1. Ecosystem Interactions Among Species

2. What Affects Populations of Species?
organism
population
community
ecosystem
biosphere
What Affects Populations of Species? 2

3. Interactions and Populations
All populations of species in an ecosystem strive for survival
What do you think populations of species need in order to survive?

4. Resources: food, water, safe shelter, mates, space, materials
But there are many factors that affect a population’s survival

5. Is there a difference between a population and a community?
Yes. A population is made up of members of one species (who breed) and live in a specific area, more or less isolated from other members of their species.
A community is made up of a collection of populations of different species interacting within a specific area, functioning more or less as a unit with certain identifiable characteristics.

6. Biotic and Abiotic Interactions
Biotic Interactions: Interactions between living things.
Example: How would a flower and a bee interact? How would a moose and a parasite interact?
Abiotic Interactions: Interactions between living and non-living things
Example: How would a deer be affected by a dry and hot weather?

7. Abiotic Interactions
Terrestrial: temperature, water, light and nutrient availability
Aquatic: same as above plus light availability, acidity, and salt concentration
Tolerance range:
The range in which a species can survive
Optimal range:
The range of abiotic factors a species is best adapted to

8. Ecological Niche An organism’s niche is its ecological role
habitat = address vs. niche = job
Spot in food web
Habitat
Breeding area
Time of day that its active 8

9. Species Interactions Competitive Exclusion Hawk Owl
Food
mice / small rodents
Habitat
trees (fields)
trees (forest)
Time of Day
Daylight
Nighttime
Adaptations
Long wings for soaring
Great distance vision
Short wings for weaving
Great night vision
Amazing hearing
Competitive Exclusion
No two similar species can occupy the same niche at the same time 9

10. Biotic Interactions
There are three main ways in which species in populations interact with each other:
Predator-Prey interactions
Competition
Symbiosis

11. 1) Predator-Prey Interactions
the act of one organism eating another organism in order to obtain food. Prey animals adapt in order to avoid being eaten.
Ex. Camouflage or the ability to run very fast.
- Mimicracy: one species that looks like another species.

12. Predation When one organism consumes another organism Examples:
Wolf hunting a deer
Lady bugs eating aphids
Owl hunting a mouse

13. 2) Competition interactions between two or more organisms
competing for the same resource in a given habitat.

14. Competition
Organisms might compete for resources such as food and materials, mates or territory/habitat
Interspecific: competition between species
Intraspecific: competition within organisms of the same species
Examples:
Interspecific: cheetahs and lions both compete for antelope; spruce and ash trees compete for sunlight
Intraspecific : two male deer competing for a female

15. Competition Neither species benefits
For example, by the early 1950s the American chestnut ( Castanea dentata) had been eliminated as a dominant canopy species in deciduous forests of eastern North America by the accidental introduction of a fungal pathogen known as chestnut blight (Endothia parasitica). Other tree species took advantage of their sudden release from competition with the chestnut by opportunistically filling in the canopy gaps that were left by the mature chestnut trees.

16. 3) Symbiosis
a close interaction between two different species where one species lives in, on, or near another species.
Three types of Symbiosis:
Mutualism
Commensalism
Parasitism
What do you think each of these mean?

17. Mutualism
A relationship between two species where both benefit. The yucca moth both pollinates and feeds on the yucca plant;
acacia ants live in the thorns of, defend, and are fed by the acacia tree in which they live;
Butterfly-weed provides food for and is pollinated by butterflies like Pipevine Swallowtails.
Many plants and their pollinators have evolved mutualistic relationships.

18. Clown fish and sea anemone
The clownfish have a protected territory and the sea anemone needs the mucus from the clown fish to make their venom

19. Parasitism
When two organisms coexist and one organism benefits while the other is harmed
Examples:
Dogs and Cats + Fleas, ticks, intestinal worms
Lampreys and salmon
Leeches
Bed bugs
mosquitoes

20. Parasitism

21. Zombie Ants A parasitic fungus can infect an ant.
The fungus then takes over the control center of the ant and manipulates it forcing it to climb to the highest point available and then latch on to the vegetation.
The fungus then pushes through
the ants head releasing spores
and uses the ants body for
nutrition.

22. Commensalism
When two organisms coexist and one organism benefits while the other remains unharmed
Examples:
Cattle and the egret: the egret consumes insects that have been disturbed while the cattle forage
Barnacles and scallops: the barnicles have a place to live and the scallop is unaffected

23. Remora sharks: Remora sharks are endowed with an adhesive disk on the dorsal surface of their heads. They use this adhesive disk to “hitch a ride” on larger animals, usually whales, which tend to be sloppy eaters. When food floats away from the whale’s mouth, the remora can unhitch itself and collect the scraps of food floating by.
Commensalism

24. Other Examples of Biotic Interactions
Mutualism –Ex: the boxer crab carries around anemones in its claws. The anemone protects the boxer crab from predators, and the anemone eats scraps of food that the boxer crab drops.
Commensalism –Ex. A bird building a nest in a tree (tree doesn’t suffer)
Parasitism –Ex. Leach or a tick sucking blood from an animal.
SEE PAGE for MORE EXAMPLES

25. Which type of Symbiosis?1 3 2

26. Which type of Symbiosis?
Image 1 – parasitic tick on a dog
Image 2 - As buffalo eats grass, the egrets (birds) eat the insects that they stir up. The buffalo is unaffected.
Image 3 – The bee feeds from the flower’s nectar, but it also helps cross-pollenate the flower so it can reproduce.

27. What relationship is this?
clown fish & sea anemone
ants & acacia
impala & oxpeckers 27

28. More examples mutualism +/+ commensalism +/0 predation +/- competition
-/- 28

29. Comparing Relationships
type of interaction
sign
effects
mutualism
+/+
both species benefit from interaction
commensalism
+/0
one species benefits, one unaffected
competition 
-/-
each species affected negatively
predation, parasitism, herbivory
+/-
one species benefits, one is disadvantaged
Neutralism
0/0
Neither species benefits or is harmed

30. Species Interactions competition (-/-) predation / parasitism (-/+)
compete for limited resource
competitive exclusion!
predation / parasitism (-/+)
Parasite: an organism whose ecological niche is closely linked to its host causing discomfort and possibly death to host
mutualism (+/+) (symbiotic)
lichens (algae & fungus)
commensalism (+/0)
barnacles attached to whale 30