Bio 122- exam 4- Biotic Interactions

Niche

•how an organism uses resources

Ecological Niche

•Hypothetical space an organism occupies in a system

Interactions between ____play important roles in communities

species

Ecological Niche

•‘how an organism makes a living’

–Dietary

–Spatial

–Temporal

Interactions between species play important roles in communities

•Community ecologists study interspecific interactions-

–relationships between species, classified according to how they affect each population involved

Interactions between species play important roles in communities

•Types of interaction

–Competition

–Mutualism

–Predation

–Herbivory

–Parasitism/pathogens

is mutually harmful

Competition

Competition is mutually harmful

•Competition may occur when…..

two or more species in a community rely on similar limiting resources.

Competition is mutually harmful

According to the competitive exclusion principle,

if the resources required by two species are too similar, they cannot coexist

interspecies completion ex

bears and squirl both eating same nuts/ plants

is beneficial to both species

Mutualism

Mutualism is beneficial to both species

Mutualism

•a form of interspecies interaction in which both species benefit.

Mutualism is beneficial to both species

–It often occurs among species that are symbiotic,

living in close physical association with one another, but not all symbiotic relationships are mutual.

Mutualism is beneficial to both species 

ex

pollinators, coral, mycorrhizae (a dandelion being blown)

Some interactions are beneficial to

one species and harmful to the other

Some interactions are beneficial to one species and harmful to the other

Predation

• an interaction in which a predator species kills and eats a prey species.

Some interactions are beneficial to one species and harmful to the other

Herbivory

the eating of plant parts by an animal

Some interactions are beneficial to one species and harmful to the other

parasite

•lives on or in (but does not kill) a host, from which it obtains nutrients.

Some interactions are beneficial to one species and harmful to the other

Pathogens

disease-causing microorganisms

Food webs describe

multiple trophic structures

Food webs describe multiple trophic structures

Trophic structure

describes the feeding relationships within a community.

Food webs describe multiple trophic structures

Food chains and food webs

•describe the transfer of organic material from one trophic level to the
next.

A food chain

simplified description of one part of the trophic structure

The trophic structure of an ecosystem describes

simplified description of one part of the trophic structure

The trophic structure of an ecosystem describes the feeding relationships

trophic structure

decomposer—> trophic level 1 —> trophic level 2 —> trophic level 3 —→ trophic level 4

The trophic structure of an ecosystem describes the feeding relationships

trophic structure ex

decomposer, heat travels up from here through all loves and out 

decomposer, then leaves, worms eat leaves, birds eat worms , fox eats birds 

solar energy comes in at level 2, plants

The trophic structure of an ecosystem describes the feeding relationships

fox eats birds,  birds eat worms ,worms eat leaves, then leaves, worms eat leaves, decomposer is an example of 

chemical energy 

The trophic structure of an ecosystem describes the feeding relationships

TROPHIC LEVEL 4

Tertiary consumers (ex: fox)

The trophic structure of an ecosystem describes the feeding relationships

TROPHIC LEVEL 3

Secondary consumers

The trophic structure of an ecosystem describes the feeding relationships

TROPHIC LEVEL 2

Primary consumers

The trophic structure of an ecosystem describes the feeding relationships

TROPHIC LEVEL 1

Primary producers (plants)

The trophic structure of an ecosystem describes the feeding relationships

decomposer

breaks down nonliving matter

The trophic structure of an ecosystem describes the feeding relationships

At each energy conversion

heat is released.

The trophic structure of an ecosystem describes the feeding relationships

Energy enters an ecosystem as

sunlight

Energy flows through

ecosystems

Energy flows through ecosystems

Primary producers

•convert solar energy to chemical energy via photosynthesis.

Energy flows through ecosystems

Primary consumers

herbivores that eat primary producers.

Energy flows through ecosystems

Secondary consumers

carnivores that eat primary consumers.

