Evolutionary consequences of climate change and the historical basis of modern biodiversity patterns: a case study using Australian floras from the Cretaceous to the Recent
This work continues on earlier research on plant diversification pattern in the Cretaceous. Using a comprehensive compilation of fossil pollen and spores from Australia from the Cretaceous to Recent, I will address the following major questions: How do plants respond to climate change? Are there global patterns in macroevolution?How have past events influenced modern diversity distributions?
Gymnosperms on the tree
My research in the gymnosperm tree of life project aims to reconstruct the evolution of seed plants through an integrated phylogeny of morphological and molecular data sets. I am interested in methods to intergrate these data sets to produce a phylogeny of fossil and living taxa. As part of this project, I am involved in obtaining DNA sequence data for the nuclear marker PHYP in all cycad species.
Using phylogeny to investigate
evolution in heterosporous ferns (Salviniales)
My postdoctoral studies have focused on the heterosporous ferns, which comprise Salviniaceae and Marsileaceae. I conducted molecular phylogenetic analyses of Marsilea, Pilularia, Salvinia, and a combined data set of Salviniales (Nagalingum et al., 2007; Nagalingum et al., in press). Through these phylogenies, I assessed species relationiships, biogeographic patterns, and morphological character evolution.
Using morphology and anatomy, I investigated the homology of heterosporous fern reproductive structures traditionally called 'sporocarps' (Nagalingum et al., 2006), and conducted comparative studies of fossil and living megaspores of heterosporous ferns (Nagalingum et al., unpublished data; Lupia et al., unpublished data). At present, I am working on estimating the age of Salviniales through a combined approach utilizing fossil first appearances and molecular divergence time estimation (Nagalingum et al., in prep).
Cretaceous ferns from Australia
For my dissertation in paleobotany, I investigated ferns from the Early Cretaceous in Australia and Antarctica. For the taxonomic component of my dissertation work, I described 25 fern species, and of these 11 are new species. This work is presented in three publications: one detailing the Gondwanan components of the fern flora (Cantrill and Nagalingum, 2005), another documenting two new species belonging to the extant fern families Matoniaceae and Gleicheniaceae (Nagalingum and Cantrill, 2006), and a third describing a new genus for fossil Marsileaceae from Australia and Antarctica (Nagalingum, 2007).
To examine floristric trends in Australia during the Cretaceous, I compiled a large database of over 10,000 records of spore and pollen. Diversity and abundance data were analysed for free-sporing plants, gymnosperms, angiosperms, and ferns. This research showed that the timing of the angiosperm increase in Australia was delayed compared to North American trends, while gymnosperms did not decline in diversity and abundance. Interestingly, the large decline in free-sporing plants is attributable to only some fern groups, and other fern groups radiated at this time (Nagalingum et al., 2002).
An Early Cretaceous flora from
My honors research involved a taxonomic investigation of the Boola Boola, Early Cretaceous flora focussing on ferns, seedferns, and conifers. This research was published together with a complete description of the Boola Boola flora (McLoughlin et al., 2002), and as a publication on a new fossil conifer species (Nagalingum et al., 2005).
Course instructor: Bachelor
of Naturopathy, The Southern School of Natural Therapies, Melbourne
Head teaching assistant:
Bachelor of Science, The University of Melbourne
Teaching assistant: Bachelor
of Science, The University of Melbourne