Evolution of dwarf galaxy observable parameters

We present a semi-analytic model of isolated dwarf galaxy evolution and use it to study the build-up of observed correlations between dwarf galaxy properties. We analyse the evolution using models with averaged and individual halo mass assembly histories in order to determine the importance of stochasticity on the present-day properties of dwarf galaxies. The model has a few free parameters, but when these are calibrated using the halo mass stellar mass and stellar mass-metallicity relations, the results agree with other observed dwarf galaxy properties remarkably well. Redshilt evolution shows that even isolated galaxies change significantly over the Hubble time and that 'fossil dwarf galaxies' with properties equivalent to those of high-redshift analogues should be extremely rare, or non-existent, in the local Universe. A break in most galaxy property correlations develops over time, at a stellar mass M-* similar or equal to 10(7) M-circle dot. It is caused predominantly by the ionizing background radiation and can therefore in principle be used to constrain the properties of reionization.