During Monday’s poster session at Evolution 2019, I had the chance to talk with Dr. Lindsay Miles (currently a postdoc at the University of Toronto-Mississauga and an editor of this blog) about research she conducted during her PhD at Virginia Commonwealth University. Lindsay and her fellow researchers report on how anthropogenic land use is influencing gene flow in the endemic shrub, Leucadendron salignum. The setting of this research is the Cape Floristic Region (CFR) of South Africa, an UNESCO heritage site and a plant biodiversity hotspot situated towards the southern coastal tip of South Africa, is home to around 9000 plant species, 70% of which are endemic. The CFR boasts a rather heterogeneous landscape throughout its range, with elevation changes and microhabitat differences in soil quality, precipitation, as well as differences in anthropogenic land use. Leucadendron salignum is unique in that it has a wide biogeographic reach spanning the entire range of the environmentally heterogeneous CFR.
Population genetics analyses of L. salignum collected across the range of the CFR were conducted. Sequencing of chloroplast DNA (cpDNA), which is maternally inherited and thus a seed-associated molecular marker, revealed high structure regionally as well as strong connectivity across regions, with haplotypes clustering together in the North, South, East, West, and Central areas of the CFR. Conversely, analysis of nuclear DNA (nuDNA) and thereby pollen-associated molecular marker showed evidence of panmixia with little population structure observed in the sampled regions. The high population structure seen in the seed-associated cpDNA as opposed to the pollen-associated nuDNA indicates that historical events such as agricultural land use may have played a role in driving gene flow in this shrub. Based on the structure seen in the cpDNA, an analysis was performed with the cpDNA and environmental factors of elevation, rainfall amount and concentration, vegetation and soil type, and land-use type. The most striking finding from these analyses is that large-scale agricultural growth is the biggest driver of gene flow. These results highlight the importance of considering the various factors influencing genetic diversity of each region separately throughout this environmentally patchy area in order to maximize and target conservation efforts.
To learn more about Dr. Miles and her research, visit her webpage or Twitter page!
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