Contrasting genetic signal of recolonization after rainforest fragmentation in African trees with different dispersal abilities
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Contrasting genetic signal of recolonization after rainforest fragmentation in African trees with different dispersal abilities. / Piñeiro, Rosalía; Hardy, Olivier J.; Tovar, Carolina; Gopalakrishnan, Shyam; Vieira, Filipe Garrett; Gilbert, M. Thomas P.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 118, No. 27, e2013979118, 2021.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Contrasting genetic signal of recolonization after rainforest fragmentation in African trees with different dispersal abilities
AU - Piñeiro, Rosalía
AU - Hardy, Olivier J.
AU - Tovar, Carolina
AU - Gopalakrishnan, Shyam
AU - Vieira, Filipe Garrett
AU - Gilbert, M. Thomas P.
N1 - Publisher Copyright: © 2021 National Academy of Sciences. All rights reserved.
PY - 2021
Y1 - 2021
N2 - Although today the forest cover is continuous in Central Africa, this may have not always been the case, as the scarce fossil record in this region suggests that arid conditions might have significantly reduced tree density during the ice ages. Our aim was to investigate whether the dry ice age periods left a genetic signature on tree species that can be used to infer the date of the past fragmentation of the rainforest. We sequenced reduced representation libraries of 182 samples representing five widespread legume trees and seven outgroups. Phylogenetic analyses identified an early divergent lineage for all species in West Africa (Upper Guinea) and two clades in Central Africa: Lower Guinea-North and Lower Guinea-South. As the structure separating the Northern and Southern clades-congruent across species-cannot be explained by geographic barriers, we tested other hypotheses with demographic model testing using δαδι. The best estimates indicate that the two clades split between the Upper Pliocene and the Pleistocene, a date compatible with forest fragmentation driven by ice age climatic oscillations. Furthermore, 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. Different recolonization abilities after recurrent cycles of forest fragmentation seem to explain why species with long-distance dispersal show more recent genetic admixture between the two clades than species with limited seed dispersal. Despite their old history, our results depict the African rainforests as a dynamic biome where tree species have expanded relatively recently after the last glaciation.
AB - Although today the forest cover is continuous in Central Africa, this may have not always been the case, as the scarce fossil record in this region suggests that arid conditions might have significantly reduced tree density during the ice ages. Our aim was to investigate whether the dry ice age periods left a genetic signature on tree species that can be used to infer the date of the past fragmentation of the rainforest. We sequenced reduced representation libraries of 182 samples representing five widespread legume trees and seven outgroups. Phylogenetic analyses identified an early divergent lineage for all species in West Africa (Upper Guinea) and two clades in Central Africa: Lower Guinea-North and Lower Guinea-South. As the structure separating the Northern and Southern clades-congruent across species-cannot be explained by geographic barriers, we tested other hypotheses with demographic model testing using δαδι. The best estimates indicate that the two clades split between the Upper Pliocene and the Pleistocene, a date compatible with forest fragmentation driven by ice age climatic oscillations. Furthermore, 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. Different recolonization abilities after recurrent cycles of forest fragmentation seem to explain why species with long-distance dispersal show more recent genetic admixture between the two clades than species with limited seed dispersal. Despite their old history, our results depict the African rainforests as a dynamic biome where tree species have expanded relatively recently after the last glaciation.
KW - Genotyping by sequencing
KW - Glacial refugia
KW - Phylogeography
KW - Spatial gradients of genetic diversity
KW - Tropical Africa
U2 - 10.1073/pnas.2013979118
DO - 10.1073/pnas.2013979118
M3 - Journal article
C2 - 34210795
AN - SCOPUS:85109184455
VL - 118
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 27
M1 - e2013979118
ER -
ID: 276954067