The document discusses factors that regulate population sizes, including density-dependent factors like competition and density-independent factors like natural disasters. It defines important terminology like population, community, and biotic factors. It also describes two life history strategies species may evolve under different environmental pressures - r-selected species that thrive in unstable environments and K-selected species adapted to stable, competitive environments.

1. Ecology of Individuals and
Populations
Factors that Regulate
Populations
Basilan, Glecy B.
Orenday, Johnrey V.
Ugtuhan, Carren P.
BS Biology III
Basilan | Orenday | Ugtuhan | (c) 2014 1

2. IMPORTANT TERMINOLOGIES
 Population
 Community
 Density
 Natality
 Mortality
 Biotic factors
 Carrying capacity
Basilan | Orenday | Ugtuhan | (c) 2014 2

3. Factors Regulating
Population Size
 Density-dependent factors -
act on a population such that
the proportion eliminated
depends on the population
density. Basilan | Orenday | Ugtuhan | (c) 2014 3

4. Fig. 1 showing the examples of density-dependent effects
Basilan | Orenday | Ugtuhan | (c) 2014 4

5. Factors Regulating
Population Size
 Density-independent - factors
that eliminate a proportion of a
population regardless of
population density.
Basilan | Orenday | Ugtuhan | (c) 2014 5

6. Density-independent
factors
• Forest fire
• Modification of weather
conditions
• Severe storm and flooding
• Earthquakes and volcanic
eruptions
Basilan | Orenday | Ugtuhan | (c) 2014 6

7. Fig. 2 showing the examples of density-independent effect –
Forest fire Basilan | Orenday | Ugtuhan | (c) 2014 7

8. “Resource availability affects life
history adaptations.”
Basilan | Orenday | Ugtuhan | (c) 2014 8

9. TWO TYPES OF LIFE
STRATEGIES
• K-selected species (Equilibrium)
• Characteristics of r-selected
species (Opportunist)
Basilan | Orenday | Ugtuhan | (c) 2014 9

10. Characteristics of K-selected
species (Equilibrium)
 late maturation
 longer life spans
 more parental care
 intense competition for resources
Basilan | Orenday | Ugtuhan | (c) 2014 10

11. Characteristics of r-selected
species (Opportunist)
 early maturation
 shorter life spans
 less parental care
 little competition for resources
Basilan | Orenday | Ugtuhan | (c) 2014 11