Complex fine-scale phylogeographical patterns in a putative refugial region forFagus sylvatica(Fagaceae)

Abstract

Broad-scale plastid (chloroplast) DNA studies of beech (Fagus sylvatica) populations suggest the existence of glacial refugia and introgression zones in south-eastern Europe. We choose a possible refugium of beech in northern Greece, Mt. Paggeo, which hosts a private plastid haplotype for beech, to conduct a fine-scale genetic study. We attempt to confirm or reject the hypothesis of the existence of a small-scale refugium and to gain an understanding of the ecological and topographical factors affecting the spatial distribution of plastid haplotypes in the area. Our results reveal a high haplotype diversity on Mt. Paggeo, but the overall distribution of haplotypes shows no significant correlation with the ecological characteristics of the beech forests. However, the private haplotype is found at high frequencies in beech forests located in or near ravines, having a high spatial overlap with a relict vegetation type occurring in ecological conditions found mainly in ravines. This result emphasizes the importance of topography in the existence of glacial refugia in the wider area. Furthermore, haplotypes originating from two more widespread beech lineages in Greece are found on Mt. Paggeo, indicating a possible mixing of populations originating from a local refugium with populations from remote refugia that possibly migrated into the area after the last glaciation.

Rethinking long‐term vegetation dynamics: multiple glacial refugia and local expansion of a species complex

“…Thus local persistence of refugial populations through the LGM was likely facilitated by microhabitats that buffered against adverse regional climatic conditions (Ackerly , Dobrowski , Hampe and Jump ). This interpretation is consistent with other studies suggesting that glacial refugia typically occur in areas with complex topography and low climate velocity (Corlett and Westcott , Papageorgiou et al ). Rapid adaptive evolution may have also played a role in promoting the long‐term persistence of refugial populations (Kawecki , Hoffmann and Sgrò , Mee and Moore 2014).…”

The relationship between vegetation and modern pollen assemblages on Mount Paggeo (NE Greece)

“…This plant community corresponds to the Tilio tomentosae-Castanetum (Bergmeier & Dimopoulos, 2008). Beech forests appear abovetheoakorthechesnutforestsongneissschist, marble, and, more rarely, on granite (Papageorgiou & al., 2014), although in the lower altitudes they form mixed stands with oaks (Tsiripidis&Athanasiadis,2003 (López-Sáez & al., 2013).The subsamples were sealed in plastic bags and mixed into one sample per site.Mosspolstersarecommonlyusedassurfacesamplesforlocalmodernpollenrainas it is assumed that they record an average of several years of pollen deposition and are considered as a good analogue of fossil pollen assemblages (López-Sáez & al., 2015).InheterogeneouslandscapeslikeMt. Paggeo, relevant source areas of about 50-100 m from a sample location have been shown to properly reflect the local vegetation (Sugita, 1994).…”

“…In any case, both morphological traits and gene markers revealed the uniquenessofbeechpopulationsonthesouth-eastern side of Rhodope Mountains (Mt. Paggeo, eastern Macedonia, and NE Greece) at low elevations (Hatziskakis&al.,2009).Infact, private haplotypes in this area are usually found at high frequencies in beech forests locatedinornearravines,havingahighspatial overlap with a relict vegetation type occurring in ecological conditions mainly found in ravines (Papageorgiou & al., 2008(Papageorgiou & al., , 2014. Furthermore, haplotypes originating from two more widespread beech lineages in GreecearealsofoundonMt.Paggeo,indicating apossiblemixtureofpopulationsoriginating fromalocalrefugiumwithpopulationsfrom remoterefugiathatpossiblymigratedintothe areaafterthelastglaciations.…”

Beyond skepticism: uncovering cryptic refugia using multiple lines of evidence

“…In this respect, the two locations where we found the oldest beech charcoal particles in south‐western France are moist ravines along permanent rivers (Fig. ), a habitat shown to have acted as a microrefugium for the species (Papageorgiou et al ., ).…”