Primulaceae) in the European Alps

Original Paper 623

Phylogeography of the High Alpine Cushion Plant Androsace alpina (Primulaceae) in the European Alps

P. Schönswetter1, A. Tribsch2, and H. Niklfeld1 1 Department of Plant Chorology and Vegetation Science, Institute of Botany, University of Vienna, Vienna, Austria 2 Department of Systematics and Evolution of Higher Plants, Institute of Botany, University of Vienna, Rennweg14, 1030 Vienna, Austria

Received: January 31, 2003; Accepted: November 11, 2003

Abstract: Recent studies elucidating the glacial history of alpine the centre of the Pleistocene ice shields covering the Alps and plants have yielded controversial results. While some have fav- Scandinavia also harbour such taxa. The nunatak hypothesis, oured glacial survival on mountain tops above the glaciers claiming that plants could survive on mountain tops protrud- (nunataks), others did not find support for this hypothesis. Fur- ing from the ice shield (reviewed in Dahl, 1987), was formulat- thermore, all of the published phylogeographic patterns are ed to explain this pattern. The alternative tabula rasa (latin for strikingly different. In order to provide more data for a future ªempty tableº) hypothesis argues for sole periglacial survival comparative phylogeographical approach, we investigated 53 (reviewed in Nordal, 1987; Birks, 1993). populations of the high alpine cushion plant Androsace alpina (Primulaceae), endemic to the European Alps, using amplified Whereas many contributions exist toward understanding gla- fragment length polymorphism (AFLP). While Principal Co-ordi- cial survival of tree species in southern European refugia (re- nate Analysis (PCoA) of populations revealed four genetically- viewed by, e.g., Taberlet et al., 1998; Newton et al., 1999; defined phylogeographical groups corresponding to geographic Comes and Kadereit, 2001), arctic and alpine plants have been regions, Neighbour Joining analysis (NJ) separated only three neglected until recently. A series of studies dealing with arctic groups. Mantel tests were used to assess the goodness-of-fit be- taxa (Brochmann et al., 1996; Gabrielsen et al., 1997; Tollefsrud tween the grouping in PCoA and the genetic similarity matrix, et al., 1998) found no evidence for the nunatak hypothesis, and and these showed high similarity between the two eastern phy- it was thus concluded that ªglacial survival does not matterº logeographical groups. This, together with other lines of evi- (Gabrielsen et al., 1997; Tollefsrud et al., 1998). Only in the dence, is interpreted as an indication for colonization of the last few years have alpine plants become the focus of inter- eastern part of the distributional range of A. alpina from wester- est (Stehlik et al., 2001a, b, 2002a, b; Stehlik, 2002; Holder- ly adjacent populations. The phylogeographical groups can all egger et al., 2002; Kropf et al., 2002, 2003; Schönswetter et be related to potential refugia for alpine plants, based on geo- al., 2002, 2003, in press; Tribsch et al., 2002). Stehlik et al. logical and palaeoclimatological data. However, due to the com- (2001a; 2002 b) provided evidence for nunatak survival in the paratively weak phylogeographical structure, our data do not centralmost parts of the Alps for the high alpine Eritrichum allow us to rule out glacial survival on nunataks in central parts nanum. Even in the low alpine Erinus alpinus (Stehlik et al., of the Pleistocene ice shield. 2002 a), glacial survival on nunataks in the northern Swiss Alps may account for its present phylogeographic pattern. Key words: AFLP, Androsace alpina, glacial survival, nunatak, However, results from Phyteuma globulariifolium (Schönswet- phylogeography, Pleistocene. ter et al., 2002), and Ranunculus glacialis (Schönswetter et al., in press), which have an altitudinal distribution similar to E. nanum, favour survival in unglaciated refugia and peripheral nunatak areas close to the southern and eastern margin of the Introduction Alps. Peripheral nunataks were situated close to the margin of the ice shield and provided potential habitats below the Pleis- Where did plants growing at high altitudes in mountain ranges tocene snow line (Schönswetter et al., 2002, in press). In con- like the European Alps survive the glaciations of the Pleisto- trast, central nunataks were restricted to interior parts of the cene? This question has been addressed by biogeographers ice shield. The classical nunatak debate traditionally only dis- many times (reviewed in Brockmann-Jerosch and Brock- tinguished unglaciated refugia and central nunataks (Stehlik, mann-Jerosch, 1926; Stehlik, 2000). It was observed that the 2000); peripheral nunataks, however, obviously offered condi- distribution of ªglacial relicsº (i.e., rare, disjunct, or palaeoen- tions more suitable for growth and survival of higher plants. demic taxa) is not confined to areas that remained ice-free during the last glaciation, but rather that mountain ranges in The general aim of the present study was to provide detailed phylogeographic data from an exclusively high alpine to subni- val plant, to test further the still controversial nunatak hypoth- Plant Biology 5 (2003): 623 ±630 esis. Our objectives were (1) to attempt to identify Pleistocene Georg Thieme Verlag Stuttgart ´ New York refugia by comparing the phylogeographic pattern with poten- ISSN 1435-8603 ´ DOI 10.1055/s-2003-44686 tial refugia described in Schönswetter et al. (2002), and (2) to 624 Plant Biology 5 (2003) P. Schönswetter, A. Tribsch, and H. Niklfeld

