Genomic and geographic diversification of a “great-speciator” (Rhipidura rufifrons)

ABSTRACT The radiation of so-called “great speciators” represents a paradox among the myriad of avian radiations endemic to the southwest Pacific. In such radiations, lineages otherwise capable of dispersing across vast distances of open ocean differentiate rapidly and frequently across relatively short geographic barriers. Here, we evaluate the phylogeography of the Rufous Fantail (Rhipidura rufifrons). Although a presumed “great-speciator”, no formal investigations across its range have been performed. Moreover, delimitation of lineages within R. rufifrons, and the biogeographic implications of those relationships, remain unresolved. To investigate whether R. rufifrons represents a great speciator we identified thousands of single nucleotide polymorphisms for 89 individuals, representing 19 described taxa. Analyses recovered 7 divergent lineages and evidence of gene flow between geographically isolated populations. We also found plumage differences to be a poor proxy for evolutionary relationships. Given the relatively recent divergence dates for the clade (1.35–2.31 mya), rapid phenotypic differentiation, and evidence for multiple independent lineages within the species complex, we determine that R. rufifrons possesses the characteristics of a great speciator. LAY SUMMARY To study biodiversity, we must have a clear understanding of the differences between species, and how those differences came to be. We obtained tissue samples for nearly 100 Rufous Fantails for this study making sure to include birds with as many different coloration patterns and geographic locations as possible We used DNA sequence data to identify distinct genetic groups within the Rufous Fantail complex, and subsequently to determine how similar those groups are to one another. We found strong support for seven genetically distinct groups that are all currently considered one species, the Rufous Fantail. We found evidence for interbreeding among groups, despite some having different coloration patterns and geographic ranges. Studying the Rufous Fantail shows us that groups of birds can look different from one another and/or be separated from each other by large distances, and still be similar genetically. RESUMEN La radiación de los llamados “grandes especiadores” representa una paradoja entre la miríada de radiaciones de aves endémicas del Pacífico suroeste. En tales radiaciones, los linajes que de otro modo serían capaces de dispersarse a lo largo de grandes distancias en mar abierto se diferencian rápida y frecuentemente a través de barreras geográficas relativamente cortas. Aquí, evaluamos la filogeografía de Rhipidura rufifrons. Aunque se presume que es un “gran especiador”, no se han realizado investigaciones formales en todo su rango. Además, la delimitación de linajes dentro de R. rufifrons y las implicaciones biogeográficas de esas relaciones siguen sin resolverse. Para investigar si R. rufifrons representa un gran especiador, identificamos miles de polimorfismos de un solo nucleótido para 89 individuos, que representan 19 taxones descritos. Los análisis recuperaron 7 linajes divergentes y evidencia de flujo génico entre poblaciones geográficamente aisladas. También encontramos que las diferencias de plumaje son un mal indicador de las relaciones evolutivas. Dadas las fechas de divergencia relativamente recientes para el clado (1.35–2.31 millones de años), la rápida diferenciación fenotípica y la evidencia de múltiples linajes independientes dentro del complejo de especies, determinamos que R. rufifrons posee las características de un gran especiador.