Population Attributes
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POPULATION ATTRIBUTES
description
Population Attributes. Natality or birth rate. Natality is the number of births per 1000 people per year. . Natality or birth rate. Natality is the number of births per 1000 people per year. It is calculated at the mid-point of the year. . Natality or birth rate. - PowerPoint PPT Presentation
Transcript of Population Attributes
POPULATION ATTRIBUTES
Natality or birth rate Natality is the number of births per 1000
people per year.
Natality or birth rate Natality is the number of births per 1000
people per year. It is calculated at the mid-point of the
year.
Natality or birth rate Natality is the number of births per 1000
people per year. It is calculated at the mid-point of the
year. In humans, natality can be calculated as
a crude birth rate – the rate per 1000 members of the population.
Mortality or death rate Mortailty is the number of deaths per
1000 people per year.
Mortality or death rate Mortailty is the number of deaths per
1000 people per year. Calculated at the mid-point of the year
Mortality or death rate Mortailty is the number of deaths per
1000 people per year. Calculated at the mid-point of the year In humans:
number of deaths per yearCrude death rate = Total population
X 1000
Density Number of individuals of a population
per unit of area of habitat at a specific time (wo!)
Density Number of individuals of a population
per unit of area of habitat at a specific time
EG. Human inhabitants per square km in Rotorua (2004)
EG. Pines trees per hectare in a forest in 2005
Age Structure See handout.
Survivorship curves Help us to study the number of
organisms in a population that survive to any particular age.
Survivorship curves Help us to study the number of
organisms in a population that survive to any particular age.
The numbers are usually expressed as survivors per 1000 members of a population.
Survivorship curves Help us to study the number of
organisms in a population that survive to any particular age.
The numbers are usually expressed as survivors per 1000 members of a population.
The curves relate life expectancy to life span
Questions for Survivorship curves1. How is average life expectancy measured?2. What was the NZ female life expectancy 1995-
1997?3. Why are the ‘old humans’ life expectancy so low?4. What is the general theme for life span?5. Why do you think some organisms reproduce with
a high number?6. Why do you think mammals reproduce with a
small number?7. Explain in a few paragraphs what a survivorship
curve is: (think of this as your summarising) – YOU NEED TO KNOW ABOUT THIS STUFF.
8. Draw a survivorship curve of people in a 3rd world country where life expectancy is about 30 years.
