Mating systems, insect pollination and chemical ecology of grassland Protea species (Proteaceae)

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.Major transitions between vertebrate and insect pollination systems have occurred many times during the angiosperm radiation and are associated with evolutionary modifications in floral traits. In the large ancestrally bird-pollinated African genus Protea (Proteaceae), an evolutionary shift from bird to insect pollination in the genus is suggested by the fruity diurnal scent of flowers in a recently evolved clade of grassland species. In this study, I confirm that four of these grassland Protea species have mixed mating systems and are indeed insect pollinated, and furthermore demonstrate the functional significance of their floral presentation and scent chemistry for attraction of pollinators, specifically cetoniine beetles. The study species, Protea caffra, Protea dracomontana, Protea simplex and Protea welwitschii, have colourful bowl-shaped inflorescences that produce copious amounts of pollen and dilute, xylose-rich nectar. Cetoniine beetles were found to be the most suitable pollinators due to their abundance, size, relatively pure Protea pollen loads, and their preference for the fruity scent and low growth form of these scented Protea species, as demonstrated by choice experiments in which inflorescences were offered at either end of a y-maze or at various heights above the ground, respectively. Bagging and hand pollinations revealed that these Protea species are self-compatible and capable of autonomous selfing. Self progeny of P. caffra were as vigorous as cross progeny in terms of germinability and survivorship to two months. Vertebrate-excluded and open-pollinated inflorescences yielded similar seed numbers for all species. Supplemental hand-pollinations, however, failed to increase seed set substantially, an indication of resource limitation. Outcrossing rates estimated using polymorphisms at eight allozyme loci in progeny from vertebrate-excluded and open-pollinated treatments of P. caffra were no different (t=0.59), indicating outcrossing by insects and an equal or insubstantial contribution from bird pollinators. The fruity-sweet scents of these species were more complex, with higher whole flower and mass-specific emission rates, than those in eight bird-pollinated congenerics. The overall floral scent is shown to be a blend of emissions from various plant parts, especially nectar. Electroantennography (EAG) revealed that the generalist pollinator Atrichelaphinis tigrina responds to a variety of volatile compounds found in fruity Protea scents. Field trapping confirmed that this cetoniine beetle is strongly attracted to ß-linalool (up to 60% of scent profile) and methyl benzoate. In conclusion, this study demonstrates the evolution of beetle pollination and mixed mating systems in a grassland clade of Protea. Volatile compounds that make up the unique (within Protea) fruity scent of the study species are shown to attract beetles, and the emission of large amounts of these compounds was probably a key step in the transition from bird to insect pollination in Protea

The Fourth Industrial Revolution – what does it mean to our future faculty?

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Metschnikowia proteae sp. nov., a nectarivorous insect-associated yeast species from Africa

A collection of yeasts isolated from nectar of flowers of Protea caffra (Proteaceae) and associated scarab beetles (Atrichelaphinis tigrina, Cyrtothyrea marginalis, Trichostetha fascicularis and Heterochelus sp.) and drosophilid flies in South Africa, contained 28 isolates that could not be assigned to known species. Comparisons of the D1/D2 domains of the large subunit rRNA gene demonstrated the existence of three separate phylotypes with an affinity to the genus Metschnikowia and more specifically to the beetle-associated large-spored Metschnikowia clade. Twenty-six strains that had similar D1/D2 sequences were mixed in all pairwise combinations. They were found to mate and give rise to large asci typical of those in the clade. The name Metschnikowia proteae sp. nov. (type strain EBDT1Y1T5CBS 12522T5NRRL Y-48784T; allotype strain EBDC2Y25CBS 125215NRRL Y-48785) is proposed to accommodate this novel species. The ecology of this novel yeast species is discussed in relation to its potential plant and insect host species. The additional two single strains isolated from Heterochelus sp. represent two novel undescribed species (Candida sp. 1 EBDM2Y3 and Candida sp. 2 EBDM8Y1). As these single strains are probably haploid mating types of Metschnikowia species, their description is deferred until the species are sufficiently well sampled to permit meaningful descriptionsPeer reviewe

The role of plant–pollinator interactions in structuring nectar microbial communities

Floral nectar harbours a diverse microbiome of yeasts and bacteria that depend predominantly on animal visitors for their dispersal. Since pollinators visit specific sets of flowers and carry their own unique microbiota, we hypothesize that plant species visited by the same set of pollinators may support non-random nectar microbial communities linked together by the type of pollinator. Here we explore the importance of plant–pollinator interactions in the assembly of nectar microbiome and study the role of plant geographic location as a determinant of microbial community composition. We intensively sampled the nectar of 282 flowers of 48 plant species with beetles, birds, long-tongued and short-tongued insects as pollinators in wild populations in South Africa, one of the world's biodiversity hotspots, and using molecular techniques we identified nectar yeast and bacteria taxa. The analyses provided new insights into the richness, geographic structure and phylogenetic characterization of nectar microbiome, and compared patterns of composition of bacteria and yeast communities in relation to plant and pollinator guild. Our results showed that plant–pollinator interactions played a crucial role in shaping nectar microbial communities. Plants visited by different pollinator guilds supported significantly different yeast and bacterial communities. The pollinator guild also contributed to the maintenance of beta diversity and phylogenetic microbial segregation. The results revealed different patterns for yeast and bacteria; whereas plants visited by beetles supported the highest richness and phylogenetic diversity of yeasts, bacteria communities were significantly more diverse in plants visited by other insect groups. We found no clear microbial spatial segregation at different geographical scales for bacteria, and only the phylogenetic similarity of yeast composition was correlated significantly with geography. Synthesis. Interactions of animal vector, plant host traits and microbe physiology contribute to microbial community assemblages in nectar. Our results suggest that plants visited by the same pollinator guild have a characteristic nectar microbiota signature that may transcends the geographic region they are in. Contrasted patterns for yeast and bacteria stress the need for future work aimed at better understanding the causes and consequences of the importance of plants and pollinators in shaping nectar microbial communities in nature.Ministerio de Economía y Competitividad SEV-2012- 0262Ministerio de Ciencia e Innovación RYC2018-023847-

