Dr Si-Chong Chen ‘Latitudinal Gradients in Seed Predation, Seed Defence and Seed Dispersal’ - CANCELLED

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Thursday, 2 April 2020 - 12:30pm

CANCELLED - further information to follow

Si-Chong is an ecologist working on the macroecological patterns in seed ecology at the Millennium Seed Bank, Royal Botanic Gardens, Key, United Kingdom.  Dr Chen’s research tests the hypothesis that seed predation and seed defence are more intense at lower latitudes, finding that both pre-dispersal seed defences and predation are more significant in more tropical climates at higher latitudes than previously expected.


There has been heated debate on the existence and generality of the latitudinal gradient in biotic interactions.  We quantified seed predation and seed physical defence across 25 sites spanning 28° of latitude on the east coast of Australia, to test the hypotheses that seed predation and seed defence are more intense at lower latitudes.  Contrary to the traditional expectations, both pre-dispersal seed defences and pre-dispersal seed predation are higher at high latitudes, while neither post-dispersal seed defences nor post-dispersal seed removal are significantly related to latitude.  These findings run counter to the Janzen-Connell hypothesis that the striking diversity of plant species in tropical habitats is caused by stronger herbivore pressure in the tropics.  This study, combined with some previous studies, highlight an urgent need for new theories for understanding global patterns in biotic interactions and species coexistence.  We propose an amended model in which greater distances between maternal plants and their offspring in the tropics are generated by greater seed dispersal distances.  Therefore, compiling the largest dataset of seed dispersal distance to date, we present the first global evidence that seed dispersal distance is an order of magnitude greater at the equator than at higher latitudes.  This latitudinal gradient in seed dispersal distance is partially explained by plant life-history traits, such as seed dispersal syndrome and plant height.  The extended seed shadow of tropical plants could increase the distance between conspecific individuals and contribute to the maintenance of high plant diversity.  The study also has implications for species’ persistence in the face of habitat fragmentation and climate change.


Dr Si-Chong Chen is an ecologist working on the macroecological patterns in seed ecology at the Millennium Seed Bank of the Royal Botanic Gardens Kew, United Kingdom.  She received her PhD from the University of New South Wales, Australia, and a postdoctoral fellowship at the Ben-Gurion University of the Negev, Israel.  For years, she continuously built her interests in various aspects of seed predation, seed dispersal, seed germination and relevant disciplines.  Her research aims to contribute to our understanding of seed ecology in three key ways: 1) by narrowing the gaps between data, intuitive ideas and theories; 2) by enhancing the integration of replicated studies at a macro-ecological scale; and 3) by extending understanding from a local scale and a small number of species to a global scale spanning many biomes and taxonomic groups.