BIG MARKERS

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

1. Geographic(al) isolation;
2. Separate gene pools / no interbreeding / gene flow (between populations);
   Accept: reproductive isolation
   This mark should only be awarded in context of during the process of speciation. Do not credit if context is after speciation has occurred.
3. Variation due to mutation;
4. Different selection pressures / different abiotic / biotic conditions / environments / habitats;
   Neutral: different conditions / climates if not qualified
   Accept: named abiotic / biotic conditions
5. Different(ial) reproductive success / selected organisms (survive and) reproduce;
   Accept: pass on alleles / genes to next generation as equivalent to reproduce
6. Leads to change / increase in allele frequency.