Energy flows through ecosystems

Tertiary consumers

top-level predators.

Energy flows through ecosystems

Tertiary consumers are top-level predators.

–As trophic levels increase, less energy is available at each transfer.

Energy flows through ecosystems

Decomposers

•organisms that break down nonliving matter.

Energy flows through ecosystems

•Decomposers are organisms that break down nonliving matter.

–Death at any level sends energy to the decomposers.

A food web interconnects

multiple food chains

A food web interconnects multiple food chains

A food web of a hypothetical forest community

Arrows indicate energy transfer or “who eats whom.”

• pic on slide

____can accumulate in higher levels

Toxins

Toxins can accumulate in higher levels

Biological magnification

the tendency of toxins to become concentrated as they pass through a food chain.

Species diversity includes

species richness and relative abundance

Species diversity includes both species richness and relative abundance

Both forests have the same number of species, or

species richness.

Species diversity includes both species richness and relative abundance

•However, the fraction accounted for by each species, or _____________, differs between the two communities.

relative abundance

Keystone species

can drive diversity

Keystone species can drive diversity

keystone species

a species that has a disproportionately large effect on its environment relative to its abundance.

Keystone species can drive diversity

Ecologists studying the Alaskan coast discovered that a decline in the sea otter population allowed sea urchins
to quickly multiply —>

devouring of kelp forest

_____ are rarely static

Communities

Communities are rarely static

Primary succession

•occurs when an area has been rendered virtually lifeless with no soil

Communities are rarely static

Primary succession •occurs when an area has been rendered virtually lifeless with no soil.

–1^st multicellular life to return is often photosynthetic lichens & mosses, followed by small plants

Communities are rarely static

Secondary succession

•occurs after a disturbance that kills much of the life in an area but leaves the soil intact.

Communities are rarely static

After a disturbance, an area will be reoccupied by a series of species. Ecological succession

may take hundreds or thousands of years

Invasive species

disrupt ecosystems

Invasive species disrupt ecosystems

When non-native organisms are introduced to a community, they can spread rapidly, becoming an

invasive species

Invasive species disrupt ecosystems

Invasive species are now a

leading cause of extinctions of local populations.

Invasive species disrupt ecosystems

ex

Lionfish were introduced into the Caribbean and consumed other fish voraciously.

Caulerpa taxifolia

•Originally from the Monaco Aquarium

•Released into the Mediterranean

•Can spread through fragmentation

•Poisonous to many organisms

•Fast growing

A Gallery of Invasive Species

Burmese pythons are invasive in the Florida Everglades.

Kudzu is a climbing vine, introduced to the southern U.S

A Gallery of LA Invasive Species

ALLIGATOR WEED, Alternanthera philoxeroides

Giant Salvinia, Salvinia molesta

HYDRILLA, Hydrilla verticillataWater Hyacinth, Eichornia crassipes

A Gallery of LA Invasive Species

Chinese tallow, Triadica sebifera

WILD TARO, Colocasia esculenta

Wild Boar, Sus scrofa

Controlling Invasive Species

•Ecologists may implement biological control,

the intentional release of a natural enemy.

Controlling Invasive Species

•Biological control species must be closely studied.

ex

Mongooses were introduced to Hawaii to eat rats à they also decimated many native species

Modern agriculture presents

unique challenges of biological control

Modern agriculture presents unique challenges of biological control

Integrated pest management

•is a method that utilizes several strategies

Modern agriculture presents unique challenges of biological control

Integrated pest management •is a method that utilizes several strategies:

–Biological control, pest-resistant crop varieties, judicious use of chemicals, release of sterile pests, and other biological and behavioral changes.

Modern agriculture presents unique challenges of biological control

•Integrated pest management is a method that utilizes several strategies:

–Biological control, pest-resistant crop varieties, judicious use of chemicals, release of sterile pests, and other biological and behavioral changes.

ex:

Integrated pest management has been used effectively for cotton crops in India