Altitudinal gradients, biogeographic history and microhabitat adaptation affect fine-scale spatial genetic structure in African and Neotropical populations of an ancient tropical tree species

Zhengfeng Wang (1, 2, 3) , Paloma Torroba Balmori (4) , Katharina Birgit Budde (4) , Katrin Heer (5, 6) , Santiago C. Gonzalez Martinez (4, 1, 2, 3) , Sanna Olsson (1) , Caroline Scotti-Saintagne (7) , Maxime Casalis (8) , Bonaventure Sonké (9, 10, 11) , Christopher W. Dick (12, 13) , Myriam Heuertz (4, 1, 14)

1 Department of Forest Ecology and Genetics
2 Sustainable Forest Management Research Institute
3 INIA - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria = National Institute for Agricultural and Food Research and Technology
4 BioGeCo - Biodiversité, Gènes & Communautés
5 Institute of Experimental Ecology Germany, Conservation Biology and Ecology
6 Conservation Biology and Ecology
7 URFM - Ecologie des Forêts Méditerranéennes
8 UMR ECOFOG - Ecologie des forêts de Guyane
9 UY1 - Université de Yaoundé I
10 ENS-PSL - École normale supérieure - Paris
11 Faculté des Sciences
12 Faculty of Biology - Department of Ecology and Evolutionary Biology
13 Smithsonian Tropical Research Institute
14 ULB - Université libre de Bruxelles

The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations.

Mots clés: chiroptera

Mots clés: structuration génétique spatiale; structure génétique des populations; haplotype; morphotype; guyane française; gradient altitudinal; structure génétique; dispersion de graine; biogeographie; microhabitat; arbre tropical; chauve souris

Domaines: Milieux et Changements globaux

Zhengfeng Wang, Paloma Torroba Balmori, Katharina Birgit Budde, Katrin Heer, Santiago C. Gonzalez Martinez, et al.. Altitudinal gradients, biogeographic history and microhabitat adaptation affect fine-scale spatial genetic structure in African and Neotropical populations of an ancient tropical tree species. PLoS ONE, 2017, 12 (8), pp.1-23. ⟨10.1371/journal.pone.0182515⟩. ⟨hal-01608324⟩