Genetic diversity and regional identity in the Australian remnant Nothofagus moorei
K. J. Taylor A , A. J. Lowe A , R. J. Hunter B , T. Ridgway A , P. M. Gresshoff C and M. Rossetto D EA School of Life Sciences, University of Queensland, St Lucia, Qld 4072, Australia.
B National Parks and Wildlife Service, Coffs Harbour, NSW 2480, Australia.
C ARC Centre of Excellence for Integrative Legume Research, University of Queensland, St Lucia, Qld 4072, Australia.
D National Herbarium of NSW, Botanic Gardens Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia.
E Corresponding author. Email: maurizio.rossetto@rbgsyd.nsw.gov.au
Australian Journal of Botany 53(5) 437-444 https://doi.org/10.1071/BT04215
Submitted: 15 December 2004 Accepted: 4 April 2005 Published: 11 August 2005
Abstract
Nothofagus moorei (F.Muell.) Krasser has a disjunct and narrow distribution in south-eastern Australian cool temperate rainforest. To assess the conservation-genetic priorities for this species, the genetic diversity of 20 populations sampled from the largest remnant patches at northern and southern distributional extremes, the McPherson and Barrington ranges (a total of 146 individuals), was investigated by using inter simple sequence repeats (ISSR). Regeneration in northern regions of N. moorei has been documented to be predominantly by vegetative means, but our results indicate little evidence of clonality outside the multi-stemmed rings of trees. In addition, genetic diversity was considerably higher in the northern (McPherson, h = 0.1613) than in the southern range (Barrington, h = 0.1159), and genetic differentiation was significantly positively correlated with geographic distance in the former region, but not the latter. Total intraspecific variation was moderate, as measured by Shannon’s diversity index, I = 0.2719, and Nei’s gene diversity, h = 0.1672, and is considered at the high end of spectrum for estimates of narrow endemic species. An analysis of molecular variation indicated that the majority of genetic variation is partitioned among individuals within population (60%; P < 0.001), rather than among populations within regions (10%; P < 0.001). However, a large and significant component of the measured diversity was partitioned between northern and southern regions (29%; P < 0.001). Several hypotheses are outlined to explain these differences and management implications are discussed. However, given the narrow range, poor dispersal mechanism and restriction to cool temperate rainforest, the continued existence of N. moorei is most threatened by environmental instability and habitat loss resulting from global climate change. In this context the northern regions of the species are most at risk and extinction of such populations would lead to a significant loss of genetic variation for the species as a whole.
Acknowledgments
The authors acknowledge the financial support of the New South Wales National Parks and Wildlife Service. We are grateful to National Parks from both New South Wales and Queensland for allowing this work to be undertaken in protected areas. We also thank Trevor Wardill, Kim Taylor, Dave Sparks and Alex Floyd for assistance and support with various aspects of this project.
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