Notes on Article
Parts of the System:
Phytophthora ramorum - Sudden Oak Death Pathogen
Ixodes pacificus - Western black-legged tick Invertebrate
Deer mice
Lizards
Deer
Definitions:
Reservoir Hosts
Key Interaction studied in the Article:
Effect of an invasive plant pathogen - P. ramorum ON
Information on P. ramorum:
To date, 68 species in 40 plant genera are vulnerable
Main Idea of the Article is that EVERYTHING is connected.
A super complex web.
Canopy cover reduction -> More lizard activity -> More tick hitchhiking.
Acronyms:
CWD === Coarse woody debris
CCSP === China Camp State Park (California)
MMWD === Marin Municipal Water District (California)
Effects of an invasive forest pathogen on
abundance of ticks
and their vertebrate hosts
Swei, A.
Lane, R.
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Ostfeld, R.
Briggs, C
Background Information
Ecosystem of Interest:
California’s Oak Woodlands
-
Composed of
- Quercus spp. (Oak species)
- Tanoak trees
Organisms Studied:
- Oaks
- Fence Lizards
- Ticks (I. pacificus)
[Coast Live Oak] - A major player in this ecosystem!
Background Information (Continued)
Organisms Studied (contd.)
- Mammals (Tick Hosts)
-
Deer Mice
Deer mice
Woodrats
Deer
- Pathogens
-
Borrelia. burgdorferi
- (Lyme Disease!)
-
P. Ramorum [Oomycete]
- (SUDDEN OAK DEATH)
- Spread through spores
“Bleed”
…….
Sudden
Oak Death
The Big Idea???
INTERCONNECTEDNESS OF EVERY ECOSYSTEM
THROUGH THE LENS OF
AN INVASIVE PATHOGEN
Run-Down of Interactions
1.
P. Ramorum + Oaks
-
Parasitic Relationship
Oaks are Terminal Hosts
- Other plants come before ….
- Final Destination ….
2.
Ticks + Vertebrates
-
Parasite !
a. Deer
b. Deer Mice
c. Woodrats
d. Western Fence Lizards
3. Borrelia burgdorferi (Lyme Bacteria)
+ Hosts
-
Ticks are carriers
Vertebrates are also carriers (in bloodstreams)
Critical Points on Lyme Disease
1.
-
2.
-
Reservoir Hosts for Lyme Disease Bacteria
Maintain bacteria population
Crucial for spread
a. Deer Mice
b. Woodrats
Non-Reservoir Hosts for Lyme Disease Bacteria
Do NOT support the bacteria
“actively suppress the prevalence of B. burgdorferi”
- CLEANSES the ticks of their infections
- The Western Fence Lizard
us
r
o lis
p
o
el enta
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S cid
oc
Collected Data
TWO SITES! [Subplots Sampled]
1
Plant + SOD
2
3
Vertebrate
Abundance
Ticks +
Lyme Disease
Key Findings
SOD
Oak
Health +
Canopy
Coverage
SOD
Woodrats
SOD
Tick
Nymphs!
SOD
CRITICAL
Western
Fence
Lizard
Why? SOD → Tick Connections
-
Canopy Coverage Decline
- Good for Lizards
- Consistent with Prior Studies
- Timber-Heavy Regions correlated
with S. Occidentalis populations
-
Lizards are favorite (90%) hosts for young ticks.
- More lizards → More ticks →
More tick exposure
Figure 2 (ESM)
Sudden Oak Death results in:
Discussion
More Data:
-
Researchers noted:
- Relationships not clear!
- Conflicting factors
-
Lizard Immunization
More Nymphs
More Tick Exposure
OUTCOME?? ….
Alternative management methods
-
Indirect solutions:
-
POTENTIAL RISK OF CAUSING “invisible” catastrophes.
- Latent disasters that present themselves too late …
Activity
Discussion Question:
“Is it acceptable to harm/eliminate a
parasite or pathogen’s host species in
order to fulfill some objective?
This objective could be:
- Human Pandemic
- Ecological Stability”
Part I:
-
Free-write
7 Minutes
Jot down some thoughts about this discussion question
This writing will be the foundation of an in-class discussion
Give some thought ….
Think of one case/example that matters to you!
Part II: Fishbowl Style Discussion
-
30 to 45 Minutes
-
Two Groups: A and B
-
Two Halves of Activity
First Half:
Group A sits on the inside of a circle
Group B surrounds Group A
Group A discusses the central question we pose
Each person should provide one defence of their stance
-
Meanwhile, Group B takes notes!
Second Half:
Group B then becomes the inside circle
Each person should provide one defence of their stance
-
Group A takes notes!