The Allocation of Net Assimilate
73
60
,.-...
U
btl 40
:::1.
'--'
d)
N
.- en
...c: u
::s
- u
1-0
20
0
>-.
"0
0
o:l
0
0
10
20
30
40
Age Cd)
Fig. 4.4. Simulated development of body mass (upper curve) and egg mass (lower curve) in
Daphnia pulex growing in surplus food. Shaded areas are ranges of body and dutch sizes
(recalculated to IJg C) for animals grown at food concentrations> 1 (mg C) I-I, as reported by
Lynch (1989)
The growth pattern predicted by the simulations (Fig. 4.4) reproduces
quite nicely the main life-history events in Daphnia pulex. The largest
discrepancy is found between observed and predicted adult body mass
(especially from an age of 25 days and onwards), while correspondence
between observed and predicted egg mass is uniformly good. As so much of
adult production is devoted to reproduction, total production will be
predicted with better accuracy than body mass.
Table 4.1. Body size characteristics in the growth history of Daphnia pulex
Parameter
Value
Bo
Egg size
l.llJg C
B/
Neonate size
l.llJg C
B'
Size at first reproductive investment
7.S IJg C
B"
Size at first maternity (primipara)
13.6IJg C
B m Maximum attainable size
60.0 IJg C