Figure 6. Patterns of genotype-environment association in Arabian mangroves.  (A) Redundancy analysis (RDA) between population frequencies of 446 SNP candidate loci, and four explanatory variables corresponding to environmental factors (maximum air temperature of the warmest month, minimum air temperature of the coldest month, monthly maximum of sea surface salinity and annual precipitation). Points represent the projection of individual genotype frequencies on the first two RDA axes. The explanatory variables are shown within the space defined by RDA1 and RDA2 by labeled vectors. Vector arrows indicate the direction of the gradient of variation for the corresponding environmental parameter. The loading score of each sample point on each explanatory variable can be obtained by an orthogonal projection on the corresponding plotted vector. For facilitating visual interpretation, marker colors correspond to different subregions within the Red Sea, the Arabian Sea and the Persian/Arabian Gulf. In the case of the Sea of Oman, the corresponding populations were denoted individually as the follow distinct association patterns. The abbreviations 'Monthly max SSS' and 'Monthly min SST' represent the monthly maximum sea surface salinity and monthly minimum sea surface temperature, respectively. (B) Heatmap of the pairwise Euclidean distances averaged over population within the RDA1 and RDA2 ordinal space shown in the (A) plot.