Fig.1 Distribution of Androsace alpina (shad- ed) and sampled populations (numbered, see Table 1) in the Alps. Groupings based on genetic results are indicated by the following symbols: rhombi = SW, squares = W, trian- gles = E1, dots = E2. The maximum extent of the Pleistocene ice shield duringthe last glacial period (Würm) is illustrated with a black line (modified from van Husen, 1987; Jäckli, 1970; and Voges, 1995).

distinguish between peripheral survival and survival on cen- Materials and Methods tral nunataks. Nunatak survivors, if not completely swamped by re-migrating genotypes (Gabrielsen et al., 1997; Tollefsrud The species et al., 1998; Holderegger et al., 2002), should exhibit a patchy distribution of groups of related genotypes in formerly glaciat- Androsace alpina is a typical alpine pioneer species with appar- ed central areas of the Alps. These groups should be potentially ently low competitive abilities, as it is strictly bound to open differentiated from and surrounded by peripheral genotypes. vegetation (P. Schönswetter, pers. obs.). In many aspects, it is An example for this kind of glacial survival in the western similar to high alpine Ranunculus glacialis, that Grabherr et al. central Alps is provided by Stehlik et al. (2002 b). In contrast, (1986) regarded as ªalpine ruderalº. The population size of A. one would expect re-migration of (now mostly extinct) refu- alpina varies considerably, from small populations on summits gial populations from peripheral refugia to result in large, rel- and ridges with fewer than ten individuals to very large popu- atively uniform areas populated by closely related genotypes lations, e.g. in glacier forefields, with thousands of plants (P. (Schönswetter et al., 2002, in press). Schönswetter, pers. obs.). This is also reflected by the sampled populations (Table 1). A pollen/ovule-ratio of 1600±1800 (H. Androsace alpina (Primulaceae) belongs to the three highest- Weiss, unpubl.) for the southwesternmost population 1 and dwelling vascular plant taxa in the European Alps, frequently population 46 near the eastern distribution limit (Fig.1) sug- growing at or even above the snow line (at ca. 3000 m asl) gests (facultative) xenogamy (Cruden, 1977). Androsace alpina and sometimes reaching 4200 m asl (Ellenberg, 1996). The is also highly self-compatible, as seed set does not differ signif- species is endemic to the Alps (Fig.1). It is most frequent in icantly between plants packed in silk bags to prevent xenoga- the highest, most central parts (Mt. Blanc to Hohe Tauern), be- my and open-pollinated individuals used as reference (Schöns- coming rarer towards the southwest and the east. Judging by wetter, unpublished data; t-test, p = 0.154). The size of the its present habitat preferences, A. alpina hypothetically would seeds varies from 1.5 to 2.2 mm, their specific weight is > 1 have been able to survive the hostile conditions on nunataks (Müller-Schneider, 1986), and they lack morphological adapta- within the Pleistocene ice shield. This, together with its re- tions for dispersal over longer distances. striction to siliceous bedrock, makes A. alpina a good model or- ganism to test hypotheses on glacial refugia. Due to the geolo- Sampling gy of the Alps, with a central siliceous core flanked by peripheral limestone ranges over long distances, there are only a few Fifty-three populations (Table 1) throughout the distributional well circumscribed potential peripheral refugia providing sili- area of A. alpina were sampled, with five individuals in each ceous bedrock which was unglaciated, or at least situated be- population (exceptions: populations 13, 31, 49, and 52 with low the Pleistocene snowline (Schönswetter et al., 2002). Gla- four and 47 and 50 with three individuals). Voucher specimens cial survival of A. alpina in the Po plain near presumed refugia of all sampled populations are deposited in the herbarium of was improbable, as it was covered by boreal forests and steppe the Institute of Botany of the University of Vienna (WU). Fol- vegetation and locally even by oak forest, and thus provided no lowing Taberlet (1998), special emphasis was given to sample alpine environments even during the last glacial maximum potential refugia, in our case presumed peripheral refugia (Paganelli, 1996). (Schönswetter et al., 2002). Phylogeography of Androsace alpina Plant Biology 5 (2003) 625

