Colonization and diversification of the Euphorbia species (sect. Aphyllis subsect. Macaronesicae) on the Canary Islands.

Ye Sun,Faguo Wang,Carlos Fabián Vargas-Mendoza,Fuwu Xing,Yanshu Li

doi:10.1038/srep34454

Abstract

Diversification between islands and ecological radiation within islands are postulated to have occurred in the Euphorbia species (sect. Aphyllis subsect. Macaronesicae) on the Canary Islands. In this study, the biogeographical pattern of 11 species of subsect. Macaronesicae and the genetic differentiation among five species were investigated to distinguish the potential mode and mechanism of diversification and speciation. The biogeographical patterns and genetic structure were examined using statistical dispersal-vicariance analysis, Bayesian phylogenetic analysis, reduced median-joining haplotype network analysis, and discriminant analysis of principal components. The gene flow between related species was evaluated with an isolation-with-migration model. The ancestral range of the species of subsect. Macaronesicae was inferred to be Tenerife and the Cape Verde Islands, and Tenerife-La Gomera acted as sources of diversity to other islands of the Canary Islands. Inter-island colonization of E. lamarckii among the western islands and a colonization of E. regis-jubae from Gran Canaria to northern Africa were revealed. Both diversification between islands and radiation within islands have been revealed in the Euphorbia species (sect. Aphyllis subsect. Macaronesicae) of the Canary Islands. It was clear that this group began the speciation process in Tenerife-La Gomera, and this process occurred with gene flow between some related species.

Highlights

The endemics of the Canarian archipelago include taxa that have undergone diversification between islands but remain in similar ecological zones[12,13] and groups that have radiated rapidly into distinct ecological zones[14]
The other Macaronesian species are in the Canary Islands, where E. aphylla occurs in the central islands (La Gomera, Tenerife, Gran Canaria), E. atropurpurea occurs in Tenerife, E. bourgeana occurs in Tenerife and La Gomera, E. berthelotii and E. bravoana occur in La Gomera, E. lamarckii occurs in the western islands (Tenerife, La Gomera, La Palma, and EI Hierro), and E. regis-jubae occurs in the eastern islands (Gran Canaria, Lanzarote, and Fuerteventura) and the Atlantic coast of Morocco[15]
We were able to determine the area of origin for one of the most characteristic groups in the region of Macaronesia, namely the genus Euphorbia sect

Summary

Introduction

The endemics of the Canarian archipelago include taxa that have undergone diversification between islands but remain in similar ecological zones[12,13] and groups that have radiated rapidly into distinct ecological zones[14]. The other Macaronesian species are in the Canary Islands, where E. aphylla occurs in the central islands (La Gomera, Tenerife, Gran Canaria), E. atropurpurea occurs in Tenerife, E. bourgeana occurs in Tenerife and La Gomera, E. berthelotii and E. bravoana occur in La Gomera, E. lamarckii occurs in the western islands (Tenerife, La Gomera, La Palma, and EI Hierro), and E. regis-jubae occurs in the eastern islands (Gran Canaria, Lanzarote, and Fuerteventura) and the Atlantic coast of Morocco[15]. These Canarian species have high morphological similarity and their taxonomic classification is easy to confuse, especially for E. lamarckii and E. regis-jubae[15]. Once we establish the ancestral area and the species that occurred there, we expect to reveal the process of colonization and diversification of this group, the genetic differentiation of these closely related species, and the potential role of inter-island colonization and ecological shifts in the evolution of endemic species by investigating the genetic diversity of E. atropurpurea, E. berthelotii, E. lamarckii, and E. regis-jubae across the Canary Islands with chloroplast DNA sequences and nuclear SSR (simple sequence repeat) markers from population-level sampling

Methods

Results

Conclusion