Introduced populations offer valuable systems to study evolution. Our main study system is the common wall lizard. This is a species from southern Europe that has been introduced many times in different locations in Europe and in North America. We have focused on populations in England and established their origin and patterns of genetic diversity. Of particular interest is how the latter is shaped by the colonization history. We have also studied adaptive shifts in response to the cooler climate in England compared to the native origin. Interestingly, it turns out that introduced lizards have taken a small, but very important, step towards viviparity by retaining their embryos for longer before the lay eggs. This reduces the time needed for completing embryogenesis in the nest, which is very important since the cool soil in England means development sometimes is so slow they fail to complete it before autumn. Embryos also develop faster at cooler temperatures. These responses help the wall lizards to persist north of their natural range. We are now interested in asking what the underlying mechanisms behind these responses are, if they are similar to adaptive divergence during natural range expansion, and if developmental bias facilitates rapid adaptation to climate.