Does a reciprocal transplant experiment of neighboring Vachellia karroo populations demonstrate local adaptation?

Vachellia karroo (Hayne) Banfi & Galasso (formerly Acacia karroo) is the most widespread tree in southern Africa, and exhibits wide morphological variation such that phenotypes have been considered as separate species. We sought to determine whether local adaptation was occurring two neighboring populations (ca. 15 km apart) South Africa show tremendous size adults. examined seedling sapling performance of genotypes grown reciprocal environments differ climatic edaphic conditions. used a field transplant experiment at Richards Bay Empangeni, complemented this with common garden study. measured total height, stem diameter, thorn length, leaf area, weight, plant aboveground dry weight specific area after 4 months 16 for field-grown plants, respectively. For greenhouse-grown root also measured. Phenotypes seedlings saplings from maintained their differences greenhouse field. Greenhouse-grown plants showed lower proportional allocation than Empangeni (i.e. mass fraction: 0.20 ± 0.01 vs 0.60 0.02). In field, there were significant genotype-by-environment interactions seven traits reciprocally-transplanted populations. found limited evidence attributed Local evident (leaf weight) interaction. These clearly important fitness consequences photosynthesis. However, one population grew taller had longer thorns both sites. conclude magnitude divergent selection relatively low may be accompanied by processes genetic drift, leading differentiation.