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Wind-dispersed pollen mediates postglacial gene flow among refugia
Sascha Liepelt1, Ronald Bialozyt, Birgit Ziegenhagen
1Federal Research Centre for Forestry and Forest Products, Institute for Forest Genetics and Forest Tree Breeding, Sieker Landstrasse 2, 22927 Grosshansdorf, Germany.
Summary
Genetic studies on silver fir (Abies alba) reveal that while maternal lineages show isolation, widespread pollen flow effectively mixes genes between refugia. This suggests wind-pollinated plants can overcome glacial isolation through paternal introgression.
Area of Science:
- Evolutionary biology
- Plant genetics
- Conservation genetics
Background:
- Pleistocene glacial periods led to refugial isolation in many species.
- Maternal lineages often retain genetic imprints of this isolation.
- The role of pollen flow in erasing these genetic signatures is debated.
Purpose of the Study:
- To investigate if pollen-mediated gene flow erases genetic imprints of refugial isolation in silver fir (Abies alba).
- To assess the extent of genetic separation and gene flow in silver fir across its European range.
- To understand the impact of long generation times and heavy pollen on gene flow.
Main Methods:
- Analysis of 100 European silver fir populations.
- Use of two DNA markers (mitochondrial nad5 and chloroplast psbC) with contrasting inheritance.
- Examination of allele frequencies and clinal patterns.
Main Results:
- Maternal mitochondrial DNA (mtDNA) variation supported at least two isolated refugia.
- Chloroplast DNA (cpDNA) showed a much wider cline, indicating extensive paternal gene flow.
- Steeper mtDNA clines contrasted with broader cpDNA clines across the species' range.
Conclusions:
- Silver fir exhibits efficient pollen-mediated gene flow, effectively mixing genetic material between refugia.
- Paternal introgression can overcome long-term genetic isolation in wind-pollinated species.
- This challenges assumptions about the persistence of glacial refugial genetic signatures.