STRATEGIC SCIENCE ADVISORY PANEL

PAPER: SSAP 2007/35

SUBJECT: CLADISTICS

MEETING: 15&16 JANUARY 2007

SUMMARY

This paper sets out:

• An introduction to Cladistics and its possible use in the study of biodiversity

ACTION

The panel members are invited to:

• Note and discuss the paper

Professor Chris Pollock will be happy to answer questions on this paper at the meeting on 15 January 2007

Science & Analysis Group

December 2006

CLADISTICS

1. Biological taxonomy has always suffered from two partially conflicting aims. The first is to allow unambiguous identification, such that like can be compared with like in different experiments or sets of observations. The second is to understand phylogeny. Morphological taxonomy is good at the first, but has real problems with the second, mainly because of the immense (and often poorly-appreciated) drive towards convergent evolution.

2. DNA-based "time-clock" analysis of selectively neutral mutations in non coding regions of DNA has revolutionised this definition of taxonomy and has allowed precise and unambiguous assignment of relationships across both large and small genetic distances. A range of "clocks" with different periods have been found within DNA, depending upon the nature of the mutations that are being measured. Most of the taxonomic interest has been at the high scales (genera, orders and species) but the higher resolution clocks give us the opportunity to look at evolutionary biology in progress and to follow speciation at a molecular level.

3. As such, DNA-based Cladistics seems to me to offer huge potential in the rigorous scientific study of biodiversity, offering opportunities to study the big questions (What is biodiversity? How much of it is needed in stable ecosystems? How can you preserve it in situ etc etc). My concern is that unless underpinned by modern genetical and evolutionary biological techniques, the study of biodiversity is merely another word for nature study.

4. To deliver effective new managements that can support economic activity whilst delivering environmental benefits we need to understand much more about the basic biological principals and I believe that Cladistics is a good way to achieve this. I would point out, however, that my views are anathema to many practising ecologists.

Professor Chris Pollock

SSAP member