Julia FermPostdoctoral researcher

Diversification and evolution in the Neotropical rainforest mimosoid genus Zygia (Fabaceae) based on phylogenomics and morphology

Neotropical rainforests are the world's most species rich areas, and the legumes (Fabaceae) are among the most diverse and ecologically abundant plant families that grow there (Lewis et al. 2005). Thus, legume genera are the ideal candidates for studying the evolution of the hyperdiversity of Neotropical rainforests, which is poorly understood (Eiserhardt et al. 2017). Traditionally, the diversity in tropical rainforests has been considered old, but another potential reason for the high diversity of species in rainforests is rapid and recent diversification processes (Richardson et al. 2001; Koenen et al. 2015). Species relationships within the Neotropical genus Zygia (Fabaceae) have been difficult to resolve based on data generated with Sanger sequencing (i.e. sequences up to 1200 bp) (Ferm et al. 2019), something which may indicate a recent evolutionary radiation. The present project will clarify evolutionary patterns and processes within Zygia in order to add to the understanding of tropical rainforest diversification in the Neotropics, and evaluate and improve the current taxonomy and classification of the genus.

The aims of the project are to investigate diversification and evolution in Zygia, and more specifically to a) resolve phylogenetic relationships and node ages in Zygia using massive amounts of nuclear DNA data produced by next-generation sequencing (NGS) methods, b) determine if Zygia has undergone a recent rapid diversification caused by highly effective dispersal, c) investigate to what extent hybridisation, introgression and polyploidy may explain evolution and diversification within the genus, and d) conduct extensive morphological studies of Zygia and in combination with the phylogenetic results, update the taxonomy and classification of the genus.

The results of this project, using Zygia as the study system, will contribute important knowledge about the processes that drive the exceptional species diversity of Neotropical rainforests. More specifically, fundamental questions on diversification will be addressed regarding Zygia. Is speciation (mostly) allopatric or sympatric? Has diversity accumulated (mostly) through recent efficient speciation or low extinction over vast times? The alpha-taxonomic work, including identification of diagnostic species characters, will aid in urgently needed work with biodiversity and conservation in targeted areas of Amazonia.

 

Eiserhardt W. L., Couvreur T. L. & Baker W. J. 2017. Plant phylogeny as a window on the evolution of hyperdiversity in the tropical rainforest biome. New Phytol. 214(4): 1408–1422.

Ferm J., Korall P., Lewis G. P. & Ståhl B. 2019. Phylogeny of the Neotropical legume genera Zygia and Marmaroxylon and close relatives. Taxon 68(4): 661–672.

Koenen E. J., Clarkson J. J., Pennington T. D. & Chatrou L. W. 2015. Recently evolved diversity and convergent radiations of rainforest mahoganies (Meliaceae) shed new light on the origins of rainforest hyperdiversity. New Phytol. 207(2): 327–339.

Lewis G. P., Schrire B., Mackinder B. & Lock M. (eds.) 2005. Legumes of the world. Kew: Royal Botanic Gardens.

Richardson J. E., Pennington R. T., Pennington T. D. & Hollingsworth P. M. 2001. Rapid diversification of a species-rich genus of neotropical rain forest trees. Science 293(5538): 2242–2245.