Pollen dispersal was characterized within a population of the narrowly endemic perennial herb, Centaurea corymbosa, using exclusion-based and likelihood-based paternity analyses carried out on microsatellite data. Data were used to fit a model of pollen dispersal and to estimate the rates of pollen flow and mutation/genotyping error, by developing a new method. Selfing was rare (1.6%). Pollen dispersed isotropically around each flowering plant following a leptokurtic distribution, with 50% of mating pairs separated by less than 11 m, but 22% by more than 40 m. Estimates of pollen flow lacked precision (0-25%), partially because mutations and/or genotyping errors (0.03-1%) could also explain the occurrence of offspring without a compatible candidate father. However, the pollen pool that fertilized these offspring was little differentiated from the adults of the population whereas strongly differentiated from the other populations, suggesting that pollen flow rate among populations was low. Our results suggest that pollen dispersal is too extended to allow differentiation by local adaptation within a population. However, among populations, gene flow might be low enough for such processes to occur.

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Aim The phylogeographical history of Neotropical species can be difficult to reconstruct because of superimposed Neogene and Quaternary histories, and because of taxonomic uncertainty. We analysed range‐wide genetic diversity in a widespread pioneer tree species, Jacaranda copaia (Aubl.) D. Don, to characterize phylogeographical structure, date the evolutionary relationships among lineages, and evaluate the role of dispersal and vicariance in establishing the present geographical range. Location Guiana Shield; central, southern and western Amazon Basin; Chocó region; Central America. Methods We analysed nine nuclear simple sequence repeat loci (nuSSR), eight chloroplast SSRs (cpSSR), and two cpDNA intergenic sequences in 341 adult trees. Genetic differentiation at nuSSRs was inferred using Bayesian clustering. Dating of chloroplast lineage divergence was obtained using a range of published mutation rates and Bayesian coalescence analyses. Population divergence dating was performed using an isolation‐with‐migration model for eight loci (one cp sequence and seven nuSSRs). Results Nuclear SSR variation identified three geographically overlapping clusters (nu‐1, nu‐2, nu‐3). Twelve cpDNA haplotypes were clustered into two haplogroups (cp‐1, cp‐2) with the central Amazon harbouring the highest diversity. Molecular dating analysis suggests that cpDNA haplotype diversification started around the end of the Pliocene (2.61 Ma on average), whereas population divergence was more recent and occurred during the mid‐Quaternary (point estimates between 357 and 436 ka). Main conclusions The genetic variation of J. copaia in the Neotropics was shaped mainly by Pleistocene events. Chloroplast diversity did not display the expected cis/trans Andean disjunction, indicating recent dispersal. Nuclear variation revealed that separate regions share a recent history, with a centre of diversity in the central Amazon Basin. The geographical pattern of diversity is congruent with the distribution of the two subspecies, J. copaia copaia and J. copaia spectabilis, and evidence of nuSSR admixture between the two taxa supports their classification as subspecies.

Thirty-six Hevea clones were inoculated with conidia of Microcyclus ulei, the causal agent of South American Leaf Blight in an air-conditioned chamber. Components of disease resistance such as latent period, infectious period, lesion size, percentage of damaged leaf area, number of lesions, spore production and stromatic generation period were studied during a single infection cycle. The clones were easily separated on the basis of these characters that were evaluated under controlled conditions. The main components that were highly correlated were the spore production, lesion size and number of lesions with the percentage of damaged leaf area. Others, such the stromatic generation period, were slightly correlated with all other components; latent period and infectious period was slightly correlated with the lesion size; and lesion size was slightly correlated with lesion density. For screening of varieties, damaged leaf area and spore production were the two components that should be considered the most important. Furthermore, the clones were tested for their capacity to produce scopoletin, a phytoalexin of Hevea, and to produce lignins in their infection sites. A strong correlation was observed between scopoletin accumulation and clone resistance. Moreover, strong lignin accumulation was often associated with a longer stromatic generation period. These two physiological reactions could interfere by limiting fungal development in several clones. However, neither scopoletin nor lignin accumulation could individually explain the behaviour of all clones.