Summary
Uses DNA and protein sequences to infer relationships between organisms.
In depth
DNA, RNA and protein sequences provide numerous characters. Mitochondrial DNA, rRNA and nuclear genes are used. Reveals relationships hidden by convergent anatomy, e.g. whales near hippos.
Molecular data are abundant but need alignment and models. Different genes may give different trees (gene tree versus species tree).
Example: DNA shows hippos are closest to whales.
Molecular systematics uses differences in DNA, RNA and protein sequences to reconstruct relationships. Because mutations accumulate over time, more closely related species have more similar sequences. Genes used depend on depth: ribosomal RNA for deep divergences, mitochondrial DNA and nuclear loci for closer relationships, and whole genomes now.
Sequences are aligned, a substitution model is chosen, and tree-building methods (neighbour-joining, maximum likelihood, Bayesian inference) are applied, with bootstrap support. Molecular clocks calibrated with fossils estimate divergence times. Problems include long-branch attraction, horizontal gene transfer and incomplete lineage sorting.
Example: DNA showed that giant pandas are bears and that hippos are the closest relatives of whales.
Frequently asked questions
What is Molecular Systematics?
Uses DNA and protein sequences to infer relationships between organisms.
Which area of biology covers Molecular Systematics, and how advanced is it?
Molecular Systematics is one of the 52 topics in Taxonomy & Biodiversity. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Phylogenetic Classification, Horizontal Transfer and the Tree of Life, Community Phylogenetics.
Why does Molecular Systematics matter?
It has transformed the tree of life.
Can you give an example of Molecular Systematics?
The giant panda is a bear according to DNA.
What should I learn before Molecular Systematics?
Work through the Beginner topics in Taxonomy & Biodiversity first, such as Taxonomy, Binomial Nomenclature, Taxonomic Hierarchy, then return to Molecular Systematics. Intermediate topics assume the Beginner vocabulary.
What topics are related to Molecular Systematics?
The closest topics to Molecular Systematics are Phylogenetic Classification, Horizontal Transfer and the Tree of Life, Community Phylogenetics, Taxonomy. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Molecular Systematics?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Molecular Systematics. To practise the whole of Taxonomy & Biodiversity, use the Taxonomy & Biodiversity quiz.
How is Molecular Systematics different from Phylogenetic Classification?
Molecular Systematics: Uses DNA and protein sequences to infer relationships between organisms. Phylogenetic Classification: Groups organisms by evolutionary relationships so that taxa reflect common ancestry. Read both side by side and note what each one explains.
How should I study Molecular Systematics 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 Phylogenetic Classification and explain the difference aloud. Finally, take the Taxonomy & Biodiversity quiz and come back to this page for any question you miss.