NVTB 2008 Jaap van der Meer
description
Transcript of NVTB 2008 Jaap van der Meer
Royal Netherlands Institute for Sea Research
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Seasonal timing of reproduction in the bivalve Macoma balthica: a model study of fitness consequences
NVTB 2008
Jaap van der Meer
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Question
Timing of reproduction: Make sure the larvae can grow up under optimal food conditions
Spawn just before the spring bloom
Many species don’t do this
An why should they?
Alternative rule: Make sure the bloom occurs at the size of maximum growth
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System
Semi-chemostat
Seasonal pattern in food concentration of inflowing water
Seasonal pattern in temperature
Standard DEB model
Macoma balthica parameters as estimated by Van der Veer et al. (2006)
R extremely small: 0.012%; background mortality
One spawning event per year
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60 days after
5000 5010 5020 5030 5040 5050
3.5e
+08
4.5e
+08
5.5e
+08
6.5e
+08
year
popu
latio
n si
ze
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110 days after
2500 2550 2600 2650
2e+
083e
+08
4e+
085e
+08
year
popu
latio
n si
ze
6
160 days after
0 10 20 30 40 50
2e+
083e
+08
4e+
085e
+08
6e+
08
year
popu
latio
n si
ze
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Spawning date: bifurcation analysis
-100 0 100 200
2e+
083e
+08
4e+
085e
+08
6e+
087e
+08
days before the plankton peak
popu
latio
n si
zeafter before
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160 days after
0 1 2 3 4 5 6 7
8.3
8.5
8.7
year
log n
um
bers
0 1 2 3 4 5 6 7
200
400
600
800
year
food
0 1 2 3 4 5 6 7
56
78
year
log n
um
bers
0 1 2 3 4 5 6 7
0.0
0.2
0.4
0.6
year
length
0 1 2 3 4 5 6 7
0100
200
300
year
reserv
es
1200 1400 1600 1800
0.0
0.2
0.4
0.6
e
length
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Adaptive dynamics
Introduce a mutant that has no effect on the (food) environment, and see whether it can invade
In a k-year cycle of the resident, mutants are introduced during each of k succeeding years
In one run, three types of mutants were introduced: the first
group spawns slightly earlier, the second group does as the residents, the last group spawns slightly later
Mutants
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12000 12050 12100 12150 12200 12250 12300
1213
1415
16
time in years
log
num
bers
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Invadability
0 5000 10000 15000 20000
1012
1416
1820
time in years
log
num
bers
after before
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140 days before the plankton peak
0 200 400 600 800 1000 1200 1400
010
020
030
0
age
repr
oduc
tion
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140 days before the plankton peak
700 705 710 715 720 725 730
140
150
160
170
180
age
repr
oduc
tion
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60 days after the plankton peak
0 200 400 600 800 1000 1200
050
100
150
200
250
300
age
repr
oduc
tion
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60 days after the plankton peak
1050 1060 1070 1080 1090 1100
220
240
260
280
300
age
repr
oduc
tion
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Individual state
800 1000 1200 1400 1600 1800 2000
0.00
0.05
0.10
0.15
0.20
0.25
0.30
reserves
volu
me
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Invadability
0 5000 10000 15000 20000
1012
1416
1820
time in years
log
num
bers
after before
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Preliminary conclusion
Stable strategy: spawn exactly half a year before the food peak
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Next steps
Present survival rule: [E]/[Em] > L/Lm
Resorption of reproductive material
Low R
A-symmetric interference, which decreases the competitive ability of the youngsters