Isozyme variation and recent biogeographical history of the long-lived conifer Fitzroya cupressoides

Aim Palaeoenvironmental records of Pleistocene glaciation and associated vegetation changes in Patagonia have led to the hypothesis that during the last glacial maximum (LGM) tree species survived locally in favourable habitats. If present populations originated from spread from only one refugium, such as an ice‐free area of coastal Chile (Single Refugium hypothesis), we would expect that eastern populations would be genetically depauperate and highly similar to western populations. In contrast, if the ice cap was not complete and tree species persisted in forest patches on both slopes of the Andes (Multiple Refugia hypothesis), we would expect a greater degree of genetic divergence between populations either on opposite sides of the Cordillera (Cordillera Effect scenario) or towards its present‐day southern distributional limit where the ice sheet reached its maximum coverage (Extent‐of‐the‐Ice scenario). Location We tested this refugia hypothesis using patterns of isozyme variation in populations sampled over the entire modern range of the endemic conifer Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae) in temperate South America. Methods Fresh foliage was collected from twenty‐four populations and analysed by horizontal electrophoresis on starch gels. Results Twenty‐one putative loci were reliably scored and 52% were polymorphic in at least one population. Populations from the eastern slope of the Andes were genetically more variable than those from the western slope; the former had a greater mean number of alleles per locus, a larger total number of alleles and rare alleles, and higher polymorphism. Genetic identities within western populations were greater than within eastern populations. Discriminant analyses using allelic frequencies of different grouping schedules of populations were non significant when testing for the Single Refugium hypothesis whereas significant results were obtained for the Multiple Refugia hypothesis. Main conclusions Our results indicate that present Fitzroya populations are the result of spreading from at least two, but possibly more, glacial refugia located in Coastal Chile and on the southern flanks of the Andes in Argentina.     

Pleistocene refugia and polytopic replacement of diploids by tetraploids in the Patagonian and Subantarctic plant Hypochaeris incana (Asteraceae, Cichorieae)

We report the phylogeographic pattern of the Patagonian and Subantarctic plant Hypochaeris incana endemic to southeastern South America. We applied amplified fragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) analysis to 28 and 32 populations, respectively, throughout its distributional range and assessed ploidy levels using flow cytometry. While cpDNA data suggest repeated or simultaneous parallel colonization of Patagonia and Tierra del Fuego by several haplotypes and/or hybridization, AFLPs reveal three clusters corresponding to geographic regions. The central and northern Patagonian clusters (∼38–51° S), which are closer to the outgroup, contain mainly tetraploid, isolated and highly differentiated populations with low genetic diversity. To the contrary, the southern Patagonian and Fuegian cluster (∼51–55° S) contains mainly diploid populations with high genetic diversity and connected by high levels of gene flow. The data suggest that H. incana originated at the diploid level in central or northern Patagonia, from where it migrated south. All three areas, northern, central and southern, have similar levels of rare and private AFLP bands, suggesting that all three served as refugia for H. incana during glacial times. In southern Patagonia and Tierra del Fuego, the species seems to have expanded its populational system in postglacial times, when the climate became warmer and more humid. In central and northern Patagonia, the populations seem to have become restricted to favourable sites with increasing temperature and decreasing moisture and there was a parallel replacement of diploids by tetraploids in local populations.     

Genetic evidence for glacial refugia of the temperate tree Eucryphia cordifolia (Cunoniaceae) in southern South America

? Premise of the study: The temperate forests of southern South America were greatly affected by glaciations. Previous studies have indicated that some cold-tolerant tree species were able to survive glacial periods in small, ice-free patches within glaciated areas in the Andes and in southern Patagonia. Here we asked whether populations of the mesothermic species Eucryphia cordifolia also were able to survive glaciations in these areas or only in unglaciated coastal areas. ? Methods: The chloroplast intergenic spacer trnV-ndhC was sequenced for 150 individuals from 22 locations. Genetic data were analyzed (standard indexes of genetic diversity, a haplotype network, and genetic differentiation) in a geographical context. ? Key results: Two of the nine haplotypes detected were widespread in high frequency across the entire range of the species. The highest levels of genetic diversity were found around 40°S, decreasing sharply northward and more moderately southward. No differences in genetic diversity were found between Andean and coastal populations. Notably, seven haplotypes were found in a small area of the Coast Range known as the Cordillera Pelada (40°S). The differentiation coefficients G(ST) and N(ST) revealed that most of the genetic variation detected was due to variation within populations. ? Conclusions: The low levels of population differentiation and the high genetic diversity found in the Cordillera Pelada suggest that this area was the main refugium for E. cordifolia during glaciations. Nevertheless, given the high levels of genetic diversity found in some Andean populations, we cannot discount that some local populations also survived the glaciation in the Andes.     

