Gene flow and its consequences for microevolution in Taraxacum (Asteraceae)

Abstract

[7] Summary Microevolution refers to evolutionary changes at or below the species level. These changes are the result of mutation, natural selection, gene flow and genetic drift. When microevolutionary processes in agamic complexes, like Taraxacum, are studied, gene flow deserves special attention. Taraxacum is very large and widespread genus with a very complicated taxonomy. It forms a polyploid series with basic chromosome number x=8, diploids (obligate sexuals) and triploids (apomicts) prevail. The presented work studies reproductive behaviour and pathways of the gene flow in Taraxacum sect. Ruderalia and compares it with Taraxacum sect. Erythrosperma. Diploid, triploid and tetraploid individuals were sampled from mixed diploid - polyploid natural populations of Taraxacum sect. Ruderalia, diploids and triploids from Taraxacum sect. Erythrosperma. Seeds resulting both from the crosses between particular ploidy levels, from isolated anthodia and from open pollinated anthodia (from cultivated and wild plants) were subjected to the flow-cytometric seed screening (FCSS) to determine ploidy levels in the progeny and to infer breeding behaviour of maternal plants. Three possible pathways of the gene flow were studied: (A) fertilization of sexuals by pollen of apomicts, (B) BIII (2n+n) hybrid formation, (C)...

[7] Summary Microevolution refers to evolutionary changes at or below the species level. These changes are the result of mutation, natural selection, gene flow and genetic drift. When microevolutionary processes in agamic complexes, like Taraxacum, are studied, gene flow deserves special attention. Taraxacum is very large and widespread genus with a very complicated taxonomy. It forms a polyploid series with basic chromosome number x=8, diploids (obligate sexuals) and triploids (apomicts) prevail. The presented work studies reproductive behaviour and pathways of the gene flow in Taraxacum sect. Ruderalia and compares it with Taraxacum sect. Erythrosperma. Diploid, triploid and tetraploid individuals were sampled from mixed diploid - polyploid natural populations of Taraxacum sect. Ruderalia, diploids and triploids from Taraxacum sect. Erythrosperma. Seeds resulting both from the crosses between particular ploidy levels, from isolated anthodia and from open pollinated anthodia (from cultivated and wild plants) were subjected to the flow-cytometric seed screening (FCSS) to determine ploidy levels in the progeny and to infer breeding behaviour of maternal plants. Three possible pathways of the gene flow were studied: (A) fertilization of sexuals by pollen of apomicts, (B) BIII (2n+n) hybrid formation, (C)...