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Unravelling the evolutionary history of Eucalyptus cordata (Myrtaceae) using molecular markers
journal contribution
posted on 2023-05-18, 07:16 authored by Peter HarrisonPeter Harrison, Rebecca JonesRebecca Jones, Rene VaillancourtRene Vaillancourt, Robert Wiltshire, Bradley PottsBradley PottsWe studied the evolutionary processes shaping the genetic diversity in the naturally fragmented Eucalyptus cordata, a rare homoblastic tree endemic to the island of Tasmania. A genome-wide scan showed that E. cordata and the endangered heteroblastic E. morrisbyi were closely related, suggesting a neotenous origin of E. cordata from an endemic heteroblastic ancestor. Bayesian cluster analysis based on nuclear microsatellites assayed in 567 E. cordata and E. morrisbyi individuals revealed five genetic clusters. Two clusters comprised populations that correspond to putative ancestral gene pools linking E. cordata and E. morrisbyi. Another cluster included populations that transgressed the drowned Derwent River valley, suggestive of a wider glacial distribution. However, the majority of individuals occurred in the two genetic clusters distributed in the south-west and north-east of the range of E. cordata. The elevated genetic diversity in populations comprising these clusters suggests that they represent two recently fragmented cores of the distribution. Genetic evidence suggests that the newly described, localised E. cordata subspecies quadrangulosa has been recently selected from within the morphologically diverse, south-western cluster. We argue that multiple phases of isolation and drift have led to the contemporary pattern of molecular variation and the scattering of relictual and more recently derived populations across the species distribution.
Funding
Australian Research Council
History
Publication title
Australian Journal of BotanyVolume
62Pagination
114-131ISSN
0067-1924Department/School
School of Natural SciencesPublisher
CSIRO PublishingPlace of publication
150 Oxford St, Po Box 1139, Collingwood, Australia, Victoria, 3066Rights statement
Copyright 2014 CSIRORepository Status
- Restricted