1. Population of Ecology

2. Ecology
Study of the interactions of organisms in their biotic and abiotic environments
Organism  population community  Ecosystem  biophsere

3. Demographics of populations
Demography – statistical study of a population (density, distribution, growth rate)
Population density - # of individuals per unit area (can be misleading)
Population distribution – pattern of dispersal across an area (controlled by resources and limiting factors) clumped, random, uniform

4. Population growth
Rate of natural growth (r) based on birth and death rate.
Biotic potential – highest possible growth rate with unlimited resources.

5. Survivorship curves
Probability that newborn will survive to certain ages.
Curve I – characteristic of a population in which most individuals survive well past midpoint of lifespan. Ex. Large mammals, humans

6. Curve II – survivorship decreases at a constant rate throughout the life span. Ex. Songbird, small mammals (death is usually unrelated to age)
Curve III – most individuals die young. Ex. Insects, fish, humans in less developing countries.

7. Survivorship Curves

8. Age distribution Age structure diagrams Increasing population
Prereproductive ages is largest, birth rate is higher than death rate.
Stable population (bell shape)
Reproductive ages equal prereproductive ages
Decreasing population (urn shape)
reproductive ages is larger than prereproductive ages, postreproductive age is largest

10. U.S. Population

11. Population Growth Models
2 patterns of population growth:
Discrete breeding – single reproductive event
Continuous breeding – many reproductive events
Research: not always have to be one or the other.

12. Exponential Growth
Number of individuals added each generation increases as the total # of females increases.
Lag phase – growth is slow to start
Exponential growth phase – accelerated growth
J shaped curve

15. Logistic growth S-shaped curve Lag phase, exponential growth phase
Deceleration phase – growth slows
Stable equilibrium phase – little to no growth, BR = DR

16. Logistic Growth

17. Carrying capacity
Maximum # of individuals of a species an environment can support.
Exponential growth can not continue due to carrying capacity
Resources become scarce
Competition and predation
Exponential growth occurs when population size is much lower than carrying capacity.
Population stabilizes when carrying capacity is reached.

18. Regulation of population size
Density independent factors – those that are not dependent on numbers
Weather, natural disasters
Density dependent factors – occur because of population of species
Competition, predation, parasitism
Intrinsic factors? – anatomy, behavior have an affect on population?

19. Life History Patterns - Opportunistic
r – strategists
Small individuals, short life span, fast to mature, many offspring, little/no care for offspring, early reproductive age
Bacteria, fungi, insects, rodents, annuals

21. Life History Pattern - Equilibrium
K-strategists
Large individuals, long life span, slow to mature, few and large offspring, care for offspring, most live to reproductive age
Large mammals, birds of prey, long-lived plants

23. Human population growth
MDC’s – North America, Europe, Japan, Australia, growth is slow
LDC’s – Latin America, Africa, Asia, population rising rapidly
Ways to reduce projected population increase:
Strengthen family planning
Education, raising status of women, reduce child mortality
Delay onset of childbearing, wider spacing of births

24. Population Growth and Environmental Impact
LCD = population growth in numbers
MCD = consume larger proportion of Earth’s resources
Average family in North America consumes the amount of resources and produces wastes of 30 people from India.