Contemporary spatial association of genetic diversity determinants in Asian Dipterocarps: a systematic review

Considering the research gaps and areas to be prioritized specifically in the forestry research sector with stress given on conservation genetics and tree improvement, we make an effort to understand the spatial patterns and identify the key determinants, which produce major effects on genetic diversity of Asian Dipterocarps. This review focuses on identifying patterns and establishing relationships between genecological parameters derived on the basis of molecular markers with factors, such as geographical range, vertical profile and IUCN categories along with recognizing research gaps pertaining to operational forestry and terrestrial ecosystems. Corresponding to 47 research papers, meta-analysis of 50 species under subfamily Dipterocarpoideae revealed significant differences in genetic parameters, namely expected heterozygosity (HE) and number of alleles per locus (NA), for most genera and factors. These parameters showed significant correlations with vertical strata (rk=-0.241; p<0.05) and altitude (rs=0.283; p<0.01). However, on the basis of co-dominant and dominant markers, the parameters exhibited contrasting results for the species’ characteristics. Further, pollen exchange and seed dispersal predominantly explained the genetic variations among the contributing factors, generally believed to be correlated with vertical strata and geographical range of the species. Conclusively, two major clusters were formed through principal component analysis (PCA), where HE and NA were the main deciding factors. Anthropogenic interferences, viz. forest fragmentation and deforestation found to be subsidising major impacts, which increase inbreeding and genetic drift, causing the loss of rare alleles and consequently, decreasing genetic variation. The study emphasizes the importance of genecological conservation and access to diverse genetic resources information, which will ensure global forest conservation and climate change mitigation network for sustainable development