Summary
Measures biodiversity by the total evolutionary history represented by a set of species.
In depth
Faith's PD sums branch lengths connecting species. Conservation based on PD prioritises unique lineages; EDGE scores combine evolutionary distinctiveness and global endangerment.
PD captures the unique evolutionary history. Conservation could maximise PD for a given budget.
Key idea: not all species are equally unique evolutionarily.
Phylogenetic diversity (PD), introduced by Daniel Faith in 1992, measures biodiversity by summing the branch lengths of the phylogenetic tree that connects a set of species, so it captures the amount of evolutionary history preserved.
A set of species from widely divergent lineages has higher PD than the same number of close relatives. It helps to prioritise conservation: protecting a group that includes unique lineages saves more of the tree of life than protecting many close relatives. Related metrics include mean pairwise distance and nearest taxon index, and EDGE scores.
Example: two areas each have ten species; the area containing a tuatara, a lizard-like lineage that diverged from all others around 250 million years ago, has higher PD.
Frequently asked questions
What is Phylogenetic Diversity?
Measures biodiversity by the total evolutionary history represented by a set of species.
Which area of biology covers Phylogenetic Diversity, and how advanced is it?
Phylogenetic Diversity is one of the 52 topics in Taxonomy & Biodiversity. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Evolutionarily Distinct Species, Community Phylogenetics, Living Fossils.
Why does Phylogenetic Diversity matter?
Not all species are equal in terms of evolutionary distinctiveness.
Can you give an example of Phylogenetic Diversity?
Protecting the aye-aye saves a lineage with no close relatives.
What should I learn before Phylogenetic Diversity?
Work through the Beginner topics in Taxonomy & Biodiversity first, such as Taxonomy, Binomial Nomenclature, Taxonomic Hierarchy, then return to Phylogenetic Diversity. Advanced topics assume the Intermediate vocabulary.
What topics are related to Phylogenetic Diversity?
The closest topics to Phylogenetic Diversity are Evolutionarily Distinct Species, Community Phylogenetics, Living Fossils, Biodiversity and Ecosystem Function. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Phylogenetic Diversity?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Phylogenetic Diversity. To practise the whole of Taxonomy & Biodiversity, use the Taxonomy & Biodiversity quiz.
How is Phylogenetic Diversity different from Evolutionarily Distinct Species?
Phylogenetic Diversity: Measures biodiversity by the total evolutionary history represented by a set of species. Evolutionarily Distinct Species: Species with few close relatives, such as the tuatara, representing unique branches of evolutionary history. Read both side by side and note what each one explains.
How should I study Phylogenetic Diversity step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Evolutionarily Distinct Species and explain the difference aloud. Finally, take the Taxonomy & Biodiversity quiz and come back to this page for any question you miss.