A subspecies is a genetically distinct population within a species that shows some phenotypic differences from the rest of the species, although it is not yet reproductively isolated. Nine subspecies of the tiger, Panthera tigris, have been identified. Six of these subspecies occur on mainland Asia. The remaining three subspecies come from the Sunda Islands, which include Bali, Java and the much larger island of Sumatra. Fig. 3.1 shows these three islands.
(a)[4]
Suggest and explain how the three subspecies of tiger on the Sunda Islands originated.
(b)[2]
Explain why specific primers were used for the tiger mtDNA sections.
(c)[2]
Describe and explain one feature of mtDNA that makes it more useful than nuclear DNA for providing evidence of evolution.
(d)[2]
Suggest two reasons why P. t. balica and P. t. sondaica went extinct.
(e)[2]
Suggest why $P.\ t.\ sumatrae$ is still regarded as a member of the species $Panthera\ tigris$.
Worked solution & mark scheme
This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Isolation caused by geography” …