Cineraria L. (Senecioneae, Asteraceae) - its taxonomy, phylogeny, phytogeography and conservation
Date
2006-11-01T13:29:55Z
Authors
Cron, Glynis Valerie
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Abstract
This study aimed to investigate the phylogeny of Cineraria L. to elucidate its position in
the tribe Senecioneae (Asteraceae), to delimit its generic and species boundaries, explore
species relationships (infrageneric structure) and produce a monograph of the genus. It also
aimed to examine its distribution, phytogeographic affinities, levels of rarity and endemism
in Cineraria, to identify some of the factors contributing to rarity in Cineraria and to
highlight implications for conservation.
Phylogenetic analyses were performed using morphological and molecular (DNA sequence)
characters to elucidate relationships within the genus and between Cineraria and selected
related genera in the subtribe Senecioninae. The phylogenetic species concept was applied
- suites of diagnostic characters were used to characterise species. The phenetic approach,
using Cluster Analysis and Principal Coordinates Analysis, was applied to investigate
variation in two highly variable species, C. deltoidea Sond. and C. lobata L’Hér. Species
distributions were mapped and the number of species per degree square was plotted for
southern Africa to identify centres of diversity and endemism. Rare species were identified
and categorised according to Rabinowitz’s criteria of geographic range, habitat specificity
and local population size.
Cineraria now has a more homogenous generic concept, characterised as herbs or
subshrubs with palmately veined leaves, radiate, calyculate capitula, penicillate style apices
and obovate, compressed cypselae with two distinct margins or wings and a substantial
carpopodium. Eleven species have been removed from the genus and two new genera,
Bolandia Cron and Oresbia Cron & B.Nord. have been established to accommodate three
of the species. Two species have been reassigned to and another reinstated in Senecio L.
The affinities of five species remain unresolved.
Cineraria now comprises 35 species with four new subspecies and two new varieties
recognised. Eight species have been placed in synonymy and five new species have been
described during this revision. The status of C. deltoidea as a single, highly variable
species, widespread throughout the eastern mountains of Africa, has been confirmed.
Cineraria lobata has been shown to be a very variable species and the geographic and
morphological variation has been formally (and informally) recognised. No infrageneric
classification has been applied to Cineraria as a robust phylogeny of all the species has yet
to be hypothesised.
A southern African origin for Cineraria in the Western and/or Eastern Cape is postulated,
based on the current distribution of the sister genus Bolandia and Cineraria mollis DC.
iv
Cineraria appears to have undergone rapid speciation fairly recently, as indicated by the
lack of variation in the molecular data analysed, with reticulate evolution playing an
important role in its evolutionary history (as seen by the lack of congruence between the
chloroplast and nuclear DNA sequences).
The centre of diversity of Cineraria is the KwaZulu-Natal Midlands, part of the
Maputaland-Pondoland Centre of endemism in southern Africa. Cineraria has an
afromontane affinity, and fifteen species endemic to specific mountains or regions of
endemism and five near-endemics have been identified in Cineraria. Eleven species have
been shown to be rare (in the sense of low abundance, restricted range and high habitat
specificity), however only five are considered to be threatened as indicated by IUCN Red
Data Criteria. However, at least seven species are Data Deficient and require further
investigation. Causes of rarity in Cineraria are linked to narrow habitat specificity,
particularly soil or rock type and/or altitudinal range.
Description
Student no:7719196
PhD thesis 2005
Faculty of Science, School of Animal, Plant and Environmental Sciences.
Keywords
multivariate analysis, monograph, reticulate evolution, molecular and morphological phylogenetics