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← Theoretical A

Q1 — Tulip Parsimony and Morphological Characters

Theoretical A Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Phylogenetic Trees & Cladistics

Kazakhstan boasts a rich ecosystem harboring numerous species of tulips, some of which are direct ancestors to many modern cultivated varieties. These tulips exhibit a diverse range of morphological traits, although not all of these traits are reliable indicators of species identification.

In Table 1 below, we outline five distinct types of tulips and their variations across five characteristics (A-E), typically utilized in the classification of tulip types.

Table showing photos of five tulip species — Tulipa lemmersii, T. salsola, T. altacia, T. bifloroformis, T. borszczowii — with a grid of five character states (A: stamen hairs, B: flower number, C: bulb hairs, D: leaf number, E: filament color) below each photo. Table 1. Morphological comparisons; A - presence/absence of hairs on the stamen, B - number of flowers (2(+) = 2 or more), C - presence/absence of a dense layer of hairs on the bulbs, D - number of leaves, E - color of the stamen filament, Y - yellow, K - black.

It’s worth noting that T. borszczowii has the same features as the common ancestor among these tulip species.

On your answer sheet, indicate “T” for true statements and “F” for false ones.

A. In a phylogenetic tree constructed using maximum parsimony, the species T. lemmersii, T. salsola, and T. bifloroformis are expected to constitute a polyphyletic group.
B. The maximum parsimony tree contains at least one character reversal.
C. All plants within the genus Tulipa share the characteristic of having leaves with either arcuate or parallel veins.
D. According to the data, the presence of two or more flowers is the most recently evolved characteristic compared to the others.
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Question reproduced from IBO 2024, Theoretical Exam Part A, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)