A century of Zoology and Entomology at Rhodes University, 1905 to 2005
- Authors: Hodgson, Alan N , Craig, Adrian J F K
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6922 , http://hdl.handle.net/10962/d1011905
- Description: The history of the Department of Zoology & Entomology at Rhodes University is traced from its origin with a single staff member, through the era of permanent heads of department to the present day staff. Significant achievements and developments in teaching and research are highlighted, and some anecdotal material is included.
- Full Text:
- Date Issued: 2005
A comparison of two sampling methods for surveying mammalian herbivore impacts on beetle communities in the canopy of Acacia drepanolobium in Kenya
- Authors: Kuria, K S , Villet, Martin H , Palmer, T , Stanton, M
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6860 , http://hdl.handle.net/10962/d1011150
- Description: Even though several methods are used to sample and monitor canopy arthropods, there are no studies to indicate which of these methods is more effective.We compared the efficacy of the beating and canopy fogging methods in collecting beetles that inhabit Acacia drepanolobium (Harms) tree canopies at Mpala Research Centre in Laikipia district, Kenya. These trees grow naturally on the black cotton soils of the Laikipia ecosystem, accounting for more than 98%of the overstorey at the study site, and are important for local cattle and wildlife production. The ultimate objective of this study was to determine the effect of differential grazing and browsing pressure from large mammalian herbivores on the beetle communities of A. drepanolobium. Seven hundred and twenty trees 1.0–2.5 m tall were sampled using each method, making a total of 1440 trees. Sampling using the two methods was done concurrently and repeated quarterly over a period of 14 months. In total, 4320 individuals were collected, 1456 by beating and 2864 by fogging. The methods jointly yielded beetle specimens from 13 families and 55 morphospecies. Fogging collected significantly more beetle morphospecies than beating, and there was a significant interaction effect between method and sampling date. We found that numerically Anthicidae and Curculionidae responded positively to the presence of cattle.We also found that Anthicidae sp. A and Myllocerus sp. A numbers significantly increased in plots where livestock were grazed.
- Full Text:
- Date Issued: 2010
A memorable band
- Authors: Unknown
- Subjects: McGregor, Chris--1936-1990 , Gallotone , The Castle Lager Big Band , Jazz
- Language: English
- Type: Article
- Identifier: vital:13757 , http://hdl.handle.net/10962/d1012772
- Description: Photocopied article from the newspaper Pretoria News about the recordings by Chris McGregor and the Castle Lager Big Band.
- Full Text:
A proposed prioritization system for the management of invasive alien plants in South Africa
- Authors: Robertson, Mark P , Villet, Martin H , Fairbanks, Dean H K , Henderson, L , Higgins, Simon I , Hoffmann, John H , Le Maitre, David C , Palmer, Anthony R , Riggs, I , Shackleton, Charlie M , Zimmermann, Helmuth G
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6911 , http://hdl.handle.net/10962/d1011872
- Description: Every country has weed species whose presence conflicts in some way with human management objectives and needs. Resources for research and control are limited, so priority should be given to species that are the biggest problem. The prioritization system described in this article was designed to assess objectively research and control priorities of invasive alien plants at a national scale in South Africa. The evaluation consists of seventeen criteria, grouped into five modules, that assess invasiveness, spatial characteristics, potential impact, potential for control, and conflicts of interest for each plant species under consideration. Total prioritization scores, calculated from criterion and module scores, were used to assess a species' priority. Prioritization scores were calculated by combining independent assessments provided by several experts, thus increasing the reliability of the rankings. The total confidence score, a separate index, indicates the reliability and availability of data used to make an assessment. Candidate species for evaluation were identified and assessed by several experts using the prioritization system. The final ranking was made by combining two separate indices, the total prioritization score and the total confidence score. This approach integrates the plant's perceived priority with an index of data reliability. Of the 61 species assessed, those with the highest ranks (Lantana camara, Chromolaena odorata and Opuntia ficus-indica) had high prioritization and high confidence scores, and are thus of most concern. Those species with the lowest ranks, for example, Harrisia martinii, Opuntia spinulifera and Opuntia exaltata, had low prioritization scores and high confidence scores, and thus are of least concern. Our approach to ranking weeds offers several advantages over existing systems because it is designed for multiple assessors based on the Delphi decision-making technique, the criteria contribute equally to the total score, and the system can accommodate incomplete data on a species. Although the choice of criteria may be criticized and the system has certain limitations, it appears to have delivered credible results.
- Full Text:
- Date Issued: 2003
A tale of two neglected systems-structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves
- Authors: Botha, Christiaan E J
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:6499 , http://hdl.handle.net/10962/d1004514 , http://dx.doi.org/10.3389/fpls.2013.00297
- Description: There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5–7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer.
- Full Text:
- Date Issued: 2013
A technique for evaluating species richness maps generated from collections data
- Authors: Robertson, Mark P , Barker, Nigel P
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6538 , http://hdl.handle.net/10962/d1005979
- Description: There is considerable pressure on conservation planners to use existing data from herbarium and museum collections for planning and monitoring, despite the weaknesses of such data. It is thus important to be able to assess the quality of this information. One application of these data is the production of species richness maps. However, sampling effort is generally not consistent throughout a region for maps generated from collections data, and it is thus desirable to identify geographic grid cells (such as quarter degree squares: QDS) for which there has been low sampling effort. We describe a technique that can be used to identify QDS that are likely to have low species richness that is due to insufficient sampling effort rather than to low actual species richness. The technique exploits relationships between climate and species richness to detect QDS that are poorly sampled. This approach offers advantages over the current practice of applying a single threshold across the entire map region to detectQDSthat are poorly sampled. Here we report on the application of our technique to plant species richness data in the PRECIS database. Results reveal that the majority of QDS in the Flora of Southern Africa region can be considered to be poorly sampled, even when using conservative thresholds for richness values. The advantages and weaknesses of the technique are discussed and issues requiring further investigation are highlighted.
- Full Text:
- Date Issued: 2006
A temporal dimension to the influence of pollen rewards on bee behaviour and fecundity in Aloe tenuior
- Authors: Duffy, Karl J , Johnson, Steven D , Peter, Craig I
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6561 , http://hdl.handle.net/10962/d1011735 , http://dx.doi.org/10.1371/journal.pone.0094908
- Description: The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.
- Full Text:
- Date Issued: 2014
A test for Allee effects in the self-incompatible wasp-pollinated milkweed Gomphocarpus physocarpus
- Authors: Coombs, Gareth , Peter, Craig I , Johnson, Steven D
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6511 , http://hdl.handle.net/10962/d1005938 , http://dx.doi.org/10.1111/j.1442-9993.2009.01976.x
- Description: It has been suggested that plants which are good colonizers will generally have either an ability to self-fertilize or a generalist pollination system. This prediction is based on the idea that these reproductive traits should confer resistance to Allee effects in founder populations and was tested using Gomphocarpus physocarpus (Asclepiadoideae; Apocynaceae), a species native to South Africa that is invasive in other parts of the world. We found no significant relationships between the size of G. physocarpus populations and various measures of pollination success (pollen deposition, pollen removal, and pollen transfer efficiency) and fruit set. A breeding system experiment showed that plants in a South African population are genetically self-incompatible and thus obligate outcrossers. Out-crossing is further enhanced by mechanical reconfiguration of removed pollinaria before the pollinia can be deposited. Selfpollination is reduced when such reconfiguration exceeds the average duration of pollinator visits to a plant. Observations suggest that a wide variety of wasp species in the genera Belonogaster and Polistes (Vespidae) are the primary pollinators. We conclude that efficient pollination of plants in small founding populations, resulting from their generalist wasp-pollination system, contributes in part to the colonizing success of G. physocarpus. The presence of similar wasps in other parts of the world has evidently facilitated the expansion of the range of this milkweed.
- Full Text:
- Date Issued: 2009
Chris McGregor and the Castle Lager Big Band
- Authors: Alexander, Tebogo
- Date: 2012-09-20
- Subjects: McGregor, Chris -- 1936-1990 , Jazz , Jazz musicians , Castle Lager Big Band
- Language: English
- Type: Article
- Identifier: vital:13471 , http://hdl.handle.net/10962/d1001393 , McGregor, Chris -- 1936-1990 , Jazz , Jazz musicians
- Description: Photocopied article from the newspaper Vrye Weekblad about a recording of Chris McGregor with the Castle Lager Big Band.
- Full Text:
Collaborative versus adversarial stances in scientific discourse : implications for the role of systematic case studies in the development of evidence-based practice in psychotherapy
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6245 , http://hdl.handle.net/10962/d1007861
- Description: There is still a need for advocacy in the promotion of case study research because there has been insufficient appreciation of its role as a source of evidence relevant to the development and evaluation of practice in psychotherapy. Distorted use of terms like "gold standard", "anecdotal",and "empirical" in the discourse in which research methodology is typically presented has disempowered the practitioner's perspective and discredited the role of case-based knowledge building. The framework of evidence-based practice (EBP) recognizes the complementarity of different research methods and acknowledges the significance of casebased research. To spell out some of these complementary links, a typology of seven research methods - including both experimental group comparison designs and individual case studies - is proposed and the contribution of each to the development of EBP is set out. Finally some suggestions are made for strategies to promote the publication of high quality case studies.
- Full Text:
- Date Issued: 2007
Comparing models for predicting species' potential distributions : a case study using correlative and mechanistic predictive modelling techniques
- Authors: Robertson, Mark P , Peter, Craig I , Villet, Martin H , Ripley, Bradley S
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6539 , http://hdl.handle.net/10962/d1005980 , http://dx.doi.org/10.1016/S0304-3800(03)00028-0
- Description: Models used to predict species’ potential distributions have been described as either correlative or mechanistic. We attempted to determine whether correlative models could perform as well as mechanistic models for predicting species potential distributions, using a case study. We compared potential distribution predictions made for a coastal dune plant (Scaevola plumieri) along the coast of South Africa, using a mechanistic model based on summer water balance (SWB), and two correlative models (a profile and a group discrimination technique). The profile technique was based on principal components analysis (PCA) and the group-discrimination technique was based on multiple logistic regression (LR). Kappa (κ) statistics were used to objectively assess model performance and model agreement. Model performance was calculated by measuring the levels of agreement (using κ) between a set of testing localities (distribution records not used for model building) and each of the model predictions. Using published interpretive guidelines for the kappa statistic, model performance was “excellent” for the SWB model (κ=0.852), perfect for the LR model (κ=1.000), and “very good” for the PCA model (κ=0.721). Model agreement was calculated by measuring the level of agreement between the mechanistic model and the two correlative models. There was “good” model agreement between the SWB and PCA models (κ=0.679) and “very good” agreement between the SWB and LR models (κ=0.786). The results suggest that correlative models can perform as well as or better than simple mechanistic models. The predictions generated from these three modelling designs are likely to generate different insights into the potential distribution and biology of the target organism and may be appropriate in different situations. The choice of model is likely to be influenced by the aims of the study, the biology of the target organism, the level of knowledge the target organism’s biology, and data quality.
- Full Text:
- Date Issued: 2003
Comparison of structural damage caused by Russian wheat aphid (Diuraphis noxia Mordvilko) and Bird cherry-oat aphid (Rhopalosiphum padi L.) in a susceptible barley cultivar, Hordeum vulgare L. cv Clipper
- Authors: Saheed, Sefiu Adekilekun , Botha, Christiaan Edward Johannes , Liu, Lin , Jonsson, Lisbeth
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6540 , http://hdl.handle.net/10962/d1005981
- Description: The Russian wheat aphid (RWA, (Diuraphis noxia Mordvilko) and the Bird cherry-oat aphid (BCA, (Rhopalosiphum padi L.) cause severe damage to grain crops, including barley. An investigation of the effects of these aphids on a susceptible cultivar revealed that BCA-infested barley plants remained healthy-looking for two weeks after feeding commenced. In contrast, signs of stress and damage, including chlorosis and leaf necrosis were evident in RWA infested plants. Our study suggests that damage to the vascular tissue due to sustained feeding by BCA, was not as extensive as that caused by RWA. In addition, there is a marked difference in the salivary secretion pattern within xylem elements punctured by aphids tapping the xylem for water. RWA deposit electron-dense, amorphous to smooth saliva, which completely encases the inner walls of affected elements, and saliva encases pit membranes between xylem elements, and between xylem vessels and xylem parenchyma. Xylem tapped by BCA, contained more granular saliva, which apparently does not occlude vessel wall apertures or the pit membranes to the same extent as was observed with RWA. Damage to phloem tissue, including phloem parenchyma elements, sieve tube-companion cell (CC-ST) complexes as well as thick-walled sieve tubes, was extensive. Plasmodesmata between phloem parenchyma elements as well as pore-plasmodesmata between the CC-ST were occluded by callose. We conclude that severe, perhaps permanent damage to conducting elements in RWA infested leaves may be responsible for the detrimental chlorosis and necrosis symptoms. These symptoms are absent in BCA-infested plants.
- Full Text:
- Date Issued: 2007
Confronting the African nightmare: Yael Farber’s SeZaR (theatre review)
- Authors: Wright, Laurence
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7046 , http://hdl.handle.net/10962/d1007388
- Description: Yael Farber’s adaptation of Julius Caesar marks something of a breakthrough in South African Shakespeare productions. The key achievement is that the play is no longer about Rome or Renaissance England, nor is it about processes of cultural translation or trendy theatrical Africanisation, largely cosmetic. This production is, in a generous way, squarely and pointedly about Africa.
- Full Text:
- Date Issued: 2001
Connectivity between marine reserves and exploited areas in the philopatric reef fish Chrysoblephus laticeps (Teleostei: Sparidae)
- Authors: Teske, Peter R , Forget, F R G , Cowley, Paul D , Von der Heyden, S , Beheregaray, L B
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6776 , http://hdl.handle.net/10962/d1008086
- Description: "No-take‟ Marine Protected Areas (MPAs) are successful in protecting populations of many exploited fish species, but it is often unclear whether networks of MPAs are adequately spaced to ensure connectivity among reserves, and whether spillover occurs into adjacent exploited areas. Such issues are particularly important in species with low dispersal potential, many of which exist as genetically distinct regional stocks.The roman, Chrysoblephus laticeps, is an overexploited, commercially important fishery species endemic to South Africa. Post-recruits display resident behavior and occupy small home ranges, making C. laticeps a suitable model species to investigate connectivity in marine teleosts with potentially low dispersal ability. We used multilocus data from two types of highly variable genetic markers (mitochondrial DNA control region and microsatellites) to clarify patterns of genetic connectivity and population structure in C. laticeps using samples from two MPAs and several moderately or severely exploited regions. Despite using analytical tools that are sensitive to detect even subtle genetic structure, we found that this species exists as a single, well-mixed stock throughout its core distribution. This finding lends supports to the status of MPAs as an adequate tool for managing overexploited marine teleosts. Even though adult dispersal out of MPAs is limited, the fact that the large adults in these reserves produce exponentially more offspring than their smaller counterparts in exploited areas makes MPAs a rich source of recruits. We nonetheless caution against concluding that the lack of structure identified in C. laticeps and several other southern African teleosts can be considered to be representative of marine teleosts in this region in general. Many such species are represented in more than one marine biogeographic province and may be comprised of regionally-adapted stocks that need to be managed individually.
- Full Text:
- Date Issued: 2010
Conserving pattern and process in the Southern Ocean: designing a Marine Protected Area for the Prince Edward Islands
- Authors: Lombard, A T , Reyers, B , Schonegevel, L Y
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:7140 , http://hdl.handle.net/10962/d1011822
- Description: South Africa is currently proclaiming a Marine Protected Area (MPA) in the Exclusive Economic Zone (EEZ) of its sub-Antarctic Prince Edward Islands. The objectives of the MPA are to: 1) contribute to a national and global representative system of MPAs, 2) serve as a scientific reference point to inform future management, 3) contribute to the recovery of the Patagonian toothfish (Dissostichus eleginoides), and 4) reduce the bird bycatch of the toothfish fishery, particularly of albatrosses and petrels. This study employs systematic conservation planning methods to delineate a MPA within the EEZ that will conserve biodiversity patterns and processes within sensible management boundaries, while minimizing conflict with the legal toothfish fishery. After collating all available distributional data on species, benthic habitats and ecosystem processes, we used C-Plan software to delineate a MPA with three management zones: four IUCN Category Ia reserves (13% of EEZ); two Conservation Zones (21% of EEZ); and three Category IV reserves (remainder of EEZ). Compromises between conservation target achievement and the area required by the MPA are apparent in the final reserve design. The proposed MPA boundaries are expected to change over time as new data become available and as impacts of climate change become more evident.
- Full Text:
- Date Issued: 2007
Conserving pattern and process in the Southern Ocean: designing a Marine Protected Area for the Prince Edward Islands
- Authors: Lombard, A T , Reyers, B , Schonegevel, L Y , Cooper, J , Smith-Adao, L B , Nel, D C , Froneman, P William , Ansorge, Isabelle J , Bester, M N , Tosh, C A , Strauss, T , Akkers, T , Gon, Ofer , Leslie, R W , Chown, S L
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6881 , http://hdl.handle.net/10962/d1011637
- Description: South Africa is currently proclaiming a Marine Protected Area (MPA) in the Exclusive Economic Zone (EEZ) of its sub-Antarctic Prince Edward Islands. The objectives of the MPA are to: 1) contribute to a national and global representative system of MPAs, 2) serve as a scientific reference point to inform future management, 3) contribute to the recovery of the Patagonian toothfish (Dissostichus eleginoides), and 4) reduce the bird bycatch of the toothfish fishery, particularly of albatrosses and petrels. This study employs systematic conservation planning methods to delineate a MPA within the EEZ that will conserve biodiversity patterns and processes within sensible management boundaries, while minimizing conflict with the legal toothfish fishery. After collating all available distributional data on species, benthic habitats and ecosystem processes, we used C-Plan software to delineate a MPA with three management zones: four IUCN Category Ia reserves (13% of EEZ); two Conservation Zones (21% of EEZ); and three Category IV reserves (remainder of EEZ). Compromises between conservation target achievement and the area required by the MPA are apparent in the final reserve design. The proposed MPA boundaries are expected to change over time as new data become available and as impacts of climate change become more evident.
