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and flower compared to other populations. It is necessary to find appropriate molecular
markers of oilseed rape species for confirming the introgression in populations and genes
that imply the modification of selected traits, for example flower color for attracting
pollinators and silique form for dispersal and survival (Chapter 4.2).
2. Competition interaction and individual fitness
As it is inevitable that populations composed transgenic and non-transgenic individuals after
the occurrence of introgressions (Ramachandran et al. 2000; Vacher et al. 2004; Moon et al.
2007), their relative competition capacity will affect the individual growth and reproduction
and further affect population dynamics.
Insect-resistant plants had competitive advantage when competing with insect-
susceptible plants under insects. This relative advantage was increased with the percentage
of healthy plants in susceptible populations. However, as the increasing of percentage of
resistant plants in populations, the intra-class competition among resistant plants affects
their inter-class competition between resistant and susceptible plants. In addition, this
competition advantage of resistant plants was magnified under harsh conditions, like
limiting resources, high plant density. The effects of competition and herbivory on plant
fitness were additive. Competition interaction among plants in populations was changed
because of the presence of introgressed resistant plants. (Chapter 3.3)
In case of the introgression succeed, the transgene will be treated as other genes in
wild relatives, and it could arrive at equilibrium situation or fixed or disappeared that
depends on the selection pressure. Hence, which traits and in which condition a transgene
confers fitness advantage should be detected. A transgene transferred from transgenic crops
to wild relatives might be neutral, but it is likely to increase or decrease the fitness of
receiving hybrid/ backcross plants (Stewart et al. 1997; Ramachandran et al. 2000; Mason et
al. 2003; Di et al., 2009; Letourneau and Hagen 2009). This depends on the transgenic
character, its selection and costs, the context of transgene introgressed in the genome, and
the population composition.
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