1. The document discusses various levels of biological organization from the ecosystem level down to the molecular level, providing examples like the eucalyptus forest ecosystem and the flying fox population. 2. It then focuses on population ecology, defining key population features like size, density, dispersion, growth rates, and factors that influence population growth like immigration, emigration, birth rates and death rates. 3. Models of population growth are discussed, including exponential and logistic growth curves, and the concept of carrying capacity is introduced as the maximum population size supported by available resources.

1. sir awan

2. Ecology - Study of interactions among organisms and
their environment
Conservation biology, environmentalism:
preservation of natural world

3. • Biosphere
• Bioma
• Ecosystemas
ECOSYSTEM LEVEL
Eucalyptus forest
• Community
• Population
• Individu
• Organ system
• Organ
• Tissue
• Cell
• Molecular
COMMUNITY LEVEL
All organisms in
eucalyptus forest
POPULATION LEVEL
Group of flying foxes
ORGANISM LEVEL
Flying fox
ORGAN SYSTEM LEVEL
Nervous system
ORGAN LEVEL
Brain
Brain
Nerve
TISSUE LEVEL
Nervous
tissue
CELLULAR LEVEL
Nerve cell
MOLECULAR LEVEL
Molecule of DNA
Spinal cord

4. 
Population:
 All the individuals of a species that live
together in an area

Demography:
 The statistical study of populations,
allows predictions to be made about
how a population will change

5. 
Three Key Features of Populations



Size
Density
Dispersion

6. Three Key Features of
Populations
Size: number of individuals in an area

7. Three Key Features of Populations

Growth Rate:



Birth Rate (natality) - Death Rate (mortality)
How many individuals are born vs. how many die
Birth rate (b) − death rate (d) = rate of natural
increase (r)

9. Three Key Features of Populations
Density: measurement of population per unit
area or unit volume
Pop. Density = # of individuals ÷ unit of space

10. 
Immigration: movement of individuals into a
population

Emigration: movement of individuals out of
a population

Density -dependent factors: Biotic factors in
the environment that have an increasing
ef fect as population size increases
(disease, competition, parasites)

Density -independent factors: Abiotic factors
in the environment that af fect populations
regardless of their density (temperature,
weather)

11. Factors That Affect Future Population Growth
Immigration
Natality
+
+
Population
Emigration
-
Mortality

12. Population Dispersion

13. Three Key Features of Populations

Dispersion: describes the spacing of organisms
relative to each other
–
Clumped - often correlates with resources
–
Uniform: interactions among individuals
–
Random: no pattern

14. 



Population density = number of
individuals in a given area or volume
Count all the individuals in a population
Estimate by sampling
Mark-Recapture Method

15. 
Idealized models describe two kinds of
population growth:
1. Exponential Growth has no upper limit and
populations grow very quickly
2. Logistic Growth has a limit and growth approches
this limit in a sigmoidal fashion
Logistic growth is more realistic in real life, but
exponential growth is a better model for bacterial
cultures, etc. that have unlimited resources and
space

16. 
Carr ying Capacity (k):
 The maximum population size that can be
supported by the available resources
 There can only be as many organisms as the
environmental resources can support

17. • A J-shaped growth curve, described by the
equation G = rN, is typical of exponential
growth
– G = the population growth rate
– r = the intrinsic rate of increase, or growth
rate in an ideal environment (births-deaths)
– N = the population size

18. Figure 35.3A

19. – K = carrying capacity
– The term
(K - N)/K
accounts
for the
leveling
off of the
curve

21. During the initial
stage, during the lag
phase, the rate of
plant growth is slow.
Rate of growth then
increases rapidly
during the
exponential phase.
After some time the
growth rate slowly
decreases due to
limitation of nutrients.
This phase constitutes
the stationary phase.

22. 
Declining birth rate or increasing death rate
are caused by several factors including:

Limited food supply

The buildup of toxic wastes

Increased disease

Predation

23. About every 10 years, both
hare and lynx populations
have a rapid increase (a
"boom") followed by a sharp
decline (a "bust")

24. 
r Selection (many
offspring)
 Short





life span
Small body size
Reproduce quickly
Have many young
Little parental care
Ex: cockroaches,
weeds, bacteria

25. • K Selection (few
offspring)
 Long life span
 Large body size
 Reproduce slowly
 Have few young
 Provides parental
care
 Ex: humans,
elephants

26. 
Distribution of males and females in each age
group of a population

Used to predict future population growth

28. 

J curve growth
Why doesn’t environmental resistance take effect?
 Altering their environment
 Technological advances
 The cultural revolution
 The agricultural revolution
 The industrial-medical revolution

29. 


Doubled three times in the last three
centuries
About 6,1 billion and may reach 9.3 billion by
the year 2050
Improved health and technology have lowered
death rates

31. What next?