Webinar 2: Prof Steve Johnson (SAAB Gold Medal Winner 2023)
The role of volatiles in mediating plant-animal interactions
Plant signalling to animals often involves volatiles that are difficult for humans to detect. Since 2007 the pollination research group at UKZN has been using chemical ecology methods such as GC-MS, GC-EAD and field bioassays to better understand the functional basis of plant-pollinator interactions. In recent years this approach has been extended to include plant-seed disperser interactions. We are still on a steep learning curve, but the incorporation of chemical ecology has enriched our research capacity and has also led to many interesting new avenues of research. This talk will highlight some of the progress we have made and outline some of our plans for the future. I will summarize some of our findings on the chemical ecology of pollination systems involving rodents, beetles, flies, wasps and hawkmoths. This will include studies of how plants use false advertising in mimicry systems. I will also discuss a few key findings of our research on plant deployment of fruit volatiles as signals that lead to seed dispersal.
Webinar 1: Dr Mia Momberg (SAAB Bronze Medal Winner 2023)
‘Where does wind matter?’
How biological communities respond to changes in climate has been studied extensively, but with a large bias to focusing on temperature and precipitation as climatic factors. The roles of other climatic factors are, however, comparatively poorly understood, despite potentially also strongly structuring community patterns. For example, wind may have direct physiological and mechanical impacts on plants, soil, and animals, yet is seldom considered in forecasts of species responses to future change. It is, therefore, important to understand the magnitude of the potential impacts of changing wind conditions on biological communities. Wind speeds have accelerated globally over the past decade, making this topic increasingly relevant. The largest global changes to wind speed to date have occurred in the Southern Ocean. Marion Island is used a study system which experiences wind on most days of the year, and the response of taxa across multiple spatial scales is investigated. At the broadest scale, across the whole island, wind velocity was an important predictor in driving the occurrence of vegetation types on the island, as well as to a lesser degree determining the total vegetation cover. At a finer spatial scale, using data from 1 m2 quadrats, wind stress significantly affected plant species richness, vegetation cover, and community composition, even after accounting for other ecophysiologically-important predictors. Species richness showed a hump-shaped relationship with wind stress, where the most species were found under intermediate wind stress conditions, while locations with the highest wind stress contained the highest percentage of vegetation cover. Individual species showed differing responses to wind conditions, leading to turnover along the wind stress gradient that resulted in differences in community composition. Wind stress had a significant effect on the occurrence of 75% of the species, and was a more important predictor than any temperature- or moisture-related variables for half of the species that were significantly affected. Wind conditions are, therefore, strongly related to multiple aspects of biological communities in this ecosystem that experiences chronic winds. Consequently, it is clear that wind should be considered as a climatic driver of ecological patterns, and be included in future climate forecasts.
Webinar: Wiley Digital Archives
A virtual tour of the Environmental Science and History archives and other Wiley Digital Archives.
Please follow the link to the recording of this webinar:
South African Association of Botanists 