Genetic diversity is the engine of evolution. Thanks to it species can adapt to different environmental conditions and we humans are able to domesticate wild species, modifying them to fit our needs. When climate changes, species either move with it, become extinct or adapt to the new conditions. The domesticated species upon which our food systems are based are also affected by environmental conditions, so adapting them to the current human induced climate change is of special concern. Mexico is a mega-diverse country where the domestication of important cultivates occurred, such as maize, beans and pumpkins. As a consequence, here there are crop wild relatives that have been evolving for million of years; and traditional crop varieties that have been grown in a wide range of environmental conditions for thousands of years, and that currently continue evolving. The genetic diversity enclosed within these crop wild relatives and traditional varieties is enormous, and likely holds the needed diversity to adapt our cultivate to climate change. Here, I will discuss the need to appreciate Mexican crops genetic diversity in terms of the evolutionary service it provides; and then I will discuss the outcomes and challenges of characterizing, modeling, conserving and using such genetic diversity at a national scale.