Year: 2017
Type: article
Abstract: Mangroves are a polyphyletic group of ∼80 species of trees that live at the interface between land and sea in tropics and subtropics worldwide. The intertidal environments of mangroves pose a set of strong selections (e.g., hypoxia and high salinity) that mangroves must have survived. Using comparative genomics, Xu and colleagues begin to uncover the potential molecular mechanisms underlying mangroves’ extraordinary adaptations [1]. They report a whole-genome duplication some 70 million years ago in the descent of a major mangrove lineage represented by Rhizophora apiculata. They identify a number of mangrove genes that were likely subjects of positive selection, and make tantalizing links between these genes and mangrove-specific traits such as vivipary and red bark. Of significant interest is the observation of distinct amino acid compositions in mangroves when compared with outgroups. Xu et al. hint that similar patterns are apparent in several independently evolved mangrove lineages, suggesting proteome-wide parallel evolution driven by Darwinian selection. But the enriched amino acids in mangroves do not seem to share any apparent physicochemical property such as hydrophilicity, making the selective agent of the composition change elusive at this time. Demographic inference from genome sequences suggests a prolonged and drastic decline in population size starting ∼1 million years ago for several mangroves of the Rhizophora genus, casting doubt on their long-term survival into the future, especially in the uncertain climate ahead of us. Xu et al.’s work is a tour de force that opens what promises to be a series of studies attempting to unlock the evolutionary histories and mechanisms of the astonishing parallel adaptations of multiple lineages of mangroves. The histories and mechanisms learned will hopefully help in the conservation of these natural wonders.
Source: National Science Review
DOI: 10.1093/nsr/nwx065d
Author: Jianzhi Zhang
Institution: University of Michigan
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $2,000
OpenAlex ID: W2768835353