Sketches of a tree produced by a birth-death process.

<p>The process starts with a single lineage at the origin. At each speciation event the ancestral lineage is replaced by two descendant lineages. At an extinction event the lineage simply terminates. a) A complete tree including the extinct lineages. b) The reconstructed tree of tree a) without the extinct lineages. c) A randomly sampled tree of the same reconstructed tree. Every taxa had the same probability to be sampled. d) A five-taxon tree where taxa are selected to maximize diversity (diversified sampling).