Pearson & Dawson Quiz
1. What is a bioclimatic envelope?
2. How might bioclimatic envelope models be
useful for invasive species management?
3. List and describe two weaknesses of bioclimatic
envelope models.
Pearson & Dawson Quiz
4. What is equilibrium in the context of bioclimatic
envelope modeling? Do you think disequilibrium
is likely to be a problem for modeling invasive
species?
5. In addition to climate, what other environmental
variables are likely important for the distribution
of species?
Chinese mitten crab (Eriocheir sinensis)
Exam Review
Definition of an invasive species
• Non-native
• Capable of surviving without direct help from
people (established or naturalized)
• Spreading away from sites of initial
establishment
• Often with negative ecological and economic
consequences
Lockwood et al., 2007
Are resource opportunities from global
change likely to be evenly or unevenly
distributed globally? Give an example
of an ecosystem or location at high risk
of invasion due to higher resources
Anthropogenic global changes:
- Climate change
- Nutrient addition
- Invasive species
- Habitat loss (disturbance & degradation)
At Risk: Ecosystems with scarce resources
• If resources are
limited, native
species are adapted
to scarcity
• Anthropogenic
addition of
resources creates
new ‘empty’ niches
Biogeography
Definition:
• Understanding more about a species by using
information from where the species is located
Examples:
– In what range of temperatures does the species
establish? (Physiological tolerance)
– Is the species located near human activity?
(Disturbance responsive)
What affects invasive species spread?
What affects invasive species spread?
Species Traits:
• Dispersal ability
• Fecundity (number of seeds or
offspring)
• Wide environmental tolerance
• Fast generation time (early
sexual maturity)
• Generalist
What affects invasive species spread?
Environmental Factors:
• Disturbance
• Climatic suitability
• Other environmental suitability
(soils, nutrients, prey)
• Dispersal corridors
(environmental connectivity)
• Dispersal vectors (e.g., seed
carriers)
Climatic Similarity Predicts Invasion
Significant Predictor of Establishment
Characteristic
# Datasets
Characteristic
# Datasets
Significant Predictor of Invasion
Hayes & Barry, 2008
Similar climatic regions
Similar climatic regions
Biogeographical Modeling of Species
Potential Distributions
Relevant to invasive species because it can potentially
predict invasion risk
BEMs use biogeography to empirically
determine climatic tolerance
Problem: Equilibrium Assumption
• Assumes a species is at equilibrium with its
environment (it exists everywhere that it could exist)
• The equilibrium assumption FAILS for invasive species
• Invasives are still spreading…
Evidence of an equilibrium problem
At early stages of invasion
(upper left), models of
potential suitability are
incomplete.
Only at later stages of
invasion (lower right), when
the species has had time to
spread, can models
encompass environmental
suitability
Vaclavik & Meentmeyer, 2011
A way around the equilibrium problem?
Use the native range to predict invasion
Only 7 out of 50 invasive
plant species tested had
invaded ranges that exceeded
the climatic conditions of
their native ranges by more
than 10%
Climatic Space
Less than 10% of A+B
Petitpierre et al., 2012
Climate matching
Carpobrotus edulis (ice plant)
Native to South Africa
Thuiller et al., 2005
Realized vs. Fundamental Niche
Fundamental Niche:
• All the environmental
conditions in which a
species can survive.
Realized Niche:
• Fundamental niche minus
dispersal limitations &
competition with other
species.
Climatic Space
Realized Niche
Invaded Range
Realized Niche
Native Range
Fundamental Niche
Use climatic
conditions from
all native and
invaded range to
define
fundamental
niche
Kriticos et al., 2011
Another Approach:
Use Species’ Physiological Tolerance
Physiological Tolerance to Extremes
Survival (%)
Responses of 7
grass species to a
heat wave of
+11°C
Heat wave duration (days)
Milbau et al. 2005
Use physiological characteristics to
model potential geographic range
Buckley, 2008
Biogeography team task
1. What are the spatial extents of invasion risk
for your target species?
2. How do the results of a bioclimatic envelope
model differ from an assumption based on
physiology?
Biogeography team task
Biogeography team task
Reading assignment for Thursday:
Find and read one paper (use Google Scholar or Web
of Science!) describing the physiological tolerance or
climatic limits of your target species.
Search examples:
Genus species +
temperature tolerance, freezing tolerance,
physiological limitation, heat stress, climatic
limitation
Species of the day: Caulerpa taxifolia
“Killer Algae”
• Forms dense, monotypic stands
• Crowds out native vegetation
• Toxic to herbivores
• Affects behavior of fish & other organisms
Impacts on (one example) fish
Mullus surmuletus activity in the Mediterranean
C. taxifolia:
Established
Not Established
Levi and Francour, 2004
Popular aquarium algae
• Cold-tolerant strain developed in 1980 at an aquarium in Stuttgart
• Cold-tolerant strain shared with aquariums in Nancy, Geneva & Monaco
• Monaco aquarium likely source of release into the Mediterranean
Jousson et al., 1998
Invasive strains are genetically
identical to the aquarium strain
Branches of the tree denote
genetic difference 
‘Aquarium strain’ also found
off the coasts of Australia and
Southern California
‘Aquarium strain’ likely
tolerant of lower temperatures
than species in native range
Jousson et al., 1998
Pearson & Dawson, 2003
Why do you think BEMs only include climate? Why
not include biotic interactions?