Differential adaptation and species diversification between two Melastoma species and their F1 hybrid

In speciation, the formation of new lineages can be driven by two basic evolutionary processes—lineage divergence and lineage fusion. Lineage divergence can happen through differential adaptation or genetic drift, with the former expected to proceed more rapidly when the effective population size is large.Lineage fusion through hybridization, on the other hand, can provide raw material for adaptation to various habitats by creating new allelic combinations and phenotypes. When the two drivers of speciation take effect on a single group of taxa, rapid species radiation can occur. Variation in gene expression has been shown to promote adaptive divergence, and can lead to speciation. The plant genus Melastoma, thought to have diversified through adaptive radiation, provides an excellent model for the study of gene expressional changes during adaptive differentiation and following interspecific hybridization.

Leaf shape (left) and hair-like structures on the leaf surface (right, shown by arrows) observed under 10× magnification for M. candidum, M. sanguineum, and their F1 hybrid. Differences in the length and density of these hair-like structures partly contribute to the difference in visible coloration of the leaves. Image credit: Ng et al.
Leaf shape (left) and hair-like structures on the leaf surface (right, shown by arrows) observed under 10× magnification for M. candidum, M. sanguineum, and their F1 hybrid. Differences in the length and density of these hair-like structures partly contribute to the difference in visible coloration of the leaves. Image credit: Ng et al.

In a recent study published in AoBP, Ng et al. performed comparative transcriptomics on Melastoma candidum, M. sanguineum, and their F1 hybrid to investigate the role of gene expression in plant species diversification and hybridization. Differentially expressed genes were mostly found between the two parental species and were related to adaptive traits that limit the species to their respective habitats. In the F1 hybrid, although the expression levels of most genes were similar to either parent, a small number of genes had expression levels exceeding both parents, possibly explaining its vigour in certain morphological and adaptive traits. The findings of this study provide insight into the roles of gene expression in the diversification of Melastoma, and is an important example for more cross-taxa comparisons in the future.

Researcher highlight

Wei Lun Ng was born and raised in Malaysia. He conducted his PhD research at the Lab of Evolutionary Genetics in Kyushu University, Japan. After graduating in 2014, he started his postdoctoral research journey at Universiti Putra Malaysia before moving to Sun Yat-sen University, China, where he studied the evolutionary impact of plant hybridization under the guidance of Associate Professor Renchao Zhou. Wei Lun is currently an assistant professor at Xiamen University Malaysia.

As a molecular ecologist, Wei Lun is interested in applying the knowledge of genetics and genomics to questions about the ecology and evolution of various organisms. He has mainly worked with tropical plants and animals, but is starting to venture into work with microorganisms.

Further reading

Ng, W. L., Wu, W., Zou, P., & Zhou, R. (2019). Comparative transcriptomics sheds light on differential adaptation and species diversification between two Melastoma species and their F1 hybrid. AoB PLANTS, 11(2). https://doi.org/10.1093/aobpla/plz019