title: Genetic consequences of cladogenetic vs. anagenetic speciation in endemic plants of oceanic islands.
abstract: Adaptive radiation is a common mode of speciation among plants endemic to oceanic islands. This pattern is one of cladogenesis, or splitting of the founder population, into diverse lineages in divergent habitats. In contrast, endemic species have also evolved primarily by simple transformations from progenitors in source regions. This is anagenesis, whereby the founding population changes genetically and morphologically over time primarily through mutation and recombination. Gene flow among populations is maintained in a homogeneous environment with no splitting events. Genetic consequences of these modes of speciation have been examined in the Juan Fernández Archipelago, which contains two principal islands of differing geological ages. This article summarizes population genetic results (nearly 4000 analyses) from examination of 15 endemic species, involving 1716 and 1870 individuals in 162 and 163 populations (with amplified fragment length polymorphisms and simple sequence repeats, respectively) in the following genera: Drimys (Winteraceae), Myrceugenia (Myrtaceae), Rhaphithamnus (Verbenaceae), Robinsonia (Asteraceae, Senecioneae) and Erigeron (Asteraceae, Astereae). The results indicate that species originating anagenetically show high levels of genetic variation within the island population and no geographic genetic partitioning. This contrasts with cladogenetic species that show less genetic diversity within and among populations. Species that have been derived anagenetically on the younger island (1-2 Ma) contain less genetic variation than those that have anagenetically speciated on the older island (4 Ma). Genetic distinctness among cladogenetically derived species on the older island is greater than among similarly derived species on the younger island. An important point is that the total genetic variation within each genus analysed is comparable, regardless of whether adaptive divergence occurs.
authors: Museum of Natural and Environmental History, Shizuoka, Oya 5762, Suruga-ku, Shizuoka-shi, Shizuoka 422-8017, Japan.
authors: Koji
authors: K
authors: Takayama
authors: Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors: Patricio
authors: P
authors: López-Sepúlveda
authors: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.
authors: Josef
authors: J
authors: Greimler
authors: Department of Ecology and Evolutionary Biology and the Biodiversity Institute, University of Kansas, Lawrence, KS 60045, USA.
authors: Daniel J
authors: DJ
authors: Crawford
authors: Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
authors: Patricio
authors: P
authors: Peñailillo
authors: Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors: Marcelo
authors: M
authors: Baeza
authors: Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
authors: Eduardo
authors: E
authors: Ruiz
authors: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.
authors: Gudrun
authors: G
authors: Kohl
authors: Institute of Botany, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences, Gregor Mendel Straße 33, A-1180 Vienna, Austria.
authors: Karin
authors: K
authors: Tremetsberger
authors: Bioma Consultores S.A., Mariano Sanchez Fontecilla No. 396, Las Condes, Santiago, Chile.
authors: Alejandro
authors: A
authors: Gatica
authors: Universidad Bernardo O'Higgins, Centro de Investigaciones en Recursos Naturales y Sustentabilidad, General Gana 1702, Santiago, Chile.
authors: Luis
authors: L
authors: Letelier
authors: Jardín Botánico de Viña del Mar, Corporación Nacional Forestal, Camino El Olivar 305, Viña del Mar, Chile.
authors: Patricio
authors: P
authors: Novoa
authors: Institute for Applied Botany and Pharmacognosy, University of Veterinary Medicine, Veterinärplatz 1, A-1210 Vienna, Austria.
authors: Johannes
authors: J
authors: Novak
authors: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria Herbarium, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 1315 Kinnear Road, Columbus, OH 43212, USA stuessy.1@osu.edu.
authors: Tod F
authors: TF
authors: Stuessy
keywords: Adaptive radiation; Robinson Crusoe Islands; anagenesis; cladogenesis; genetic diversity; phyletic speciation