I am really passionate about theoretical and quantitative biology and I would like to build my future career around this topic. I've just got my bachelor's degree in biology (ecology) but scince I've had only one math class through the years, my math skills are very poor, so I have problems in understanding even simpe models. My main interests are population dynamics, adaptive dynamics and game theoretical models of social conflicts.
I would like to improve my skills, but I have just no idea where/how to start. What kinds of math should I try to focus on learning to get where I want to go?