Conclusion and prospects
Known patterns of morphological variations coupled with new results of genetic diversity and structure obtained during the present study revealed a long history of geographic isolation and local adaptation inE. coccineum in South American temperate forests. Here, we observed a strong genetic structure in E. coccineum in part linked to local adaptation, especially to differential access to water during the driest months. These results support previous studies that have reported the existence of distinct ecotypes along the species natural distribution (Souto and Premoli, 2007). The identification and quantification of the environmental variables structuring population genetic variation could inform management decisions for conservation, restoration or reforestation purposes (Gugger et al., 2017). For example, knowledge about the association between genotype and environment is important for selecting proper seed when tree populations are locally adapted (Aitken and Whitlock, 2013) as is the case ofE. coccineum. However, as the environment changes, nonlocal seed sources may be considered for restoration or reforestation purpose based on their match to the novel environment. Therefore, seed transfer guidelines can benefit from knowledge on factors structuring the landscape of genetic variation. Many conservation efforts rely on delineating distinct populations for management but often ignore the continuous nature of landscape variation and its potential relationship with local adaptation or other processes that lead to genotype–environment associations (Frankham, 2010; Rodríguez-Quilón et al., 2016). Concerning land management decisions, the present results advocate for seed transfer guidelines that should be restricted within each ecological zone (Dudley et al., 2017). The strong genetic structure also offers an opportunity to further explore local adaptation among groups and exploit these for agroforestry.