Biodiversity Within A Community

Question 1

Ecologists measured the body lengths of male and female thorny lizards living in the
same habitat.
The ecologists measured the body lengths to the nearest 5 mm.
The graph shows how they presented their results.

• ( Bar graph shows body length is higher in males until 85 mm in length then females have a higher body onwards, graph is labelled “ Number of thorny lizards “ against “ body length in mm “ )

Give two differences in the variation in body length of male and female thorny lizards.

Answer 1

• Females are generally longer

- Females show a greater variation

Question 2

Another group of ecologists investigated biodiversity of lizards in a woodland area.

Their results are shown in the table.

Lizard species:

1 ) Dominican giant anole

2 ) Hispaniolan green anole

3 ) Hispaniolan stout anole

4 ) Bark anole

5 ) Hispaniolan grass anole

6 ) Cope’s galliwasp

7 ) Cochran’s least gecko

8 ) Peninsula least gecko

Number of individuals:

1 ) 5

2 ) 11

3 ) 22

4 ) 91

5 ) 13

6 ) 5

7 ) 8

8 ) 1

The index of diversity can be calculated using the formula

d = N ( N - 1 ) / Sum of n ( n - 1 )

where

d = index of diversity
N = total number of organisms of all species
n = total number of organisms of each species 

Use the formula to calculate the index of diversity of lizards in the woodland area.
Show your working.

Answer 2

n ( n - 1 ):

• 5 ( 5 - 1 )
• 11 ( 11 - 1 )
• 22 ( 22 - 1 )
• 91 ( 91 - 1 )
• 13 ( 13 - 1 )
• 5 ( 5 - 1 )
• 8 ( 8 - 1 )
• 1 ( 1 - 1 )
• Sum of n ( n - 1 ) = 9014
• N = 5 + 11 + 22 + 91 + 13 + 5 + 8 + 1 = 156
• d = 156 ( 156 - 1 ) / 9014
• d = 2.68

Question 3

The ecologists also determined the index of diversity of lizards in an oil palm plantation next to the woodland area.
They found fewer species of plant in the
oil palm plantation.
Lizards feed on plants and insects.

Explain why fewer species of plant would lead to fewer species of lizard in the oil palm plantation.

Answer 3

• Fewer habitats
• So lower diversity for insects
• Therefore fewer food sources

Question 4

The Amazonian forest today contains a very high diversity of bird species.

• Over the last 2 000 000 years, long periods of dry climate caused this forest to separate into a number of smaller forests.
• Different plant communities developed in each of these smaller forests.
• Each time the climate became wetter again, the smaller forests grew in size and merged to reform the Amazonian forest.

Use the information provided to explain how a very high diversity of bird species has developed in the Amazonian forest.

Answer 4

• No interbreeding
• Mutation
• Different foods
• Adapted organisms survive and breed
• Increase in allele frequency

Question 5

( The Amazonian forest today contains a very high diversity of bird species.

• Over the last 2 000 000 years, long periods of dry climate caused this forest to separate into a number of smaller forests.
• Different plant communities developed in each of these smaller forests.
• Each time the climate became wetter again, the smaller forests grew in size and merged to reform the Amazonian forest. )

Speciation is far less frequent in the reformed Amazonian forest. Suggest one reason for this.

Answer 5

• Similar selection pressures