Table 1 Population number, location name, phylogeographical group (E1 = Centre, E2 = East, SW = Southwest, W = West), co-ordinates, population size (small < 25 individuals; medium 25±250 individuals; large > 250 individuals); number of fragments (Frag.) per population and Shannon

Diversity Index (HSh) of the 53 investigated populations of Androsace alpina from the Alps

Pop. no. Location Pop. grp. Co-ordinates Pop. size Frag. HSh 1 Col Sommelier SW 6.838/45.128 l 115 4.81 2 Col de lIseran SW 7.028/45.428 m 124 8.17 3 Champorcher SW 7.558/45.628 l 124 8.27 4 Col Gr. St. Bernard SW 7.178/45.878 s 127 8.53 5 Gornergrat W 7.808/45.988 l 133 11.26 6 Simplon pass W 8.028/46.238 l 129 8.93 7 Eggishorn W 8.088/46.428 m 129 10.30 8 Nufenen pass W 8.388/46.478 m 130 10.16 9 Furka pass W 8.428/46.578 l 133 11.49 10 Passo Lucomagno W 8.808/46.588 m 130 10.30 11 Cassonsgrat W 9.278/46.878 m 133 8.80 12 Monte Spluga E1 9.558/46.188 s 120 8.57 13 Val Muretto E1 9.738/46.358 s 141 13.21 14 Piz Julier E1 9.758/46.488 l 135 11.83 15 Schwarzhorn E1 9.938/46.738 s 139 11.68 16 Pizzo di Coca E1 10.008/46.078 m 130 9.30 17 Bocchetta Forbici E1 9.908/46.328 l 134 10.27 18 Monte Breva E1 10.058/46.478 l 140 13.88 19 Hohes Rad E2 10.108/46.888 s 126 9.54 20 Monte Rocca E1 10.228/46.508 l 134 10.32 21 Monte Verva E1 10.228/46.428 m 133 11.19 22 Passo Crocedomini E1 10.438/45.938 s 141 12.20 23 Val Folgorida E1 10.618/46.178 m 138 12.02 24 Passo Paradiso E1 10.578/46.238 s 140 13.02 25 Passo di Gavia E1 10.478/46.338 m 131 9.43 26 Stilfser Joch E2 10.468/46.528 l 138 11.86 27 Piz Lad E2 10.478/46.838 s 129 7.25 28 Weissseejoch E2 10.688/46.878 s 139 12.30 29 Pfossental E2 11.028/46.758 l 131 9.82 30 Gaisbergtal E2 11.058/46.858 l 132 9.77 31 Timmelsjoch E2 11.108/46.908 m 132 8.83 32 Glungezer E2 11.528/47.208 s 130 9.88 33 Monte Ziolera E1 11.458/46.178 s 136 11.84 34 Cima dAsta E1 11.608/46.188 s 125 6.86 35 Passo Pordoi E2 11.828/46.428 l 132 10.71 36 Tristenspitz E2 11.828/46.958 m 135 11.63 37 Toblacher Pfannhorn E2 12.288/46.788 s 127 8.43 38 Kalksteinjoch E2 12.288/46.828 s 130 9.37 39 Totenkarspitze E2 12.188/46.978 m 131 10.20 40 Obersulzbachtal E2 12.308/47.128 s 134 11.63 41 Kalser Höhe E2 12.608/47.008 m 136 12.68 42 Kitzsteinhorn E2 12.688/47.208 l 131 10.08 43 Monte Peralba E2 12.728/46.638 m 124 8.93 44 Hochtor E2 12.838/47.088 m 135 10.70 45 SadnigE2 12.98 8/46.938 l 129 9.49 46 Wurtenkees E2 13.028/47.028 m 134 9.82 47 Gesselkopf E2 13.088/47.028 s 129 9.28 48 Ankogel E2 13.258/47.058 l 125 7.64 49 Reisseck E2 13.368/46.958 s 125 7.23 50 Wandspitze E2 13.538/47.028 m 126 9.01 51 Hafner E2 13.408/47.078 l 128 10.37 52 Hochgolling E2 13.768/47.278 m 124 6.75 53 Bretthöhe E2 13.938/46.918 s 123 8.51 626 Plant Biology 5 (2003) P. Schönswetter, A. Tribsch, and H. Niklfeld

