Species InteractionPrepared by: Jaycris C. Agnes

In a chase between a cat and a

mouse? Which organism run

faster? Is it the cat running for its

lunch or the mouse running for its

life?

Species Interactions influence the respective

populations at two timescales:

1. By influencing the demographic processes of birth

and death, and population dynamics.

2. By differentially influencing the survival and

reproduction of individuals within the population,

these interactions can function as agents of

natural selection.

Species Interaction

Types of Interaction

Type of Interaction

Response

Species A Species B

Neutralism 0 0

Mutualism + +

Commensalism + 0

Competition - -

Amensalism - 0

Predation + -

Parasitism + -

Parasitoidism + -

Competition

• Mutual use of a limited resource bypopulations of two or more species.

• Each individual adversely affect another inthe quest for food (nutrients), living space,mates, or other common needs.

• Abundance of both is greater when alone,than when together.

Competition

• May be:

interspecific, or intraspecific

• Due to:

exploitation, or interference

• Result in:

mutual extinction, exclusion ofone, or coexistence

Competition

• When competition is between individualsof:

---- same species (intraspecific)

---- different species (interspecific)

• When a resource is in short supply thatused by one it is not available to theother (exploitation).

• When an action or substance producedby one is directly harmful to the other(interference).

Categories of Competition

• Resource depletion may result in too many individuals in the

population. Thus, the population crashes.

• Reindeer on Saint Matthews Island died off as the result of depletion of lichens (food).

Reindeer on St Mathews Island

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Year

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Exploitation & Intraspecific Competition

• Territorial behavior has evolved in many species as

a response to intraspecific competition.

• Male red wing blackbirds stake out a territory in

defense of nests and mates.

Interference & Intraspecific Competition

• The older, taller trees create a canopy effectively

absorbing the available light. Thus, the younger,

smaller trees do not have access to that resource

and are less likely to survive.

Exploitation & Interspecific Competition

• An example would be with American Bullfrogs. They

will eat almost anything, including birds, rats and

other frogs.

Interference & Interspecific Competition

1. One wins; other loses =competitive exclusion

2. Neither wins =coexistence

3. Both loses =mutual extinction

Outcomes of Competition

• Strong competition can lead to

competitive exclusion, local elimination ofa competing species

• The competitive exclusion principle states

that two species competing for the same

limiting resources cannot coexist in the

same place. Also known as Gause's law of

competitive exclusion or just Gause's law .

Competitive Exclusion

• The Red Squirrel (Sciurus vulgaris) is native to Britain but itspopulation has declined due to competitive exclusion,

disease and the disappearance of hazel coppices and

mature conifer forests in lowland Britain.

Competitive Exclusion

• The total of a species’ use of biotic and abiotic

resources is called the species’ ecological niche.

• An ecological niche can also be thought of as

an organism’s ecological role.

• Ecologically similar species can coexist in a

community if there are one or more significant

differences in their niches

Coexistence

• The term Niche differentiation (synonymous with

niche segregation, niche separation and niche

partitioning), as it applies to the field of ecology,

refers to the process by which natural selection

drives competing species into different patterns of

resource use or different niches.

• This process allows two species to partition certain

resources so that one species does not out-compete

the other as dictated by the competitive exclusion

principle; thus, coexistence is obtained through the

differentiation of their ecological niches.

Coexistence

• A species’ fundamental niche is the ecological niche in the absence of interactions of other species.

• A species’ realized niche is the portion of the fundamental niche that a species actually exploits as a result of interactions with other species.

• As a result of competition, a species’ fundamental niche may differ from its realized niche

– For example, the presence of one barnacle species limits the realized niche of another species

Coexistence

Coexistence

• The common spiny mouse and the golden spiny mouse

show temporal partitioning of their niches.

• Both species are normally nocturnal (active during the night)

• Where they coexist, the golden spiny mouse becomes

diurnal (active during the day)

Coexistence

Predation

Predation

Predation (+/– interaction) refers to interaction

where one species, the predator, kills and eats

the other, the prey.

Kinds of Predation

• Kinds based on the source of food.

1. Herbivory – consumption of plants and algal

tissue

Feeding Strategy Diet Example

Frugivores Fruit Monkey

Folivores Leaves Koalas

Nectarivores Nectar Humming Bird

Granivores Seeds Parrot

Palynivores Pollen Bees

Mucivores Plant fluids, i.e. sap Aphids

Xylophages Wood Termites

Kinds of Predation

2. Carnivory – consumption of animal tissue

Feeding Strategy Diet Example

Insectivore Insects Anteaters

Haematophage Blood Mosquito, Lice

Molluscivore Mollusc Whale, Walrus

Piscivore Fish Sea Lion

Avivore Bird Caracal

Vermivore Worms Platypus

Kinds of Predation

2. Omnivory – consumption of animal and

plant tissue.

Kinds of Predation

• Kinds based on Function.

1. True Predators

2. Grazing

3. Parasitoid

Kinds of Predation

True Predators

Kinds of Predation

Grazing

Kinds of Predation

Parasitoid

Defense Mechanisms

• Throughout millions of years of evolution,

animals have evolved numerous ways of

defending themselves against predators.

