BIOE 20C Lecture Notes - Lecture 14: Religion In China, Exponential Growth, Logistic Function

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Lecture 14 11/17/2015 8:59:00 PM
Demography
Study of factors that influence population size and structure over
time
4 main components that influence size
o Birth rate: increase
o Death rate: decrease
o Immigration: increase
o Emigration: decrease
Factors Needed to Predict Population Growth
How many individuals are alive now
How many are likely to survive (survivorship)
How many offspring will be produced (fecundity)
Immigration/emigration rates
Time from birth to first reproduction (generation time)
Survivorship
Proportion surviving to a particular age class
Always relative to original amount present
Individuals born in same period=cohort
Survivorship curves=log(survivorship)
Three basic types
o Type I (Physiological): young survivorship high, old low
o Type II (Ecological): survivorship constant through life
o Type III (Maturational): young survivorship low, old high
Fecundity
# of offspring produced
Often limited to # of female offspring produced by female parents
Age-specific fecundity=average # of females produced by a female
of a certain age class
Survivorship and Fecundity
Individuals have finite amount of energy
Trade off between growth and reproduction
Selection favors optimum allocation for fitness
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Low survivorshiphigh age specific fecundity
High survivorshiplow age specific fecundity
Life Tables
Used for demographic analyses
Required information
o Initial number born in a cohort (N)
o # that survive to each age class (lx)
o Average fecundity for each age class (mx)
Calculating Population Growth with Life Tables
If you only consider females
(lx)=age specific survivorship
(mx)=age specific fecundity
(lxmx)=number of female offspring produced by an individual in
each year class
Net Reproductive Rate
Sigma(lxmx)=R0=net reproductive rate (growth rate for generation)
If R0>1, then population growing
If R0<, then population shrinking
Per Capita Rate of Increase
R0=generational growth rate
r is per capita growth rate
o AKA instantaneous growth rate
Intrinsic Rate of Increase
r can be +, -, or 0
rmax=intrinsic rate of increase
Highest possible r for a species
Determined by biological constraints
Discrete vs Continuous Growth
Populations with distinct breeding season demonstrate discrete
growth
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Document Summary

11/17/2015 8:59:00 pm: study of factors that influence population size and structure over time, 4 main components that influence size, birth rate: increase, death rate: decrease, immigration: increase, emigration: decrease. Factors needed to predict population growth: how many individuals are alive now, how many are likely to survive (survivorship, how many offspring will be produced (fecundity, immigration/emigration rates, time from birth to first reproduction (generation time) Fecundity: # of offspring produced, often limited to # of female offspring produced by female parents, age-specific fecundity=average # of females produced by a female of a certain age class. Survivorship and fecundity: individuals have finite amount of energy, trade off between growth and reproduction, selection favors optimum allocation for fitness, low survivorship high age specific fecundity, high survivorship low age specific fecundity. Life tables: used for demographic analyses, required information, initial number born in a cohort (n, # that survive to each age class (lx, average fecundity for each age class (mx)

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