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al. 2003; Ammitzboll and Jorgensen 2006). Ammitzboll and Jorgensen (2006) suggested that
the presence of cultivated radish genes introgressed in wild radish populations might result in
higher ability to h ybridize with B. napus . G ene f low be tween w ild a nd c ultivated r adish i s
known to occur rather easily (Klinger et al. 1992; Eber et al. 1994; Snow et al. 2001), and the
hybridization r ate b etween o ilseed r ape an d cultivated r adish s eems to b e ag ain eas ier
(Ammitzboll and Jorgensen 2006). If NM were really ancient crop-introgressed populations,
our results cannot support the hypothesis of such an improved interspecific outcrossing ability.
Another feature in this experiment is that plants from BT and NM showed lower seeds
output than that from BG and DM. Again, it might relate to the introgression from crops if the
putative i ntrogression w as pr oved. T he s uccessful s ex m ate m ight be l ower i n i ntrogressed
plants under low pollen density because of the greater heterozygosity in introgressed lineages
(Snow e t a l. 2010 ). For e xample, C ampbell a nd S now ( 2007) found t hat h ybrid pr ogeny
produced lower fitness than wild radish under no competition conditions. It is noteworthy that
the populations producing the most seed number were DM that was the farthest one from the
location where the experiment was carried out, in Burgundy, from which the BG populations
belonged. T his s uggests t hat D M h ad t he m ost f lowers or t he hi ghest out crossing r ate
compared t o pl ants f rom t he ot her t hree r egions. It ha s also hi gher r eproduction a llocation
than B G a lthough t hey have s imilar s ilique m orphology. T he a daptation t o nor thern and
colder region could have caused DM to be the best competitor in our experiment, indicating
that popul ation di vergence c an o ccur among s eparated r egions a nd c oncern growth a nd
reproduction capacities.
When grown in cages in condition of intra specific competition, but at a low density of
3.3 pl m -2 , plants of DM had again higher performances than the local BG plants, but BT and
NM had the highest values for most traits (Fig. 4.8). Due to lower plant density than in the
oilseed r ape, s eed s et w as on a verage 4000 s eeds pa r plant T he c onstant a nd a bundant
presence of a non-specific pollinator, the domestic fly, which certainly saturated the flowers
with pol len be longing t o a ll t he pr esent pl ants, c ould e xplain t he a bsence of di fference o f
reproductive a llocation among r egions while t here was m arked di fferences i n t he field
experiment. The difference of ranking between t he cage and the field ex periments could be
due to differential adaptation to the habitat, or again to possible introgressed crop genes that
make t he BT a nd N M p opulations m ore pr oductive under low c ompetition, but less unde r
high c ompetition. For e xample, i n M ichigan, C ampbell a nd S now (2007) f ound t hat
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