Across the southern Andes on fin: glacial refugia,drainage reversals and a secondary contact zone revealed by the phylogeographical signal of Galaxias platei in Patagonia

We employed DNA sequence variation at two mitochondrial (control region, COI) regions from 212 individuals of Galaxias platei (Pisces, Galaxiidae) collected throughout Patagonia (25 lakes/rivers) to examine how Andean orogeny and the climatic cycles throughout the Quaternary affected the genetic diversity and phylogeography of this species. Phylogenetic analyses revealed four deep genealogical lineages which likely represent the initial division of G. platei into eastern and western lineages by Andean uplift, followed by further subdivision of each lineage into separate glacial refugia by repeated Pleistocene glacial cycles. West of the Andes, refugia were likely restricted to the northern region of Patagonia with small relicts in the south, whereas eastern refugia appear to have been much larger and widespread, consisting of separate northern and southern regions that collectively spanned most of Argentinean Patagonia. The retreat of glacial ice following the last glacial maximum allowed re‐colonization of central Chile from nonlocal refugia from the north and east, representing a region of secondary contact between all four glacial lineages. Northwestern glacial relicts likely followed pro‐glacial lakes into central Chilean Patagonia, whereas catastrophic changes in drainage direction (Atlantic → Pacific) for several eastern palaeolakes were the likely avenues for invasions from the east. These mechanisms, combined with evidence for recent, rapid and widespread population growth could explain the extensive contemporary distribution of G. platei throughout Patagonia.     

Glacial refugia and postglacial expansion of the alpine–prealpine plant species Polygala chamaebuxus

The shrubby milkwort (Polygala chamaebuxus L.) is widely distributed in the Alps, but occurs also in the lower mountain ranges of Central Europe such as the Franconian Jura or the Bohemian uplands. Populations in these regions may either originate from glacial survival or from postglacial recolonization. In this study, we analyzed 30 populations of P. chamaebuxus from the whole distribution range using AFLP (Amplified Fragment Length Polymorphism) analysis to identify glacial refugia and to illuminate the origin of P. chamaebuxus in the lower mountain ranges of Central Europe. Genetic variation and the number of rare fragments within populations were highest in populations from the central part of the distribution range, especially in the Southern Alps (from the Tessin Alps and the Prealps of Lugano to the Triglav Massiv) and in the middle part of the northern Alps. These regions may have served, in accordance with previous studies, as long‐term refugia for the glacial survival of the species. The geographic pattern of genetic variation, as revealed by analysis of molecular variance, Bayesian cluster analysis and a PopGraph genetic network was, however, only weak. Instead of postglacial recolonization from only few long‐term refugia, which would have resulted in deeper genetic splits within the data set, broad waves of postglacial expansion from several short‐term isolated populations in the center to the actual periphery of the distribution range seem to be the scenario explaining the observed pattern of genetic variation most likely. The populations from the lower mountain ranges in Central Europe were more closely related to the populations from the southwestern and northern than from the nearby eastern Alps. Although glacial survival in the Bohemian uplands cannot fully be excluded, P. chamaebuxus seems to have immigrated postglacially from the southwestern or central‐northern parts of the Alps into these regions during the expansion of the pine forests in the early Holocene.     

Out of the Alps: colonization of Northern Europe by East Alpine populations of the Glacier Buttercup Ranunculus glacialis L. (Ranunculaceae)

Ranunculus glacialis ssp. glacialis is an arctic-alpine plant growing in central and southern European and Scandinavian mountain ranges and the European Arctic. In order to elucidate the taxon's migration history, we applied amplified fragment length polymorphism (AFLP) to populations from the Pyrenees, Tatra mountains and Northern Europe and included data from a previous study on Alpine accessions. Populations from the Alps and the Tatra mountains were genetically highly divergent and harboured many private AFLP fragments, indicating old vicariance. Whereas nearly all Alpine populations of R. glacialis were genetically highly variable, the Tatrean population showed only little variation. Our data suggest that the Pyrenees were colonized more recently than the separation of the Tatra from the Alps. Populations in Northern Europe, by contrast, were similar to those of the Eastern Alps but showed only little genetic variation. They harboured no private AFLP fragments and only a subset of East Alpine ones, and they exhibited no phylogeographical structure. It is very likely therefore that R. glacialis colonized Northern Europe in postglacial times from source populations in the Eastern Alps.     

