Which measure of error to use?

Hello everyone!

I'm not sure if you'd class this as University Level maths as I'm a biologist, so I added my question here.

Basically, I'm investigating the difference in extinction time, number of individuals at t=500 and persistence of two competing phenotypes: altruistic and selfish. I've used an Excel model and tested the impact of each of my parameters by keeping the others constant and plotting the mean of extinction time, number of individuals at t=500 and persistence on a scatter plot.

I'd like to add error bars to my graph and have calculated the standard deviation of the population, but I don't know if that's the right measure of variance to use in this situation. Can anyone give me some advice on what to use?

Thanks,

Chloe.