Lake Malawi in East Africa has more species of fish than any other lake in the world (line 1).

Suggest and explain how this speciation may have occurred.

The percentage of forest cover in Malawi decreased between December 1990 and December 2016 (lines 9–10).

Calculate the mean loss of forest cover in km2 per week during this time period.

Answer ______________ km2 per week

Loss of nutrients into Lake Malawi has resulted in a decrease in some fish populations (lines 12–13).

Explain why.

The mark-release-recapture method can be used to estimate the size of a fish population (lines 13–14).

Explain how.

Suggest why the mark-release-recapture method can produce unreliable results in very large lakes (lines 14–15).