The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study

Background and Aims Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades

Metschnikowia proteae sp. nov., a nectarivorous insect-associated yeast species from Africa

A collection of yeasts isolated from nectar of flowers of Protea caffra (Proteaceae) and associated scarab beetles (Atrichelaphinis tigrina, Cyrtothyrea marginalis, Trichostetha fascicularis and Heterochelus sp.) and drosophilid flies in South Africa, contained 28 isolates that could not be assigned to known species. Comparisons of the D1/D2 domains of the large subunit rRNA gene demonstrated the existence of three separate phylotypes with an affinity to the genus Metschnikowia and more specifically to the beetle-associated large-spored Metschnikowia clade. Twenty-six strains that had similar D1/D2 sequences were mixed in all pairwise combinations. They were found to mate and give rise to large asci typical of those in the clade. The name Metschnikowia proteae sp. nov. (type strain EBDT1Y1T5CBS 12522T5NRRL Y-48784T; allotype strain EBDC2Y25CBS 125215NRRL Y-48785) is proposed to accommodate this novel species. The ecology of this novel yeast species is discussed in relation to its potential plant and insect host species. The additional two single strains isolated from Heterochelus sp. represent two novel undescribed species (Candida sp. 1 EBDM2Y3 and Candida sp. 2 EBDM8Y1). As these single strains are probably haploid mating types of Metschnikowia species, their description is deferred until the species are sufficiently well sampled to permit meaningful descriptionsPeer reviewe

The Fourth Industrial Revolution – what does it mean to our future faculty?

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Metschnikowia drakensbergensis sp. nov. and Metschnikowia caudata sp. nov., two endemic yeasts associated with Protea flowers in South Africa

In a taxonomic study of yeasts recovered from nectar of flowers and associated insects in South Africa, eleven strains were found to represent two novel species. Morphological and physiological characteristics and sequence analyses of the D1/D2 large subunit rRNA gene, as well as the actin, RNA polymerase II, and elongation factor 2 genes showed that the two novel species belonged to the genus Metschnikowia. Metschnikowia drakensbergensis sp. nov. was recovered from nectar of Protea roupelliae and the beetle Heterochelus sp. This species belongs to the large-spored Metschnikowia clade and is closely related to M. proteae, with which mating reactions and single-spored asci were observed. Metschnikowia caudata sp. nov. was isolated from nectar of P. dracomontana, P. roupelliae, P. subvestita and a honey bee, and is a sister species to Candida hainanensis and M. lopburiensis. Analyses of the four genes demonstrated the existence of three separate phylotypes. Intraspecies matings lead to the production of mature asci of unprecedented morphology, with a long, flexuous tail. A single ascospore was produced in all compatible crosses, regardless of sequence phylotype. The two species appear to be endemic to South Africa. The ecology and habitat specificity of these novel species is discussed in terms of host plant and insect host species. The type cultures are: Metschnikowia drakensbergensis (type strain EBD-CdVSA09-2T=CBS 13649T=NRRL Y-63721T, MycoBank no. MB809688; allotype EBD-CdVSA10-2A=CBS13650A=NRRL Y-63720A); and Metschnikowia caudata (type strain EBD-CdVSA08-1T=CBS 13651T=NRRL Y-63722T, MycoBank no. MB809689; allotype EBD-CdVSA57-2A=CBS 13729A=NRRL Y-63723A)Estación Biológica de Doñana/Unidad de Excelencia Severo Ochoa. Financiado: Ministerio de Economía y Competitividad (España)Peer reviewe

The Fourth Industrial Revolution – what does it mean to our future faculty?

The future of a country like South Africa is predicated upon policies; whether these policies are effective or ineffective is not primarily an issue. The prospects and realities of the Fourth Industrial Revolution (4IR) have proven to be shaping strategic policies across various spheres of national life already, including the national government, academia, civil society and the private sector. Ultimately, as strategic policies begin to take shape and come along, there is a need to pose certain important questions: what direction(s) and against what context(s) is the 4IR being embraced? In this Commentary, authored by young faculty, we discuss and debate some of the strategic recommendations of the South African Presidential Panel of the Fourth Industrial Revolution¹, specifically ‘securing and availing data to enable innovation’, ‘incentivising future industries, platforms and application of 4IR’ and ‘building 4IR infrastructure’. We look at the historical context of such recommendations, and identify advantageous positions as well as gaps that may need more discussion. We then ask: What does the 4IR truly mean for our future academics and researchers?http://www.sajs.co.zahj2021Computer ScienceSpeech-Language Pathology and Audiolog