Complex genetic relationships within and among cytotypes in the Lepidosperma costale species complex (Cyperaceae) on rocky outcrops in Western Australia

Wallace, Mark J., Krauss, Siegfried L., and Barrett, Matthew D. (2019) Complex genetic relationships within and among cytotypes in the Lepidosperma costale species complex (Cyperaceae) on rocky outcrops in Western Australia. Australian Journal of Botany, 67. pp. 205-217.

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There is a growing realisation that cytotype variation within species complexes plays an important role in plant evolution; however, there are relatively few investigations that describe the genetic diversity within and among related cytotypes. In the present study, we analysed patterns of genetic variation in 774 individuals from nine diploid, 14 tetraploid and five mixed ploidy populations of the Lepidosperma costale complex (Cyperaceae) from rocky outcrops in south-west Australia. Application of nuclear (nSSR) and chloroplast (cpSSR) microsatellites suggests that polyploids are of autopolyploid and allopolyploid origin and that polyploidisation is associated with a shift to facultative clonal reproduction, including apomictic reproduction. The newly-discovered putative allopolyploids were commonly associated with disturbed environments, an association commonly reported for allopolyploids. Diploid populations generally contained more genetic diversity than polyploid populations, and there was little genetic differentiation among diploid populations. In contrast, polyploids were characterised by higher heterozygosity and differentiation among populations, but possessed lower within-population diversity. The high differentiation among polyploid populations suggests that polyploids may have formed recurrently and are an important component of morphologically cryptic diversity within the species complex. Ploidy level is a critical factor affecting genetic diversity in this species complex, highlighting the potential contributions of polyploidy to genetic differentiation, and potentially speciation.

Item ID: 60471
Item Type: Article (Research - C1)
ISSN: 1444-9862
Keywords: apomixis, clonality, hybridisation, ironstone, granite, polyploidy, population genetics
Copyright Information: © CSIRO 2019
Funders: Gindalbie Metals Pty Ltd., Mt Gibson Mining Pty Ltd, Wildlife Preservation Society of Australia
Date Deposited: 03 Oct 2019 05:27
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310402 Biogeography and phylogeography @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960899 Flora, Fauna and Biodiversity of Environments not elsewhere classified @ 100%
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