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← Theoretical 2

Q91 — Song Recognition Between Island Populations of Tree Finches

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

Researchers noted that males of small tree finches (Camarhynchus parvulus) sing by repeating one specific syllable over and over. They also found that 4 unique syllables occur among males collected from Santa Cruz island, 3 unique syllables occur among males from Floreana island, and 3 additional syllables are common among both. To make quantitative measurements, they decided to summarize the behavioral activity of every individual in response to a song by a numerical score (behavioral activity scores are on the Y-axis in the plots below). In the first experiment, researchers subjected an individual from each population to a song recording from its native or foreign island. In the second experiment, they subjected each individual to a song recording containing its own syllable (homotypic) or a different syllable (heterotypic).

Two-panel bar chart. Panel (1): behavioral activity score in response to a same-island vs. different-island song, for Santa Cruz and Floreana birds; both populations show a statistically significant drop in response to different-island song. Panel (2): behavioral activity score in response to homotypic vs. heterotypic syllables, for Santa Cruz and Floreana birds; neither population shows a statistically significant difference. (1) Geographic origin of the intruder song and (2) syllable type of the intruder song: behavioral response scores for Santa Cruz and Floreana finches. Asterisks denote a statistically significant difference.

Using the information and the figures above, determine whether the following statements are true or false.

A. Male finches can recognize intruders from another population by their song.
B. Male finches change their behavior significantly when they hear a song with unfamiliar syllables.
C. The first figure shows that male finches acquire their defining syllables genetically.
D. The second figure shows that the presence of common syllables between Santa Cruz and Floreana populations is a result of evolutionary convergence.
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Question reproduced from IBO 2022, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)