Q29 - Species Extinction on Islands Created by Reservoir Flooding

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

In 1986-1987 in Thailand, a water reservoir was established by flooding a forest area. In the reservoir, former hilltops now became new islands and on 16 of these, the small mammal fauna was monitored until 2013, i.e. 27 years after establishment (Fig.). The focus of the study was extinction of the hilltop fauna due to isolation. A, number of species remaining on different-sized islands (1–50 ha) T years after reservoir establishment; B, rate of species extinction on different-sized islands as a function of T; C, time to extinction of half of the fauna (T1/2) on different-sized islands.

Figure 1. Figure 1.

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

A. Smaller islands (1-10 ha) lose more species per year than larger islands (25-50 ha)

B. At reservoir establishment, a linear relationship existed between species number and island area

C. The study supports the hypothesis that in the long run, a single large protected island will support biodiversity better than several small ones

D. In all islands, which are larger than 10 ha, the mean time to extinction of half of all species, is comparable

← Previous: Q28 Next: Q30 →

Question reproduced from IBO 2015, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)