Data Analysis

The number of AFLP fragments per population was estimated.

Shannon Diversity HSh =±S(pj ln pj), where pj is the relative fre- quency of the j-th fragment (Legendre and Legendre, 1998) was calculated for each population. Only the presence of markers was considered. In order to allow comparison with other phylogeographic studies on Alpine plants (e.g., Stehlik et al., 2001a, 2002a; Schönswetter et al., 2002, in press; Tribsch et al., 2002), the index was calculated for each putative locus and then summed up without averaging by the number of loci.

A Neighbour Joining (NJ) analysis based on pairwise FST (FST) comparisons between populations (computed with ARLEQUIN 1.1; Schneider et al., 1997) was generated with MEGA 1.1 (Ku- mar et al., 2001). A Principal Co-ordinate Analysis (PCoA) of populations based on the same matrix was calculated and plotted with the program package NTSYS-pc 2.0 (Rohlf, 1997; programs DCENTER, EIGEN). Analyses of molecular variance (AMOVAs) were calculated with ARLEQUIN 1.1 (Schneider et al., 1997).

Mantel tests were applied in three different ways, according to Stehlik et al. (2001a): (a) to compare the genetic matrix of

Jaccard distances (D = 1 ± CJ; CJ = a/a + b + c, where a is the number of fragments shared between two individuals and b and c are present in only one individual) between individuals with a matrix of geographical distances in kilometres, i.e. the ªclassi- calº use of a Mantel test; (b) to test the goodness-of-fit of the genetic distance matrix and a model matrix of distance classes (Gabrielsen et al., 1997), where the geographical distances between individuals were coded in 12 classes; and (c) to test the Fig.2 Neighbour Joining analysis of the 53 investigated populations relationships of the phylogeographical groups defined by NJ of Androsace alpina in the Alps. and PCoA, the genetic distance matrix being tested against a model matrix where all pairwise comparisons between the

