North or South? Biogeographic origins of shorebirds with variable mating systems

Shorebirds are integral to coastal and estuarine biodiversity. However, many species are exposed to anthropogenic impacts because of their ground-nesting habit. In Australia, while the Red-capped Plover (Charadrius... [ view full abstract ]

Shorebirds are integral to coastal and estuarine biodiversity. However, many species are exposed to anthropogenic impacts because of their ground-nesting habit. In Australia, while the Red-capped Plover (Charadrius ruficapillus) is a widespread shorebird, the endangered Hooded Plover (Thinornis cucullatus; formerly Thinornis rubricollis) is vulnerable to human disturbance because it lays eggs on beaches during the peak tourist season. In addition to conservation concern, plovers in general exhibit great diversity in mating systems and plumage colouration, and our aim is to establish a phylogenetic framework to help understand the selective forces that have shaped these traits over evolutionary time. The small plovers, genus Charadrius, are cosmopolitan shorebirds, distributed across all continents except Antarctica. Here we present a global, species-level molecular phylogeny of this group based on a Bayesian multispecies coalescent analysis of four nuclear (ADH5, FIB7, MYO2 and RAG1) and two mitochondrial (COI and ND3) genes, and use the phylogeny to examine the biogeographic origin of the genus. In contrast to earlier work, ancestral area analyses supported an origin of the Charadrius plovers in the Northern hemisphere. Also, a number of species of other genera (including the Hooded Plover T. cucullatus, which is endemic to Australia) proved to be within the Charadrius clade. We propose that major radiations in this group were associated with shifts in the range of ancestral plover species, leading to colonisation of the Southern hemisphere and the Australian continent.