Ingrida Olendraitė

Molecular biologist

University of Vilnius

2012

The Tree of Life:Classification and

Phylogeny

Key terms

The great battle for life

Roots of classification

Phylogenetic branches

Outline

We will become acquainted with some of the methods by which

we can infer phylogenetic relationships and we will see

how our understanding of those relationships is reflected in the

classification of organisms.

is a method of taxonomy used to group and categorize organisms into groups such as genus or species.

it took on an entirely different significance (compared with 17-18’s) after The Origin of Species was published in 1859.

Classification –

is the study of evolutionary relation among groups of organisms, which is discovered through molecular sequencing data and morphological data matrices.

Phylogenetics –

“ All species, extant and extinct form a great “Tree of Life” or phylogenetic tree. It is the great battle for life”

Phylogenetic analysis is the study of relationships among species

Carolus Linnaeus and BINOMAL NOMENCLATURE

external and internal morphological features

differences in behaviour, cell structure, biochemistry and chromosome structure.

DNA sequences

The importance of parsimony

Persimony holds that the best phylogenetic hypothesis is the one that requires us to

postulate the fewest homoplasious changes.

Evaluating phylogenetic hypotheses

The chief way of confirming a phylogenetic hypothesis is to see if it agrees with independent data

Sites

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Haplotype

3 A T A C T A T A T G T T G C C

2 A T A C T A C A T G T T G C C

1 A T A C T A C A C G T T G C C

4 A T A C T A C A C G T T A C C

5 A T A C T A C A C G T T A C T

6 A T A C T G C A C G T T A C T

7 A T G C T G C A C G T T A C T

Gene tree

7 6 5 4 1 2 3

Gene tree

The evolution of Serine protease II

MrBayes: Bayesian inference of phylogeny.

A phylogeny is the history by which species or other taxa have successively originated from common ancestors.

A phylogenetic tree is a statement about evolutionary relationships and like all scientific statements it is a hypothesis

Phylogenetic trees, estimated from the characteristics of the taxa, represent evolutionary relationships and provide a framework for analyzing many aspects of evolution.

Both morphological and molecular data are used in phylogenetic analysis.

Summary

“Evolution”, Douglas J. Futuyma, 2005

http://evolution.berkeley.edu/evolibrary/article/phylogenetics_01

http://www.ebi.ac.uk/pdbsum/

References

Questions?