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 Premise of the study: Population genetic structuring over limited timescales is commonly viewed as a consequence of spatial constraints. Indirect approaches have recently revealed reproductive isolation resulting from fl owering time (so-called isolation by time, IBT). Since phenological processes can be subject to selection, the persistence of flasynchrony may be due to opposing selective pressures during mating, dispersal, and regeneration phases. Our study aimed to investigate phenology, fruit handling by animals, and their interaction in a timber tree species, Milicia excelsa .  Methods: We analyzed phenological data collected over 6 years on 69 genotyped trees in a Cameroonian natural rainforest complemented by data from germination trials and fi eld observations of dispersers.  Key results: Initiation of flwas correlated with variation in temperature and relative humidity, but was also affected by genetic factors: pairwise differences in fltime between nearby individuals correlated with kinship coeffi cient, and earliness of flremained stable over time. A decrease in mean seed production per fruit with increasing fl owering time suggests selection against late bloomers. However, germination rate was not affected by seed collection date, and the main seed disperser, the bat Eidolon helvum , seemed to increase in abundance at the end of the reproductive season and preferred trees in open habitats where early and late bloomers are expected.  Conclusions: The pairwise approach performs well in detecting IBT. The persistence of different mating pools in such a case may result from a trade off between selective forces during the mating and seed dispersal processes.

This study evaluates the spatial genetic structure of baobab (Adansonia digitata) populations from West African agroforestry systems at different geographical scales using AFLP fingerprints. Eleven populations from four countries (Benin, Ghana, Burkina Faso, and Senegal) had comparable levels of genetic diversity, although the two populations in the extreme west (Senegal) had less diversity. Pairwise F(ST) ranged from 0.02 to 0.28 and increased with geographic distance, even at a regional scale. Gene pools detected by Bayesian clustering seem to be a byproduct of the isolation-by-distance pattern rather than representing actual discrete entities. The organization of genetic diversity appears to result essentially from spatially restricted gene flow, with some influences of human seed exchange. Despite the potential for relatively long-distance pollen and seed dispersal by bats within populations, statistically significant spatial genetic structuring within populations (SGS) was detected and gave a mean indirect estimate of neighborhood size of ca. 45. This study demonstrated that relatively high levels of genetic structuring are present in baobab at both large and within-population level, which was unexpected in regard to its dispersal by bats and the influence of human exchange of seeds. Implications of these results for the conservation of baobab populations are discussed.

PREMISE OF THE STUDY Microsatellite loci were developed in the endangered Pericopsis elata using a combination of low-cost procedures. METHODS AND RESULTS Microsatellite isolation was performed simultaneously on three distinct species through a newly available procedure that associates multiplex microsatellite enrichment and next-generation sequencing, allowing the rapid and low-cost development of microsatellite-enriched libraries through the use of a 1/32nd GS-FLX plate. Genotyping using M13-like labeling in multiplexed reactions allowed additional cost savings. From 72 primers selected for initial screening, 21 positively amplified P. elata, and 11 showed polymorphism with two to 11 alleles per locus and a mean value of 5.4 alleles per locus. CONCLUSIONS These microsatellite loci will be useful to further investigate the level of genetic variation within and between natural populations of P. elata in Africa.

The invasive alien knotweeds, Fallopia spp. (Polygonaceae), are some of the most troublesome invasive species in Europe and North America. Invasive success in Fallopia may be enhanced by multiple hybridization events. We examined the pattern of hybridization and its evolutionary consequences in Belgium with a concerted analysis of ploidy levels (chromosome counts and flow cytometry), morphological variation, and genetic variation (RAPDs). At least four taxa with different ploidy levels were part of the pattern of invasion in Belgium. Hybrid F. 3bohemica with various chromosome numbers restored the genotypic diversity that was lacking in the parental species. Hybrid genotypes were mainly assigned to a specific genetic pool and not to a mixture between the genetic pools of the putative parental species as would be expected for hybrids. Parental species and hexaploid hybrids differed significantly for a set of well-defined morphological characters, enabling future researchers to distinguish these taxa. On the basis of our results, the importance of hybridization has probably been underestimated in large parts of the adventive range of alien Fallopia species, pointing to the need for concerted molecular and morphological analyses in the study of the evolutionary consequences of hybridization.