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PhD Studentship Available

Mike Charleston michael.charleston at zoology.oxford.ac.uk
Wed Mar 1 12:19:19 EST 2000

Dear all,

I am delighted to invite applications for an MRC-funded PhD studentship at the
University of Oxford, in the Department of Zoology, beginning October 2000. 
The general area is in phylogenetic coevolution, a fundamental research
area studying historical relationships between closely interacting groups
of species.  A very broad outline of the subject area follows.  For more details
and any expressions of interest please contact me directly at the above
e-mail address (further address details given below).

Phylogenetic models of Coevolution

Virtually all biological questions require an evolutionary context: they 
cannot be answered outside the framework in which we consider how 
organisms have evolved to the state in which we observe them today.
Phylogenetic relationships therefore play a crucial role in all 
aspects of biological study, and a great deal of research is dedicated 
to recovering the phylogenetic relationships among existing taxa, 
as an essential step towards making meaningful comparisons between 

Phylogenetic coevolution is the mechanism by which phylogenies of groups of 
taxa which interact closely tend to be more similar to each other than we 
would expect by chance.
Such pairs of groups include hosts and their parasites (such as birds 
and their lice), organisms and their genes (gene families), and geographical 
areas and the species which inhabit them (anolis lizards in the Eastern 
Caribbean).  Even more complex systems commonly arise, involving more 
than two phylogenies.

Complicating factors mean that the phylogenies do not generally match 
perfectly; these factors include extinction events, host-switching or 
migration events, and gene duplication events.

By studying and modelling such inter-phylogenetic relationships we are 
better able to recover the processes by which related phylogenies come 
to differ.
These processes describe the way in which pathogens leap between 
species, how and why migration events occur, even how genes move from 
one species to another.

This project will be extend the research of Charleston and Page [1,2].
There are a range of models and systems for solving the problem of 
mapping from dependent "parasite" to independent "host" phylogeny, 
ranging from the very simple to the most complex.
The choice of mapping is crucial since each describes a different 
evolutionary process.

The problem is combinatorially difficult: there are many possible 
mappings from parasite into host phylogeny for a given pair of "host"
and "parasite", and this means statistical methods based solely on 
the trees involved must be as powerful as possible, in order to 
distinguish among these alternatives.  

This sets the scene for an exciting problem in mixed modelling: 
students with a background in mathematics and biology will find this 
challenging, yet soluble.

New theoretical models of cospeciation will be generated and these 
will be applied to problems in phylogenetic coevolution with the aim 
of reconstructing historical movement of parasites and pathogens among 
host organisms.

Applications are welcome from all UK students with a good honours 
degree or above, who have an interest in mathematical biology and 

The University of Oxford is an equal opportunities employer.
This project is funded by the MRC.


[1] Charleston, M. A., 1998. Jungles: A new solution to the host/parasite 
   phylogeny reconciliation problem. 
   Mathematical Biosciences 149:191-223

[2] Page, R. D. M. 1994. Maps between trees and cladistic analysis of 
   historical associations among genes, organisms, and areas. 
   Systematic Biology 43:58-77

 Michael A. Charleston, PhD, LTCL
 Department of Zoology
 University of Oxford
 South Parks Road
 Oxford, OX1 3PS
 United Kingdom

 Phone:   (01865) 271-274
 Fax: c/o (01865) 271-249
 e-mail: michael.charleston at zoo.ox.ac.uk

 Michael A. Charleston
 Department of Zoology
 University of Oxford
 South Parks Road
 Oxford, OX1 3PS
 England, United Kingdom
 Fax: c/o (01865) 271-249
 e-mail: michael.charleston at zoo.ox.ac.uk

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