population ecology

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Justin ray m guce 2008

HOW DO WE DEFINE POPULATION???

TERMS TO REMEBER

• Population – group of organisms that belong to the same species and live in a given area

CHARACTERISTICS OF A POPULATION •

GEOGRAPHIC DISTRIBUTION

Describes the area inhabited by a population

CHARACTERISTICS OF A POPULATION •

POPULATION DENSITY

Number of individuals per unit area

CHARACTERISTICS OF A POPULATION •

POPULATION DISPERSION

– clumped – uniform – random

CHARACTERISTICS OF A POPULATION •

GROWTH RATE

Factors affecting population size

• • •

# of births # of deaths Immigration and emigration

• • • ARMM- 3.86% Region IV- 3.72

NCR- 1.06%

WHAT DOES this picture SHOW US???

CHARACTERISTICS OF A POPULATION • Types of GROWTH – Exponential – Logistic

CHARACTERISTICS OF A POPULATION • Exponential • • • J-shaped curve reproduction at constant rate ideal conditions

CHARACTERISTICS OF A POPULATION • Logistic • S- shaped curve • Growth stops after an exponential growth

CHARACTERISTICS OF A POPULATION

• AGE STRUCTURE – growth depend on the age of the population – age structure diagrams

CHARACTERISTICS OF A POPULATION

• DEMOGRAPHIC TRANSITION – Dramatic change in birth and death rates – Birth rate falls to meet the death rate

LIMITS TO GROWTH

• Limiting factors – Causes population to decline – Insufficient supply of nutrients • 2 types of FACTORS – DENSITY DENPENDENT – DENSITY INDEPENDENT

DENSITY DEPENDENT FACTORS

• depends on population size • becomes limiting when… – POPULATION REACHES A CERTAIN LEVEL • large and dense population size

DENSITY DEPENDENT FACTORS

• INCLUDES – Competition – Predation – Parasitism – Disease

Competition

Competition: overcrowding

Predation

Parasitism

Disease

DENSITY INDEPENDENT FACTORS

• affects all population in similar ways • REGARDLESS of its POPULATION SIZE • Characteristic crash in population size

DENSITY INDEPENDENT FACTORS

• INCLUDES – UNSUAL WEATHER – SEASONAL CYCLES – NATURAL DISASTERS – HUMAN ACTIVITIES

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