Module 7

Question 1

On islands in the Caribbean, there are almost 150 species of lizards belonging to the genus Anolis. Scientists believe that these species evolved from two species found on mainland USA. Explain how the Caribbean species could have evolved.

Answer 1

• Geographic(al) isolation;
• Separate gene pools / no interbreeding / gene flow (between populations);
• Variation due to mutation;
• Different selection pressures / different abiotic / biotic conditions / environments
  / habitats;
• Different(ial) reproductive success / selected organisms (survive and)
  reproduce;
• Leads to change / increase in allele frequency

Question 2

Describe how you would determine the mean percentage cover for beach grass on a sand dune

Answer 2

• divide the area into a grid
• use a random number generator to generate coordinates
• use a large sample size of quadrats
• place quadrats at coordinates and work out percentage cover
• divide total percentage by number of quadrats (work out mean)