Colonizations of islands are often associated with rapid morphological divergence. We present two previously unrecognized cases of dramatic morphological change and niche shifts in connection with colonization of tropical forest-covered islands. These evolutionary changes have concealed the fact that the passerine birds madanga, Madanga ruficollis, from Buru, Indonesia, and São Tomé shorttail, Amaurocichla bocagii, from São Tomé, Gulf of Guinea, are forest-adapted members of the family Motacillidae (pipits and wagtails). We show that Madanga has diverged mainly in plumage, which may be the result of selection for improved camouflage in its new arboreal niche, while selection pressures for other morphological changes have probably been weak owing to preadaptations for the novel niche. By contrast, we suggest that Amaurocichla's niche change has led to divergence in both structure and plumage.
Supplementary Table S1
List of samples, with GenBank accession numbers
Table S1 Madanga Samples.xls
RSOS-140364 contents and captions ESMs
Contents and captions to data files.
Supplementary Table S2
Measurements of Madanga ruficollis and the other species in
clade A in Fig. 1.
Table S2.pdf
Table S3 PCA Madanga
Output from PCA of morphological characters.
Fig. S1. MB Madanga Passeriformes AllLoci 4parts
Relationships of broad selection of Passeriformes, including Madanga ruficollis and Amaurocichla bocagii, based on concatenated ND2, ODC, myo and CHD1Z, analysed by Bayesian inferenece, partitioned by locus.
PassMadangaAllLoci
Alignment and settings for analysis shown in Fig. S1.
Fig. S2. MB Madanga All Loci 7parts
Bayesian inference tree of Madanga ruficollis, Amaurocichla bocagii and representatives of all clades of Anthus and Motacilla found in previous studies, including all “small pipits” (except A. petrosus, which was previously considered conspecific with A. spinoletta). Based on mitochondrial cytb and ND2, and nuclear ODC, myo and CHD1Z sequence data analysed in seven partitions (by locus and codon; see MadangaAllLoci.nxs).
MadangaAllLoci
Alignment and settings for analysis shown in Fig. S2.
Fig. S3. MB single-locus analyses
Single-locus analyses of the same taxa as in Supplementary Figure S2.
Fig. S4. BEAST Madanga Cytb
Chronogram for the same taxa as in Supplementary Figures 2 and 3, based on cytb sequences and a relaxed molecular clock (2.1% / million years), inferred by Bayesian inference, with 95% highest posterior density intervals for the node ages.
MadaCytbShort
Xml file for analysis in Fig. S4.
Photos AMNH
Photos of Madanga ruficollis and Amaurocichla bocagii from the American Museum of Natural History, including x-rays of Madanga ruficollis.