Population demography and dynamics

Population Demography and

DynamicsAdan, Fatima Ellese

Jerusalem, Czar AlfeoSolisa, Valerie

Demography • From the word “Demo” and “graphy”

• It includes the study of how a population changes over time.

Population Dynamics

• Population fluctuations from year to year or place to place

Factors Affecting Population Demography

• Fertility •Mortality • Immigration • Emigration

Population Growth

• Population growth is affected by:–sex ratio–Generation time

Sex Ratio• In a study conducted by Joseph Elkinton,

J. H. Myers and G. Boettner• egg masses of forest caterpillars from

low-density sites produced significantly more females than those from high-density sites, for which the numbers of males and females were equal or slightly in favor of males.

Sex Ratio• The female bias of the sex ratio of

low-density populations increases the potential rate of increase of the population and may arise from local mate competition when populations are sparse.

Generation Time

• Short generation time results in the increase in population growth rate but can be diminish more rapidly if birth rates decrease suddenly.

Age Structure

• Cohort or group of individuals w/in the same age.• Population with large number of

young individual tends to grow rapidly.

Age Structure Pyramid

Life Tables• Contains –fate of a cohort from birth until

death–number of offspring produced–individuals that died each year– number of individuals that

survived

Life Table

Survival Curve• a graphic method that shows some

of the data in life table

• It shows– survivorship of a population–percentage of the original population

that survive to a given age.

• Standardized Survival Schedule (lx)

• Age-Specific Survivorship (gx)

Survival Curve

• Life Expectancy (ex)

Survival Curve

Pambasag!

1. What is demography?

Pambasag!

2. What are the four factors affecting population demography?

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3. The shorter the ______ the higher the population growth rate.

Pambasag!

4. It is a type of a life table which is commonly used for organisms that are difficult to classify by age and the ecological role defend more on their size or stage of development.

Pambasag!

5. It is a curve used to demonstrate the survivorship of the organisms in a certain population.

Pambasag!

6. A population with a large number of young individuals tends _______ in growth rate.

Pambasag!

7. What is the most commonly effect to a population with a large ratio of female individuals?

Pambasag!

8. Age structure is defined by ________ in each cohort.

Pambasag!

9. The sudden change in demography and structure of a population.

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10. What is the possible effect of the increase in generation time together with the increase in number of males in a population?

Pambasag!

11-20. Show your solutions.Age (year/s) Number of living individuals

0 300

1 267

2 222

3 197

4 156

5 130

6 95

7 50

8 25

References

• Campbell,Neil. Reece