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Genetic diversity in fragmented populations of the critically endangered spider orchid Caladenia huegelii: implications for conservation


Swarts, ND and Sinclair, EA and Krauss, SL and Dixon, KW, Genetic diversity in fragmented populations of the critically endangered spider orchid Caladenia huegelii: implications for conservation, Conservation Genetics, 10, (5) pp. 1199-1208. ISSN 1566-0621 (2009) [Refereed Article]

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Copyright © Springer Science+Business Media B.V. 2008 The final publication is available at

DOI: doi:10.1007/s10592-008-9651-9


The Orchidaceae is characterised by a diverse range of life histories, reproductive strategies and geographic distribution, reflected in a variety of patterns in the population genetic structure of different species. In this study, the genetic diversity and structure was assessed within and among remnant populations of the critically endangered sexually deceptive orchid, Caladenia huegelii. This species has experienced severe recent habitat loss in a landscape marked by ancient patterns of population fragmentation within the Southwest Australian Floristic Region,a global biodiversity hotspot. Using seven polymorphic microsatellite loci, high levels of within-population diversity (mean alleles/locus = 6.73; mean HE = 0.690), weak genetic structuring among 13 remnant populations (FST = 0.047) and a consistent deficit of heterozygotes from Hardy–Weinberg expectation were found across all populations (mean FIS = 0.22). Positive inbreeding coefficients are most likely due to Wahlund effects and/or inbreeding effects from highly correlated paternity and typically low fruit set. Indirect estimates of gene flow (Nm = 5.09 using FST; Nm = 3.12 using the private alleles method) among populations reflects a historical capacity for gene flow through long distance pollen dispersal by sexually deceived wasp pollinators and/or long range dispersal of dust-like orchid seed. However, current levels of gene flow may be impacted by habitat destruction, fragmentation and reduced population size. A genetically divergent population was identified, which should be a high priority for conservation managers. Very weak genetic differentiation indicates that the movement and mixing of seeds from different populationsfor reintroduction programs should result in minimal negative genetic effects.

Item Details

Item Type:Refereed Article
Research Division:Environmental Sciences
Research Group:Environmental management
Research Field:Conservation and biodiversity
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Marine biodiversity
UTAS Author:Swarts, ND (Dr Nigel Swarts)
ID Code:72104
Year Published:2009
Web of Science® Times Cited:43
Deposited By:Agricultural Science
Deposited On:2011-08-22
Last Modified:2011-11-04
Downloads:5 View Download Statistics

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