POPULATION GRAPHING: BIOLOGY

AND ALGEBRA

Using Equations in Biology Deer Population Activity

Each year, some deer have offspring and other deer will die.

You can use this equation to determine the size of population each year:

y= ((p + b)-d)

y= the total population size plus the birth rate and minus the death rate.

p= population size at beginning of the year b= the birth rate d= the death rate

Using Equations in Biology continued

The birth rate and death rate will be given for each year.

You will find the population size for each year using the equation and given information.

When graphing the information, x = the year and y= population size to give you the ( x, y ) coordinates.

The population size for the next year will be the y of the previous year.

Year Pop size 1st Offspring Deaths y= ((p + b) –d) Population size end

1986 600 200 300 y= ((600 + 200) – 300) 500

1987 500 300 50 y= ((500 + 300) – 50) 750

1998 750 400 150 y= ((750 + 400) – 150) 1000

1989 1000 400 100 y= ((1000 + 400) – 100) 1300

1990 1300 300 100 y= ((1300 + 300) – 100) 1500

1991 1500 450 200 y= ((1500 + 450) – 200) 1750

1992 1750 600 250 y= ((1750 + 600) – 250) 2100

1993 2100 500 300 y= ((2100 + 500) – 300) 2300

1994 2300 500 250 y= ((2300 + 500) – 250) 2550

1995 2550 400 250 y= ((2550 + 400) – 250) 2700

1996 2700 50 450 y= ((2700 + 50) – 450) 2300

1997 2300 250 100 y= ((2300 + 250) – 100) 2450

1998 2450 300 150 y= ((2450 + 300 ) – 150) 2600

1999 2600 100 300 y= ((2600 + 100) – 300) 2400

2000 2400 300 100 y= ((2400 + 300) – 100) 2600

Graphing the Data

1984 1986 1988 1990 1992 1994 1996 1998 2000 20020

500

1000

1500

2000

2500

3000

Deer Population

Graphing the Data

When forming your graph, the year, or x value goes across the bottom, which is the x-axis.

The deer population size goes up the side of the graph, or the y-axis.

Number the x-axis starting with the earliest year to the latest year.

The example on the previous slide goes from 1985 to 2005 because I was not able to reformat the graph.

The y-axis should be numbered evenly to the highest number needed for the graph.

The example on the previous slide is numbered from 0 to 3000.

What does the graph tell us?

The graph shows that the population size steadily rose from 1986 to 1995.

There was a large decline in population size between 1995 and 1996.

Discuss other trends you see in the graph.

What does the graph tell us?Assessment Questions:

What could cause the population decline that occurred between 1995 and 1996?

Based on what you have learned about carrying capacity, what is the carrying capacity of this deer habitat?

Predict what will happen to the population size in 2001.

What circumstances might result in a high birth rate for a population? A low birth rate?

What circumstances might result a high death rate for a population? A low death rate?