Determining the sources and role of intra-specific genetic variation is a classical focus of evolutionary biology. Ever since the beginning of population genetic studies in forest trees, the observation of high levels of within-stand phenotypic and, later, molecular diversity has been a commonplace. In these sessile and long-lived organisms, the maintenance of adaptive genetic and phenotypic diversity within populations seems of paramount importance, because the environment is likely to change within their life span.
Further reading - Scotti I, González-Martínez SC, Budde KB et al. 2016. Annals of Forest Science 73: 69. doi:10.1007/s13595-015-0471-z
