an elevation and drainage comparison of predation by syrphid flies on willow leaf beetles by: reu...
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An Elevation and Drainage Comparison of Predation by Syrphid Flies on Willow Leaf Beetles By: REU Kallin Tea
To right: white mountain research station at sunset
Outline Introduction
• High Elevation, Life History of Critters
Experimental Design• Location of Study Sites
Materials and Methods• Choosing Sites, Monitoring
Results• What Happened?
Discussion• What it all Means?
IntroductionHigh Elevation
1800-3600 meters Lower Partial Pressure of Oxygen Cooler Temperatures
Photo by:Mark Shelp
Chrysomela aeneicollis Found in Eastern Sierra
Nevada – 2500-3300m– Cool, Moist Areas
Natural History well studied– Life stages from egg, larva,
to adult Specialist on Willow
Leaves– Salicylic Acid– Larva produce toxins
Parasyrphus melanderi Found extensively in North-Western Canada and California
– 2500-3300m Specialist Predator of C. aeneicollis
– Consumes eggs and larvae
http://www.wmrs.edu/people/BIOs/john%20smiley/beetle_project/CNPStalk_files/frame.htm
Experimental Design- 3 Drainages Rock Creek
– Heart Lake, Mosquito Flat, Pine Grove– 3190m, 3111m, 2837m
Bishop Creek (South Fork)– Pipeline, S.L. Parking Lot, La Hupp– 3131m, 2996m, 2854m
Big Pine Creek (North Fork)– Upper Site, Pond Bog, Falls Site– 3229m, 3128m, 2997m
Materials and Methods Why these Sites?
– Willow Groves– Previous Surveys, – Data Loggers
Egg Clutch Marking–All Field Work–How many clutches per site?
Follow-up
Experimental Design- Study Sites Rock Creek
– Heart Lake, Mosquito Flat, Pine Grove– 3190m, 3111m, 2837m
Bishop Creek (South Fork)– Pipeline, S.L. Parking Lot, La Hupp– 3131m, 2996m, 2854m
Big Pine Creek (North Fork)– Upper Site, Pond Bog, Falls Site– 3229m, 3128m, 2997m
ResultsDrainage Differences?
0%Big Pine
Creek
71%South Lake
30%Rock Creek
Statistically Significant P-value < 0.0001
Yes!Flies Not Found in Big Pine
Creek
0
10
20
30
40
50
60
70
80
South Lake Rock Creek Big PineCreek
% F
lies p
resen
t in
Beetl
e c
lutc
hes
Elevation Differences? Fly Predation in relation to Elevation
n= 6 in statistical analysis
NoNo
Comparing Fly Presence to Elevation
y = -0.0039x + 12.743
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2800 2900 3000 3100 3200 3300
Elevation
Avera
ge #
Fly
Eggs p
er
Clu
tch
AVERAGE # OF SYRPHI DEGGS
Linear (AVERAGE # OFSYRPHI D EGGS)
Why differences amongst drainages? Difference in Egg Clutch Size? NoNo
-Averages 41 Eggs per Clutch
Egg Clutch Size
0
5
10
15
20
25
30
35
40
45
50
South Lake Rock Creek Big Pine Creek
Drainage
# E
gg
s p
er
Clu
tch
Egg clutch size
Average clutch size at 41
Does Fly Presence Kill?
25% Survival w/ Flies
45% Survival w/o Flies
Lower Survival of Egg Clutches with Flies
y = -5.6507x + 45.269
0
20
40
60
80
100
120
0 2 4 6
# of Fly eggs present in beetle egg clutches
% B
eetl
e S
urv
iva
P-value < 0.05
YesYes
Bishop Creek:
Overall Survival Difference? 40% Average Survival
– 42.4% Big Pine Creek– 39.1% South Lake– 38.6% Rock Creek
NoNo
Same Average Beetle Survivability
0
10
20
30
40
50
South Lake Rock Creek Big Pine Creek
% B
ee
tle
su
rviv
al
surv.
Average Survival at 40
Discussion
Intuitively– If Fewer Fly Predators in Big Pine Creek, – Then More Survival of Beetle Eggs
Possible Explanations– Lower Hatching Percentage– Higher Threat by other Predators (mites,
ants)– Higher Occurrence of Cannibalism
Discussion
Nature is Complex and Sophisticated in Design– Balance
Understand it better . . . – Continue Studies in Future
THANK YOU!Wise, and Wacky Mentors
Prof. Elizabeth Dahlhoff
Prof. Nathan Rank
Humble Advisors
Dr. Eric Berlow
Dr. John Smiley
Thanks to all of WMRS Staff, who makes it all possible
And . . .
The INTERNS!