Community Ecology: Competition, Mutualism and Commensalism

Competition sign

\-/-

although one species or individual is better at competing they still have to competing for resources so it’s -/-

Intraspecific Competition

competition within the same species

* with a small population, resources are abundant so the number of individuals will continue to grow
* until the pop. size approaches the carrying capacity (the max amount of individuals that the environment can sustain)
* half-way mark of the carrying capacity (is the fastest growth)

competitive exclusion principle

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The competitive exclusion principle states that no two species can coexist if they occupy the same niche and compete for the same resources.

* basically one will outcome the other

niche

basically favorable conditions

* the sum of a species use of biotic and abiotic resources in it’s envrionment

resource partitioning

(partitioning: to split, divide)

* sharing/dividing resources among two diff species that compete
* ecologically similar species can coexist if there is greater than 1 significant difference in their niches

Fundamental vs realized niche

* fundamental niche: the niche in the absence of competition (larger)
* realized niche: portion of the fundamental niche that the species actually occupies (smaller)

Character displacement

* evolution of morphological differences

Mutualism sign

\+/+

both species benefit

Obligate

(ie think obligation- meaning it’s a REQUIREMENT)

* organisms can’t survive without the mutalism

Facultative

* organisms can survive without the mutualism

EX #1: Mutualism: ANTS AND ACACIA

\* ants get shelter and food from acacia tree

\* ants provide the acacia tree with protection

* acacia trees house the ants which feed on the trees nectar (ants get shelter and food from acacia tree)
* the ants inhibit competition from any other trees in the area
* ants: attack anything that touches the tree, remove fungal spores, small herbivores, and debris. They also clip vegetation that grows close to the acacia

EX #2: BACTERIAL HEADLIGHTS ON THE FLASHLIGHT FISH

* Bacteria receives nutrients from the fish
* bacteria provides biolumionol light so that the fish can catch prey and find mates

EX #3: PUFFER FISH

* Bacteria has lethal chemical for fish to use to catch prey
* fish provides the bacteria with nutrient from it’s food

EX #4: Endophytes (Fungi) in PLANTS

* fungi provide bitter taste to reduce grazing by herbivores
* plants provide the fungi w/ nutrients

EX #5: Fungal- Ant mutalisms

* ant brings leaves to the fungi (depend on the nutrients from the leaves the ants feed them)
* fungi to converts plant material to a form the insects can digest.

EX #6: Lichens

* symbiotic association between a photosynthetic microorganism and a fungus
*  The algal partner photosynthesizes and provides food for the fungus, so it can grow and spread.
* The fungus provides its photosynthetic partner with a suitable environment for growth

symbiosis

at least 1 species benefits (ecological relationship between organisms of 2 different species)

EX #7: HUMANS AND THE MICROBIOME

* bacteria provide us with vitamins and other nutrients
* humans provide the bacteria with shelter (a place to live and grow)

Fruits are classified into several types: SIMPLE FRUIT

* Derived from a single carpal
* pea plants

Fruits are classified into several types: Aggregate fruit

* Derived from more than 1 carpal
* raspberry

Fruits are classified into several types: MULTIPLE FRUIT

* Develops a cluster of flowers
* pineapple

Fruits are classified into several types: ACCESSORY FRUIT

* dervived from tissues other than the ovary
* the seed is protected inside the fruit and is surrounded by tissue
* ex: apple, tomato

Mutualism: Plant and bacteria

* nitrogen fixing bacteria provide the plant w/ nitrogen that the plant can use for growth/etc
* plants provide the bacteria with access to carbon

Mutualism: pollination

* pollinator gets the nutrient rich nectar from the flower
* The pollinator then take this pollen to another flower, where the pollen sticks to the stigma (the female part). The fertilized flower later yields fruit and seeds.
* pollen is plant sperm

MUTALISM: SEED DISPERSAL

* animals eat the berries/fruit (have the seed inside the fruit)
* the animals poop out the seeds (seeds will grow, the seeds are not in competition with the parent plant since the seeds are typically dispersed away from the parent plant)

Co-evolution

joint evolution of 2 species in response to the slection imposed by the other

ATTRACTING POLLINATORS: BEES

* flowers have landing pads
* delicate sweet smells
* sturdy flowers

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* small narrow tube

ATTRACTING POLLINATORS: MOTHS

* White flowers
* long floral tubes
* flat petals or bent back (moths are hover feeders)
* night blooming (strong sweet scent allows moths to find the flowers)

ATTRACTING POLLINATORS: BUTTERFLIES

* blue, yellow, red, showy flowers
* deep floral tube
* perching feeders (rest/sit on the flower)

ATTRACTING POLLINATORS: FLIES

* bad odor
* coloration of rotting flesh
* attract flies bc they will try to lay eggs

ATTRACTING POLLINATORS: BATS

* Night blooming
* white flowers
* robust (strong)
* strong smells

ATTRACTING POLLINATORS: BIRDS

* often red/yellow
* odorless
* sturdy structure
* recurved petals (hoover-feeders)

Commensalism sign and def

\+/0

* one species benefits while the other is unaffected

masting

Population synchronously produces massive amounts of seed and then they just die (some seeds will be able to escape herbivory and grow)

Critical load

Vector

an organism that transmits pathogens from one host to another 

Reservoir

the habitat in which the agent normally lives, grows, and multiplies 

**Amplification effect**

**when the presence of naturally high diversity** ***increases*** **the overall transmission or pathogen** 

Amplification host

an organism in which an infectious agent (such as virus or bacterium) that is pathogenic for some other species is able to replicate rapidly and to high concentrations

Dilution effect

 when the diversity of an ecological community reduces the transmission of a pathogen (more diversity DECREASES pathogen transmission)

Spillover

 the process by which a pathogen moves from one host population (or environmental reservoir) to another host population

**Bioremediation**

process of using organisms to detoxify polluted environments

**Bioaugmentation**

process of **r**eturning important nutrients back into ecosystem as part of restoration

**Biological magnification**

tendency for pollutants to accu**m**ulate in successive trophic levels

**Critical load**

the amount of added nutrient that can be absorbed by plants without damaging ecosystem integrity

Introduced species 

introduced species can establish themselves in area but fail to spread (not considered invasive)

**Extinction vortex**

illustrates the loss of genetic variation necessary to enable evolutionary responses to environmental change

**Minimum viable population** **(MVP)**

the smallest population size at which a species is able to sustain its numbers and survive

**Effective population size** **(Ne)**

number of individuals that contribute genes to future populations

* ie the individuals that can reproduce

**Effective population size** equation

4NfNm/ Nf + Nm

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* Nf= # of females that can reproduce
* Nm= # of males that can reproduce