Molecular taxonomy and intra-Palaearctic boundary: new insights from the biogeography of the black francolin (Francolinus francolinus) by means of microsatellite DNA

Abstract

The transition zones between and within biogeographic realms are a topical issue. Long ascribed to eastern Palaearctic, Iran was recently proposed as entirely pertaining to its western counterpart (featuring the ´Great Western Palaearctic`). Molecular and phenotypic information from polytypic taxa may help untangle the bioclimatic and environmental dynamics that shaped faunal distributions. In this study, we collected 221 black francolin (Francolinus francolinus Linnaeus, 1766) samples from Cyprus to Bangladesh and compared the spatial genetic structure as inferred from nine microsatellite loci with publically available bioacoustic data. We found striking overlap between the two sources of information, which pointed to the occurrence of a western and an eastern subdivision (F_ST = 0.435, P < 0.001) with a break across central Iran. When framed within the palaeoclimatic and geomorphological history of this region, we found that high connectivity among local subspecies was facilitated by warmer and more humid conditions preceding the cold-arid climatic phase associated with the last glacial stage. The subsequent temperature increase likely led to the substantial isolation of eastern and western black francolin populations to moist refuges. Overall, these results point to an intra-Palaearctic boundary crossing Iran longitudinally, thus raising prospect of compromise between the two most debated views.

Key words:

• bioacoustic data
• bird vocalisations
• black francolin
• galliforms
• Greater Western Palaearctic
• Iran
• microsatellites
• morphological subspecies
• polytypic species
• vocal groups

Acknowledgements

The authors are deeply indebted to the people acknowledged in Forcina et al. (2012, 2014, 2018) as well as with all co-authors of these prior papers for their help in the black francolin sample collection across the range of the species. The authors are also grateful to Gholam Hosein Yusefi, Leili Khalatbari (BIODESERT group, CIBIO-InBIO) and Niloufar Raeesi Chahartaghi (freelance researcher) for providing useful information on Iranian zoogeography and palaeoecology as well as to professional wildlife illustrators Velizar Simeonovski, Roger Hall, and Lyn Wells for granting permission to use their artworks in Fig. 4. The authors wish to thank also Corey Seeman (University of Michigan) and Saeed Hosseinian (Damghan University) for granting permission to use their photos in the same figure. The International Otter Survival Fund (UK) and Encyclopaedia Britannica are also acknowledged for sharing the artworks of the smooth-coated otter and Asian black bear, respectively.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2019.1691673.

Associate Editor: Gary Voelker