expansion growth

[sara]

Hi!

Can someone please explain me (or let me know where to find it) what
exactly the "expansion growth" tree prior (under the coalescent)
means?? Is there a range expansion implied? if not, what is its
difference to other (logistic, exponential) growth models??

thanks a lot,
sara

[sana eybpoosh]

Dear Sara,

Expansion growth happens when the "population growth rate" increases over time. In Logistic growth model, the population growth rate "decreases" over time, and in Exponential growth models, the population growth rate is "fixed" over time. In Constant size models, the population growth rate is "zero". 

For more information, you can see the paper by Pybus and Rambaut (2002): 

Pybus, O. G., and A. Rambaut. 2002. GENIE: estimating demographic history from molecular phylogenies. Bioinformatics 18:1404–1405. 

Best,

Sana