Phylogeny, morphological evolution, and speciation of endemic brassicaceae genera in the cape flora of southern Africa

K. Mummenhoff, I.A. Al-Shehbaz, F.T. Bakker, H.P. Linder, A. Mühlhausen

Research output: Contribution to journalArticleAcademicpeer-review

62 Citations (Scopus)

Abstract

Heliophila (ca. 73 spp.), the ditypic Cycloptychis and Thlaspeocarpa, and the monotypic Schlechteria, Silicularia, Brachycarpaea, and Chamira are endemic to the Cape region of South Africa, where they are the dominant genera of Brassicaceae. They may be regarded as the most diversified Brassicaceae lineage in every aspect of habit, leaf, flower, and fruit morphology. The characters used in the separation of these genera and their species, especially fruit type (silique vs. silicle), dehiscence (dehiscent vs. indehiscent), compression (latiseptate vs. angustiseptate), and cotyledonary type (spirolobal, diplecolobal, twice conduplicate), have been used extensively in the delimitation of tribes. The relationship and taxonomic limits among these genera are unclear and controversial. The present ITS study demonstrates the monophyly of tribe Heliophileae, with Chamira as sister clade. The other five smaller genera above are nested within two of the three main lineages of Heliophila, to which they should be reduced to synonymy. The current study reveals parallel evolution of fruit characters often used heavily in the traditional classification schemes of the family. However, the arrangement of species into three main clades largely corresponds with the distribution of morphological characters (e.g., habit, leaf shape, seed structure, inflorescence type, and presence/absence of basal appendages on the pedicels, petals, and staminal filaments) not adequately accounted for in previous studies. Estimation of divergence times of the main lineages of Heliophila is in agreement with recent estimations in other plant groups, all of which date the diversification against a background of aridification in the Pliocene and Pleistocene. Species of one main clade are perennial, microphyllous shrubs/subshrubs typically restricted to poor sandstone soils in the southwestern and western parts of the Cape Floristic Region of South Africa. Species of the other two clades are predominantly annuals that grow in more arid regions of Namibia and Namaqualand, as well as in the above sandstone areas of the Cape Region. The adaptive significance of various floral structures is discussed in terms of their possible role in the rapid diversification within Heliophila.
Original languageEnglish
Pages (from-to)400-424
JournalAnnals of the Missouri Botanical Garden
Volume92
Issue number3
Publication statusPublished - 2005

Fingerprint

Heliophilum
Brassicaceae
Southern Africa
phylogeny
flora
fruit
fruits
sandstone soils
South Africa
sandstone
Cape Floristic Region
aridification
parallel evolution
Namibia
pedicel
appendages
arid region
monophyly
arid zones
corolla

Keywords

  • molecular systematics
  • family brassicaceae
  • dna
  • cruciferae
  • biogeography
  • arabidopsis
  • dispersal
  • radiation
  • sequences
  • regions

Cite this

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title = "Phylogeny, morphological evolution, and speciation of endemic brassicaceae genera in the cape flora of southern Africa",
abstract = "Heliophila (ca. 73 spp.), the ditypic Cycloptychis and Thlaspeocarpa, and the monotypic Schlechteria, Silicularia, Brachycarpaea, and Chamira are endemic to the Cape region of South Africa, where they are the dominant genera of Brassicaceae. They may be regarded as the most diversified Brassicaceae lineage in every aspect of habit, leaf, flower, and fruit morphology. The characters used in the separation of these genera and their species, especially fruit type (silique vs. silicle), dehiscence (dehiscent vs. indehiscent), compression (latiseptate vs. angustiseptate), and cotyledonary type (spirolobal, diplecolobal, twice conduplicate), have been used extensively in the delimitation of tribes. The relationship and taxonomic limits among these genera are unclear and controversial. The present ITS study demonstrates the monophyly of tribe Heliophileae, with Chamira as sister clade. The other five smaller genera above are nested within two of the three main lineages of Heliophila, to which they should be reduced to synonymy. The current study reveals parallel evolution of fruit characters often used heavily in the traditional classification schemes of the family. However, the arrangement of species into three main clades largely corresponds with the distribution of morphological characters (e.g., habit, leaf shape, seed structure, inflorescence type, and presence/absence of basal appendages on the pedicels, petals, and staminal filaments) not adequately accounted for in previous studies. Estimation of divergence times of the main lineages of Heliophila is in agreement with recent estimations in other plant groups, all of which date the diversification against a background of aridification in the Pliocene and Pleistocene. Species of one main clade are perennial, microphyllous shrubs/subshrubs typically restricted to poor sandstone soils in the southwestern and western parts of the Cape Floristic Region of South Africa. Species of the other two clades are predominantly annuals that grow in more arid regions of Namibia and Namaqualand, as well as in the above sandstone areas of the Cape Region. The adaptive significance of various floral structures is discussed in terms of their possible role in the rapid diversification within Heliophila.",
keywords = "molecular systematics, family brassicaceae, dna, cruciferae, biogeography, arabidopsis, dispersal, radiation, sequences, regions",
author = "K. Mummenhoff and I.A. Al-Shehbaz and F.T. Bakker and H.P. Linder and A. M{\"u}hlhausen",
year = "2005",
language = "English",
volume = "92",
pages = "400--424",
journal = "Annals of the Missouri Botanical Garden",
issn = "0026-6493",
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Phylogeny, morphological evolution, and speciation of endemic brassicaceae genera in the cape flora of southern Africa. / Mummenhoff, K.; Al-Shehbaz, I.A.; Bakker, F.T.; Linder, H.P.; Mühlhausen, A.

