Breeding system, gene dispersal and small-scale spatial genetic structure of a threatened food tree species, Pentadesma butyracea (Clusiaceae) in Benin

• Published in: Conservation genetics Vol. 18; no. 4; pp. 799 - 811
• Main Authors: Ewédjè, E. B. K., Ahanchédé, A., Hardy, O. J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2017; Springer Nature B.V
• Subjects: Adults; Age composition; Animal Genetics and Genomics; Biodiversity; Biomedical and Life Sciences; Breeding; Conservation; Conservation Biology/Ecology; Correlation; Decay; Dispersal; Dispersion; Ecology; Evolutionary Biology; Food; Fragmentation; Gene flow; Genetic markers; Genetic structure; Genetics; Inbreeding; Inbreeding depression; Life Sciences; Markers; Mating; Microsatellites; Migration; Outbreeding; Paternity; Plant Genetics and Genomics; Plant species; Pollen; Population genetics; Populations; Rain; Rainforests; Research Article; Rural areas; Rural communities; Threatened species; Mating system; Correlated paternity; Kinship coefficient; Pollen dispersal
• ISSN: 1566-0621; 1572-9737
• DOI: 10.1007/s10592-017-0928-8

Pentadesma butyracea
Sabine, a rain forest food tree species, plays a vital role in the socio-economic livelihood of some West African rural communities due to its various products. However, its scattered populations are threatened in Benin. Defining appropriate conservation strategies requires a good knowledge of mating patterns and their consequences for population genetics. The outcrossing rate, levels of correlated paternity and fine-scale spatial genetic structure of adults and maternal sibships were estimated for one small population and three large populations in Benin using microsatellite markers. Similar outcrossing rates (88–95%) were found in all populations, showing that
P. butyracea
is mainly an outbreeding species. We found no evidence of inbreeding depression from a decay of inbreeding with age. The spatial genetic structure within the large populations (
Sp
statistic = 0.003–0.038) was consistent with isolation-by-distance expectations, showing that gene dispersal is spatially limited. Limited pollen dispersal is highlighted by the decay of the degree of correlated paternity between sibships with spatial distance. The mean pollen dispersal distance was estimated between 50 m and 450 m, but up to 21% pollen may migrate from external sources. The smallest population displayed slightly higher correlated paternity than the large populations (
r
p
 = 0.37 vs.
r
p
 = 0.17–0.30). In conclusion, our results suggest that small populations may show a reduction in sire numbers in seed, while the fragmented populations, large and small, are connected through gene flow. There is little inbreeding and no evidence of inbreeding depression.