Table 1.

Models used for pangenome analysis. For α > 1 (γ < 0), the size of the pangenome approaches a constant as more genomes are sampled, that is, the pangenome is closed. Conversely, for α < 1 (0 < γ < 1), the size of the pangenome is an increasing and unbounded function of the number of genomes considered

	Core genome size	Pangenome size	New genes	Comments
Tettelin et al. (2005)	$n={\mathit{\kappa }}_C\text{exp}[-N/{\mathit{\tau }}_C]+\mathrm{\Omega }$	Calculated based on parameters for new genes curve	$n={\mathit{\kappa }}_S\text{exp}[-N/{\mathit{\tau }}_S]+tg(\mathit{\theta })$
Tettelin et al. (2008)		n = κN γ The exponent γ > 0 indicates an open pangenome species	n = κN −α The exponent α determines whether the pangenome is open (α < 1) or closed (α > 1)	There is a relationship between α and γ: α = 1−γ