Evolution of arid zone birds in Australia: Leapfrog distribution patterns and mesic-arid connections in quail-thrush (Cinclosoma, Cinclosomatidae) Alicia Toon a,b,⇑ , Jeremy J. Austin c,d , Gaynor Dolman a , Lynn Pedler a , Leo Joseph a a Australian National Wildlife Collection, CSIRO Ecosystem Sciences, GPO Box 1700, Canberra, ACT 2601, Australia b Australian Rivers Institute, Griffith University, Nathan, Queensland 4111, Australia c Australian Centre for Ancient DNA, School of Earth and Environmental Sciences, University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia d Sciences Department, Museum Victoria, Carlton Gardens, Melbourne, Victoria 3001, Australia article info Article history: Received 12 April 2011 Revised 26 September 2011 Accepted 30 September 2011 Available online 20 October 2011 Keywords: Cinclosoma Arid zone biota Leapfrog distribution Hybridization à BEAST abstract The quail-thrush, Cinclosoma, include between five and seven species distributed broadly across arid and semi-arid inland Australia, mesic forests of south-eastern Australia and New Guinea. It has been sug- gested that the arid zone species of quail-thrush arose from forest ancestors as Australia changed from a warm wet climate to a cooler drier climate since the late-Miocene. We generated multilocus (mitochon- drial ND2 and eight nuclear loci) gene and species trees with complete taxon sampling of Cinclosoma to investigate evolutionary relationships and species status of some taxa. Topologies reconstructed in con- gruent, highly-resolved gene trees and species trees that supported the recognition of seven species. Ancestral state reconstruction and divergence time estimates suggest that arid-adapted taxa radiated in parallel with a drying climate and changing habitat. A ‘leapfrog’ distribution in phenotypes of arid zone taxa was likely a result of ancestral retention of inconspicuous (or camouflaged) plumage patterns. A specimen-based report from 1968 of hybridization between non-sister taxa Cinclosoma castanotum and Cinclosoma marginatum was verified using molecular analysis on specimens collected at the same locality 40 years later. We discuss the implications of hybridization to the evolution of this species group. Crown Copyright Ó 2011 Published by Elsevier Inc. All rights reserved. 1. Introduction Recent reviews of the evolution of Australia’s arid and mesic zone biotas (Byrne et al., 2008, 2011) highlight several major bio- geographical issues that remain largely or unsatisfactorily unre- solved. One concerns whether, to what extent, and over which time scales did elements of the Australian arid zone biota evolve from mesic ancestors. A specific component of this question is whether the tropical rainforest biota of Australia and New Guinea (hereafter Australo-Papua) was ancestral to the Australian arid zone biota. A reason for difficulty in resolving these questions is the extent of idiosyncrasy in phylogenetic patterns among relevant groups studied to date (Byrne et al., 2008, 2011) and large gaps in taxon and geographic sampling. The present paper addresses the evolutionary history of one such group of passerine birds known as quail-thrush Cinclosoma spp. that range from tropical rainforests of New Guinea to Australia’s stony deserts. To further develop the study’s context, we note that in the late- Miocene Australia’s climate began to change from warm and moist to cool and dry. The progressive drying culminated in the arid and semi-arid zones comprising ca 70% of the Australian continent to- day (Martin, 2006; Byrne et al., 2008). Significant features such as Australia’s stony deserts began to form around 2–4 million years ago (Mya) (Fujioka et al., 2005) while desert dune systems formed around 1 Mya (Fujioka et al., 2009). Later, Pleistocene climates oscillated between wet and dry cycles that intensified through to the peak of aridity of the Last Glacial Maximum (LGM), ca 20,000 years ago (Ka). Even though the arid zone is relatively young, evolution and speciation within it have thus played out against the backdrop of its own dynamic and complex environ- mental history. As might be expected, different evolutionary pat- terns of diversification within the arid zone biota have been observed. In some cases, there have been several independent ori- gins of lineages within the arid zone (see review in Byrne et al., 2008). The need remains then for robust phylogenetic analyses of more Australo-Papuan groups that occur in rainforests as well as in deserts. Quail-thrush are one such group that are ideal for these analy- ses. The five species most usually recognized comprise the genus Cinclosoma Vigors & Horsfield, 1827 of passerine birds (recent treatments in Schodde and Mason, 1999; Higgins and Peter, 2002; Boles, 2007; Christidis and Boles, 2008). The five currently recognized species and numbers of subspecies within them (e.g., Boles, 2007) are Cinclosoma ajax (Temminck, 1836) (painted 1055-7903/$ - see front matter Crown Copyright Ó 2011 Published by Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2011.09.026 ⇑ Corresponding author at: Australian Rivers Institute, Griffith University, Kessels Rd., Nathan, Queensland 4111, Australia. E-mail address: a.toon@griffith.edu.au (A. Toon). Molecular Phylogenetics and Evolution 62 (2012) 286–295 Contents lists available at SciVerse ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev