Relationships and genetic consequences of contrasting modes of speciation among endemic species of <i>Robinsonia</i> (Asteraceae, Senecioneae) of the Juan Fernández Archipelago, Chile, based on <scp>AFLP</scp>s and <scp>SSR</scp>s

<jats:title>Summary</jats:title><jats:p> <jats:list list-type="bullet"> <jats:list-item><jats:p>This study analyses and compares the genetic signatures of anagenetic and cladogenetic speciation in six species of the genus <jats:italic>Robinsonia</jats:italic> (Asteraceae, Senecioneae), endemic to the Juan Fernández Islands, Chile.</jats:p></jats:list-item> <jats:list-item><jats:p>Population genetic structure was analyzed by amplified fragment length polymorphism (<jats:styled-content style="fixed-case">AFLP</jats:styled-content>) and microsatellite (simple sequence repeat, <jats:styled-content style="fixed-case">SSR</jats:styled-content>) markers from 286 and 320 individuals, respectively, in 28 populations. Each species is genetically distinct. Previous hypotheses of classification among these species into subgenera and sections, via morphological, phytochemical, isozymic and internal transcribed spacer (<jats:styled-content style="fixed-case">ITS</jats:styled-content>) data, have been confirmed, except that <jats:italic>R. saxatilis</jats:italic> appears to be related to <jats:italic>R. gayana</jats:italic> rather than <jats:italic>R. evenia</jats:italic>.</jats:p></jats:list-item> <jats:list-item><jats:p>Analysis of phylogenetic results and biogeographic context suggests that five of these species have originated by cladogenesis and adaptive radiation on the older Robinson Crusoe Island. The sixth species, <jats:italic>R. masafuerae</jats:italic>, restricted to the younger Alejandro Selkirk Island, is closely related to and an anagenetic derivative of <jats:italic>R. evenia</jats:italic> from Robinson Crusoe.</jats:p></jats:list-item> <jats:list-item><jats:p>Microsatellite and <jats:styled-content style="fixed-case">AFLP</jats:styled-content> data reveal considerable genetic variation <jats:italic>among</jats:italic> the cladogenetically derived species of <jats:italic>Robinsonia</jats:italic>, but <jats:italic>within</jats:italic> each the genetic variation is lower, highlighting presumptive genetic isolation and rapid radiation. The anagenetically derived <jats:italic>R. masafuerae</jats:italic> harbors a level of genetic variation similar to that of its progenitor, <jats:italic>R. evenia</jats:italic>. This is the first direct comparison of the genetic consequences of anagenetic and cladogenetic speciation in plants of an oceanic archipelago.</jats:p></jats:list-item> </jats:list> </jats:p>