Microsatellite and morphological analysis ofEucalyptus globuluspopulations

Abstract

Eucalyptus globulus Labill. is native to southeastern Australia and is the most important temperate hardwood plantation species in the world. It consists of four subspecies that are morphologically and geographically distinct but that are linked by morphologically and geographically intermediate populations. The Jeeralang provenance, an intermediate population from southeastern Victoria, is an important source of seed for plantations and genetic material for breeding programs because of its superior growth and wood density. To determine the genetic affinities of this provenance, 154 trees from three subspecies and the Jeeralang provenance were sampled. Analysis of 12 morphological characters verified that the Jeeralang provenance is intermediate between subspecies bicostata (Maiden, Blakely, & J. Simm.) Kirkpatr., globulus and pseudoglobulus (Naudin ex Maiden) Kirkpatr., with individuals having closest affinities to either ssp. globulus or ssp. bicostata. However, eight microsatellite loci showed that the Jeeralang provenance has greater affinities to Victorian ssp. globulus to which it is geographically closest. In contrast, Tasmanian and Victorian ssp. globulus are morphologically similar yet appear to be distinct at the molecular level. This study emphasizes the importance of using traits that are unlikely to be influenced by selection when determining the origin and affinities of populations.Résumé : Eucalyptus globulus Labill. est une espèce indigène du sud-est de l'Australie. C'est la plus importante espèce feuillue en plantation au monde. L'espèce est constituée de quatre sous-espèces qui sont morphologiquement et géographiquement distinctes. Cependant, ces sous-espèces sont liées entre elles par des populations morphologiquement et géographiquement intermédiaires. La provenance Jeeralang, une population intermédiaire de la région sud-est de Victoria, représente une source importante de semences pour l'établissement de plantations, en plus de fournir du maté-riel génétique pour les programmes d'amélioration, en raison de sa supériorité pour la croissance et la densité du bois. Afin de déterminer les affinités génétiques de cette provenance, 154 arbres représentatifs de trois sous-espèces et de la provenance Jeeralang ont été échantillonnés. La caractérisation de 12 caractères morphologiques a permis de confirmer que la provenance Jeeralang était intermédiaire entre sous-espèces bicostata (Maiden, Blakely & J. Simm.) Kirkpatr., globulus et pseudoglobulus (Naudin ex Maiden) Kirkpatr. Les individus de cette provenance avaient plus d'affinités avec ssp. globulus et ssp. bicostata. Cependant, l'analyse de huit loci de microsatellites a révélé que la provenance Jeeralang avait le plus d'affinités avec la sous-espèce globulus de la région de Victoria, dont elle est géographiquement la plus rapprochée. À l'opposé, les individus de la sous-espèce globulus des régions de Tasmanie et de Victoria étaient morphologiquement similaires même s'ils étaient distincts à l'échelle moléculaire. Cette étude souligne ...

Progress in Myrtaceae genetics and genomics: Eucalyptus as the pivotal genus

“…In eucalypts, the frequent occurrence of geographic replacement series involving closely related taxa argues for recent speciation through allopatric processes Byrne 2008;Ladiges 1997). Geographically isolated species or subspecies can usually be differentiated on neutral molecular markers Byrne 2008;Byrne and Macdonald 2000;Jones et al 2002;Le et al 2009;McDonald et al 2009). However, when co-occurring, such closely related species are often poorly differentiated, e.g.…”

“…However, when co-occurring, such closely related species are often poorly differentiated, e.g. Corymbia (Ochieng et al 2010;Shepherd et al 2008a), Eucalyptus (Holman et al 2003;Jones et al 2002), although there are exceptions which argue for barriers to gene flow, e.g. Eucalyptus (McGowen et al 2001) and Melaleuca (Broadhurst et al 2004).…”

“…Many recognized taxa form species complexes in which morphological and molecular variation is continuous, and there is often incongruence between molecular signals of phylogenetic relatedness and morphological and ecological divergence, e.g. Myrceugenia fernandeziana (Jensen et al 2002); Metrosideros polymorpha (James et al 2004, Harbaugh et al 2009); Eucalyptus angustissima complex (Elliott and Byrne 2004); E. globulus (Jones 2009;Jones et al 2002). Such discrepancies are no better exemplified than in a recent study of five species in the Hawaiian Metrosideros complex (Harbaugh et al 2009), which suggests that major taxonomic revisions would be required to reflect the genetic structure revealed by microsatellite markers.…”

Combining microsatellites, growth, and adaptive traits for managing in situ genetic resources ofEucalyptus urophylla

“…ing system (Byrne 1999;Butcher et al 2002;Byrne et al 1998;Elliott and Byrne 2003), but some studies have estimated an excess of homozygotes, e.g., for E. globulus (Jones et al 2002), Eucalyptus marginata Donn ex Sm. (Wheeler et al 2003), and E. populnea (Holman et al 2003).…”

Generation and analysis of an Eucalyptus globulus cDNA library constructed from seedlings subjected to low temperature conditions

“…globulus is considered the most important temperate hardwood plantation species in the world due to its combination of wood properties suitable for the pulp and paper industry (Jones et al 2002;Grattapaglia, 2004). This tree species has fast growth rates and an ability to adapt to a broad range of geographic locations (ranging from latitude 35ºS to 42ºS), even though its growth rate diminishes due to frost conditions (Jones et al 2002;Miranda and Pereira, 2002). Most importantly, Eucalyptus has been listed as one of the candidate biomass energy crops by the U.S. Department of Energy (U.S. Department of Energy, 2007).…”