Q2 — Red Deer mtDNA Phylogeny & Bootstrap Support

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

There are many subspecies of Red Deer (Cervus elaphus) in Eurasia. The cytochrome b gene of mitochondrial DNA from 106 red deer samples, collected from different localities and representing different subspecies, was analyzed.

A red deer standing in dense grass and shrubs at the Kölsay Lakes National Park. Figure 1. Red Deer in the National Park “Kölsay kölderi”.

Figure 2 shows part of the phylogenetic tree of Cervus samples based on the analysis of the mitochondrial DNA cytochrome b gene.

A phylogenetic tree with numbered bootstrap values on each branch, showing Rangifer tarandus and Dama dama as outgroups and many numbered/lettered Cervus elaphus sample groups nested within. Figure 2. Phylogenetic tree of Red Deer. The numbers on each branch are called bootstrap values. They indicate how many times out of 100 iterations the same branch is observed when repeating the generation of a phylogenetic tree on a resampled set of data. (all the tips with numbers or letters indicate various groups of Cervus elaphus)

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

A. In 11 out of 100 bootstrap iterations Dama dama was not a sister group to Cervus spp.

B. Using the DNA of histone genes instead of mitochondrial DNA for construction of this phylogenetic tree would allow to better differentiate between deer subspecies.

C. Sample 163 is part of the most weakly supported branch in the tree.

D. A bootstrap value of 50 indicates the existence of only one alternative topology.

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Question reproduced from IBO 2024, Theoretical Exam Part B, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF