Biodiversity/Evolutionary Biology

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Altitudinal and seasonal variation in amethyst sunbird physiology.
(2007) Lindsay, Claire Vicky.; Downs, Colleen Thelma.; Brown, Mark.
Southern Africa is characterised by an unpredictable environment with daily and seasonal temperature fluctuations. As a local or non-migratory endothermic species occurring over an altitudinal gradient from the Drakensberg to the coast of KwaZulu- Natal in southern Africa, Amethyst Sunbirds (Chalcomitra amethystina) experience challenging thermal conditions and increased energetic stress as a result of ambient temperature variation. Flexibility of metabolic rates within a species allows for the colonization of different habitats along an altitudinal and thus temperature gradient. It was predicted that over this altitudinal gradient Amethyst Sunbirds would exhibit variation in metabolic rates, particularly basal metabolic rates, pre- and postacclimation, as well as variation in hematocrit levels in winter and summer trials. It was also predicted that Amethyst Sunbirds would exhibit seasonal variation in metabolic parameters. Sunbirds were caught in a winter and summer season (2006-2007) using mist nets in three locations; Underberg (1553 m), Howick (1075 m) and Oribi Gorge (541 m). Upon capture, metabolic rate was measured indirectly by quantifying oxygen consumption (VO2) using flow through respirometry, at 5 and 25°C. Birds were then acclimated at 25°C for 6 weeks on a 12L:12D cycle. VO2 was measured postacclimation at 8 different temperatures (15, 5, 10, 20, 30, 28, 25 and 33°C). Hematocrit levels were taken pre-acclimation and pre-release. Winter and summer data were compared. In the winter trials it was found that there was little variation in VO2 between individuals from the same locality, whereas significant variation was observed at the same temperatures between localities and thus between altitudes. The subpopulation from the highest altitudinal site had the highest basal metabolic rate (BMR). Summer trials showed that metabolic rates did not differ significantly between altitudinal subpopulations of Amethyst Sunbirds, however, BMR was observed to decrease as altitude decreased. The comparison of seasonal data showed that Amethyst Sunbird subpopulations from Underberg and Howick showed higher post-acclimation VO2 values per temperature in winter than in summer trials. Post-acclimation resting metabolic rate (RMR) values for Howick subpopulations were generally higher in winter than in summer, Underberg Amethyst Sunbirds showed a significant difference between summer and winter RMR at 5 and 10°C and Howick sunbirds showed a significant difference in RMR between seasons at 5°C. The Oribi Gorge subpopulation, however, showed no significant differences in metabolic rate between any temperatures when comparing a summer and a winter season. Thermal neutral zones of all of the subpopulations of Amethyst Sunbirds shifted between the winter and summer trial period. This study thus emphasized the need to understand plasticity in metabolic rates and acknowledge altitudinal and seasonal differences within a species, in order to make accurate predictions about a species thermal physiology and responses to changes in ambient temperatures. In particular, the variation in BMR, which is usually used as a species specific value, should be acknowledged in comparative studies of avian metabolic rates or in climate change models.
Animal model studies on the antelope schistosomes, Schistosoma margrebowiei and S. leiperi, with particular reference to their proposed role in limiting the distribution of human intestinal schistosomiasis.
(1992) Dettman, Charles David.; Schutte, Chris H. J.; Huckett, Barbara Isobel.
It has been postulated that the absence of human and cattle schistosomiasis in parts of southern Africa where lechwe antelope (Kobus leche) occur is a consequence of an immunologically-mediated protection induced by repeated exposure to the cercariae of Schistosoma margrebowiei and S. Leiperi, which are common parasites of these animals. The aim of the studies described was the development of animal models in which to investigate this hypothesis. The infection characteristics of the antelope schistosomes in BALB/c mice and Mastomys Coucha were assessed. Both schistosome species reached full patency in these hosts, although S. Margrebowiei infections deteriorated rapidly in M.Coucha. While they differed markedly in terms of egg production rates and preferred sites of tissue egg deposition, both species caused severe hepatosplenomegaly and portal hypertension in the mouse model. Modulation of the granulomatous responses to ova in the tissues was demonstrated. Mice harbouring mature antelope schistosome infections displayed strong partial resistance to challenge infections with both homologous parasites and the human schistosome, S. Mansoni. However, the failure of challenge parasites to become established was considered to be due largely to changes in the portal-hepatic vasculature resulting from egg-induced immunopathology. Resistance to S. Mansoni challenge did not develop in mice infected with radiation-attenuated cercariae of the antelope schistosomes. The suitability of rats and guinea pigs as alternative models was assessed. Worm recoveries from rats were low and there was no evidence of egg-deposition. Worm yields from the guinea pig were relatively high, but sexual development was poor and short-lived. Since excretion of S. Margrebowiei eggs has occasionally been reported from humans, and since the guinea pig supports full sexual maturation of S. Mansoni, this animal appeared to provide a particularly appropriate model for the present investigation. However, repeated exposure of guinea pigs to cercariae of the antelope schistosomes, over a period of 24 weeks, failed to induce significant resistance to S. Mansoni challenge infection. The need for further experimental and field studies is discussed. An area in the Okavango Delta (Ngamiland, Botswana) has been identified as a possible site for field work.
An avifaunal study of Pigeon Valley Park as a biogeographic island in an urban area with special reference to the Natal Robin (Cossypha natalensis Smith)
(1992) Boon, Richard Graham Campbell.; Poynton, John Charles.
Pigeon Valley Park, on Durban's Berea Ridge, is an approximately 10-ha remnant of coastal forest, which is totally surrounded by suburban housing and roads. As such it is ideal as a study area for investigating the applicability of the MacArthur-Wilson Theory of Island Biogeography (1963,1967) and Diamond's (1975) geometric reserve-design principles to fragmented Coastal Forests in Durban. This study began in January 1989 and the results are reported as at October 1992. Field notes from as far back as 1981 were used to augment the findings of the current work. Research focused on the forest-dwelling, Natal Robin Cossypha natalensis, and territory mapping showed that the reserve supports up to 53 individuals during the breeding season. An annotated checklist and its comparison to historical and regional checklists revealed where localised extinctions may have occurred, and thus identifies a set of coastal forest species which are susceptible to habitat fragmentation. Work on two potential dispersal corridors for bird movement into and out of the valley showed that the reserve is not yet fully isolated to most species which are currently present. On the other hand, there are some forest species which have isolated populations at Pigeon Valley Park, as well as others which do not seem able to establish and maintain viable populations. A set of 'indicator', forest bird species which are susceptible to habitat fragmentation, is defined. Practical management suggestions with the aim of increasing the long-term viability of the area as an avifaunal preserve, are presented.
Development of explants potentially suitable for cryopreservation of the recalcitrant-seeded species Theobroma cacao L. and Barringtonia racemosa (L.) roxb.
(2008) Naidoo, Prabashni.
The two species investigated in this study were Theobroma cacao and Barringtonia racemosa. Theobroma cacao has worldwide economic importance, as cocoa (the main ingredient in chocolate) is produced from the seeds of this tree; while B. racemosa has several applications in herbal medicine. The seeds of both T. cacao and B. racemosa are highly recalcitrant and therefore not amenable to storage for any significant periods. The long-term conservation of the germplasm of these species may only be feasible via cryopreservation. The aims of the present study were to: 1) optimize in vitro regeneration protocols for different types of explants that have the potential to be cryopreserved while maintaining the genetic integrity of these two species; and 2) develop cryopreservation protocols for selected explants. For T. cacao, protocols were established for bud-break and multiplication for both in vitro - and greenhouse-derived nodal explants, as well as a rooting medium for shoots derived from axillary buds. Parameters investigated towards the cryopreservation of axillary shoots, from greenhouse nodal segments, and nodal segments from in vitro plantlets, included the size of the explant and pre-treatments for cryopreservation. Nodal segments (6 - 7 mm) and axillary shoots (2 - 4 mm) needed to be soaked in 0.5% (w/v) ascorbic acid for 10 min to minimise phenolic production and subsequent tissue death, and surface-sterilized by soaking in 1% Ca(OCl)2 solution for 5 min to reduce microbial contamination. Subsequent cryopreservation attempts involved only in vitro nodal segments because of the lack of success in achieving elongation of excised axillary buds. Vitrification and slow freezing methods, with or without the application of cryoprotectants, did not achieve successful cryopreservation. Attempts to establish a protocol for producing somatic embryos, as an alternate to axillary shoots and in vitro nodal segments, resulted in the production of globular embryogenic callus for both leaf and cotyledon explants. Cryopreservation of these explants was not investigated in the scope of this study. The study on B. racemosa focused on the development of a somatic embryogenesis protocol. Segments of embryonic axes produced globular-stage embryos when placed on MS medium supplemented with 30 g 1-1 sucrose, 1.0 g 1-1 casein hydrolysate, 2.0 mg 1-1 2,4-D, 0.1 mg 1-1 BAP and 8.0 g 1-1 agar. Various strategies were employed to obtain embryo germination, which included 1) different time intervals on callus initiation medium; 2) the use of different auxins (IAA, NAA and 2,4-D) in combination with the cytokinins BAP and kinetin; 3) desiccation and 4) cold treatments. Although somatic embryo germination was not achieved, globular embryos proceeded with development to the cotyledonary stage when cold-treated for 8 h at 4°C. This study provides some fundamental bases for further investigation towards achieving long-term conservation for both T. cacao and B. racemosa. However, the use of meristems as explants for cryopreservation is suggested to be the way forward for the cryopreservation of both species.
Evolution of the Satyrium longicauda (Orchidaceae) species complex.
(2021) Castañeda Zárate, Miguel.; Van der Niet, Timotheus.; Johnson, Steven Dene.
The identification of morphological variation in taxa grouped within a species complex is fundamental not only in systematics, but plays an important role in evolutionary biology as well. Finding diagnostic characters among populations in plant species undergoing speciation may be challenging due to the continuous nature and intraspecific overlap of variation in reproductive and vegetative traits. The orchid Satyrium longicauda currently comprises two varieties (jacottetianum and longicauda) which can be identified mainly by differences in spur length. Additionaly, S. buchananii and S. rhodanthum were proposed as part of the group which represents a species complex. The large variation in phenotype in the species detected across its broad range makes this complex a promising candidate for studying its systematics and evolutionary origin, through the implementation of multi-disciplinary tools. In this thesis, I have characterised the morphological variation of sympatric and allopatric natural populations of S. longicauda by traditional morphometrics and uni- and multivariate analyses leading to the identification of eight morphotypes, including S. rhodanthum, that partially overlap in traits. These taxa, together with S. buchananii which was not studied in detail, served as units of comparison in a molecular phylogeny that supported the monophyly of some of the morphotypes, but at the same time revealed the non-monophyly of S. longicauda. Extensive pollinator data from direct observations and motion-trigger cameras, revealed that most morphotypes are pollinated by nocturnal moths but pollination by long-tongued flies, sunbirds, and oil-collecting bees was also recorded. Analyses of pollinator assemblages using network tools led to identification of five modules representing potential pollination niches. Several evaluated floral traits such as colour, scent chemistry, nectar volume and concentration, and functional spur length co-varied with some or all of the pollination niches, suggesting they could represent functional traits. Traits associated with the sunbird pollination niche were the most divergent compared to traits of the moth, oil-collecting bee, and a mixed pollination niche. Subtle differences in nectar properties and functional spur length could be linked to the oil-collecting bee pollination niche and two nocturnal moth pollination niches, comprising pollination by settling moths and hawkmoths, respectively. A pollinator shift from nocturnal moth to oil-collecting bee pollination was demonstrated using a combination of field-based experiments and a phylogenetic analysis. This shift appears to be triggered by changes in the type of floral reward from nectar to oil. Morphological variation associated with genetic differences in combination with the identification of an exclusive pollination niche support the recognition of a new variety that is distinct from the two accepted varieties within the complex. Results presented in this thesis contribute new evidence on pollinator-driven evolution and systematics of S. longicauda. At the same time, the thesis provides a starting point for further studies of the processes involved in the diversification of species complexes and for testing the role of pollinators in shaping and maintaining such diversity.
Experience of EIA follow up in Lesotho.
(2003) Tsehlo, Matseliso.; Diab, Roseanne Denise.
Environmental Impact Assessment (El A) is a process that is widely practised as it assists in decision-making and also helps to overcome the environmental problems that could result from development activities. However, the focus is still on EIA as a process and less on EIA follow-up. EIA follow-up is taken to mean the activities, such as monitoring and auditing, that are carried out after the Record of Decision has been made, although the importance of establishing EIA follow-up early in the project cycle is emphasised in this thesis. In most countries, EIA follow-up is not legislated and whilst it is generally recognized as important it is not widely practised. This thesis is aimed at assessing the status of EIA follow-up in Lesotho. Nine development projects were selected and their reports; Environmental Impact Assessment Reports (EIRs), Environmental Management Plans (EMPs) and auditing reports were analysed to determine if there was provision for EIA follow-up. Four criteria were utilised in the analysis. These were: the impacts that were predicted and mitigation measures proposed, the provision made for EIA follow-up before the implementation of the project, the impacts that were experienced and the mitigation measures that were put in place and the EIA follow-up process that was undertaken, and the people responsible for it. All projects had undergone an EIA process, except for one which did not have an EIR prepared, viz. C& Y garment factory at the Thetsane industrial site. Of the remainder, four projects contained provision for EIA follow-up, although in most case studies follow-up focused on the construction phase and little was stated about the implementation of follow-up. Generally, an environmental officer was appointed to monitor the impacts that were experienced and to ensure compliance with the EMP. However, in the Butha-Buthe industrial estate case study, the EIA follow-up process was detailed and specific, even giving the frequency with which EIA follow-up should be undertaken, by whom and how it should be done. This is most likely because it is the most recent industrial estate to be developed and that lessons were learned from previous industrial development sites discussed as case studies in this thesis, where problems were encountered due to lack of EIA follow-up. Apart from the assessment of these reports, questionnaires were also administered to nine environmental consultants practising in Lesotho. Monitoring and auditing were identified as EIA follow-up by the majority of consultants (7 or 78%). Only one person identified it as including public participation, while the other person (11 %) identified it as monitoring, which incorporates EMPs and Environmental Management Systems (EMSs). It was interesting to note that only one person included public participation as part of EIA follow-up, in contrast to the general understanding of EIA follow-up internationally, that the public have a role to play in follow-up activities. One person (1 or 11 %) pointed out that EIA follow-up should start at the planning or design stage, while the majority (89%) stated that it should start after the completion of the EIA process and the Record of Decision, the latter group failing to recognise the importance of collecting baseline data early in the EIA process. Of all the projects, only the Lesotho Highlands Water Project (LHWP) was observed to implement EIA follow-up, such as monitoring and auditing, on a regular basis. An assessment was also undertaken of the environmental legislation in Lesotho and the provision that it makes for EIA follow-up. Sections 31 and 32 of Part V of the Act specifically give provision for EIA follow-up. It is stated that in order to prevent environmental degradation, environmental monitoring and environmental auditing should be undertaken. Moreover, the Lesotho EIA guidelines (1997) do give guidance and procedures on how EIA follow-up should be undertaken. However, it was found that currently, the Environment Act, 2001 is not operational and that EIA follow-up like the EIA process is undertaken on a voluntary basis. It was therefore recommended that at present, the self-regulatory approach to EIA follow-up is the most suitable one for Lesotho. Recommendations were made to strengthen this approach until such time as legislation is in place or an environmentally aware public can participate in EIA follow-up. Several problems were identified that were hampering the practice of EIA follow-up in Lesotho. These included: the un-operational Environment Act, an environmentally unaware public, few environmentalists and lack of sensitive and dedicated government ministries.
The herpetofauna of the Orange Free State : with special emphasis on biogeographical patterning.
(1992) Bates, Michael Francis.; Poynton, John Charles.
The taxonomic status, distribution and ecology of the herpetofauna of the Orange Free State are discussed, based on the examination of 10 096 specimens housed in various southern African museums. The majority of specimens were collected during the years 1972 - 1978 and 1983 - 1992, and are housed at the National Museum, Bloemfontein. A total of 25 amphibian and 95 reptilian (one translocated species) forms have been determined as occurring in the Orange Free State, 12 (three amphibians, nine reptiles) of which are new (or recently published) records for the province. An additional 10 amphibian and 28 reptilian forms have been determined as occurring nearby but extralimitally to the O.F.S., and several of these forms are expected to occur in the province. New distributional records have resulted in the amendment of the ranges of several species. Detailed taxonomic data on new material, including rare species, have been given. Some problem areas in the taxonomy of O.F.S. taxa have been higlighted. An analysis of habit utilization indicated that 84,0% of amphibians and 61,1% of reptiles are terricolous, whereas up to 21,5% of reptiles are rupicolous. The majority of snakes (72,2%) are terrestrial in habits, but 13,9% are fossorial. More than half of all lizards (52,8%) are terrestrial, although 34,6% are rupicolous. A total of six amphibian and 27 reptile forms utilize inactive termitaria as a microhabitat, including several basically terrestrial forms. Snake forms were particularly well represented in termitaria, 60,6% of all forms known from the O.F.S. having been recorded from inactive termitaria. General features of the ecology of O.F.S. amphibians and reptiles have also been discussed. The biogeographical analysis indicated that O.F.S. amphibian forms can be classified into one of nine range clusters (common patterns of distribution), and reptiles into 13 such cluster groups. By testing these classifications by means of a transect through the northern O.F.S. (from eastern to western borders), it was determined that a fairly distinct east-west subtraction of amphibian and reptilian species and subspecies occurs in the O.F.S. Clustering of range boundaries and high species and subspecies diversity at the western and eastern ends of the transect zone suggest dynamic biogeographical situations occurring in those areas - the western group being associated with the transition from grassland to bushveld, and the eastern group associated with the transition from Highveld Grassland to Drakensberg Mountains. The general eastern and western groupings of taxa appear to be associated with the cooler, wetter and mountainous east vs the warmer, drier and lower-lying west, respectively. Despite a great deal of collecting having been conducted in the O.F.S. from 1972 to 1992, an analysis of the number of taxa collected in each quarter-degree unit in the O.F.S. indicated that additional collecting would be required in order to conduct effectively a mathematically-based biogeographical analysis.
A herpetofaunal survey of Swaziland.
(1992) Boycott, Richard Charlton.; Poynton, John Charles.
The present report, based on a survey conducted over four years and on the accumulation of museum records, provides the most detailed documentation yet of the herpetofauna of Swaziland. One hundred and two new forms are recorded from the country bringing the total number of forms to 154, consisting of 44 amphibians and 110 reptiles. Up-to-date checklists of the amphibians and reptiles are presented and effectively indicate a rich and diverse herpetofauna. The biogeography of the Swaziland herpetofauna is discussed based on distribution records derived from collected specimens as well as reliable sight and audio records. Swaziland does not constitute a distinctive biogeographical unit. The present study indicates that the herpetofauna shows affinities with both the Afrotemperate and Afrotropical biomes. The traditional biogeographical classification in southern Africa, of the presence of a Cape temperate fauna and a tropical East African lowland fauna, is tested by means of a transect and is reinforced. It is also shown that Swaziland, together with Natal and southern Mozambique, forms an integral part of the tropical subtraction zone of south-east Africa. Amphibian diversity and species turnover in southern Africa are investigated by means of a transect from the east coast, through Swaziland, to the interior plateau, and a north to south transect down the eastern lowveld. The Dice-Sorenson Similarity index gives a value of 41% for the entire east-west transect and 89% for the north-south transect. The conservation status of the amphibians and reptiles of Swaziland is discussed. Conservation measures are proposed.
The impact of a sugar by-products effluent on the beach Meiofauna at Sezela Beach, KwaZulu-Natal, South Africa
(2007) Blair, Alan George.; Cooke, John Anthony.
Beach meiofauna were chosen as environmental indicators to investigate the impact of Illovo sugar by-products effluent. The effluent is pumped through a 20 cm diameter pipeline into surf zone at Sezela beach on the coast of KwaZulu-Natal, South Africa. Meiofaunal communities were considered appropriate indicators as they are relatively stable both qualitatively and quantitatively on a seasonal and year to year basis. Most meiofauna also do not have planktonic stages in their life cycles, respond rapidly to pollution due to their fast generation times, and they are often abundant with high species diversity in habitats which are subject to considerable natural physical and chemical fluctuations. In this particular study there was a specific concern about trace amounts of furfural in the effluent. Furfural has been used as the active ingredient in a product designed to kill parasitic nematodes in crop fields. A large proportion of the beach meiofauna consists of nematodes. Eight stations were sampled for meiofauna along the beaches at Sezela on 7 different occasions. Seasonal effects on meiofauna and meiofaunal recovery during the period when the factory was not pumping effluent to sea was assessed. Samples were taken on the following dates: 4 July 2000 (winter); 30 August 2000 (winter); 13 December 2000 (spring); 26 January 2001 (summer); 8 March 2001 (summer); 9 April 2001 (autumn); and 2 January 2002 (summer). PRIMER (Plymouth Routines in Multivariate Ecological Research) was used for statistical analysis and included various univariate indices such as species richness, species diversity and evenness. These indices were then analysed using one-way ANOVA to determine any significant difference between sites over the 7 sampling periods and between the different seasons. Clustering and Ordination multivariate analyses were carried out on the community data and physico/chemical data to determine community patterns and relate them to the effluent and environmental data. The Nematode/Copepod ratio was also calculated. Meiofauna were analysed at major taxa level, as well as to nematode feeding groups and harpacticoid copepod and annelid family level, to determine if analysis to major taxa level is adequate as an indicator of pollution impact. The analyses indicated a possible degree of impact at stations close to the effluent discharge when effluent was being pumped to sea and a recovery was noted at the station closest to the discharge when effluent was not being discharged and analysis was conducted to the major taxonomic rank only. No improved resolution was achieved by analysing some of the meiofaunal major taxa to family level or different feeding groups. The analysis of the Nematode/Copepod ratio was shown to correspond with the multivariate analyses, however, this ratio could not reveal the severity of the impact where both nematodes and harpacticoids i.e. total meiofauna had been reduced by adverse conditions. The physical and chemical variables that showed the greatest correlation with the meiofaunal community patterns were sediment grain size, dissolved oxygen and salinity. There was a very strong positive correlation between Kjeldahl nitrogen in the interstitial waters and total numbers of meiofauna. This and the relationship with salinity may have suggested other possible sources of influence such as enrichment from the three estuaries in the area as well as a storm water drain located 150m north of the effluent discharge. A seasonal effect was observed with increased meiofauna numbers in autumn, but this was possibly influenced by the periods when effluent was not being pumped to sea.

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