phylogeographical groups were coded. All Mantel RM values DNA isolation and AFLP fingerprinting were calculated and Bonferroni-corrected using the R-PACK- AGE 4.0 (Casgrain and Legendre, 1999). DNA isolation followed the CTABprocedure from Doyle and Doyle (1987), with the modifications mentioned in Schöns- Results wetter et al. (2002). AFLP fingerprinting was performed according to Tribsch et al. (2002). The primer combinations used With the three primer combinations used, 218 unambiguously in the selective amplification were EcoRI ACA-MseICAT;EcoRI scoreable fragments were generated, 177 of which (81.2%) AAG-MseI CTG; EcoRI AAC-MseI CTT. The fluorescence-labelled were polymorphic. The length of the fragments varied from selective amplification products were separated on a 5% poly- 50 to 489 bp. Five individuals failed to amplify and were ex- acrylamide gel on an automated sequencer (ABI 377, Perkin cluded. Thus, analyses were conducted with 257 individuals. Elmer). Raw data were collected and aligned with the internal size standard (GeneScan-500 [ROX], PE Applied Biosystems) No identical genotypes were detected. The number of AFLP using the ABI Prism GeneScan Analysis Software (PE Ap- fragments per population varied between 115 in population 1

plied Biosystems). Subsequently, the GeneScan files were im- and 141 in population 22 (mean 130.92, SD = 5.55; Table 1). HSh ported into Genographer (version 1.1.0, Montana State Univer- ranged from 4.81 in population 1 to 13.88 in population 18 sity, 1998; http://hordeum.msu.montana.edu/genographer/) (mean 9.97, SD = 1.82; Table 1). There was no correlation be-

for scoring the fragments. Each AFLP fragment was scored us- tween estimated population size (Table 1) and HSh (Pearson ing the ªthumbnailº option of the program, which allows com- correlation coefficient r =0.19,p = 0.895). parison of the signal per locus over all samples. AFLP fragments that exhibited ambiguous peaks were excluded from Neighbour Joining analysis of populations (Fig. 2) revealed the the analysis. Peaks of low intensity were included into the following geographical structuring: four populations from the analysis, when unambiguous scoring was possible. The results southwesternmost part of the distributional area of A. alpina of the scoring were exported as a presence/absence matrix and (Cottic and Grajic Alps; referred to as SW in the acronym for used for further analysis. Southwestern Alps); seven populations from the western Alps, from Mont Blanc to Spluegen pass (W for middle part of the western Alps); and a third group comprising 42 populations from the central and eastern parts of the Alps, east of Spluegen Phylogeography of Androsace alpina Plant Biology 5 (2003) 627

Fig.3 Principal Co-ordinate Analysis (PCoA) of 53 populations of Androsace alpina. The three factors explain 33.1, 16.1, and 9.4% of the overall variation. Symbols as in Fig.1.

pass (E for eastern Alps). Within this latter group, the NJ anal- Table 2 Analysis of molecular variance (AMOVA) of the 53 investi- ysis revealed a sequential branching pattern from west to east. gated populations of Androsace alpina from the Alps The PCoA of all populations (Fig. 3) gave a similar pattern as Source of variation d.f. Sum of Variance % Total F the NJ, i.e., a clear separation of SW and W. Additionally, the ST squares compo- variance eastern group was clearly divided into two entities: the south- nents ern part of the middle Alps from Spluegen pass to the Dolo- mites (E1; 15 populations); and the eastern part of the Alps Amongpopulations 52 1843.75 5.55 39.36 0.39* from Silvretta and Ortler eastwards (E2; 27 populations). The (total) northernmost population from the Dolomites (population 35) Within populations 204 1744.15 8.55 60.64 also belongs to the latter group. Explanation values of the first AmongSW, W, E1, E2 3 613.69 3.24 21.32 0.44* three axes were 33.1%, 16.1%, and 9.4% (Fig. 3). Non-hierarchi- Amongpopulations 49 1230.06 3.42 22.47 cal AMOVAs assigned about two-fifths of the overall variation Within populations 204 1744.15 8.55 56.20 to the among population component and three-fifths to that within populations. If SW, W, E1, and E2 are treated as separate * p values < 0.001 groups, the percentage of variation among groups was 21.3%, that among populations 22.5%, and that within populations

