Flight of the Dodo Behavior (3)

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B REVIA Two external fossil calibrations were used EVOLUTION in separate ML molecular clock calculations after tests found no violation of clocklike Flight of the Dodo behavior (3). The analyses indicate that the dodo/solitaire and Caloenas diverged in the Beth Shapiro,1,2 Dean Sibthorpe,1 Andrew Rambaut,1 mid/late Eocene, around 42.6 million years Jeremy Austin,3 Graham M. Wragg,1 Olaf R. P. Bininda-Emonds,1 ago (Ma) (95% confidence interval ϭ 31.9 to Patricia L. M. Lee,1 Alan Cooper1,2* 56.1 Ma), whereas the dodo and the solitaire separated in the late Oligocene, about 25.6 The evolutionary history of the dodo is very tris (originally named for its dodolike beak) is Ma (17.6 to 35.9 Ma). The latter date is poorly understood. Like many avian island en- the basal member of this strongly supported biogeographically interesting as it is consid- demics, a high degree of morphological change clade of large, generally ground-dwelling, is- erably older than the islands of Mauritius and associated with flightlessness and gigantism has land endemics. Furthermore, the phylogeo- Rodrigues. Geological evidence suggests that obscured phylogenetic relationships, and histor- graphic distribution of this morphologically di- Mauritius emerged in a series of volcanic ically the dodo has been linked with avian verse clade suggests that the dodo and the sol- events, the earliest of which occurred around groups ranging from the ratites to 6.8 to 7.8 Ma, whereas Rodrigues the raptors (1). Since the mid- did not emerge until 1.5 Ma (5). 1800s, morphological studies have Therefore, it seems highly unlike- linked the dodo (initially Didus in- ly that the large genetic distance eptus, now Raphus cucullatus) and between the dodo and the solitaire its presumed close relative the sol- resulted from isolation on the two itaire (Pezophaps solitaria) with islands. Drilling projects have es- the Columbiformes (pigeons and tablished that ridges surrounding doves), but their exact position is the Mascarene Plateau were unresolved and they have been above sea level in the late Oligo- placed in many positions within the cene and have subsided slowly cosmopolitan Columbidae or in thereafter (5). The similarity be- on February 2, 2008 their own family, Raphidae, out- tween the timing of the dodo/sol- side the Columbidae but within itaire divergence and the first Columbiformes (1, 2). To answer geological evidence of land in the these questions, we extracted DNA Mascarene island chain is striking and amplified 1.4 kb of mitochon- and suggests that island stepping- drial sequence [360–base pair (bp) stones may have been used before 12S rRNA and 1050-bp cyto- the two species eventually found chrome b] from 37 species of pi- their way to Mauritius and Ro- geons and doves, including the drigues. Whether such dispersal www.sciencemag.org dodo, the solitaire, and multiple was flighted or not cannot cur- members of each of the five extant rently be determined, although subfamilies (3). Short overlapping the relatively isolated position fragments were amplified by poly- and young age of Rodrigues merase chain reaction (PCR), with would suggest that the solitaire, at museum specimens limited to 120 least, may have retained a capac- to 180 bp. Strict ancient DNA pro- ity for flight up until at least 1.5

cedures were used to minimize Ma. Downloaded from contamination and detect nuclear mitochondrial copies (4), PCR References and Notes products were cloned, and the sol- 1. A. Janoo, Bull. Mus. Natl. Hist. Nat. 18, 57 (1996). itaire sequences were independent- 2. D. Gibbs, E. Barnes, J. Cox, Pigeons and ly replicated at the Natural History Doves: A Guide to the Pigeons and Museum, London. Fig. 1. ML tree depicting the phylogenetic relationships of 37 species of Doves of the World (Pica Press, Sussex, UK, 2001). The maximum likelihood (ML) pigeons and doves. Geographic distributions of the pigeons are as follows: Australian (red), African/Madagascan (green), Asian/Southeast Asian (pur- 3. Detailed information is available on tree for the combined data set (Fig. Science Online at www.sciencemag. ple), Mascarene Island (blue), and New World (yellow) taxa. The concentra- 1) reveals that the dodo and the org/cgi/content/full/295/5560/ tion of New World taxa at the base of the tree suggests that the initial 1683/DC1. solitaire are sister taxa. Despite the radiation occurred in the New World. ML bootstrap consensus values for 4. A. Cooper, H. Poinar, Science 289, substantial morphological differ- relationships with Ն70% support (italicized) and Bayesian posterior support 1139 (2000). ences between the dodo, the soli- values (bold) are given. Detailed phylogenetic analyses of potential out- 5. I. McDougall, F. H. Chamalaun, Bull. taire, and other pigeons, the ML groups identiﬁed Laridae, and consequently two species (Great Skua, Ca- Geol. Soc. Am. 80, 1419 (1969). analysis shows them to be nested tharacta skua, and Parasitic Jaeger, Stercorarius parasiticus) were used (3). within the family Columbidae. The closest living relative is the monotypic Nicobar itaire dispersed from Southeast Asia to the Mas- 1Department of Zoology, University of Oxford, Ox- pigeon (Caloenas nicobarica) from the Nicobar carenes at some point in the past. Figure 1 ford, OX1 3PS, UK. 2Henry Wellcome Ancient Biomol- Islands and nearby Southeast Asia, and the indicates that a similar route was used by the ecules Centre, University of Oxford, Oxford, OX1 3PS, UK. 3Department of Zoology, The Natural History sister taxa to this clade are the crowned pigeons Madagascan endemic Alectroenas madagas- Museum, London SW7 5BD, UK. (Goura), from New Guinea. The unusual Sa- cariensis, which is closely related to another *To whom correspondence should be addressed. E-mail: moan tooth-billed pigeon Didunculus strigiros- Indo-Australian radiation. [email protected]