1. Commensalism & Mutualism
BIOL/BOT 160 – Ecology

2. Commensalism
One species gains a benefit from another but does not harm the other.
Very hard to prove!

3. Urechis caupo (Fat Inkeeper)
Commensal species
Permanent
Pea crab (Scleroplax granulata)
Scale worm (Hesperonoe adventor)
Clam (Cryptomya sp.)
Temporary
Goby (Clevelandia ios)

4. Mutualism Both species benefit Mycorrhizae
From Smith and Smith: Ecology & Field Biology

5. Mutualism Ants and Acacia

6. Mutualism Protection Food What benefit does the plant get?
What benefits to the ants get?

7. Why would corals need a symbiont?
Mutualism
Coral Reefs
Why would corals need a symbiont? =
Only 10% of their diet!

8. Mutualism Zooxanthellae Coral Reefs
Zooxanthellae

9. Mutualism Zooxanthellae Coral Reefs
One of the reasons why corals need shallow water
Zooxanthellae

10. Mutualism Coral Reefs Allows a rich and diverse ecosystem
Mutualism
Coral Reefs
Allows a rich and diverse ecosystem

11. Mutualism Flowers and bees

12. Mutualism Allows increased fitness for both symbionts
Drives co-evolution

13. Not always beneficial Nutrient poor soils Nutrient rich soils
Mycorrhizae
Mycorrhizae

14. Mutualism types Lichens Ant Acacia Obligate symbiotic
Physically intertwined and can’t exist independently
Obligate non-symbiotic
Are not physically intertwined but need each other to survive.

15. Mutualism types Rye grass Acremonium Non Obligate
Acremonium

16. Might parasites evolve to commensalism and then mutualism?
Tapeworm

17. Might parasites evolve to commensalism and then mutualism?
E. coli