Transcript powerpoint - White Mountain Research Center

GENETICS, PHYSIOLOGY AND ECOLOGY OF SUBALPINE BEETLE POPULATIONS:
RESPONSES TO CLIMATE CHANGE
Some examples of our work…
Some examples of our work….
beetle: Chrysomela aeneicollis
Coleoptera: Chrysomelidae
Predation
Air Temperatures and Snow Pack
wasp: Symmorphus cristatus
(Hymenoptera: Vespidae)
Fly: Parasyrphus melanderi
(Diptera: Syrphidae)
6
o
Mean minimum Ta ( C)
Elizabeth Dahlhoff (1), Nathan Rank (2), John Smiley (3)
survival of beetle larvae improves if predators are excluded
Beginning in 1981, we have studied changing populations of the leaf beetle Chrysomela
aeneicollis, feeding on willow shrubs (Salix spp.) at 2375-3550m above sea level in the Eastern
Sierra Nevada mountains, California. During 25 years of observation we have observed range
expansion and contraction during at least two wet-dry cycles, along with other changes. In
1988 we began sampling beetles at sites in three drainages (Rock Creek, Bishop Creek and Big
Pine Creek) which revealed genetic variation across temperature gradients and elevations. In
1998 we began continuous monitoring of Salix habitat temperatures and snowmelt dates in
these same drainages. These long term data sets, along with numerous other studies of the
beetles’ predators, ecology, behavior, physiology and genetics, have revealed a complex and
unusually complete picture of changing insect populations in high mountain environments.
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2
0
BPC
BC
RC
-2
-4
150
160
170
Daily Mean Ta (oC)
Elevation color bands:
4000-4250m light gray
3750-4000m light blue
3500-3750m blue
3250-3500m blue-green
3000-3250m green
2750-3000m yellow-green
2500-2750m tan
2250-2500m light tan
2000-2250m yellow
1.5
1.4
1.3
1.2
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A
1.1
1998 1999 2000 2001 2002 2003 2004
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13
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BPC
BC
RC
2000
2001
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# Days snow above 1 meter
log hunting time, min
yellow dots = Salix foliage air temperature loggers
orange dots = loggers planned for 2006
1.0
Year
2.0
log hunting time, min
200
Willow foliage air temperature: After factoring out elevational
differences using ANCOVA, mean daily minima increased
through the summer. In all 3 drainages, June was the most
likely month to experience sub-zero temperatures.
Study site drainages (arrow points north)
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190
Day of Year
15
North Palisade Peak
180
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
13 14 15 16 17 18 19 20 21
2002
2003
2004
2005
2002
2003
2004
2005
B
200
150
100
50
0
2000
2001
o
Air temperature, C
Year
Big Pine Creek
1981-present
S. cristatus hunting success (reduced
hunting time) depends on prey
abundance and air temperatures. Since
2000, wasp has colonized sites above
3100m (upper edge of green zone) in
BPC.
Rock Creek was the coolest drainage, and Big Pine Creek
the warmest. The coolest drainages often had the
longest-lasting snowpack.
Bishop Creek
1988-present
Rock Creek
1988-present
Genetics, Physiology and Evolution
Elevation Gradient and Climate Change
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CTmax ( C)
Findings
Plans for 2006-2015
wet
dry
wet?
has there been an
upward expansion
since 2000?
•Drainage-dependent air temperature differences,
superimposed on a complex altitudinal gradient.
•Summer air temperatures lethal to beetles, with corresponding
differences in mortality.
•Expansion and contraction of beetle populations during wet/dry
cycles
beetle elevation range
expands during wet periods
and contracts during dry
periods.
e CV
log beetle abundance
2.5
2.0
•Monitor air temperatures and humidity along four elevation
gradients (add North Lake-Piute Pass drainage) and relate them
to fluctuations in abundance of C. aeneicollis and two specialist
predators S. cristatus and P. melanderi.
•Beetle populations shifted upwards in elevation in BPC, the
warmest drainage, during recent warm dry years, but that this
altitudinal shift did not occur in RC or BC.
•Quantify variation in physiological response to temperature in C.
aeneicollis and its predators.
•Beetle abundance is lower in RC, the coolest drainage, than BC
or BPC.
•Survey changes in frequency of phosphoglucose isomerase
(PGI) in a drainage where PGI is polymorphic.
•Populations of the specialist hunting wasp Symmorphus
cristatus, one of the beetles’ principal predators, have shifted
upwards in elevation. We have also measured temperaturerelated foraging success for this wasp.
A
Using the University of California White Mountain Research
Station (WMRS) as a base of operations, we plan to continue and
expand these studies for at least 10 more years, funding
permitting:
beetle abundance peaks
at 3200m in BP and
3000m in BC and RC.
0.5
0.0
-0.5
2600
250
B
200
2800
3000
3200
3400
Affiliations
(1) Dept. of Biology, Santa Clara Univ.; (2) Dept. of Biology,
Sonoma State Univ., (3)Univ. of California White Mountain
Research Station
0.8
•Quantify effects of climate on S. cristatus ecology and behavior.
•Make weather and insect abundance data available on the
WMRS web site www.wmrs.edu
This work provides a unique opportunity to integrate studies of
the mechanisms underlying population change with
comprehensive data on climate, for native insect species in
physically challenging environments.
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o
0.7
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0.6
35
0.5
360
1-1
0.4
0.3
RV: 2883 m SL: 3005 m PL: 3170 m SC: 3194 m
Site
1-4
4-4
B
320
280
240
200
160
1-1
1-4
4-4
Frequency of phosphoglucose isomerase
PGI Genotype
(PGI) allele 1 declines with elevation in Bishop
Creek, yet increased at all sites between 1988
and 1996.
PGI-1 allele is associated with increased expression of heat
shock proteins (HSP70), which protect against cold
temperatures. PGI-4 confers increased tolerance to high
temperatures (CTmax critical thermal maximum)
1.2
1.5
1.0
l988
l996
HSP70 Expression
dry
Selection Coefficient (s)
wet
PGI-1 allele frequency
0.9
A
(a) Old Adults to Larvae
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(b) Larvae to New Adults
0.8
0.4
0.4
0.0
0.0
-0.4
-0.4
-0.8
r = 0.80
-0.8
r = -0.88
P = 0.01
P = 0.03
-1.2
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22
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Mean Maximum Temperature (°C)
These graphs show how PGI frequencies evolve (selection
coefficient) as a function of temperature, and how selection is
reversed in the later stages
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