Community Ecology

Species interactions

Biological processes that determine com_____ comp______

Can be po____, ne______, or neu______

Influence the fi____ of parties involved

Biological processes that determine community composition

Can be positive, negative or neutral

Influence the fitness of parties involved

Competition (-/-)

Occurs when different individuals use the same res_____ and when those res______ are lim___g

Niche-ov____ lead to com_____n

Occurs when different individuals use the same resources and when those resources are limiting.

Niche-overlap leads to competition

Asymmetric competition

O__ species suf____ a greater fi____s decline than the ot____

one species suffers a greater fitness decline than the other

Competitive Exclusion

T__ species that occupy the exact same ni___e (in all of its biotic and abiotic dimension) cannot co_____t

Weaker competitor must: ad___, mig____, or d__!

Two species that occupy the exact same niche (in all of its biotic and

abiotic dimensions) cannot coexist

Weaker competitor must: adapt, migrate or die!

Mechanism of Coexistence

Strong selective pre____ to avoid comp______

Evolutionary changes in tr____s and reduce ni___e overlap

Strong selective pressure to avoid competition

Evolutionary changes in traits reduce niche overlap

Niche differentiation

An evolutionary change in res_____ use caused by comp____ over gen______s

an evolutionary change in resource use caused by competition over

generations

Niche differentiation - how does it occur?

Occurs when sim____ spe_____ occupy the s__e geographic a__a

Niche differentiation occurs when similar species occupy same geographic area

Chapter displacement

Natural selection favors div_____ce in traits that allow for coe_______

natural selection favors divergence in traits that allow for coexistence

Consumption (+/-)

1. Her_____y

2. Pre_____n

herbivory

Predation

Herbivory - an___ eats pl_____

Predation - predator k___s and con____s another ind_____

animals eats plants

Predator kills and concurs another individual

How do plants defend themselves?

Ch_____l defenses:

• alkaloids (caf____, THC, nic____e)

Mec____ defenses:

• th___s, spi___, tri____s

Coevolaiton between plants and herbivores can lead to evolutionary “ar__ ra___”

Chemical defenses:

• Alkaloids (caffeine, THC, nicotine)

Mechanical defenses:

• Thorns, spines, trichomes

Coevolution between plants and herbivores

can lead to evolutionary “arms race”

Predation

How do animals defend themselves?

Constitutive defenses: al___s pre___t

• cryptic colo_____n (camo____)

• Sch____g

• Wea____y

always present

Cryptic coloration (camouflage)

Schooling

Weaponry

Constitutive defenses - defenses that are al____s pr____t

• tr__ b___, lig____s, tan___s

• Constitutive defense are exp_____!

  • Che_____s, enz____, increased mucilage

defenses that are always present

• tree bark, thorns, lignins, tannins

Constitutive defenses are expensive!

• Chemicals, enzymes, increased mucilage

Inducible defenses - def_____e traits produced only in response to the presence of a pre____

defensive traits produced only in response to the presence of a predator

Aposematic coloration

Don’t e__ m_!

Animals produce to___s or ven___

Use bright co___s to com____ to other animals

“Don’t eat me!”

Animals produce toxins or venoms

Use bright colors to communicate to other animals

Mimicry - one species cl___ly res____ another species

one species closely resembles another species

Batesian mimicry - mimics look like dis______l species

Mimics look like distasteful species

Mullerian mimicry - several unr____ but pois____s species come to resemble one an____r

Several unrelated but poisonous species come to resemble one another

Symbiosis - a close and long term biological relationship between t___ dif____ spe____s

A close and long- term biological relationship between two different species

Three different types of symbiosis

• Mut_____ism

• Comm______ism

• Para_____ism

Mutualism

Commensalism

Parasitism

Mutualism (+/+)

Symbiotic relationship that results in increased fit____ for both inter_____g spe____s

• vital for eco______ func______

• Major evolutionary driver of bio_____y

Symbiotic relationship that results in increased fitness for both interacting species

vital for ecosystem functioning

major evolutionary driver of biodiversity

Types of mutualisms

1. Re____-re______

2. Ser____-re______

3. Ser_____-ser_____

resource-resource

Service-resource

Service-service

Resource-resource = pl___s & my___rr___ae

Service-resource = cleaner wra____ & other fi__

Service-service - anem____ & anem___ fi___

plants & mycorrhizae

Cleaner wrasse & other fish

Anemones & anemone fish

Plant pollinate interactions

Flowering plants are ses___le ——>

Cannot directly control gam____ receipt or ex___t

Flowering plants are sessile! ——→

cannot directly control gamete receipt or export

Plant-pollinator interactions

Angiosperm “c__x” animals with rewards for repr_____e services

Angiosperms “coax” animals with rewards for reproductive services

Plant-pollinator interactions

Pollinators get: F___

Angiosperm get: rep______ ser______

food

Reproduction services

Mutualism Cheaters!

Nectar rob____ remove nec___ from flo____s without polli_____ the pl___

Nectar robbers remove nectar from flowers without pollinating the plant

Parasitism (+/-)

Parasite consumes relatively small amounts of ti____s or nutr____ from another ind_____ called the ho__

Consumes relatively small amounts of tissue or nutrients from another individual called the host

Endoparasites - live in___ h___ts

Ectoparasites - live on the ou____e of h___t

Parasitoids - fr__-liv____ as ad___ but endoparasites as la___

Live inside hosts

Live on the outside of host

Free-living as adults but endoparasites as larvae

Commensalism (+/0)

O__ species benefits the other is not aff_____

Remora fish - dorsal fin modified into su____r

Epiphytes - plants that grow on oth__ pl____

• do not affect the fi___s of host pl___

• Fe__s, orch___, bromeliads

One species benefits the other is not affected

Remora fish – dorsal fin modified into sucker

Epiphytes – plants that grow on other plants

• Do not affect the fitness of host plant

• Ferns, orchids, bromeliads