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Evolutionary patterns in microscopic wood anatomy

Complete the wood anatomical observations in our ongoing Apocynaceae wood project. Give a detailed overview of the variation in the family and highlight broad-scale evolutionary patterns in this lineage that includes some rare but fascinating features such as layered structures and included phloem.

Supervisor and contact:

Dr. Frederic Lens (Naturalis Biodiversity Center, frederic.lens@naturalis.nl)

 

Period and duration:

Ca. 6 months, project can start now

 

Study and level:

MSc project

 

Background and context:

Apocynaceae are one of the larger families within the flowering plants (5100 sp.), including tall trees, lianas, small shrubs and herbs. The family is divided into five subfamilies, of which the wood anatomy of three subfamilies has been published so far [1-2]. These two papers reveal several phylogenetically informative wood features within Apocynaceae, amongst others vessel grouping patterns (Fig. 1), and support multiple transitions towards the climbing habit. The proposed MSc proposal will build on the ongoing anatomical study of the two remaining subfamilies, Secamonoideae and Asclepioideae, which are considered to be the most derived clades of Apocynaceae. Unobserved slides of about 50 species are available, and need to be compared with existing observations, completed with additional wood samples, and interpreted using published molecular phylogenies to unravel evolutionary wood patterns within the entire family. While most of the woody species are ancestrally wood, there are arguments that some of the asclepioids are derived woody based on recent molecular phylogenies, which can be further assessed by wood anatomical observations [3].

 

Objectives and goals:

This MSc study will complete the wood anatomical observations in our ongoing Apocynaceae wood project, which would lead to a third and final wood anatomical paper which would give a detailed overview of the variation in the family and highlight broad-scale evolutionary patterns in this lineage that includes some rare but fascinating features such as layered structures and included phloem.

         

Fig. 1: Transverse wood sections of Apocynaceae showing the large variation in vessel distribution

 

Material and methods:

Slides of around 50 species are envisaged to be studied using light microscope and scanning electron microscope techniques, and lab work (sectioning wood and preparing maceration slides) will be needed to carry out all the observations required to make detailed descriptions. The trait reconstruction will be performed based on the molecular phylogenies.

 

Requirements:

The candidate should be able to work accurately to make good descriptions and to enjoy working with microscopes.

 

References:

[1] Lens F, Endress ME, Baas P, Jansen S, Smets E. 2008. Wood anatomy of Rauvolfioideae (Apocynaceae): a search for meaningful non-DNA characters at the tribal level. American Journal of Botany 95: 1199-1215

[2] Lens F, Endress ME, Baas P, Jansen S, Smets E. 2009. Vessel grouping patterns in subfamilies Apocynoideae and Periplocoideae confirm phylogenetic value of wood structure within Apocynaceae. American Journal of Botany 96: 2168-2183

[3] Lens F, Davin N, Smets E, Del Arco M. 2013. Insular woodiness on the Canary Islands: remarkable case of convergent evolution. International Journal of Plant Sciences 174: 992-1013