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

IMPORTANT TERMINOLOGIES

Population

Community

Density

Natality

Mortality

Biotic factors

Carrying capacity

Basilan | Orenday | Ugtuhan | (c) 2014 2

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

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

Factors Regulating Population Size

Density-independent - factors

that eliminate a proportion of a

population regardless of

population density.

Basilan | Orenday | Ugtuhan | (c) 2014 5

Density-independent factors

• Forest fire

• Modification of weather conditions

• Severe storm and flooding

• Earthquakes and volcanic eruptions

Basilan | Orenday | Ugtuhan | (c) 2014 6

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

“Resource availability affects life history adaptations.”

Basilan | Orenday | Ugtuhan | (c) 2014 8

TWO TYPES OF LIFE STRATEGIES

• K-selected species (Equilibrium)

• Characteristics of r-selected species (Opportunist)

Basilan | Orenday | Ugtuhan | (c) 2014 9

Characteristics ofK-selected species (Equilibrium)

late maturation

longer life spans

more parental care

intense competition for resources

Basilan | Orenday | Ugtuhan | (c) 2014 10

Characteristics of r-selected species (Opportunist)

early maturation

shorter life spans

less parental care

little competition for resources

Basilan | Orenday | Ugtuhan | (c) 2014 11