Differences in vocalisations, morphology and mtDNA support species status for New Zealand saddleback Philesturnus spp

Abstract

Appropriate definitions of species limits are critical for scientific study and conservation management. Many subspecies of birds are defined on the basis of phenotypic variation. However, it has been suggested that following close examination many of these subspecies will be recognised as good species. North Island (NI) (Philesturnus rufusater) and South Island (SI) saddlebacks (P. carunculatus) differ in plumage and apparent vulnerability to introduced predators and, until recently, were considered subspecific. Here, we formally compare vocalisations, morphology and mtDNA between NI and SI saddlebacks. We show significant differences in male song and chatter calls which are fundamental saddleback vocalisations. A discriminant analysis correctly allocated 90% of birds based on significantly larger tarsus, weight and wing measurements in SI saddlebacks relative to NI saddlebacks. Finally, molecular data show c. 5% sequence divergence in mtDNA between the two groups. We concur with previous work elevating NI and SI saddleback to full species.

Keywords:

• evolution
• geographical variation
• morphology
• mtDNA
• Philesturnus
• speciation
• song
• vocalisations

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Erratum

Acknowledgements

This research was part of KAP's PhD research and was funded by a Marsden Grant through the Royal Society of New Zealand to DHB. IGJ's research on conservation genetics of SI saddleback was funded by Department of Conservation (contract no. 3576), Landcare Research (contract no. C09X0503) and the University of Otago. We thank N. Adams, D. Alverez, J. Barr, P. Barrow, M. Booth, I. Castro, T. Cope, M. Delany, S. Heiss-Dunlop, M. Duplain, B. Evans, R. Gardner-Gee, S. Graham, R. Griffiths, M. Harrison, J. Hilton, W. Ji, H. Lindsay, L. Ortiz Catedral, G. Parker, S. Stoddard, R. Thorogood, R.J. Thorogood, B. Zeisemann and New Zealand Department of Conservation staff for assistance in collecting NI saddleback data. Ngāti Wai, Ngāti Manuhiri, Ngāti Rehua, Ngāti Paoa, Te Kawerau a Maki, Ngāti Hei, Ngāti Tamaterā, the Mokoia Trust Board, Ngāti Awa and Te Āti Awa all kindly provided access to motu (islands) within their rohe (areas). B. Masuda provided morphological data on SI saddlebacks, M. Kennedy and D.Winter assisted with the genetic analysis and I. Hogg and the New Zealand Department of Conservation Kōkako Recovery Group provided kōkako blood samples for the sequencing analysis. Fieldwork and bird capture was conducted under permit from the New Zealand Department of Conservation and the Massey and Otago University Animal Ethics Committees. This manuscript benefited from constructive comments provided by J. Banks, T. Worthy and an anonymous reviewer.