• However, there are some often overlooked but

interesting methods of defense which involve

deception and chemistry.

• These include using toxic chemicals,

camouflage, and mimicry.

• There are two main ways animals can use

chemicals to defend themselves.

• Animals can synthesize toxin using their own metabolic processes, or they can

accumulate toxin from the food they eat.

Chemical Defense

• Animals which synthesize their own toxin are able to convert chemical compounds in their body to a poison.

• There are many amphibians that produce skin toxins. The skin toxins are produced by special poison glands, usually located on the animal's back or throughout the skin.

The poison dart frog has

poison glands scattered

all over its body.

Chemical Defense

Many animals accumulate toxin

from their food rather than

synthesizing it from scratch.

For example, the larvae of

Monarch butterflies accumulate

toxins from the plants they

inhabit. Birds that eat the

Monarchs vomit and learn to

avoid them in the future.

Their bright coloration allows

birds to remember and avoid them.

Chemical Defense

Chemical Defense

You can see this in the bright colors of the Monarch and the poison dart frog.

Photo courtesy of Dr. John Daly

Photo courtesy of T. W. Davies, Cal. Acad. of Sciences.

Chemical Defense

This is called “aposematic coloration”, and is

widely used among the insects and amphibians.

The Cream-spot Tiger is aposematically colored.

Camouflage

Animals that camouflage themselves pretend to be

something they are not. Either their coloration, marking

patterns, or entire body resembles something else in

their environment.

Camouflage

This is an example of cryptic coloration.

Camouflage

This is an example of object resemblance.

Camouflage

In this picture, a four-eyed butterfly fish uses deceptive markings. The

large spot near the tail resembles an eye. When predators attack the

wrong end, the butterfly fish can swim away in the other direction.

Camouflage

Some predators

also depend on

camouflage, but

this time it is in

order to avoid

being seen by

their prey.

Mimicry

In mimicry, an organism (the mimic) closely

resembles another organism (the model) in order to

deceive a third, (the operator). The model and the

mimic are not always closely related, but both

usually live in the same area. This is similar to

camouflage, but in mimicry the model is generally

a similar organism rather than a static part of the

background environment.

Mimicry

There are several types of mimicry. The two

most common types are Batesian mimicry and

Mullerian mimicry.

Mimicry

Batesian mimicry: A harmless species mimics a harmful one.

Mimicry

Mimicry

By contrast, Mullerian mimicry occurs when two(or more) distasteful or poisonous organisms

resemble each other. Both species benefit

because a predator who learns to avoid one

species will most likely avoid the other, too.

The two invertebrates on the left are different speciesof sea slugs, while the one on the right is a marine

flatworm. All three secrete noxious substances and

are unpalatable. Notice their similar aposematiccoloring.

Mimicry

Symbiosis

• Symbiosis is a relationship where two or more

species live in direct and intimate contact

with one another. It includes:

1. Parasitism

2. Mutualism

3. Commensalism

Symbiosis

In parasitism (+/– interaction), one organism, the

parasite, derives nourishment from another

organism, its host, which is harmed in the

process.

Parasitism

1. An obligate parasite is totally dependent onthe host to complete its life cycle, while afacultative parasite is not.

2. Parasites that live on the surface of the host arecalled ectoparasites (e.g. some mites). Thosethat live inside the host are called endoparasites(including all parasitic worms).

a. Endoparasites can exist in one of two forms:intercellular parasites (inhabiting spaces in thehost’s body) or intracellular parasites (inhabiting cells in the host’s body).

Kinds of Parasitism

3. An epiparasite is one that feeds on another

parasite. This relationship is also sometimes referred

to as hyperparasitism, exemplified by a

protozoan (the hyperparasite) living in the

digestive tract of a flea living on a dog.

4. In kleptoparasitism, parasites appropriate food

gathered by the host. An example is the brood

parasitism practiced by cuckoos and cowbirds,

which do not build nests of their own and leave their

eggs in nests of other species.

Kinds of Parasitism

5. A parasitic plant is one that derives someor all of its nutritional requirements from

another living plant. All parasitic plants

have special organs, named haustoria(singular: haustorium), which connect

them to the conductive system of their

host and provide them with the ability to

extract water and nutrient from the hosts.

Kinds of Parasitism

Kinds of Parasitic Plants

Kinds of Parasitism

This parasite, called an

“eye worm” comes from

the bite of a deer fly. This

eye worm can be

crawling under one’s skin

for years unbeknownst to

them unless it reaches

the eye. There, it will feel

odd, and there will be a

visible worm just beneath

the eye surface. Usually

found in India and Africa,

the eye worm can cause

itching, joint pain, and

sometimes can be fatal.

Kinds of Parasitism

This parasitic crustacean is called

the “tongue-eating louse” for

good reason. After entering the

fish through the gills, and

attaching itself to the tongue, it

then starts to extract the fish’s

blood via its front claws. This

continues until the fish has wasted

away due to lack of blood, after

which, this parasite attaches its

body to the muscles of the

tongue. Thankfully, they can’t

attack human’s this way.

However, they do bite.

Kinds of Parasitism

Also known as the “Guinea

worm”, this parasite gets into

the body by drinking water

contaminated with copepods

(water fleas) which are infested

with the larvae of the Guinea

worm. A year or so after

ingesting the contaminated

water, a blister will appear,

usually on the leg or foot. The

blister ruptures 72 hours later,

where an end of the worm will

appear. These parasites are

usually found in Asia and Africa,

and can affect both humans

and animals.

Kinds of Parasitism

The sacculina controls the

reproduction of its host by

partially removing its

“procreative organs” . The

other option is killing the host.

With female crabs, the parasite

tricks it into carrying and

spreading its larvae just as if it

were its own larvae (baby

crabs.) With male crabs, it tricks

them into thinking they are

females and transforms their

bodies to function as that of a

female.

Kinds of Parasitism

Filarial worms are threadlike

parasites that are

transmitted from host to host

usually by black flies and

mosquitoes. These parasites

can cause an edema called

“elephantiasis”, an example

of which is shown in the

picture. They can also cause

skin rashes, urticarial papules,

and arthritis. They can also

affect the eyes, causing

onchocerciasis (river

blindness), which is one of

the main causes of blindness.

This parasite can affect both

humans and animals.

Kinds of Parasitism

Dodder Plant

Although this plant looks

innocent enough, it is a

parasite and lives off other

plants. And, it doesn’t wait

around either. This vine

can sniff out its hosts and

hunt them down. It can

grow at a rapid pace and

spread at an unbelievable

rate, and is very hearty

thanks to tough seeds. It

can destroy crops if not

caught early.

Kinds of Parasitism

Botflies aren't easily

confused with

common houseflies

- they're hairy and

about twice as big.

They lay their eggs

on a mosquito,

which then lands on

a person. Once

hatched, the larvae

invade the skin of

the unlucky host.

Mutualistic symbiosis, or mutualism (+/+

interaction), is an interspecific interaction that

benefits both species.

Mutualism

Mutualistic transversals can be thought of as a form of

"biological barter" in which species trade resources (for

example carbohydrates or inorganic compounds) or

services such as gamete, offspring dispersal, or

protection from predators.

1. Resource- resource Relationships

2. Resource- service Relationships

3. Service- service Relationships

Kinds of Mutualism

Resource-resource interactions, in which one type of

resource is traded for a different resource, are probably

the most common form of mutualism.

Example: Mycorrhizal associations between plant roots

and fungi, with the plant providing carbohydrates to the

fungus in return for primarily phosphate but also

nitrogenous compounds. Other examples include

rhizobia bacteria that fix nitrogen for leguminous plants

(family Fabaceae) in return for energy-containing

carbohydrates.

Resource-resource Relationship

1. Pollination in which nectar or pollen (food resources) aretraded for pollen dispersal (a service) or ant protection of

aphids, where the aphids trade sugar-rich honeydew (a

by-product of their mode of feeding on plant sap) in

return for defense against predators such as ladybugs.

2. Phagophiles feed (resource) on ectoparasites, therebyproviding anti-pest service, as in cleaning symbiosis.

Elacatinus and Gobiosoma, genus of gobies, also feed on

ectoparasites of their clients while cleaning them.

3. Zoochory is an example where animals disperse the seedsof plants. This is similar to pollination in that the plant

produces food resources (for example, fleshy fruit,

overabundance of seeds) for animals that disperse the

seeds (service).

Resource-service Relationship

Service-service Relationship

In commensalism (+/0 interaction), one speciesbenefits and the other is neither harmed norhelped

Commensalism is harder to demonstrate than parasitism and mutualism, for it is easier to show a single instance whereby the host is affected than it is to prove or disprove that possibility.

Commensalism

Like all ecological interactions, commensalisms vary instrength and duration from intimate, long-livedsymbioses to brief, weak interactions throughintermediaries:

Phoresy

Phoresy is one animal attached to another exclusivelyfor transport, mainly arthropods, examples of which aremites on insects (such as beetles, flies or bees),pseudoscorpions on mammals or beetles, andmillipedes on birds.Phoresy can be either obligate orfacultative (induced by environmental conditions).

Kinds of Commensalism

Inquilinism

Inquilinism is the use of a second organism for

permanent housing. Examples are epiphytic plants

(such as many orchids) that grow on trees, or birds that

live in holes in trees.

Metabiosis

Metabiosis is a more indirect dependency, in which one

organism creates or prepares a suitable environment for

a second. Examples include maggots, which feast and

develop on corpses, and hermit crabs, which use

gastropod shells to protect their bodies.

Kinds of Commensalism

Amensalism is the type of relationship that exists

where one species is inhibited or completely

obliterated and one is unaffected.

Amensalism

• The bread mold Penicillium is a common exampleof this; penicillium secrete penicillin, a chemicalthat kills bacteria.

• A second example is the black walnut tree(Juglans nigra), which secrete juglone, achemical that harms or kills some species ofneighbouring plants, from its roots.

• A third simple example is when sheep or cattlemake trails in grass that they trample on, andwithout realizing, they are killing the grass.

Amensalism

How can species

interactions affect population

dynamics and natural

selection?

End.