Interactions between trophic levels have a major influence on the distribution and abundance of organisms. Understanding how herbivory and pollination structure ecosystems is fundamental to understanding how environmental damage affects essential ecosystem processes.
Thanks to a recent award from the Leverhulme Trust, Dr Mick Hanley and project post-doc Dr Lucille Chretien (in collaboration with Professor Nicole van Dam, iDiv, Leipzig), are working to corroborate long-established biogeographic theories predicting patterns of plant defence expression at the seedling stage. Specifically, they seek to establish whether the severity of herbivore attack declines with increasing latitude and altitude, and that as a result, seedling defence shows a concomitant decline. This project builds on over 25 years of work on seedling-herbivore interactions by Hanley and co-workers showing how selective seedling herbivory is a major environmental filter for establishing plant communities (see Hanley et al 2018).
Also in on the elevational act is new member Dr James Buckley. Working with his collaborators at ETH Zürich, James has shown that high-altitude plant populations are more vulnerable to insect herbivory than low-elevation populations (Buckley et al. 2019). Populations from the highest elevations varied in their resistance to herbivores however, suggesting and adaptive capacity to cope with changes in herbivore pressure. Ongoing research aims to identify the chemical and morphological traits underlying this observation and whether similar patterns are evident in other plant species.
Several members of our group work on various aspects of plant-pollinator Interactions. Dr Pete Cotton is part of a global collaboration that uses bird–plant interactions as a model to understand how biotic interactions vary across macroecological scales. Sonne et al. (2020) used 24 plant–hummingbird interaction networks across the Americas to show that the tendency of species to interact with morphologically matching partners contributed to specialized and modular network structures. Morphological matching best explained interaction frequencies in networks found closer to the equator and in areas with low-temperature seasonality. This is important because it suggests that morphological constraints on interactions as a potential explanation for increasing resource specialization towards lower latitudes. Another key area of research has been to determine how shifts in arable land-use practice affect pollinator assemblages. In work led by Professor Camille Parmesan, recent PhD graduate Nick Berkley showed how insect distributions varied markedly in-and-around bioenergy crops (see Berkley et al 2018). Nick is currently looking at how pollinator network stability varies according to different bioenergy cropping patterns.
Buckley J, et al (2019). Variation in growth and defence traits among plant populations at different elevations: Implications for adaptation to climate change. Journal of Ecology 107: 2478-2492.
Hanley ME, Shannon RWR, et al (2018) Riding on the wind: volatile compounds dictate selection of grassland seedlings by snails. Annals of Botany 122: 1075–1083.
Berkley NAJ, Hanley ME, Boden R, Owen RS, Holmes JH, Critchley RD, Carroll K, Sawyer DGM, Parmesan C (2018) Influence of bioenergy crops on pollinator activity varies with crop type and distance. GCB Bioenergy 10: 960-971.
Maruyama PK,….(incl Cotton PA), et al (2018) Functional diversity mediates macroecological variation in plant-hummingbird interaction networks. Global Ecology & Biogeography 27: 1186-1199.
Sonne J,….(incl Cotton PA) et al (2020) Ecological mechanisms explaining interactions within plant–hummingbird networks: morphological matching increases towards lower latitudes. Proceedings of the Royal Society B 287: 20192873.
Dr Mick Hanley (PI) Geographical Patterns in Seedling Defence and Herbivore Interactions. The Leverhulme Trust £171,046. March 2019-Feb 2022.