'STAMENOID PETALS' IN A NATURAL HOMEOTIC VARIANT OF

Introduction
of tens of thousands individuals, offers the unique opportunity to elucidate the significance
of homeotic mutants with respect to population structure and ecological differentiation.
This aspect was focus of chapter 2. Here, genetic differentiation and flowering time
variation of the decandric variant and wild-type plants were analyzed in a sympatric
population in Gau-Odernheim. Again, AFLPs and allozymes of aspartate aminotransferase
(AAT) have been used as molecular markers. Genetic variation was estimated by analysis
of molecular variance (AMOVA) and principle co-ordinate analysis has been performed to
elucidate the population structure. Assignment of individuals into clusters has been carried
out using Structure and AFLPOP. A greenhouse experiment was conducted to investigate a
possible differentiation in the onset of flowering among both variants.
In the first two chapters, special focus was pointed at the following aspects:
- Is the occurrence of the stamenoid phenotype in geographically distinct
populations of C. bursa-pastoris the result of convergence?
- Does the population structure of a broad sympatric population of decandric and
wild-type individuals reflect any genetic differentiation among variants?
- Are there mechanisms which might cause reproductive isolation among both
variants?
In chapter 3, further mechanisms were evaluated which might enable the decandric variant
to establish and maintain within a wild-type population of C. bursa-pastoris. Performing a
progeny approach, life-history traits such as fitness components and flowering time of both
floral variants were assessed in two common garden field experiments. In addition to it, the
potential pollinator assemblage of shepherd's purse was surveyed by collecting flower
visitors during field work in the natural habitat Gau-Odernheim. This chapter may answer
the following questions:
- Are there differences in fitness components detectable among floral variants in
a common garden field experiment?
- Does the field experiment provide insights into different levels of gene flow
within or among floral variants?
- How is outcrossing managed in this highly selfing species?
In the chapter 4, the inheritance of the decandric phenotype was analyzed in a F2 mapping
population. Marker-assisted mapping was performed to localize the assumed single locus.
9