In: Annals of the Missouri Botanical Garden, Vol. 92, No. 3, 2005, p. 400-424.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Phylogeny, morphological evolution, and speciation of endemic brassicaceae genera in the cape flora of southern Africa

AU - Mummenhoff, K.

AU - Al-Shehbaz, I.A.

AU - Bakker, F.T.

AU - Linder, H.P.

AU - Mühlhausen, A.

PY - 2005

Y1 - 2005

N2 - Heliophila (ca. 73 spp.), the ditypic Cycloptychis and Thlaspeocarpa, and the monotypic Schlechteria, Silicularia, Brachycarpaea, and Chamira are endemic to the Cape region of South Africa, where they are the dominant genera of Brassicaceae. They may be regarded as the most diversified Brassicaceae lineage in every aspect of habit, leaf, flower, and fruit morphology. The characters used in the separation of these genera and their species, especially fruit type (silique vs. silicle), dehiscence (dehiscent vs. indehiscent), compression (latiseptate vs. angustiseptate), and cotyledonary type (spirolobal, diplecolobal, twice conduplicate), have been used extensively in the delimitation of tribes. The relationship and taxonomic limits among these genera are unclear and controversial. The present ITS study demonstrates the monophyly of tribe Heliophileae, with Chamira as sister clade. The other five smaller genera above are nested within two of the three main lineages of Heliophila, to which they should be reduced to synonymy. The current study reveals parallel evolution of fruit characters often used heavily in the traditional classification schemes of the family. However, the arrangement of species into three main clades largely corresponds with the distribution of morphological characters (e.g., habit, leaf shape, seed structure, inflorescence type, and presence/absence of basal appendages on the pedicels, petals, and staminal filaments) not adequately accounted for in previous studies. Estimation of divergence times of the main lineages of Heliophila is in agreement with recent estimations in other plant groups, all of which date the diversification against a background of aridification in the Pliocene and Pleistocene. Species of one main clade are perennial, microphyllous shrubs/subshrubs typically restricted to poor sandstone soils in the southwestern and western parts of the Cape Floristic Region of South Africa. Species of the other two clades are predominantly annuals that grow in more arid regions of Namibia and Namaqualand, as well as in the above sandstone areas of the Cape Region. The adaptive significance of various floral structures is discussed in terms of their possible role in the rapid diversification within Heliophila.

AB - Heliophila (ca. 73 spp.), the ditypic Cycloptychis and Thlaspeocarpa, and the monotypic Schlechteria, Silicularia, Brachycarpaea, and Chamira are endemic to the Cape region of South Africa, where they are the dominant genera of Brassicaceae. They may be regarded as the most diversified Brassicaceae lineage in every aspect of habit, leaf, flower, and fruit morphology. The characters used in the separation of these genera and their species, especially fruit type (silique vs. silicle), dehiscence (dehiscent vs. indehiscent), compression (latiseptate vs. angustiseptate), and cotyledonary type (spirolobal, diplecolobal, twice conduplicate), have been used extensively in the delimitation of tribes. The relationship and taxonomic limits among these genera are unclear and controversial. The present ITS study demonstrates the monophyly of tribe Heliophileae, with Chamira as sister clade. The other five smaller genera above are nested within two of the three main lineages of Heliophila, to which they should be reduced to synonymy. The current study reveals parallel evolution of fruit characters often used heavily in the traditional classification schemes of the family. However, the arrangement of species into three main clades largely corresponds with the distribution of morphological characters (e.g., habit, leaf shape, seed structure, inflorescence type, and presence/absence of basal appendages on the pedicels, petals, and staminal filaments) not adequately accounted for in previous studies. Estimation of divergence times of the main lineages of Heliophila is in agreement with recent estimations in other plant groups, all of which date the diversification against a background of aridification in the Pliocene and Pleistocene. Species of one main clade are perennial, microphyllous shrubs/subshrubs typically restricted to poor sandstone soils in the southwestern and western parts of the Cape Floristic Region of South Africa. Species of the other two clades are predominantly annuals that grow in more arid regions of Namibia and Namaqualand, as well as in the above sandstone areas of the Cape Region. The adaptive significance of various floral structures is discussed in terms of their possible role in the rapid diversification within Heliophila.

KW - molecular systematics

KW - family brassicaceae

KW - dna

KW - cruciferae

KW - biogeography

KW - arabidopsis

KW - dispersal

KW - radiation

KW - sequences

KW - regions

M3 - Article

VL - 92

SP - 400

EP - 424

JO - Annals of the Missouri Botanical Garden

JF - Annals of the Missouri Botanical Garden

SN - 0026-6493

IS - 3

ER -