Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern
Character variation in Chaetobromus, a genus of palatable grasses endemic to the arid western areas of southern Africa, was used to derive a classification reflecting taxonomic and ecological pattern. The present study differs from earlier biosystematic investigations by its much more intensive appr...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Department of Biological Sciences
2016
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613586537316352 |
|---|---|
| access_status_str | Open Access |
| author | Verboom, George Anthony |
| author2 | Linder, Peter W |
| author_browse | Linder, Peter W Verboom, George Anthony |
| author_facet | Linder, Peter W Verboom, George Anthony |
| author_sort | Verboom, George Anthony |
| collection | Thesis |
| description | Character variation in Chaetobromus, a genus of palatable grasses endemic to the arid western areas of southern Africa, was used to derive a classification reflecting taxonomic and ecological pattern. The present study differs from earlier biosystematic investigations by its much more intensive approach to sampling, with 75 anatomical, morphological and cytological characters and 169 individual samples being used. The use of larger population samples permitted quantification of variation within populations, in addition to that among populations and groups. Phenetic methods revealed the existence of three groups, approximating three formerly described taxa and reflecting divergent ecological strategies in Chaetobromus. A lack of diagnostic field characters argues against their recognition at species level, and Chaetobromus Nees is here described as monotypic, the type species, C. involucratus (Schrad.) Nees, comprising three subspecies C. involucratus subsp. involucratus, C. involucratus subsp. villosus Verboom and C. involucratus subsp. dregeanus (Nees) Verboom. There is overlap among subspecies in most characters although many showed significant mean differences. Within subspecies, character variation appears to be homogeneously distributed with respect to population boundaries suggesting that these are likely to have little impact on sampling. An investigation testing the effect of sample strategy on variation capture and taxonomic group detection suggests that a sample of 10-15 specimens is likely to account for most variation present. Phylogenetically, Chaetobromus is included in the tribe Danthonieae, and, on morphological evidence, is probably basal to a clade containing Pentaschistis, Pentameris and Pseudopentameris. The genus appears to occupy a niche unique among the African danthonioids, favouring lime-rich, basic soils and a strongly-seasonal winter-rainfall regime with arid summers. Ecological differences among the subspecies are reflected in differences in growth form and vegetative and reproductive phenologies. The niche requirements of Chaetobromus may be adequately specific to explain the patchy distribution of the genus. Bibliography: pages 119-131. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/18333 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:38:30.452Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/18333 An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern Verboom, George Anthony Linder, Peter W Botany Plant systematics Character variation in Chaetobromus, a genus of palatable grasses endemic to the arid western areas of southern Africa, was used to derive a classification reflecting taxonomic and ecological pattern. The present study differs from earlier biosystematic investigations by its much more intensive approach to sampling, with 75 anatomical, morphological and cytological characters and 169 individual samples being used. The use of larger population samples permitted quantification of variation within populations, in addition to that among populations and groups. Phenetic methods revealed the existence of three groups, approximating three formerly described taxa and reflecting divergent ecological strategies in Chaetobromus. A lack of diagnostic field characters argues against their recognition at species level, and Chaetobromus Nees is here described as monotypic, the type species, C. involucratus (Schrad.) Nees, comprising three subspecies C. involucratus subsp. involucratus, C. involucratus subsp. villosus Verboom and C. involucratus subsp. dregeanus (Nees) Verboom. There is overlap among subspecies in most characters although many showed significant mean differences. Within subspecies, character variation appears to be homogeneously distributed with respect to population boundaries suggesting that these are likely to have little impact on sampling. An investigation testing the effect of sample strategy on variation capture and taxonomic group detection suggests that a sample of 10-15 specimens is likely to account for most variation present. Phylogenetically, Chaetobromus is included in the tribe Danthonieae, and, on morphological evidence, is probably basal to a clade containing Pentaschistis, Pentameris and Pseudopentameris. The genus appears to occupy a niche unique among the African danthonioids, favouring lime-rich, basic soils and a strongly-seasonal winter-rainfall regime with arid summers. Ecological differences among the subspecies are reflected in differences in growth form and vegetative and reproductive phenologies. The niche requirements of Chaetobromus may be adequately specific to explain the patchy distribution of the genus. Bibliography: pages 119-131. 2016-03-28T14:43:33Z 2016-03-28T14:43:33Z 1995 Master Thesis Masters MSc http://hdl.handle.net/11427/18333 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Botany Plant systematics Verboom, George Anthony An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern |
| thesis_degree_str | Master's |
| title | An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern |
| title_full | An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern |
| title_fullStr | An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern |
| title_full_unstemmed | An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern |
| title_short | An investigation of character variation in Chaetobromus Nees (Danthonieae: Poaceae) in relation to taxonomic and ecological pattern |
| title_sort | investigation of character variation in chaetobromus nees danthonieae poaceae in relation to taxonomic and ecological pattern |
| topic | Botany Plant systematics |
| url | http://hdl.handle.net/11427/18333 |
| work_keys_str_mv | AT verboomgeorgeanthony aninvestigationofcharactervariationinchaetobromusneesdanthonieaepoaceaeinrelationtotaxonomicandecologicalpattern AT verboomgeorgeanthony investigationofcharactervariationinchaetobromusneesdanthonieaepoaceaeinrelationtotaxonomicandecologicalpattern |