D4.1 Natural selection - written task
This structured extension question is in the style of the IB exam questions. It has a particular focus on the concept of natural selection, in particular the ideas of intraspecific competition, selection pressure, and fitness. How these help inform our understanding of survival value and reproductive potential of a genotype is key.
The question begins with a little bit of information which provides some clues to help answer the questions, but it doesn't give the answers.
Selection pressure acts on all members of a population and it a driving force of evolution.
Many deer species exist as herds of females reproducing with one dominant male. Young males are excluded from the herd by the dominant male when they approach maturity and will only be able to reproduce and pass on their genes if they can challenge the dominant male successfully and replace him in the herd.
Outline how overproduction of offspring is an important factor in natural selection.
(2 marks)
Teachers note - The genes which lead to traits with the greatest survival value will become more numerous in the offspring.
Outline how an abiotic factor can be a selection pressure, using one clear example.
(3 marks)
Explain the importance of intraspecific competition and the concept of fitness in deciding the survival value and reproductive potential of a genotype (trait).
(3 marks)
Teachers note: in this answer two marks are for explaining the terms in the statement and one for explaining the link between these terms.
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