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Résumé :
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The closely related, endangered Braya longii and threatened Braya fernaldii (Brassicaceae) are endemic to the Limestone Barrens on the Northern Peninsula of Newfoundland, Canada. These species were not known to co-occur naturally, but anthropogenic disturbance has mediated contact. Future preservation strategies must consider population variability, breeding system and possible hybridization in the context of human use. Breeding system and hybridization were assessed using floral measurements and hand-pollination experiments under field conditions. Morphological analysis revealed the presence of two well-defined groups as well as population-level variation in floral characters. PCA confirmed intraspecific variation in both species, mediated by origin of disturbance. Natural populations of B. longii are differentiated due to very limited seed dispersal, whereas non-differentiated anthropogenically disturbed populations reflect the homogenising effect of aggregate movement among sites. Although both species are primarily autogamous, floral characters indicate B. longii has great potential for outcrossing compared with B. fernaldii. Outcrossed hand-pollinations resulted in significantly lower fruit set for B. fernaldii (
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