Contrasting genetic signal of recolonization after rainforest fragmentation in African trees with different dispersal abilities

We found remarkably older split dates for the shade-tolerant tree species with nonassisted seed dispersal than for light-demanding species with long-distance wind-dispersed seeds

Rosalía Piñeiro; Olivier J. Hardy; Carolina Tovar; Shyam Gopalakrishnan; Filipe Garrett Vieira; M. Thomas P. Gilbert

2021

Scholarcy highlights

  • | | | phylogeography Tropical Africa genotyping by sequencing | spatial gradients of genetic diversity glacial refugia
  • Recent studies based on chloroplast DNA, nuclear microsatellites, and low-copy nuclear genes suggest that the historical isolation of the tree populations in Tropical Africa was caused by forest fragmentation during the cold and dry ice age periods, which occurred on several cycles, through the Pleistocene
  • Our protocol compensated the limitation of uneven coverage across loci typical of genotyping by sequencing studies by building and sequencing two libraries per individual
  • For the GBS genotype calls without outgroups done with TASSEL, between 10,665 and 27,838 single-nucleotide polymorphisms were present in at least
  • This finding suggests the survival of D. benthamianus in coastal refugia in Cameroon and Gabon, the exact location cannot be determined since no differences were revealed among the different hypotheses of Last Glacial Maxima forest refugia considered based on the paleoclimatic reconstructions or estimated from the potential climatic distribution of each species during the LGM
  • While estimating Site Frequency Spectrum, admixed individuals with less than 70% genetic ancestry to a single group were excluded
  • We conclude that different responses of tree species to recurrent forest fragmentation cycles driven by past climate fluctuations may explain why we observe congruent genetic spatial structures with contrasted timescales
  • Species with higher colonizing abilities seem to have been able to erase old signals of genetic differentiation compared with species with limited seed and pollen dispersal and light tolerance

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