- Full Text:
- Date Issued: 2007
Contrasting habitat associations of imperilled endemic stream fishes from a global biodiversity hot spot
- Authors: Chakona, Albert , Swartz, E R
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:7148 , http://hdl.handle.net/10962/d1011850 , http://www.biomedcentral.com/1472-6785/12/19
- Description: Knowledge of the factors that drive species distributions provides a fundamental baseline for several areas of research including biogeography, phylogeography and biodiversity conservation. Data from 148 minimally disturbed sites across a large drainage system in the Cape Floristic Region of South Africa were used to test the hypothesis that stream fishes have similar responses to environmental determinants of species distribution. Two complementary statistical approaches, boosted regression trees and hierarchical partitioning, were used to model the responses of four fish species to 11 environmental predictors, and to quantify the independent explanatory power of each predictor.
- Full Text:
- Date Issued: 2012
Contrasting habitat associations of imperilled endemic stream fishes from a global biodiversity hot spot
- Authors: Chakona, Albert , Swartz, E R
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6777 , http://hdl.handle.net/10962/d1008087
- Description: Knowledge of the factors that drive species distributions provides a fundamental baseline for several areas of research including biogeography, phylogeography and biodiversity conservation. Data from 148 minimally disturbed sites across a large drainage system in the Cape Floristic Region of South Africa were used to test the hypothesis that stream fishes have similar responses to environmental determinants of species distribution. Two complementary statistical approaches, boosted regression trees and hierarchical partitioning, were used to model the responses of four fish species to 11 environmental predictors, and to quantify the independent explanatory power of each predictor.
- Full Text:
- Date Issued: 2012
Converts and conservatives: missionary representations of African rulers in the Northern Transvaal, c. 1870-1900
- Authors: Kirkaldy, Alan , Kriel, Lize
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6146 , http://hdl.handle.net/10962/d1003715 , http://www2.unil.ch/lefaitmissionnaire/pages/tables_publi/lfm18_tbl.htm
- Description: During the second half of the nineteenth century, the Berlin Mission Society made strenuous efforts to convert the rulers of the people in whose areas they worked in the Northern Transvaal. In this they were largely unsuccessful. This raises questions about what forces influenced success and failure, and how the missionaries interpreted this. In this article, we interrogate the Berlin Missions Society’s accounts of the life and death of August Makhahane, a ruler of the Vhavenda who converted to Christianity, against the background of the accounts dealing with Matsiokwane Leboho, a ruler of the Bahananwa who did not convert. Through such a comparison, we aim at exploring the contrasted ways in which the Berlin missionaries reported about the two rulers.
- Full Text:
- Date Issued: 2006
Diverse pollination systems of the twin-spurred orchid genus Satyrium in African grasslands
- Authors: Johnson, S.D , Peter, C.I , Ellis, A.G , Boberg, E , Botes, C , Van der Niet, T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6558 , http://hdl.handle.net/10962/d1006025 , http://dx.doi.org/10.1007/s00606-010-0411-1
- Description: The large terrestrial orchid genus Satyrium underwent evolutionary radiations in the Cape floral region and the grasslands of southern and eastern Africa. These radiations were accompanied by tremendous diversification of the unusual twin-spurred flowers that characterize the genus, but pollination data required to interpret these patterns of floral evolution have been lacking for grassland species in the genus. Here we document pollinators, nectar properties, and levels of pollination success for 11 grassland Satyrium species in southern and south-central Africa. Pollinators of these species include bees, beetles, butterflies, hawkmoths, noctuid moths, long-proboscid flies, and sunbirds. Most species appear to be specialized for pollination by one functional pollinator group. Long-proboscid fly pollination systems are reported for the first time in Satyrium (in S. macrophyllum and a high-altitude form of S. neglectum). Floral morphology, especially spur length and rostellum structure, differs markedly among plants with different pollinators, while nectar volume, concentration, and sugar composition are fairly uniform across species. Most taxa exhibited high levels of pollination success (>50% of flowers pollinated), a trend that can be attributed to the presence of nectar in the twin spurs.
- Full Text:
- Date Issued: 2011