56.2% (for further details see Table 2). The overall RM value were characterized by positive within-group correlations, the calculated with the genetic and the geographical distance corresponding RM value continuously increased eastwards matrices was 0.23 (p = 0.001), indicating that genetic distances with SW having the lowest RM value to E2 having the highest. increased significantly with geographic distances (i.e. isola- Phylogeographical group SW is significantly negatively corre- tion by distance). A Mantel test with distance classes (Fig. 4) lated with E1 and E2, while W exhibits significantly negative revealed significantly positive correlations among popula- correlation only with E2. E1 and E2 are significantly positively tions up to 180 km distance and significantly negative values correlated. Hence, there is no significantly negative correlation in the classes from 180 to more than 400 km distance. The between neighbouring groups. highest correlation was found within populations (RM =0.27, p < 0.001) and the lowest among populations separated by maximum distance (i.e. > 400 km; RM = ± 0.36, p < 0.001). Re- gional Mantel tests (Table 3) only partly corroborated the pattern detected with NJ and PCoA. All phylogeographical groups 628 Plant Biology 5 (2003) P. Schönswetter, A. Tribsch, and H. Niklfeld

Table 3 Results of ¹regionalª Mantel tests of SW, W, E1, and E2 compared to themselves and the other regions. Asterisks indicate Bonfer-

roni-corrected RM values significantly different from zero at p £ 0.05

SW W E1 E2

SW 0.074* W ± 0.041 0.112* E1 ± 0.224* ± 0.039 0.198* E2 ± 0.391* ± 0.330* 0.088* 0.385*

Glacial refugia

Despite the relatively weak genetic structure of A. alpina as compared to that of, e.g., Phyteuma globulariifolium (Schöns- wetter et al., 2002) or Ranunculus glacialis (Schönswetter et Fig.4 Correlogram of Mantel R per distance class. Filled squares in- M al., in press), cautious conclusions on the glacial history of the dicate Bonferroni-corrected RM values significantly different from zero at p £ 0.05. species can still be drawn. The phylogeographical groups SW, W, and E1 form distinct entities in NJ analysis (Fig. 2) as well as in the PCoA (Fig. 3) and appear to be distinct enough to be regarded as descendants of different glacial refugia. For several Discussion reasons the separation of E2 is ambiguous. In spite of their sep- High levels of ancient or recent gene flow aration in the PCoA (Fig. 3), in the NJ analysis (Fig. 2) all populations of E2 are nested as a group within E1 and there is a Various analyses indicate a rather weak phylogeographic sequential west±east orientated branching pattern. Regional structure in A. alpina as compared to previously studied co- Mantel tests (Table 3) identified E1 and E2 as significantly pos- distributed high alpine Phyteuma globulariifolium (Schönswet- itively correlated. As E2 exhibited by far the highest positive ter et al., 2002) and Ranunculus glacialis (Schönswetter et al., in correlation with itself as compared to the other three regions, press). This is most probably due to high levels of ancient or it seems possible that this phylogeographical group is of rather recent gene flow in this presumably outbred but self-compat- recent origin. This high similarity of the populations fits well

ible species. The FST value of 0.44 (Table 2) obtained by a hier- to the concept of leading edge migration, as proposed by He- archical AMOVA with the four groups SW, W, E1, and E2 was witt (1996). Additionally, within-population genetic diversity lower than in P. globulariifolium from more stable habitats was high in populations of E1 and very low at the southwest-

(FST = 0.64; Schönswetter et al., 2002) but higher than among ern and eastern margin of the distributional area (Table 1). This Alpine populations of the coloniser Saxifraga oppositifolia was not due to inbreeding in small populations as there was

