The phylogenomics of diversification on an island: applying anchored hybrid enrichment to New Zealand Leptospermum scoparium (Myrtaceae)

Abstract

Abstract Leptospermum scoparium (Myrtaceae) is a morphologically highly variable species found in mainland Australia, Tasmania and New Zealand. For example, in New Zealand up to six morphologically distinct varieties of this species have been described, although only two (var. scoparium and var. incanum) are now formally recognized. In the present study we provide a first examination of genetic diversity in this culturally and commercially important species with the aim of gaining insights into its origins and evolution. We used anchored hybrid enrichment to acquire sequence data from 485 orthologous low-copy nuclear loci for 27 New Zealand and three Australian accessions of L. scoparium and representatives of several other Leptospermum spp. The final concatenated data matrix contained 421 687 nucleotide positions of which 55 102 were potentially informative. Despite the relative large data set, our analyses suggest that a combination of low and incompatible data signal limits the resolution of relationships among New Zealand populations of L. scoparium. Nevertheless, our analyses are consistent with genetic diversity being geographically structured, with three groups of L. scoparium recovered. We discuss the evolutionary and taxonomic implications of our findings.