what, exactly, is a biotic interactions?
TRANSCRIPT
What, exactly, is a biotic interaction?
Bob O'Hara
Senckenberg BiK-F
Frankfurt am Main
Germany@bobohara
slides:
– www.slideshare.net/oharar/what-exactly-is-a-biotic-interactions
Thanks to - Damaris Zurell
Laure Gallien
Jens-Christian Svenning
Lesley Lancaster
Katja Schiffer
For comments & organisation
Are these animals interacting?
Photo: “sea war, 1 of 8 - no, you can't have it” by Sean Hoyer https://flic.kr/p/qHjzk
Are these animals interacting?
Photo: Tim Felce (Airwolfhound) [CC BY-SA 2.0], via Wikimedia Commons
Two Dissections
Direct and Indirect Interactions
Processes and Outcomes
Processes and Outcomes
For many biotic interactions, the species do not actually interact
Source: U.S. Navy NAVSUPFAC DIEGO GARCIA, Natural Resources Management Plan, 2005: http://bit.ly/1OTt6vz
Source: http://www.bees.unsw.edu.au
Competition ≠ Interaction?
Scramble Competition (for resources)
"Scarabaeus laticollis" by Rafael Brix - [CC BY 2.5] via Commons http://bit.ly/1QcgXDa
Mutualism
No direct Interactions
"Cows at dawn" by fir0002 [GFDL 1.2] via Commons - http://bit.ly/1lqEN1I
Grass can be a limited resource for grazing cows
Outcomes
Biotic Interactions!
Changes in community structure due to changes in other parts of the community
Process ≠ Outcome
Try not to confuse outcome with process
Scramble competition is only an interaction because of its effect
What is a biotic interaction?
When is a process a biotic interaction?
Photo by Janderk (Jan Derk) [Public domain], via Wikimedia Commons
Not a Biotic Interaction
Species 1 Species 2
Environment
Two species affected by the environment
Direct Interactions
One species does something to another
Species 1 Species 2
Predation Parasitism
Herbivory Pollination
Seed Dispersal
Mediated Interactions
Species 1 Species 2
Environment
Two species affect the environment
Scramble Competition Ecosystem engineering
Shading
Indirect Effects
Species 1 Species 2 Species 3
PlantHerbivore/PreyPredator
Is there a biotic interaction between plant and predator?
Trophic cascades?
Apparent Competition
Helpless Prey 1
EvilPredator
Helpless Prey 2
Is there a biotic interaction between prey species?
Spot the Difference
Does it matter if indirect effects go through a biotic or abiotic component?
Prey 1
Predator
Prey 2Species 1 Species 2
Environment
Spot the Difference
Does it matter if indirect effects go through a biotic or abiotic component?
Prey 1
Predator
Prey 2Species 1 Species 2
Environment
Perhaps not – because feedback
Is this it?
Feedbacks are important
Biotic Interactions = ecological effects due to individual behaviours with feedbacks
Species 1
Species 2Species 1 Species 2
Environment
What have we learned?
Biotic interactions are about cause and effect
Indirect effects might or might not be biotic interactions
By Janderk (Photographed by Jan Derk) [Public domain], via Wikimedia Commons
Feedback is important
Is this important?
You decide!