Species interactions

2010 version

1. Species Interactions in
Communities
A good look at coevolution at work
in our world…

2. Types of Interactions
(type of impact on each species in parentheses)
•Competition ( - , - )
–interspecific vs. intraspecific
•Predation ( + , - )
–carnivory or herbivory
•Parasitism (+ , - )
•Commensalism ( + , 0 )
•Mutualism ( + , + )
•Amensalism ( - , 0 )

3. The Competitive Exclusion
Principle
If two species, with the same niche,
coexist in the same ecosystem, then
one will be excluded from the
community due to intense competition
•both species suffer so ( -, - )
•losers usually migrate or die
or
•this leads to resource partitioning and species
assume smaller realized niches since they
cannot occupy their full fundamental niches

4. Impacts of Competition
Species B

5. Louisiana heron
wades into water
to seize small fish
Black skimmer
seizes small fish
at water surface
Ruddy
turnstone
searches
under shells
and pebbles
for small
invertebrates
Avocet sweeps bill
through mud and
surface water in
search of small
crustaceans, insects,
and seeds
Brown pelican
dives for fish,
which it locates
from the air
Dowitcher probes
deeply into mud in
search of snails,
marine worms, and
small crustaceans
Herring gull
is a tireless
scavenger
Flamingo feeds on
minute organisms
in mud
Scaup and other diving
ducks feed on mollusks,
crustaceans, and aquatic
vegetation
Piping plover
feeds on insects
and tiny
crustaceans on
sandy beaches
Knot (sandpiper)
picks up worms
and small crustaceans
left by receding tide
Oystercatcher feeds on
clams, mussels, and other
shellfish into which it
pries its narrow beak
Resource Partitioning
Environmental Science: Problems, Concepts, and Solutions. (12th ed.) by G. Tyler Miller, Jr. and Scott Spoolman

6. Cape May
Warbler
Blakburnian
Warbler
Black-throated
Green Warbler
Yellow-rumped
Warbler
Bay-breasted
Warbler
Resource Partitioning
Environmental Science: Problems, Concepts, and Solutions. (12th ed.) by G. Tyler Miller, Jr. and Scott Spoolman

7. Purple Martin & Starling
•Interspecific
competition
•Starlings tend to
fight off Martins, kill
nestlings, and break
their eggs

8. Red & Grey Squirrels
•Interspecific competition
•The Grey Squirrel (Sciurus
carolinensis) was introduced to Britain
in about 30 sites between 1876 and
1929. It has easily adapted to parks
and gardens replacing the red squirrel.
•The Red Squirrel (Sciurus vulgaris) is
native to Britain but its population has
declined due to competitive exclusion,
disease and the disappearance mature
conifer forests in lowland Britain.
Grey Squirrel Range
Red Squirrel Range
Maps prepared by the Biological Records Centre, CEH Monks Wood, from records collated
by the Mammal Society and others mainly between 1965 and 1993, also including earlier,
published records and a few additions up to 1997.

9. Africanized & European HB
•Interspecific
competition
•AHB mature faster
and are more
opportunistic
feeders

10. Spread of AHB
(also good example of a nonnative species)

11. Speaking of Bees…
•EHB larvae with a
parasitic mite on it
•Host = EHB
•Parasite = mite
•Example of
ectoparasite

12. Elk and Liver Fluke
•Parasitism
•Elk = host
•Fluke = parasite
•Example of an
endoparasite

13. Liver Fluke Life Cycle
•Many endoparasites may have a cyst form or
occupy intermediate hosts that they may not
harm…

14. Impacts of Predation

15. Lion & Zebra
•Carnivory predation
•Zebra-prey
•Lions-predator
* While individual
zebras are harmed,
the prey population
benefits by loss of
old and sick
members

16. Rough-Skinned Newt &
Common Garter Snake
•Carnivory predation
•Newt-prey
–Has genes to produce potent
toxins which discourage predation
•Snake-predator
–Has genes for resistance to newt
toxin
* Results in an
“evolutionary arms
race”… coevolution!

17. Monarch Butterfly & Milkweed
•Herbivory predation
•Milkweed-prey (defense)
–Latex: A milky white sap that
becomes sticky and coagulates when
exposed to air.
–Cardiac glycoside: To various
degrees, it is toxic to herbivores with
hearts (birds and mammals).
Monarchs and several other
arthropods that eat milkweed have a
tolerance for cardiac glycosides,
although evidently not at the high
levels found in some milkweed
species.
•Butterfly-predator
–Monarch larve cut the petiole of the
leaf before beginning to eat it. This
"leaf-notching" behavior cuts off the
supply of latex.

18. Commensalism vs. Mutualism
How do you decide?

19. Shark & Remora
•Commensalism or
mutualism?
•Depends…
–If remora gets
transport, protection
and scraps and
shark nothing ( +, 0 )
–If shark has
parasites removed
by remora ( +, + )

20. Oak & Mycorrhizae Fungi
•Mutualism
•Oak tree provides
sugars for fungi
•Fungi absorbs
moisture and
nutrients for tree

21. Lichen (algae & fungus)
•Tricky?
•Mutualism (self)
•Commensalism
(with living tree)

22. Eastern Lamp Mussel &
Largemouth Bass
Commensalism: Glochidia (larvae) live on fish gills for about a month…

23. Speaking of Eastern Lamp
Mussels…
•Carnivory predation
by herons

24. More on Eastern Lamp
Mussels…
•Interspecific
competition with
Zebra Mussels
•Zebra Mussels are
also nonnatives
from Europe that
arrived in ship’s
ballast tanks

25. Spread of Zebra Mussels
(good example of a accidentally introduced
nonnative species)

26. Epiphytes and Trees
•Spanish Moss
•Commensalism
•Epiphyte roots on
bark and has better
access to light and
water--no harm to
tree

27. More Epiphytes…
•A common site on
tropical or temperate
rain forest trees

28. Humans and E. coli Bacteria
•Mutualism
•Humans provide
food and shelter
(large intestine) for
the bacteria
•E. coli assist in
human digestion
and provide Vitamin
K for host

29. One More…

30. Ammensalism
•One species is hurt, but the
other does not benefit ( -, 0 )
•No apparent coevolutionary
relationship (one way
process)
•Example: As wild pigs
forage, they often disturb the
upper layer of soil and many
organisms may be taken
from their burrows and
exposed to predation by the
action of the pigs, although
the harm that the burrowers
suffer does not improve the
pig's situation at all.

31. Black Walnut & Azalea
•Example of alleopathy
(not in your text)
•Black Walnut secretes
chemical (juglone) that
inhibits growth of other
plants like azalea
•Could be ammensalism,
competition, or
avoidance of predation?

32. Quiz Time

33. You decide!
Herbivory predation
or
Mutualism?
MUTUALISM!

34. You decide!
Easy?
HERBIVORY
PREDATION!

35. You decide!
A hermit crab with an
anemone attached to
the shell…
MUTUALISM!

36. You decide!
A Tobacco Hornworm
covered with wasp
pupae…
ECTOPARASITE!
Adult: Carolina Sphinx Moth

37. You decide!
Mistletoe?
ECTOPARASITE!

38. So…species must:
•Adapt (in other words, coevolve due to
competition, predation, or develop
symbiosis)
•Migrate (run away)
•Die (go extinct)