Life on the edge – High levels of genetic diversity in a cliff population of 'Bertya ingramii' are attributed to 'B. rosmarinifolia' (Euphorbiaceae)

Title
Life on the edge – High levels of genetic diversity in a cliff population of 'Bertya ingramii' are attributed to 'B. rosmarinifolia' (Euphorbiaceae)
Publication Date
2009
Author(s)
Fatemi, Mohammad
( author )
OrcID: https://orcid.org/0000-0001-6618-4234
Email: mfatemi2@une.edu.au
UNE Id une-id:mfatemi2
Gross, Caroline L
( author )
OrcID: https://orcid.org/0000-0001-8014-1548
Email: cgross@une.edu.au
UNE Id une-id:cgross
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Elsevier BV
Place of publication
Netherlands
DOI
10.1016/j.biocon.2009.02.014
UNE publication id
une:4546
Abstract
Wind-facilitated migration of new genotypes into small, geographically disjunct populations should buffer them against local extinction. 'Bertya ingramii', a monoecious, wind-pollinated shrub, is restricted to three populations in a 4 km² area in eastern Australia. Populations are separated by deeply dissected gorges where it is unlikely that seeds are exchanged but where wind movement may facilitate pollen dispersal. Using 156 highly polymorphic ISSR markers, we found moderate genetic variation within and among populations of 'B. ingramii' and less genetic diversity in a nearby and small population of the widespread 'Bertya rosmarinifolia'. The smallest population of 'B. ingramii' (<30 plants) had the highest genetic variation (65% polymorphic markers, Shannon Information Index = 0.30). AMOVA and a Bayesian analysis showed that molecular variance was equally distributed within and among populations suggesting that gene flow is as limited within as in among populations. Genetic distances between populations were only weakly explained by their relative geographic distances (mantel test, R² = 0.21, P = 0.001) but the distribution of private bands, the departure from Hardy–Weinberg equilibrium, and a UPGMA tree showed that the smallest population of 'B. ingramii' was generally more similar to an upstream population of 'B. rosmarinifolia'. Thirty-eight percent of bands in this small population of 'B. ingramii' were exclusively shared with 'B. rosmarinifolia'. This covert hybridisation may have been an ancient event but may be responsible for contemporary declines in germination and establishment in 'B. ingramii'. The conservation implications are amplified by the endangered status of 'B. ingramii'.
Link
Citation
Biological Conservation, 142(7), p. 1461-1468
ISSN
1873-2917
0006-3207
Start page
1461
End page
1468

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