(FST = 0.15 derived from RAPD data, Holderegger et al., 2002). no correlation between genetic diversity measured with HSh Further indication for high gene flow is given by a NJ tree of (Table 1) and approximate population size. all investigated individuals of A. alpina (data not shown), with only five populations (populations 1±3, 11, and 35) forming Regions SW, W, and E1 encompass presumed refugia for silicic- distinct clusters with bootstrap values above 50. According to olous higher plants defined previously on the basis of geologi- the Mantel test with distance classes, individuals separated by cal and palaeoclimatological data (Fig.1 in Schönswetter et al., distances of up to 180 km were positively correlated (Fig. 4). In 2002). All of them have already been suggested as refugia for regional Mantel tests, neighbouring phylogeographical groups Phyteuma globulariifolium (Schönswetter et al., 2002), Sapona- were not significantly negatively correlated. The obviously ef- ria pumila (Tribsch et al., 2002), Androsace wulfeniana (Schöns- ficient gene flow, most probably via seed dispersal, in Andro- wetter et al., 2003), and/or Ranunculus glacialis (Schönswetter sace alpina is remarkable because in large parts of its range et al., in press). For region SW of A. alpina, these potential the species is rare and bound to plant communities of the source areas could have been the eastern Cottic Alps, eastern highest summits and thus ªisland-likeº habitats. The alterna- Grajic and southern Penninic Alps for W, and western Alpi Ber- tive scenario, i.e. similarity of the populations caused by frag- gamasche, southern Adamello, and southwestern Dolomites mentation of formerly continuous populations, is less plausi- for E1. The large unglaciated area in the easternmost central ble. (1) During the warm stages of the Pleistocene, the taxon Alps of Austria, that was identified as refugium for A. wulfeni- was most likely restricted to island-like occurrences on moun- ana, P. globulariifolium, R. glacialis, and S. pumila, and harbours tain tops, similar to the present situation. (2) During cold a high number of endemic silicicolous taxa (Tribsch and stages, according to tabula rasa and nunatak hypotheses, A. al- Schönswetter, 2003), most probably did not act as a refugium pina survived either outside of the continuous ice shield, thus for A. alpina. outside of its present distribution, or on isolated nunataks within the ice shield. Under both assumptions, there were no Although generally favouring glacial survival in peripheral re- continuous populations whose fragmentation could have led fugia, our results do not allow us to entirely rule out nunatak to the presently recognizable high similarity of populations survival for A. alpina, due to the relatively weak phylogeo- within the phylogeographical groups. graphical structure. However, the detection of phylogeographical groups that can be related to presumed glacial refugia in- Phylogeography of Androsace alpina Plant Biology 5 (2003) 629 dicates that, in contrast to the situation in Scandinavia where Jäckli, H. (1970) Die Schweiz zur letzten Eiszeit (1: 550 000). Atlas there is complete uncertainty about the location of Pleistocene der Schweiz (ed. Eidgenössiche Landestopographie). Wabern- refugia (e.g., Gabrielsen et al., 1997; Tollefsrud et al., 1998), Bern: Eidgenössiche Landestopographie. glacial survival in peripheral refugia certainly does matter in Kropf, M., Kadereit, J. W., and Comes, H. P. (2002) Late Quaternary the Alps. distributional stasis of the submediterranean mountain plant An- thyllis montana L. (Fabaceae) inferred from ITS sequences and amplified fragment length polymorphism markers. Molecular Ecolo- Acknowledgements gy 11, 447±463. Kropf, M., Kadereit, J. W., and Comes, H. P. (2003) Differential cycles Funding by the Austrian Science Foundation (FWF, P13874- of range contraction and expansion in European high mountain Bio) is gratefully acknowledged. We are indebted to Tod F. plants during the Late Quaternary: insights from Pritzelago alpina Stuessy and Gerald M. Schneeweiss for discussion and critical (L.) O. Kuntze (Brassicaceae). Molecular Ecology 12, 931±949. comments on the manuscript. 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