On a phylogenetic tree, what do the branch lengths represent?

The age of the organisms
amount of genetic change since divergence
amount of genetic change since convergence
The age of divergence

the evolutionary time between two nodes

Explanation:

Branch lengths indicate genetic change i.e. the longer the branch, the more genetic change (or divergence) has occurred

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.

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