Q41 - Projecting a Three-Stage Population Forward and Finding the Extinction-Preventing Birth Rate

Theoretical 2 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Population Genetics & Hardy-Weinberg Equilibrium

Population dynamics are principally determined by birth and death rates. An animal species has three age structures: juvenile (J), adult 1 (A1), and adult 2 (A2). S1 and S2 denote survival rates between successive stages, and m1 and m2 show the numbers of juveniles produced by an adult individual at the two adult stages. All surviving individuals advance to the next stage the following year, and mothers give birth immediately after entering the next stage. The number of juveniles at year 1 (NJ,1) is m1 x NA1,1 + m2 x NA2,1. All individuals in the adult 2 group die the following year. Given: S1=0.2, S2=0.5, m1=3, m2=2, NJ,0=100, NA1,0=20, NA2,0=20 (females only).

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

NJ,2. What is the number of juveniles (NJ,2) at year 2?

NA1,2. What is the number of adult-1 individuals (NA1,2) at year 2?

NA2,2. What is the number of adult-2 individuals (NA2,2) at year 2?

minimum m1 to prevent extinction. The population with the above parameters will go extinct in the near future. To prevent extinction (holding other parameters constant), m1 should be increased such that m1 >= ?

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Question reproduced from IBO 2020, Theoretical Exam 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)