1. Ecology!
Sections
43.5

2. Populations Population: all individuals of 1 species in area
Population size : number of individuals
Population density : number per area
Population distribution : dispersal pattern

3. Distribution patterns
1) Clumped: most common,
a) group around resources
b) social behavior
c) lack of offspring dispersal
2) Uniform (or close enough)
a) territory division
b) fairly uniform resources
3) Random – rare
a) uniform resources
b) ignore each other

4. Population Size Estimates
1) full count
2) Quadrats
3) Transects
4) Mark-recapture
m-r good for organisms
that move around a lot

5. Mark-recapture Based on assumption:
% of recaptured individuals that are marked..
same as
the % of the total population that is marked
Steps: day 1 capture organisms & mark them
day 2 capture organisms & see what
% of the organisms are marked
calculation day 2 marked = day 1 marked
day 2 total total population

6. Population Growth Positive growth …….. birth & immigration
Negative growth …… death & emigration
Migration : periodic change w/ seasons
Zero population growth (ZPG) : deaths = births
Per capita = per individual
Population growth (dN/dt) = births – deaths
where
d indicates change ….same as Δ
N is the number of individuals, t is time
so ΔN/Δt

7. r = net reproduction per capita per unit time
N = number of individuals in population
Population growth rate = r x N

8. Rapid Population Growth
High r….have lots of babies fast, few deaths
High N……large populations grow faster
Exponential growth : population grows at a rate proportional to its size
a) r remains constant
b) ideal conditions allow max r
Biotic potential : max r for a population
Doubling time: time for pop to double size

9. Logistic Population Growth
Exponential Growth slowed by
1) Density dependent limiting factors
predation, parasites, disease
limited resources, competition
not by Density independent limiting factors
weather, natural disasters, humans

10. Carrying capacity =
Max # individuals an area can support indefinitely (D)
Steady state
#2 on graph
Life history patterns: adaptations that influence survival, reproduction & population size

11. Reproduction Requires Energy
Amount of available energy affects reproductive rates and success
Seasonal reproduction timed to match resource availability
Reproductive strategies match environment to maximize repro success

12. Reproductive strategies
r-selected (r = net reproduction per capita per unit time)
a) favor low pop density (d independent)
b) quick production of many small babies
c) high biotic potential so called r-selected
K-selected (K = carrying capacity )
a) favor high pop density (d dependent)
b) good competitors
c) low biotic potential & high parental care

13. Life History Strategies

14. Environmental effect on Repro.
1) Unstable/changing environments
a. can show more rapid evolution
b. can select different traits each generation
c. mature quickly and have lots of babies
d. r-selected
2) Stable environments
a. longer life span slower to mature
b. produce fewer offspring
c. more efficient use of E
d. K-selected

15. Different Life Histories =
Different Survivorship Curves
Type I : live long & prosper
(parental care)
k-selected
Type II : could die at any time…
good luck
Type III : high infant mortality
r-selected

17. Human Population growth
First 1 billion……2.5 mya
growth to 2 billion…………..123 years
Growth to 3 billion …………. 33 years
Growth to 4, 5, 6 ………….. 14, 13, 12

18. Dot video

19. Fertility Rates and $$$$$$$
Total Fertility Rate (TFR) –
average # children born per woman
World wide TFR = 6.5
Replacement = 2.1
TFR in developed countries = at or below 2.1
TFR in developing countries = highest

20. Demographic Transition Model
Niger, Guatemala, Afghanistan : stage 2
India, South Africa, Columbia : stage 3
Brazil, United States, China : stage 4
Germany, Japan : Stage 5

21. Age Structure Diagrams
3 categories of individuals:
-pre-reproductive (base)
-reproductive (center)
-post-reproductive (top)
Fast growth = wide shape
Slow growth = narrow shape
ZPG = straight at bottom, narrows at top
Negative growth = bottom & top more narrow than center

22. 2014 pop pyramid data

25. U.S.A.