Genetic diversity and distribution of Senegalia senegal (L.) Britton under climate change scenarios in West Africa

Abstract

Climate change is predicted to impact species’ genetic diversity and distribution. We used Senegalia senegal (L.) Britton, an economically important species distributed in the Sudano-Sahelian savannah belt of West Africa, to investigate the impact of climate change on intraspecific genetic diversity and distribution. We used ten nuclear and two plastid microsatellite markers to assess genetic variation, population structure and differentiation across thirteen sites in West Africa. We projected suitable range, and potential impact of climate change on genetic diversity using a maximum entropy approach, under four different climate change scenarios. We found higher genetic and haplotype diversity at both nuclear and plastid markers than previously reported. Genetic differentiation was strong for chloroplast and moderate for the nuclear genome. Both genomes indicated three spatially structured genetic groups. The distribution of Senegalia senegal is strongly correlated with extractable nitrogen, coarse fragments, soil organic carbon stock, precipitation of warmest and coldest quarter and mean temperature of driest quarter. We predicted 40.96 to 6.34 per cent of the current distribution to favourably support the species’ ecological requirements under future climate scenarios. Our results suggest that climate change is going to affect the population genetic structure of Senegalia senegal, and that patterns of genetic diversity are going to influence the species’ adaptive response to climate change. Our study contributes to the growing evidence predicting the loss of economically relevant plants in West Africa in the next decades due to climate change.

Population genomics of the widespread African savannah treesAfzelia africanaandAfzelia quanzensisreveals no significant past fragmentation of their distribution ranges

“…The absence of clear‐cut genetic discontinuities over large distances for A. africana and A. quanzensis is consistent with results reported in the savannah tree species Adansonia digitata and Khaya senegalensis , which showed no geographic discontinuities of the genetic variation (Tsy et al., ; Sexton et al., ). Acacia senegal displays strong differentiation between Sudanian and Zambezian populations, but low diversity and structure at a nuclear ribosomal marker across the Sudanian savannahs suggest a recent range expansion (Odee et al., , but see Lyam et al., ). These results suggest that the African savannahs have not experienced major upheavals that led to their fragmentation (Salzmann et al., ; Vincens et al., ; Watrin et al., ), in contrast to the major fluctuations of the rainforest cover over time (Maley, ).…”

“…Three of the species occur in the Sudanian savannah (northern hemisphere): the shea tree (Vitellaria paradoxa; Allal et al, 2011;Logossa et al, 2011), the African mahogany (Khaya senegalensis; Sexton et al, 2015), and the locust bean (Parkia biglobosa; Lompo et al, 2018). The other two species have a Sudano-Zambezian distribution (northern and southern hemispheres): the baobab (Adansonia digitata; Tsy et al, 2009;Kyndt et al, 2009) and Arabic gum (Acacia senegal; Odee et al, 2012;Lyam et al, 2018). Within the Sudanian savannah, weak genetic structure was detected in K. senegalensis and A. digitata, while moderate differentiation was found in A. senegal, mostly in chloroplast markers.…”

Climate change will disproportionally affect the most genetically diverse lineages of a widespread African tree species

“…Historical distribution and range dynamics of S. senegal indicate variation along climatic and edaphic regimes, separating the eastern and southern ranges from the western and central African ranges 27 . In addition, population genetic studies of Kenyan and West African populations of S. senegal have shown that anthropogenic perturbations and climatic shifts could impact levels of genetic diversity (GD), population sizes, structure of gene pools, and natural regeneration patterns of the species at regional scale 6 , 39 . Investigating the impact of climate change on GD of S. senegal will provide insights into population structure, and can further advance our understanding of the genetic consequences of post-glacial expansion processes and climate warming on the future distribution of genetic variation.…”

Senegalia senegal (L.) Britton Response to Microbial and Manure Amendments for the Rehabilitation of Waste Rock Dumps in the Essakane Gold Mining Site, Burkina Faso

“…Senegalia Senegal can attain a height of 5-12 m, and grows on sandy, skeletal and slightly loamy soils, with a soil pH of 5-8. The gum acacia also grows in areas that receive 100-950 mm annual rainfall (Lyam et al, 2018). It can tolerate five to 11 months of drought and can survive temperatures high as 43 °C, dry wind, and sandstorms.…”