larvae

from predation.

Plebejus acmon

Protection mutualisms: Heliconius butterflies

• Both species are distasteful to

avian predators (Mullerian mimicry)

• Predators learn to avoid color

patterns more rapidly when color

patterns are prevalent

• Mimicry decreases the likelihood

of predation for each species in this

mutualism!

•Strong convergence of color pattern

within populations

Nutrient acquisition mutualisms

Rhizobium nodules

(Bacteria)

•The plant (legumes)

supplies energy to the

bacteria from

photosynthesis

•The bacteria ‘fix’ nitrogen

for the plant (convert

atmospheric N2 gas to

ammonium (NH4+) in the

nodules

•Economically very

important

Niche The limits, for all important environmental features, within which individuals of a species can survive, grow and reproduce.

Ecological nicheThe 'occupation' or 'profession' of an organism or species.

Eg› Herbivore/carnivore/omnivore?

› Where it lives?

› Adaptations?

› Life history?

› Feeding behaviour/times

Co-evolution occurs when two species interact so strongly with one another that they are dominant evolutionary forces on one another.

Examples:

- Obligate, specialist mutualisms

- Specialist predator/prey interactions (the term was first coined in describing the “evolutionary arms race” between plant chemical defenses and insect herbivores that evolve resistance to those defenses).

The flower produces nectar that provides

the perfect nutrition for the bird, and

exists in colors that the bird sees best.

Meanwhile the bird's beak is perfectly

shaped to drink from the flowers. The

flower provides food for the bird, and the

bird, by drinking from several different

flowers spread pollen between flowers.

Not all coevolutionis the result of, or results in symbiosis.

Coevolution can also occur in a predator -prey relationship. Think of it as a sort of arms race, as the predator and prey each evolve new advantages to either pounce, orkeep from being pounced.

garter snake, and the rough skinned

newt

Predator- Prey relationship that has

caused co-evolution. The newt has

evolved an potent toxin in the skin,

while the snake (which eats the newt)

has developed a resistance to this

poison.

Neutralism the most common type of

interspecific interaction. Neither

population affects the other. Any

interactions that do occur are indirect or

incidental.

Example: the tarantulas living in a

desert and the cacti living in a desert

-A type of interspecific interaction, which is the interaction between

species. These interactions may have effects on the species'

populations. In neutralism, interactions are incidental or indirect and

are said to not have an effect on either population. Neutralism

occurs when two populations interact without having an effect on

the evolutionary fitness of each other.

cacti and tarantulas living in

the desert.

Type of Interaction Sign Effects

Mutualism

+/+both species benefit from

interaction

Obligate Mutualism

+/+obligatory; both

populations benefit

Commensalism

+/0one species benefits, one

unaffected

Neutralism

0/0populations do not affect

one another

Amensalism

0/-One species is

disadvantaged/one species

unaffected

Directions: Tell whether the relationship is Mutualism, Commensalism Amensalism or

Neutralism

Barnacles create home sites by attaching themselves to

whales. This relationship neither harms nor benefits the

whales.

Yucca flowers are pollinated by yucca moths. The moths lay

their eggs in the flowers where the larvae hatch and eat some of

the developing seeds. Both species benefit.

Remoras attach themselves to a shark’s body. They then

travel with the shark and feed on the leftover food scraps from

the shark’s meals. The relationship neither harms nor benefits

the shark.

Oxpeckers feed on the ticks found on a rhinoceros. The

oxpeckers get a meal and the rhinoceros is helped by the

removal of the ticks.

The stork uses it saw-like bill to cut up the dead animals it

eats. As a result, the dead animal carcass is accessible to

some bees for food and egg laying. The relationship neither

harms nor benefits the stork.

Hermit crabs live in shells made and then abandoned by

snails. This relationship neither helps nor harms the snails.

Wrasse fish feed on the parasites found on the black sea

bass’s body. The wrasse fish get a meal and the black sea

bass is helped by the removal of the parasites.

A sparrow will build its nest under the nest of an osprey.

The smaller birds get protection because other predators

will not mess with the osprey. The osprey are not helped

nor harmed by the sparrow.

Ostriches and gazelles feed next to each other. They

both watch for predators and alert each other to danger.

Because their visual abilities are different, they can

identify threats that the other animal would not see as

readily.

Honey guide birds alert and direct badgers to bee hives.

The badgers then expose the hives and feed on the honey

first. Next the honey guide birds eat. Both species benefit.

A cuckoo may lay its eggs in a warbler’s nest. The

cuckoo’s young will knock the warbler’s eggs out of a

nest and the warbler will raise the cuckoo’s young.

As bison walk through grass, insects become active and

are seen and eaten by cowbirds. The relationship neither

harms nor benefits the bison.

Orchids grow inside a bromeliad plant. The orchid

obtains water and nutrients from the bromeliad, but does

not help or harm it.