Download Chapter 6: Establishment Success: The Influence of Biotic Interactions

Chapter 6:
Establishment Success:
The Influence of Biotic Interactions
Jessica Oh and Ruth Singer
3 Difficulties in Exploring
Biotic Interactions
1) Difficulty in observing establishment
• Mathematical models
• Observation
• Controlled experiments
Question:
What are the pros and cons of the three
different methods? Should they be used in
combination with each other?
3 Difficulties in Exploring
Biotic Interactions
2) Defining establishment versus spread
3) Defining resistance
Question:
The definition of resistance varies throughout
the literature from any negative influence on
establishment to repelling non-natives
completely. Where does your definition of
resistance fall within this range?
Competition
Example for resistance:
Example for facilitation:
Predation
Example for resistance:
Example for facilitation:
Mutualism
Example for resistance or facilitation (depending on the
presence/absence of its obligate or facultative mutualist):
Questions:
A great debate in invasion ecology exists about the
relationship between native and non-native
species richness.
•Do you agree with the book’s definition of species
richness as sheer number of species in an area?
•How would you define species richness? (ie.
functional groups)
•What are the most important components of
species richness for biotic resistance?
Questions:
The Eltonian “Diversity-Invasibility hypothesis” states
that places with many diverse native species are more
likely to repel non-natives. While data from smallscale experiments (ex. Smith & Knapp 2001) have
agreed with Elton’s hypothesis, the opposite trend
has been seen in experiments with larger scale
observational studies and mathematical models.
• What are some of the factors that might be
contributing to these contradicting findings?
Questions:
Of the three categories of biotic interactions
(competition, predation, and mutualism), which
one do you think is the most important in either
resisting or facilitating non-native establishment?
Questions:
On Isla Victoria in Argentina, Simberloff et al found
that introduced deer reduced the presence of the
non-native pine species in areas where native
competition was minimal.
• From an ethical/management perspective, how do
we take a stand against non-native species when
that same species prevent the establishment of
another, potentially harmful, non-native species?
Questions:
Ted Case (1990) found that a native species had an
advantage over a non-native species by simply being
there first.
• Why do you think the “priority effect” takes
place?
•If there was a disturbance that created an opening
for a non-native to establish, do you think the
priority effect would still cause the native species
to re-establish?