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

Patricio López-Sepúlveda,Marcelo Baeza,Alejandro Gatica,Daniel J Crawford,Eduardo Ruiz,Karin Tremetsberger,Josef Greimler,Patricio Novoa,Johannes Novak,Luis Letelier,Koji Takayama,Tod F Stuessy,Gudrun Kohl,Patricio Peñailillo

doi:10.1007/s10265-014-0666-7

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.

Highlights

Patterns and processes of speciation in oceanic islands have long captured the attention of evolutionary biologists (Drake et al 2002; Rosindell and Phillimore 2011; Schaefer et al 2011; Stuessy and Ono 1998)
We investigate speciation in Drimys confertifolia, endemic to the two major islands of the Juan Fernandez Archipelago, Chile, to determine genetic consequences of anagenesis, to examine relationships among
Among the species of Drimys, we found a total of 583 fragments, of which 574 are polymorphic (98.5 %, Table 1)

Summary

Introduction

Patterns and processes of speciation in oceanic islands have long captured the attention of evolutionary biologists (Drake et al 2002; Rosindell and Phillimore 2011; Schaefer et al 2011; Stuessy and Ono 1998). The genetic consequence of this process is low level of genetic variation within and among populations of each species (Baldwin et al 1998; Crawford and Stuessy 1997; Emerson 2002; Johnson et al 2000; Stuessy et al 2006) Examples of this mechanism of divergence and speciation in oceanic islands are numerous, such as Aeonium (Crassulaceae) and Echium (Boraginaceae) in the Canary Islands (Bohle et al 1996; Jorgensen and Olesen 2001), Dendroseris and Robinsonia (Asteraceae) in the Juan Fernandez Archipelago (Crawford et al 1998), Bidens (Asteraceae), Schiedea (Caryophyllaceae), Cyanea, Lobelia and Trematolobelia (Lobeliaceae) in the Hawaiian Islands (Givnish et al 2009; Knope et al 2012; Price and Wagner 2004), and Scalesia (Asteraceae) in the Galapagos Islands (Eliasson 1974; Schilling et al 1994)

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