Branching diagrams showing the ecological and evolutionary relationships among cetaceans.

<p>Sizes of the cetaceans are shown to scale, and colours reflect whether the species have high (red), moderate (green) or low (blue) costs of living. A: The ecological strategy tree was produced using a cluster analysis of the three combined indicators (mitochondrial density of the muscle, lipid content of the muscle and diet quality). Species are arranged from highest (top) to lowest (bottom) costs of living. B: The actual cetacean phylogenetic tree <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0050096#pone.0050096-Price1" target="_blank">[72]</a>. Species are grouped by family from top to bottom into Phocoenidae (harbour porpoise); Delphinidae (bottlenose, striped and common dolphins, and long-finned pilot whale), Ziphiidae (Cuvier's beaked whale and Mesoplodon whales), Kogiidae (pygmy sperm whale), Physeteridae (sperm whale) and Balaenopteridae (minke and fin whales).