Botanic Gardens Trust, Sydney, Australia

 

Lejeuneaceae

Dr Elizabeth Brown, Botanist

Three years of hard work culminated in the submission of PhD student Matt Renner’s thesis, titled ‘Morphological variation informs evolutionary relationships within the Lejeunea tumida aggregate (Lejeuneaceae: Marchantiophyta)’. Matt was jointly supervised by Elizabeth Brown and Dr Glenda Wardle (University of Sydney).

The Lejeuneaceae is characterised by the lateral leaves having the lower margin curled back under the leaf to form a lobule (see diagram on right); teeth patterns and lobule shape are of critical importance in taxonomic placements in the family. The Lejeuneaceae is a large family of often very small taxa, many known from only one or a few collections. This places a number of limitations on the interpretation of characters, not least being the inability to assess what constitutes infraspecific variation as opposed to inter species variation. Members of the family are commonly assumed to be highly variable and phenotypically plastic. 
 
Matt used a range of innovative techniques to measure and analyse variation, focussing considerable attention on how the morphology of the lobule has been interpreted. He investigated groupings within the Lejeunea tumida aggregate, how variation within the gametophyte may obscure species boundaries, how species can be interpreted when there are too few observations (the single specimen problem) and looked at the bias that certain types of characters may introduce to cladistic datasets. He then compared his results with those obtained from molecular work. Matt rejected the view that morphology as a data source, and a “morphological approach” must be treated as being of lesser weight than molecular data. ‘All data must be treated with care, and it is only the interpretation of data, not the data itself which is potentially dangerous.’

One paper has already been published, one is in page proofs and several others have been submitted for publication in scientific journals.

 

 

Lejeunea
Species of Lejeunea showing underside of plant (to left) with lateral leaves, lobules and underleaves and variation observed in lobule (line drawings to right). Scale bar = 80 μm for plant and 33 μm for lobule details. Drawn by Matt Renner

Endymion-Cooper-and-Matt-Renner
PhD students Endymion Cooper and Matt Renner (to right) on Mount Sprent, Tasmania. The paper packets being folded give the clue to their profession! Photo: Elizabeth Brown

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