Figure 3
From: Aquatic birds have middle ears adapted to amphibious lifestyles
(a) Loading plots for pPC1 and pPC2 (TM stands for tympanic membrane) with inset bar plot of percent variance explained for first six principal components. (b) Scatterplot of pPC1 and pPC2 grouped by ecological groups. Several extreme scores are highlighted: owls (Bubo africanus and Tyto alba) on the negative pPC1 end and Phalacrocorax cormorants (P. lucidus, P. capensis, P. neglectus) on the positive pPC1 end. (c) Scatterplot of pPC1 and pPC2 grouped by dive score with increasing value of pPC1 indicating smaller values of most morphological measurements for a given head mass. (d) Scatterplot of pPC1 and pPC2 grouped by orders with at least one underwater-pursuit species. The diversity within Charadriiformes is highlighted by low pPC1 scores in two terrestrial species (Burhinus capensis, Vanellus coronatus) and high pPC1 scores in three diving species (Alca torda, Fratercula arctica, Cepphus grylle). Silhouette images provided by PhyloPic’s database (http://phylopic.org/), see electronic supplemental materials S8 for detailed credits.
