Genetic structure among Charadrius plovers on the African mainland and islands of Madagascar and St Helena

Natalie Dos Remedios,Fiona Burns,Sama Zefania,Clemens Küpper,Tamás Székely,Mark Bolton,Patricia L M Lee

doi:10.1111/ibi.12694

Abstract

Colonization of islands by long‐distance dispersers has great impact on genetic diversification among populations and may spearhead speciation events. We investigated intra‐ and interspecific divergence in Charadrius plovers with populations on mainland Africa, Madagascar and St Helena. We analysed microsatellite loci and sequence data from four nuclear and two mitochondrial gene regions. Charadrius plovers are shorebirds with high dispersal and mobility. Our results confirmed genetic differentiation between Madagascar and mainland populations of three plover species (White‐fronted Plover Charadrius marginatus, Kittlitz's Plover Charadrius pecuarius and, based on sequence data only, Three‐banded Plover Charadrius tricollaris) but highlight substantial variation in levels of intraspecific divergence among the three species. Namely, the Kittlitz's Plover, a dispersive habitat generalist with a polygamous mating system, exhibited lower island–mainland differentiation (0.05% COI sequence divergence) compared with the two monogamous species, the White‐fronted Plover (0.6% COI divergence) and Three‐banded Plover (1.6% COI divergence). In addition, past colonization of the islands of St Helena and Madagascar by ancestors of today's Kittlitz's Plover has led to the evolution of two endemic island species, the Madagascar Plover Charadrius thoracicus and the more closely‐related St Helena Plover Charadrius sanctaehelenae. We discuss the factors driving species differences in island–mainland divergence and highlight the importance of conserving genetically unique island populations and island habitats to safeguard future evolutionary potential.

Highlights

Colonization of islands by long-distance dispersers has great impact on genetic diversification among populations and may spearhead speciation events
To investigate further the role of islands in promoting genetic differentiation and speciation in avian populations, we focused on the small plovers, genus Charadrius (c. 31 species; Linnaeus 1758)
Clear genetic differentiation was present between Madagascar and mainland Africa for all three species assessed at the population level, the degree of differentiation varied among species

Summary

Introduction

Colonization of islands by long-distance dispersers has great impact on genetic diversification among populations and may spearhead speciation events. Our results confirmed genetic differentiation between Madagascar and mainland populations of three plover species (White-fronted Plover Charadrius marginatus, Kittlitz’s Plover Charadrius pecuarius and, based on sequence data only, Three-banded Plover Charadrius tricollaris) but highlight substantial variation in levels of intraspecific divergence among the three species. Islands are important in speciation for highly mobile species such as birds, for which mainland habitats often provide no barriers to dispersal. The Madagascar Plover has a larger population of approximately 2000 individuals, but this population is currently thought to be in decline due to the destruction of habitats on the west coast of Madagascar (Birdlife International 2016b) Both species are habitat specialists, breeding in areas of short-sward grassland, making them vulnerable to habitat loss

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