1. Do Now, 4.4 Food Web Labs, Please
OBJECTIVE:
Describe interspecific interactions, including: predation, herbivores, competition, symbiosis, parasitism, mutualism, commensalism, and mimicry.
TASK:
Using the food web shown, describe what might happen if the squid population were to decrease greatly. Which populations would benefit, and which would be harmed?

2. Population Interactions

3. Predators and their Prey
Predator survival depends on capturing food.
Prey survival depends on hiding, escape, or other defenses.
Since only successful organisms survive and reproduce, the genetic material of the best (or luckiest) organisms gets passed onto the next generation. This is called natural selection.

5. Plants and Herbivores Animals that eat plants = herbivores.
Some plants produce poisonous or bad-tasting secondary compounds as a defense against herbivores… but not the grass this cow is munching!

6. Competition
Resources (like food / energy) are limited. When two populations share the same niche, they will compete for use of that resource.
Do human populations compete for resources?
What resources?

7. Competitive Exclusion: One species is removed from the community because it could not get enough of the resource
Resource Partitioning: Several species use part of the available resource, reducing competition.

8. Symbiosis
Symbiosis is the close association between two or more different species or organisms.
Three main types
Parasitism
Mutualism
Commensalism

9. Parasites and Parasitism
A parasite feeds on its host.
Similar to predator / prey, but the prey isn’t usually killed.
Endoparasites are internal, Ectoparasites aren’t.
Ectoparasite: Deer tick
Endoparasite: Trichonella

10. Mutualism
A cooperative relationship where both organisms benefit

11. Commensalism
One organism benefits, the other is unaffected

12. Mimicry
Batesian mimicry: A harmless organism resembles a poisonous or distasteful one.
Or…

13. More Mimicry
Müllerian mimicry: Several poisonous or distasteful species look similar