1. Primary consumer 2. Tertiary consumer 3. Primary consumer 4. Primary producer

1. Ch 37 Community Ecology
Goals:
• Define interspecific competition & explain how it has an impact on evolution.
• Define coevolution.
• List the 4 major types of interspecific interactions & explain their effects on population
density . (ex: parasitism, neg population impact on host, positive on parasite)
• Define cryptic coloration, aposematic coloration, Mullerian mimicry, Batesian mimicry.
• Explain brood parasitism & why it increases the fitness of the parasite (think in terms of
energy… what species is expending energy & which is conserving it?).
• Define niche.
• Define keystone species & keystone predator.
• Discuss how predators can affect community structure by moderating competition among
prey.
• Explain how exotic species can alter community structure.
• Define ecological succession & distinguish between primary & secondary succession.
• Explain how disturbance causes succession & give examples.
• Define trophic levels, primary producers, used for food are herbivores.
• primary consumers, secondary consumers, tertiary consumers, detritivores, ecological
efficiency, food chain & food web.
• Explain why much energy is lost as it flows through an ecosystem.
• Based on ecological efficiency being so low, explain why nearly all domestic animals

2. Ch 37 Community Ecology
• Community –
• Interspecific interactions can be strong selection factors in
evolution
• Coevolution – when 2 species develop evolutionary adaptation in
response to each other.
• Interspecific interactions may have +, - , or neutral effects on a
pops density:
– Predation & parasitism (+/-)
– Competition (-/-)
– Commensalism (+/0)
– Mutualism (+/+)

3. Predation
• predators - adaptations to locate & catch prey.
• Prey - developed evolutionary adaptations in
defense
• Plant defenses:
– thorns, hooks, chemicals
– Ex: morphine from poppy, nicotine from tobacco,
cinnamon, peppermint
• counter adaptations by herbivores:
– absorb or detox chemicals, Ex: monarch butterfly

4. Predation
• animal defenses
– can be passive –hiding – or active - fleeing or fighting (less common)
– alarm calls to cause mobbing Ex: sparrows mobbing hawks
– distraction
– adaptive coloration
– cryptic coloration (camouflage)
– deceptive markings – eyes
– shape
– smells
– aposemetic coloration – brightly colored to warn predators of toxicity
– mimicry – look like something else
• batesian mimicry – a harmless species looks like a harmful one. Ex:
catapillar looking like a snake, wiggling head & hissing!
• Mullerian mimicry – 2 or more dangerous brightly colored species look
like each other
viceroy & monarch butterflies

5. Parasitism (+/-)
• interesting type of parasitism – brood parasitism
– host is not eaten, just taken advantage of
– Ex: cowbirds lay eggs in nests of other species, newly hatched
brood parasite kicks out native eggs,
– Evolutionary adaptation to this by hosts being able to detect
parasite eggs & kick them out
• Counter adaptation to this is the development of egg mimicry

6. Commensalism (+/0) & Mutalism (+/+)
• Commensalism:
– Ex: cowbirds feeding on insects the grazing cows kick up
– Ex: barnacles hitching a ride on a whale
• Mutualism – both benefit
– Ex: nitrogen fixation by bacteria in roots of legumes
– Ex: digestion of cellulose by microorganisms in cows & termites
– Ex: flowers & pollinators

7. Interspecific competitions (-/-)
• Interspecific competition – when pops of 2 or more species in a
community rely on similar limiting resources
• Ecological niche – all biotic & abiotic resources an org uses in its env,
its “occupation”
• Ex: tree lizards niche is temp is lives at, size of trees it lives in,
time its active, size & type of food it eats

8. INTERSPECIFIC INTERACTIONS & COMMUNITY
STRUCTURE
• keystone species – a species that makes an unusually strong impact
on the community structure.
• Ex: beavers with dams, elephants with uprooting trees
• keystone predator – a predator species that moderates competition
among its prey, keeps the strongest competitor in check so it
doesn’t destroy community structure
• Ex: sea stars eat special type of mussel which then took over when
the sea stars were removed

9. Mutualism & parasitism can have community-
wide effects
• Ex: nitrogen fixing bacteria & roots of legumes

10. Interspecific competition influences pops of
many species & can affect community structure.
• Exotic species - can outcompete native species & alter
community structure.
– Ex: zebra mussels – clogged reservoir intake pipes in
great lakes. no natural enemies.
• the more varied a habitat, the more ecological niches
available.

11. Disturbance & Nonequalibrium
• Stability – tendency of a community to reach & maintain an
equilibrium in the face of disturbance
• Nonequalibrium resulting from disturbance is a prominent feature of
most communities
• Ex: storms, fire, drought, human activities
•
• Humans - most widespread agents of disturbance
– Ex: logging, mining, farming, overgrazing – are all bad
– Ex: fires – sometimes good cause some species need them

12. Succession
• Succession - process of change that results from disturbance in
communities.
• Ecological succession – transitions in species composition over time.
– 2 types:
– primary – begins lifeless such as new volcanic island or rubble
from retreating glacier
– secondary – existing community cleared & soil is intact. Ex:
logged areas
• What determines who grows / lives there? Competition for resources

13. Matter & energy flow through an
ecosystem.
Ch 54 They are never created or destroyed!
NEVER! EVER!
Matter &
Energy
Flow
Through
Ecosystems
EVER!
The energy just gets transformed into other types of
energy.
The matter just gets passed on to other organisms.

14. It’s like this, baby…

16. Food Chain – the transfer of energy from
one organism to another.
• As each org is eaten, the energy is transferred.

17. Only 10% of the energy gets transferred from one
organism to the next!
Why so little? What happens to all the energy?
Much of it gets transformed into heat energy when the
organism performs cellular respiration.
Energy
pyramid –
shows trophic
levels & the
amt of energy
that moves up
from one level
to next.

18. Food Web – shows many connected food
chains.

19. Trophic level – contains organisms that
are the same number of steps away from
the sun.

20. Quaternary consumers – eat tertiary consumers (carns
that eat carns that eat carns)
Tertiary consumers – eat secondary consumers
(carnivores that eat carnivores)
secondary consumers – eat primary consumers
(carnivores)
primary consumers – eat producers (herbivores)
primary producers – make food from sun’s energy

21. 1. What trophic level is the grasshopper at?
2. What trophic level is the great horned owl at?
3. The sparrow?
4. The grass?