Master-Thesis (Speciale) project: The legacy of pre-historical megafauna extinction on tropical tree species distribution (02.06.2017)




Background:
Large-bodied animals (megafauna) had and still has strong effects on the structure and functioning of our global ecosystems. One major ecosystem service of megafauna is the dispersal of seeds over long distances with major implications for the distribution of plant species especially in the neo- and paleotropics (South America and Africa). Plant species like Avocado have big, fleshy fruits including big seeds which originally were dispersed by mega-frugivores. However, large parts of the South American megafauna went extinct in the Late Pleistocene and early Holocene with strong effects on seed dispersal and, thus, the distribution of plant species adapted to this mode of animal dispersal. A recent study by Doughty et al. (2016) shows for South America a significant reduction of range size of megafauna dispersed plant species in comparison to other, animal dispersed plant species. On the other hand, large-sized frugivores are still present in Africa which raises the question whether African plant species adapted to megafauna dispersal did not experience significant range retraction so far.

Methods: Comparison of range sizes for megafauna vs. other animal dispersed plant species between South America and Africa. Range sizes of megafauna and other animal dispersed plant species will thereby be quantified by applying simple species distribution modelling approaches (generalized linear models, convex hulls or similar methods) on species distribution data and will be compared between South America and Africa. Information on the dispersal mode will be obtained from big databases on animal/megafauna dispersed plant species.

Starting time: The project can be started any time from now on.

Supervision: The project will be supervised by Prof. Dr. Jens-Christian Svenning and Dr. Andreas Schweiger, Section for Ecoinformatics and Biodiversity, Department of Bioscience.

Contact: Prof. Dr. Jens-Christian Svenning (svenning@bios.au.dk), Dr. Andreas Schweiger (andreas.schweiger@bios.au.dk).

Relevant literature: Doughty et al. (2016). Megafauna extinction, tree species range reduction, and carbon storage in Amazonian forests. Ecography, 39, 194-203. Guimaraes et al. (2008). Seed dispersal anachronisms: Rethinking the fruits extinct megafauna ate. Plos One 3, e1745. Janzen & Martin (1982). Neotropical anachronisms: the fruits the gomphotheres ate. Science, 215, 19-27.