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7. ROLE OF QTLs IN THE EARLY EVOLUTION...
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identify changes that are occurring during the process of diversification and that might lead to
separation into different species in the future. Moreover, growing in semi-natural habitats and
being important fodder and turf crops and thus being under strong selection during breeding,
L. multiflorum and L. perenne can be a good model allowing understanding how species
respond evolutionarily to growing pressure from humans. It has to be pointed out, however,
that any generality of speciation scenarios is difficult. This is in part because many of the
genetic events associated with speciation often occur at the population level as well without
producing new species (Avise 2004).
7.2. MATERIAL AND METHODS
7.2.1. Comparison of quantitative characters in intra- and interspecific crosses
To estimate the role of quantitative characters in the early evolution of L. multiflorum
and L. perenne, these traits were analysed in four F 2
populations involved both inter- and
intraspecific crosses. Two F 2
populations, namely BR3 x NZ15 and HU5 x BO2 represented
interspecific level, whereas populations VA7 x AS17 and KY20 x BB6 intraspecific level,
L. multiflorum and L. perenne, respectively. The detailed description of these populations,
plant development and field experiments are given in Annex 13.1. Shortly, a randomized
complete block design with 3 blocks was used to analyze all populations. Each block consisted
of three replications and each replication consisted of three ramets as replicates of
each genotype. Hence, in each block a single genotype was represented by nine ramets.
Quantitative characters were analysed during two seasons and during two crops in each
season. Where possible each plant was scored for 21 morphological characters. The following
traits were measured, basal leaf length, basal leaf width, green weight and dry weight of
vegetative leaves, height at ear emergence, spike length, spikelet length, spikelet number,
floret number, flag leaf length and flag leaf width as well as green and dry weight of generative
tillers. Basal and flag leaf areas were recalculated from length and width. In addition
such characters as a growth type, leaf colour, resistance to crown rust (Puccinia coronata
f. sp. lolii) and presence of awns were estimated during each crop by visual investigations.
For growth types, the number 1 indicated prostrate growth type while 5 erect, for leaf colour
the number 1 was assigned to very light green and 5 to very dark green, for rust the number
1 means resistant without any signs of a disease and 9 completely susceptible with necrotic
areas on the whole leaves. The presence of awns was described as 1, the absence as 0, and
0.5 was assigned to all intermediate types. Similarly, plant survival in the field was estimated
in the second year of cultivation by a visual assessment score (as percentage) of plant recovery.
Days to ear emergence were counted from the beginning of spring rush.
Data were analysed using STATISTICA 7.1 software. Skewness was calculated for
each trait to determine the extent to which it deviated from normality. For each cross combinations
mean values of all analysed traits were estimated for parents, F 1
hybrids and F 2
individuals. Moreover, mean, minimum and maximum values were calculated for each F 2
population. Means of F 2
individuals, parents and F 2
were calculated taking into account two