Full tree versus reconstructed tree.

<p>A full tree produced by the sampled ancestor birth-death process on the left and a reconstructed tree on the right. The sampled nodes are indicated by dots labeled by letters A through H. Nodes A, B and D are sampled ancestors. The reconstructed tree is represented by a sampled ancestor tree , where denotes the ranked tree topology and , , and denote the node ages. In the reconstructed tree the root is a sampled node. In the skyline model, birth-death parameters vary from interval to interval. There are two intervals in this figure bounded by the time of origin , parameter shift time , and present time . Between and parameters , , and apply and between and parameters , , , and . There are additional sampling attempts at times and with sampling probabilities and .