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CHAPTER 8: POPULATION DYNAMICS,
CARRYING CAPACITY AND CONSERVATION
BIOLOGY
POPULATION DYNAMICS ARE OFTEN INFLUENCED BY COMMUNITY
STRUCTURE AND KEYSTONE SPECIES. THE SOUTHERN SEA OTTERS
ALMOST WENT EXTINCT, AND BECAUSE OF THIS, IT WAS POSSIBLE TO
GATHER DATA SUPPORTING THE HYPOTHESIS THAT THEY ARE
KEYSTONE SPECIES DUE TO THEIR ROLE IN CONTROLLING SEA
URCHINS BECAUSE URCHINS EAT KELP PREVENTING SEA FORESTS.
Slide 1
POPULATIONS ARE DISPERSED IN 3 BASIC PATTERNS
AND THIS DISPERSION IS A INTEGRAL PART OF
COMMUNITY STRUCTURE. HERDS CLUMP FOR
PROTECTION, CREOSOTE BUSHES PRODUCE SOIL
TOXINS KEEPING NEIGHBORS AT A SET DISTANCE AND
DANDELIONS DO WHAT THEY PLEASE.
Figure 8-2
Page 161
Clumped
(elephants)
Uniform
(creosote bush)
Random
(dandelions)
Slide 2
TWO COMMON TYPES OF POPULATION GROWTH
CURVES. KNOW THE PHASES OF THE LOGISTIC
CURVE (LAG, EXPONENTIAL, STATIONARY, DEATH)
© 2004 Brooks/Cole – Thomson Learning
Population size (N)
Population size (N)
K
Time (t)
Exponential Growth
Time (t)
Logistic Growth
Figure 8-4
Page 163
Slide 3
FOR TASMANIA
2.0
CARRYING
CAPACITY
Number of sheep (millions)
OVERSHOOT
1.5
1.0
.5
1800
1825
1850
1875
Year
1900
1925
Figure 8-5
Page 163
Slide 4
RAINDEER INTRODUCED
TO ALASKAN ISLAND
(1900-50)
TYPES OF POPULATION CURVES
© 2004 Brooks/Cole – Thomson Learning
Irregular
Number of individuals
Stable
Cyclic
Irruptive
Time
Slide 5
IS THIS DENSITY DEPENDENT OR DENSITY INDEPENDENT SELECTION?
Density independent affect population size regardless of its numbers.
Examples are floods, hurricanes, bad weather, fire habitat destruction
and pesticides (agent orange).
Density dependent factors have a greater effect as population density
increases. Examples are competition for resources, predation,
parasitism and disease (bubonic plague).
Population size (thousands)
160
140
Hare
120
Lynx
100
80
60
40
20
0
1845
1855
1865
1875
1885
1895
Year
1905
1915
1925
1935
Slide 6
cockroach
r-Selected Species
K-Selected Species
dandelion
elephant
Many small offspring
Little or no parental care and
protection of offspring
Early reproductive age
Most offspring die before
reaching reproductive age
Small adults
Adapted to unstable climate
and environmental
conditions
High population growth rate
(r)
Population size fluctuates
wildly above and below
carrying capacity (K)
Generalist niche
Low ability to compete
Early successional species
saguaro
Fewer, larger offspring
High parental care and protection of offspring
Later reproductive age
Most offspring survive to reproductive age
Larger adults
Adapted to stable climate and environmental
conditions
Lower population growth rate (r)
Population size fairly stable and usually close
to carrying capacity (K)
Specialist niche
High ability to compete
Late successional species
Figure 8-10
(2)
PageSlide
1677
A SURVIVORSHIP CURVE SHOWS NUMBER OF SURVIVORS OF EACH AGE
GROUP AND VARY BY REPRODUCTIVE TYPE. 3 TYPES.
Percentage surviving (log scale)
100
10
1
0
Age
Slide 8