Origins, Diversity and Naturalization of Eucalyptus globulus (Myrtaceae) in California

Jennifer M Yost,Dorothy A Steane,Matt K Ritter,Rebecca C Jones,Natalie L R Love,Sascha L Wise,Brad M Potts

doi:10.3390/f12081129

Jennifer M Yost, Dorothy A Steane + Show 5 more

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https://doi.org/10.3390/f12081129

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Abstract

Eucalyptus globulus is native to southeastern Australia, including the island of Tasmania, but is one of the most widely grown hardwood forestry species in the world and is naturalized on several continents. We studied its naturalization in California, where the species has been planted for over 150 years. We sampled 70 E. globulus trees from 53 locations spanning the entire range of the species in California to quantify the genetic variation present and test whether particular genotypes or native origin affect variation in naturalization among locations. Diversity and native affinities were determined based on six nuclear microsatellite markers and sequences from a highly variable chloroplast DNA region (JLA+). The likely native origin was determined by DNA-based comparison with a range-wide native stand collection. Most of California’s E. globulus originated from eastern Tasmania. Genetic diversity in California is greatly reduced compared with that of the native Australian population, with a single chloroplast haplotype occurring in 66% of the Californian samples. Throughout California, the degree of E. globulus naturalization varies widely but was not associated with genotype or native origin of the trees, arguing that factors such as local climate and disturbance are more important than pre-introduction evolutionary history.

Highlights

The genus Eucalyptus L’ Hér. (Myrtaceae) consists of over 700 species, the great majority of which are endemic to the continent of Australia [1,2,3]
Fifteen JLA+ chloroplast DNA (cpDNA) haplotypes were found in the 67 Californian samples sequenced successfully
The presence of five haplotypes (S112, S143–S146) in the Californian landrace that have not been found in native stands in Australia suggests either that genetic changes have occurred since the initial introduction, or these haplotypes are exceedingly rare in the contemporary native range

Summary

Introduction

The genus Eucalyptus L’ Hér. (Myrtaceae) consists of over 700 species, the great majority of which are endemic to the continent of Australia [1,2,3]. The genus contains some of the most widely planted forestry species in the world, some of which have been cultivated for over 150 years [4,5]. These trees have become controversial in some places where they are grown, simultaneously being recognized as economically important and as problematic non-native weeds [6,7]. (Tasmanian blue gum) is the most grown temperate eucalypt, with extensive plantations in countries such as Australia, Chile, China, Ecuador, Ethiopia, Portugal, Spain and Uruguay [8]. While E. globulus has become naturalized and formed landraces in many regions of the world, its spread from the original planting areas is considered ‘limited’

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