Quinua biosystematics I: Domesticated populations

Domesticated populations of the South American grain chenopod quinua (Chenopodium quinoa subsp.quinoa) have been formally classified on the basis of pigmentation and inflorescence morphology, and informally grouped according to ecotypic variation. Comparative analysis of morphometric and electrophoretic data taken from 98 populations reveals two fundamental elements: a coastal type from southwestern Chile and an Andean type distributed at elevations above 1,800 m from northwestern Argentina to southern Colombia. Andean quinua can be further divided into northern and southern groups, with the northern populations weakly marked by broad, unlobed leaf blades, sharply margined fruit, and relative uniformity. With the exception of allozymes unique to coastal quinua, characteristics that differentiate populations from the Chilean coast and the northern Andes represent a subset of variation present in the southern Andes. This could reflect diffusion from a possible center of origin in the southern highlands. Overall phenetic association places populations from the Altiplano of Peru and Bolivia in a central, linking position. The high genetic identities among all quinua populations argue against a polyphyletic origin for the crop and specific differentiation among cultivar groups. The overall pattern of variation supports the ecotypic approach toward landrace classification of quinua, although congruence between ecological and morphogenetic variation is not complete. While genetic diversity is clearly centered in populations of the southern Andes, conservation efforts should focus on well differentiated quinua populations at the poorly marked northern and southern extremes of distribution.     

New insights into the genetic structure of Araucaria araucana forests based on molecular and historic evidences

The conservation of genetic resources is a prerequisite for the maintenance of long-lived forest species. Araucaria araucana (Mol.) K. Koch is one of the oldest conifers in South America and a representative symbol of Chilean forest due to its endemicity and longevity. The aim of this study was to evaluate the genetic structure of the current A. araucana populations in Chile, to verify the possible genetic divergence between Coastal and Andean populations and to assess whether bottleneck events have influenced habitat fragmentation and threaten the genetic resources and evolutionary potential of the species. Twelve natural populations, nine from the Andes Cordillera and three from the Coast Cordillera were analysed by means of eight genomic microsatellite markers developed in A. araucana. Results of analysis of molecular variance (AMOVA) highlighted significant differentiation between Coastal and Andean populations (16 %; P?=?0.004), detecting one significant barrier that separated populations from both Cordilleras as maximally differentiated areas. At local scale, both ranges revealed significant inter-population differentiation, with higher values for Coastal populations compared with Andean populations. These results suggested the presence of four gene pools (three in the Andes and one in the Coast Cordilleras) and one population (VIL) in the Coast Cordillera that differed to the rest. The differentiation between the Andean and Coastal populations may provide important baseline data that should allow further studies of landscape genetics in the species and that can contribute to develop conservation strategies for its genetic resources.     

Population status of Andean Condors in central and southern Bolivia

Andean Condors (Vultur gryphus) are a Near Threatened species that was formerly distributed along the entire length of the Andes from western Venezuela to Tierra del Fuego. Populations have been severely reduced north of Peru, but several thousand Andean Condors still exist in the southern portion of their range in Argentina and Chile. Little is known, however, about the size of the Andean Condor population in the central part of their range in Peru and Bolivia. From June to September 2012, we used feeding stations to attract Andean Condors and estimate the size and structure of the population in the eastern Andes of central and southern Bolivia. We estimated a minimum population of 253 condors, an adult male‐to‐female ratio of 1:0.6, an immature male‐to‐female ratio of 1:0.9, and an adult‐to‐immature ratio of 1:1.1. At our five survey areas, estimated abundance ranged from 15 to 100 condors per area. Males outnumbered females in three areas and the opposite was true in two areas. Our estimated adult‐to‐immature ratio, overall and in each area, suggests that the populations could be reproducing at a high rate. As previously observed in other Andean Condor populations, skewed sex ratios could be associated with differences between sexes and age classes in habitat selection. Although our results suggest that Bolivian populations of Andean Condors are still reasonably large, population monitoring is urgently needed, including use of feeding stations throughout the entire Bolivian range of the species and intensive searches for roosting and nesting sites.     

Phylogeography of the Percichthyidae (Pisces) in Patagonia: roles of orogeny, glaciation, and volcanism

We used molecular evidence to examine the roles that vicariance mechanisms (mountain-building and drainage changes during the Pleistocene) have played in producing phylogeographical structure within and among South American fish species of the temperate perch family Percichthyidae. The percichthyids include two South American genera, Percichthys and Percilia, each containing several species, all of which are endemic to southern Argentina and Chile (Patagonia). Maximum-likelihood phylogenies constructed using mitochondrial DNA (mtDNA) control region haplotypes and nuclear GnRH3-2 intron allele sequences support the current taxonomy at the genus level (both Percichthys and Percilia form strongly supported, monophyletic clades) but indicate that species-level designations need revision. Phylogeographical patterns at the mtDNA support the hypothesis that the Andes have been a major barrier to gene flow. Most species diversity occurs in watersheds to the west of the Andes, together with some ancient divergences among conspecific populations. In contrast, only one species (Percichthys trucha) is found east of the Andes, and little to no phylogeographical structure occurs among populations in this region. Mismatch analyses of mtDNA sequences suggest that eastern populations last went through a major bottleneck c. 188 000 bp, a date consistent with the onset of the penultimate and largest Pleistocene glaciation in Patagonia. We suggest that eastern populations have undergone repeated founder-flush events as a consequence of glacial cycles, and that the shallow phylogeny is due to mixing during recolonization periods. The area of greater diversity west of the Andes lies outside the northern limit of the glaciers. mtDNA mismatch analysis of the genus Percilia which is restricted to this area suggests a long-established population at equilibrium. We conclude that patterns of genetic diversity in these South American genera have been primarily influenced by barriers to gene flow (Andean orogeny, and to a lesser extent, isolation in river drainages), and by glacial cycles, which have resulted in population contraction, re-arrangement of some watersheds, and the temporary breakdown of dispersal barriers among eastern river systems.     

