Progressive migration and anagenesis in Drimys confertifolia of the Juan Fernández Archipelago, Chile

Abstract

A common mode of speciation in oceanic islands is by anagenesis, wherein an immigrant arrives and through time transforms by mutation, recombination, and drift into a morphologically and genetically distinct species, with the new species accumulating a high level of genetic diversity. We investigate speciation in Drimys confertifolia, endemic to the two major islands of the Juan Fernández Archipelago, Chile, to determine genetic consequences of anagenesis, to examine relationships among populations of D. confertifolia and the continental species D. winteri and D. andina, and to test probable migration routes between the major islands. Population genetic analyses were conducted using AFLPs and nuclear microsatellites of 421 individuals from 42 populations from the Juan Fernández islands and the continent. Drimys confertifolia shows a wide genetic variation within populations on both islands, and values of genetic diversity within populations are similar to those found within populations of the continental progenitor. The genetic results are compatible with the hypothesis of high levels of genetic variation accumulating within anagenetically derived species in oceanic islands, and with the concept of little or no geographical partitioning of this variation over the landscape. Analysis of the probability of migration within the archipelago confirms colonization from the older island, Robinson Crusoe, to the younger island Alejandro Selkirk.Electronic supplementary materialThe online version of this article (doi:10.1007/s10265-014-0666-7) contains supplementary material, which is available to authorized users.

A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system

“…Among living species, anagenesis has occurred in cyprinid teleosts15 and it has produced genetic diversity among oceanic island plants1617. Anagenesis gained currency in studies of dinosaur evolution with Horner et al .’s1 landmark study that found evidence for phyletic evolution in four lineages of dinosaurs, including tyrannosaurs, from the Late Cretaceous of the American West.…”

Biogeography and genetic consequences of anagenetic speciation ofRhaphithamnus venustus(Verbenaceae) in theJuanFernández archipelago,Chile: insights fromAFLPandSSRmarkers

“…; López‐Sepúlveda et al . ). Those results are concordant with the hypothesis that anagenetic speciation in the islands has, over time, been associated with an increase in genetic diversity and has erased the footprint of a genetic bottleneck that may have resulted from the original colonization of the islands.…”

“…In contrast to prior investigations in other JF genera such as Drimys (López‐Sepúlveda et al . ) and Myrceugenia (López‐Sepúlveda et al . ), Rhaphithamnus is an example of anagenetic speciation in which there is generally lower genetic diversity in the insular species than in their continental relatives, presumably the result of the founder effect associated with the recent colonization of the island.…”

Explaining disjunct distributions in the flora of southern South America: evolutionary history and biogeography of Myrceugenia (Myrtaceae)

“…A similar pattern has been found with Drimys confertifolia , endemic to both islands but having diverged around 9–10.8 Ma (Marquínez et al ., ). Recent studies using amplified fragment length polymorphisms and nuclear microsatellites (López‐Sepúlveda et al ., , ), however, have proposed that all of these species have a more recent origin. In these population‐genetic studies, no molecular clock was employed and it is not impossible that the direct ancestors of these lineages may have already become extinct.…”