Plant-plant interactions, which are defined as the effect of one plant on another of the same or different species, are inherently local in nature. Plants interact in both positive and negative ways, which are governed by the same underlying ecological dynamic processes. The Mexican endemic Picea chihuahuana Martínez is a largely untouched tree species and it is therefore an excellent model for estimating genetic potential of plant-plant interactions under natural conditions.

Because of the scarce research examining plant-plant interactions at the genetic level, we tested the hypothesis that specific genetic variants of P. chihuahuana are associated with (and likely selected by) the presence of particular neighbouring tree species. To explore this question, we applied AFLP genotyping to five P. chihuahuana populations in the State of Durango, North-western Mexico.

Under the assumption that the variables genetic variant of P. chihuahuana and nearest-neighbour tree species are directly related to each other, the results show a statistically significant association between such genetic variants - at one AFLP locus in one Picea population - and two nearest-neighbour conifer species (P. chihuahuana Martínez and Pinus arizonica Engelm.). The findings indicate that interactions between genetic variants and species diversity may be crucial in shaping plant communities. However, further studies are required for a better understanding of the possible roles that such associations between genetic variants might play.