The utility of subspecies classification in evolutionary studies and conservation
As a rank between population and species, the subspecies is useful for predicting the evolutionary divergence levels among geographical populations (Barrowclough, 1982). Populations defined as subspecies are expected to be more highly differentiated than within groups and should have separate demographic history. The classification of subspecies should not be the end but a byproduct of investigations of genetic variation within a species if patterns that warrant designation of subspecies are found (Barrowclough, 1982).
The other important utility of subspecies is to inform conservation decisions. Mayr proposed that subspecies are of conservation importance for their potential to evolve into full species and their acquisition of unique characteristics (O’Brien & Mayr, 1991). The emphasis on species diversity in conservation policy had driven taxonomists to revise subspecies upward to species (Mallet, 2007). More recently, managers have become increasingly aware of the necessity to protect biodiversity at all levels of life. Hence the recognition of subspecies based on well-founded evidences will be important for conserving genetic diversity below the species rank. As a mostly widespread mangrove tree,A. marina is important for the ecological health of coastal ecosystems, especially under the prospect of global climate change. Management efforts to protect each of the three subspecies should refer to their distinct genetic backgrounds.