Long distance pollen dispersal and intrapopulation genetic structure determined by clonal diversity in Hymenaea stigonocarpa populations of the Brazilian savanna

• Published in: Trees (Berlin, West) Vol. 36; no. 1; pp. 471 - 484
• Main Authors: Moreno, Maria A., Boshier, David, Tarazi, Roberto, Tambarussi, Evandro V., Aguiar, Bruna I., Ferraz, Elza M., Kageyama, Paulo Y., Sebbenn, Alexandre M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2022; Springer Nature B.V
• Subjects: Agriculture; Biodiversity; Biodiversity hot spots; Biomedical and Life Sciences; Conservation areas; Dispersal; Dispersion; Forestry; Genetic diversity; Genetic structure; Genetics; Hymenaea; Immigration; Inbreeding; Life Sciences; Mating; Original Article; Plant Anatomy/Development; Plant Pathology; Plant Physiology; Plant Sciences; Pollen; Population; Population genetics; Population number; Populations; Progeny; Savannahs; Seeds; Trees; Tropical tree species; Forest fragmentation; Inbreeding; Microsatellite loci; Conservation genetics
• ISSN: 0931-1890; 1432-2285
• DOI: 10.1007/s00468-021-02222-8

Key message Although all populations show extensive pollen immigration, the occurrence of spatial genetic structure and biparental inbreeding decreased genetic diversity and effective population size. The Brazilian savanna is the second largest Neotropical biome, and a globally important biodiversity hotspot. Basic knowledge of the ecology and genetics of its species can help conserve this important biome. We investigated genetic diversity, spatial genetic structure (SGS), pollen dispersal, and mating system in three Hymenaea stigonocarpa populations (AS, PE, IT) in the Brazilian savanna, using microsatellite loci and samples of adult trees from all populations and seeds from the IT population. As a result of the long geographic distance between populations, the genetic differentiation among them was high (0.397). Individuals of the IT population presented a grouped distribution due to root propagation, resulting in low genotypic richness ( GR  = 0.194) and allelic richness ( R  = 4), and high SGS ( Sp  = 0.064) compared to AS and PE ( GR  > 0.98, R  > 5, Sp  < 0.026) populations. The IT population showed high pollen immigration (46.4%), pollen dispersal distance (up to 3.57 km), and outcrossing rate (0.934–1.0), but matings were correlated (0.01–1), and some occurred among relatives (up to 0.098), resulting in some inbred seeds (0.140), a lower variance effective population size ( N e  = 3.02) than expected with random mating, and an estimate of 50 seed-trees required to retain an N e of 150 in samples of maternal progeny. The estimated minimum viable area to retain a reference ( N er ) of 1000 indicates that the current AS and IT population areas are insufficient to maintain viable populations in the long-term, demonstrating the importance of maintaining surrounding areas for conservation of these H. stigonocarpa populations.