1. What is Average Nucleotide Identity?

Average Nucleotide Identity (ANI) is a measure of genetic similarity between the genomes of two organisms. It's calculated as the percentage of identical nucleotides between the genomes when compared across the whole genome sequence.

2. How Does the Calculator Work?

The calculator uses the ANI formula:

Where:

• \( identical\_bases \) — Number of matching nucleotide bases
• \( total\_bases \) — Total number of bases compared

Explanation: The equation provides a percentage value representing the average identity between two genomic sequences.

3. Importance of ANI Calculation

Details: ANI is widely used in microbial taxonomy to determine species boundaries, with values >95% typically indicating organisms belong to the same species.

4. Using the Calculator

Tips: Enter the number of identical bases and total bases compared. Both values must be positive numbers, and identical bases cannot exceed total bases.

5. Frequently Asked Questions (FAQ)

Q1: What is a good ANI value for species delineation?
A: Typically, ANI values >95-96% suggest organisms belong to the same species, though this threshold may vary for different groups.

Q2: How does ANI compare to 16S rRNA gene similarity?
A: ANI provides more resolution than 16S rRNA comparisons, as it examines the whole genome rather than just one gene.

Q3: What are common methods to calculate ANI?
A: Common methods include ANIb (BLAST-based), ANIm (MUMmer-based), and TETRA (tetranucleotide frequency).

Q4: How many genes are needed for accurate ANI calculation?
A: ANI typically uses whole genome sequences, not individual genes, for the most accurate comparison.

Q5: Can ANI be used for eukaryotic genomes?
A: While primarily used for prokaryotes, ANI can be applied to eukaryotes though interpretation may differ due to genome complexity.