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

Mark J. Wallace, Siegfried L. Krauss, Matthew D. Barrett

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Abstract

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.

Original languageEnglish
Pages (from-to)205-217
Number of pages13
JournalAustralian Journal of Botany
Volume67
Issue number3
DOIs
Publication statusPublished - 2019

Cite this

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title = "Complex genetic relationships within and among cytotypes in the Lepidosperma costale species complex (Cyperaceae) on rocky outcrops in Western Australia",
abstract = "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.",
keywords = "apomixis, clonality, hybridisation, ironstone, granite, polyploidy, population genetics, POPULATION-GENETICS, REPRODUCTIVE ISOLATION, POLYPLOID FORMATION, DIVERSITY, MARKERS, PLOIDY, DIFFERENTIATION, GENOTYPE, PATTERNS, AUTOPOLYPLOIDY",
author = "Wallace, {Mark J.} and Krauss, {Siegfried L.} and Barrett, {Matthew D.}",
year = "2019",
doi = "10.1071/BT18103",
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journal = "Australian Journal of Botany",
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TY - JOUR

T1 - Complex genetic relationships within and among cytotypes in the Lepidosperma costale species complex (Cyperaceae) on rocky outcrops in Western Australia

AU - Wallace, Mark J.

AU - Krauss, Siegfried L.

AU - Barrett, Matthew D.

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - apomixis

KW - clonality

KW - hybridisation

KW - ironstone

KW - granite

KW - polyploidy

KW - population genetics

KW - POPULATION-GENETICS

KW - REPRODUCTIVE ISOLATION

KW - POLYPLOID FORMATION

KW - DIVERSITY

KW - MARKERS

KW - PLOIDY

KW - DIFFERENTIATION

KW - GENOTYPE

KW - PATTERNS

KW - AUTOPOLYPLOIDY

U2 - 10.1071/BT18103

DO - 10.1071/BT18103

M3 - Article

VL - 67

SP - 205

EP - 217

JO - Australian Journal of Botany

JF - Australian Journal of Botany

SN - 0067-1924

IS - 3

ER -