Transcript Chap.13 Adaptation of Life Histories

Chap.13 Adaptation of Life
Histories
鄭先祐 (Ayo)
國立台南大學 環境生態研究所
Adaptation of Life Histories
13.1 Introduction
13.2 Concepts in life-history theory
13.3 Growth and maturation
13.4 Scaling of time and energy
13.5 Parental effort and investment
13.6 Seasonal timing
13.7 Offspring size and numbers
13.8 Population heterogeneity in life histories
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13.1 Introduction
Life history is the distribution of major events
over the lifetime of individuals.
Life history studies concern the timing and the
intensity of reproduction, as well as the
processes generating this temporal distribution.
They analyze life span, age and size at maturity,
the trade-offs between somatic growth,
maintenance and repair versus reproduction, the
decisions on number and size of the offspring,
the investment in current offspring and in future
reproductive attempts.
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13.2 Concepts in life-history theory
13.2.1 Traits
– A trait is any quantitative property of a living
organism.
– Life history concentrates on traits such as age
of first reproduction, clutch size and sex ratio
of the offspring.
13.2.2 Fitness
– (p.312)
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13.2.3 Trade-offs
– Since fitness is a complex measure, based on
multiple components, a change in strategy
may have negative consequences for one
component, and positive effects on another.
– Such consequences determine a trade-off, e.g.
between current and future reproduction, or
between the number of offspring and their
reproductive value.
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13.2.4 Optimization
– By identifying trade-offs, we may hope to
define models predicting optimal values for
particular life-history traits; optimal at least
under particular conditions.
– These values are those which maximize
fitness.
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13.2.5 Decision rules and reaction norms
– A reaction norm describes the variation in trait
values as a function of environment and/or
condition.
– Decision rules refer to the mechanism of
response to these conditions.
– In essence the two concepts are the same.
– Reaction norms or decision rules are optimal
if they maximize fitness for each
environmental condition.
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13.2.6 Constraints
– We use the word constraints in the sense of the
boundaries of the option set or parameter space.
Fig 13.1 The
dashed line is the
optimal reaction
norm connecting
the optima for
different
environments.
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13.3 Growth and maturation
The first major life-history problem an animal
faces is when to start reproduction?
LRS (體積)
Fig. 13.2 Optimization of
age and size at maturity
in Kozlowski’s model.
fecundity
存活率
Age at maturity
The switch from growth
to reproduction at age
a2 yields a higher
lifetime reproduction
success (LRS).
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Fig13.3 Body mass as a function of age in female Arctic
Charr in Labrador.
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13.4 Scaling of time and energy
Body mass 的大小限制
時間與空間的使用。
Fig. 13.4 Allometry of
the rate of living.
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A = assimilation = awb
R = respiration = rwb
w = body mass
P = production = (a-r)wb
C= a- r
m = mortality = dP/dw
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Squares =
c constant,
m varying
Dots = c varying,
m constant
Circles =
c varying,
m varying
Fig. 13.5 Production (a) plotted against body mass
for 50 species in a resource allocation model
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Squares =
c constant,
m varying
Dots = c varying,
m constant
Circles =
c varying,
m varying
Fig. 13.5 age of maturity plotted against body mass for 50
species in a resource allocation model.
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Open circles
m=0.0002
c=0.015
Dots
m=0.0002
c=0.030
Trangles
m=0.0004
c=0.015
Fig. 13.6 Production (a) plotted against body mass
for 50 species in a resource allocation model
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問題與討論
http://mail.nutn.edu.tw/~hycheng
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