Demecology – the Ecology of Populations
Topic 3: Demecology – the ecology of populations
The main idea: Note how mathematical models are used to examine variation in growth of a population.
Lecture outline:
1. Statistic and dynamic characteristics of population.
2. Growth curves patterns: J-shaped curve and S-shaped curve
3. Population regulation: Density-dependent and density-independent factors. 4. Human population patterns: - Population numbers. - Demographic transition and structure - Population urbanization
1. Statistic and dynamic characteristics of population
Population – is a group of individuals of the same species that live in the same area.
Population is an elementary and evolutionary unit of biosphere.
Statistic characteristics: • Population Number - number of individuals in a given population. • Population Density – the number of individuals in a population in given area. Population density = 100 fish / 1.000m3 of water = 1fish/ 10 m3 of water or 10 plants/ 1m2
Dynamic characteristics: • Population growth – an increase in a population at a given time. • Population growth rate – the change in the number of individuals in a population over time
2. Growth Curves Patterns:
Growth Curves – a graph showing the number of individuals in a population over time.
• The J-shaped curve – a growth curve that shows population growth which occurs indefinitely at a constant reproductive rate.
The J-shaped curve presents two phases of population growth:
Lag-phase: little or no increase occurs in a population.
Exponential phase: an increase occurs in a population so rapidly that the number of individuals doubles in a specific time interval and keeps doubling in increasingly shorter periods of time.
The J-shaped curve is also called as Exponential curve.
Biotic potential – the maximum rate at which a population could increase under ideal conditions – an environment with unlimited resources. The biotic potential is rarely achieved by population in natural
The main idea: Note how mathematical models are used to examine variation in growth of a population.
Lecture outline:
1. Statistic and dynamic characteristics of population.
2. Growth curves patterns: J-shaped curve and S-shaped curve
3. Population regulation: Density-dependent and density-independent factors. 4. Human population patterns: - Population numbers. - Demographic transition and structure - Population urbanization
1. Statistic and dynamic characteristics of population
Population – is a group of individuals of the same species that live in the same area.
Population is an elementary and evolutionary unit of biosphere.
Statistic characteristics: • Population Number - number of individuals in a given population. • Population Density – the number of individuals in a population in given area. Population density = 100 fish / 1.000m3 of water = 1fish/ 10 m3 of water or 10 plants/ 1m2
Dynamic characteristics: • Population growth – an increase in a population at a given time. • Population growth rate – the change in the number of individuals in a population over time
2. Growth Curves Patterns:
Growth Curves – a graph showing the number of individuals in a population over time.
• The J-shaped curve – a growth curve that shows population growth which occurs indefinitely at a constant reproductive rate.
The J-shaped curve presents two phases of population growth:
Lag-phase: little or no increase occurs in a population.
Exponential phase: an increase occurs in a population so rapidly that the number of individuals doubles in a specific time interval and keeps doubling in increasingly shorter periods of time.
The J-shaped curve is also called as Exponential curve.
Biotic potential – the maximum rate at which a population could increase under ideal conditions – an environment with unlimited resources. The biotic potential is rarely achieved by population in natural