Genetic and palaeo-climatic evidence for widespread persistence of the coastal tree species Eucalyptus gomphocephala (Myrtaceae) during the Last Glacial Maximum

Paul Nevill, D. Bradbury, Anna Williams, Sean Tomlinson, Siegfried Krauss

    Research output: Contribution to journalArticle

    21 Citations (Scopus)

    Abstract

    Background and AimsFew phylogeographic studies have been undertaken of species confined to narrow, linear coastal systems where past sea level and geomorphological changes may have had a profound effect on species population sizes and distributions. In this study, a phylogeographic analysis was conducted of Eucalyptus gomphocephala (tuart), a tree species restricted to a 400 × 10 km band of coastal sand-plain in south west Australia. Here, there is little known about the response of coastal vegetation to glacial/interglacial climate change, and a test was made as to whether this species was likely to have persisted widely through the Last Glacial Maximum (LGM), or conforms to a post-LGM dispersal model of recovery from few refugia.MethodsThe genetic structure over the entire range of tuart was assessed using seven nuclear (21 populations; n = 595) and four chloroplast (24 populations; n = 238) microsatellite markers designed for eucalypt species. Correlative palaeodistribution modelling was also conducted based on five climatic variables, within two LGM models.Key ResultsThe chloroplast markers generated six haplotypes, which were strongly geographically structured (GST = 086 and RST = 075). Nuclear microsatellite diversity was high (overall mean HE 075) and uniformly distributed (FST = 005), with a strong pattern of isolation by distance (r2 = 0362, P = 0001). Distribution models of E. gomphocephala during the LGM showed a wide distribution that extended at least 30 km westward from the current distribution to the palaeo-coastline.ConclusionsThe chloroplast and nuclear data suggest wide persistence of E. gomphocephala during the LGM. Palaeodistribution modelling supports the conclusions drawn from genetic data and indicates a widespread westward shift of E. gomphocephala onto the exposed continental shelf during the LGM. This study highlights the importance of the inclusion of complementary, non-genetic data (information on geomorphology and palaeoclimate) to interpret phylogeographic patterns. © The Author 2013.
    Original languageEnglish
    Pages (from-to)55-67
    Number of pages13
    JournalAnnals of Botany
    Volume113
    Issue number1
    Early online date26 Nov 2013
    DOIs
    Publication statusPublished - Jan 2014

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