3.7.4 - POPULATIONS IN ECOSYSTEMS

Question 1

changes in ecosystems can lead to speciation. in southern california 10000 years ago, a number of interconnecting lakes contained a single species of pupfish.

increasing temperatures caused evaporation and the formation of separate, smaller lakes and streams. this led to the formation of a number of different species of pupfish.

explain how these different species evolved (5)

Answer 1

1. geographical isolation
2. separate gene pools/no interbreeding
3. variation due to mutation
4. different environmental/abiotic/biotic conditions/selection pressures
5. selection for different alleles/characteristucs
6. differential reproductive success
7. leads to change in allele frequency
8. occurs over a long period of time

Question 2

give two conditions for results from mark-release-recapture investigation to be valid (2)

Answer 2

1. marking does not affect predation
2. no immigration
3. sufficient time for marked individuals to mix with the population
4. no/little births/deaths/breeding