The role of geography and ecology in shaping the phylogeography of the speckled hummingbird (Adelomyia melanogenys) in Ecuador

The Andes of South America contain one of the richest avifaunas in the world, but little is known about how this diversity arises and is maintained. Variation in mitochondrial DNA and morphology within the speckled hummingbird (Adelomyia melanogenys) was used to elucidate the phylogeographic pattern along an Ecuadorian elevational gradient, from the coastal cordillera to the inland Andean montane region. We examined sequence, climatic/remote sensing and morphological data to understand the effects of topography and ecology on patterns of variation. Populations on either side of the Andes are genetically divergent and were separated during a period that corresponds to the final stages of Andean uplift during the Pliocene. Despite isolation, these two populations were found to be morphologically similar suggesting a strong effect of stabilizing selection across ecologically similar Andean cloud forests, as assessed using climatic and remote sensing data. In contrast, little genetic divergence was found between coastal and west-Andean individuals, suggesting recent interruption of gene flow between these localities. However, coastal populations were found to inhabit different habitats compared to Andean populations as shown by climatic and remote sensing variables. Furthermore, coastal individuals had significantly longer bills compared to their montane relatives, indicative of differential directional selection and the influence of habitat differences in shaping phenotypic variation. Results highlight the role of both isolation and ecology in diversification in Ecuadorian montane regions, while suggesting the two may not always act in concert to produce divergence in adaptive traits.     

Patterns of isozyme variation as indicators of biogeographic history in Pilgerodendron uviferum (D. Don) Florín

The effects of Pleistocene glaciations on the genetic characteristics of the most austral conifer in the world, Pilgerodendron uviferum, were analysed with specific reference to the hypothesis that the species persisted locally in ice‐free areas in temperate South America. It was expected that genetic variation would decrease with latitude, given that ice fields were larger in southern Patagonia and thus refugia were probably located towards the northern distributional limit of the species as suggested by the fossil record. In addition, an increase in among‐population genetic divergence was expected with increasing distance to putative glacial refugia. We examined the relationship between location and within‐population variability indices of 20 Pilgerodendron populations derived from isozyme analyses. We analysed possible refugia hypotheses by the distribution of allele frequencies using multivariate discriminant analysis. The degree of genetic differentiation with geographical distance between all population pairs was investigated by Mantel tests. Results indicated that Pilgerodendron populations are highly monomorphic, probably reflecting past population bottlenecks and reduced gene flow. Southernmost populations tend to be the least genetically variable and were therefore probably more affected by glacial activity than northern ones. Populations located outside ice limits seem to have been isolated during the glacial period. The presence of centres of genetic diversity, together with the lack of a significant correlation between genetic and geographical distances and the absence of geographical patterns of allelic frequencies at most analysed alleles, may indicate that Pilgerodendron did not advance southward after the last glaciation from a unique northern refugium, but spread from several surviving populations in ice‐free areas in Patagonia instead.     

Genetic diversity, structure, and demographic change in tanoak, Lithocarpus densiflorus (Fagaceae), the most susceptible species to sudden oak death in California

Knowledge of population genetic structure of tanoak (Lithocarpus densiflorus) is of interest to pathologists seeking natural variation in resistance to sudden oak death disease, to resource managers who need indications of conservation priorities in this species now threatened by the introduced pathogen (Phytophthora ramorum), and to biologists with interests in demographic processes that have shaped plant populations. We investigated population genetic structure using nuclear and chloroplast DNA (cpDNA) and inferred the effects of past population demographic processes and contemporary gene flow. Our cpDNA results revealed a strong pattern of differentiation of four regional groups (coastal California, southern Oregon, Klamath mountains, and Sierra Nevada). The chloroplast haplotype phylogeny suggests relatively deep divergence of Sierra Nevada and Klamath populations from those of coastal California and southern Oregon. A widespread coastal California haplotype may have resulted from multiple refugial sites during the Last Glacial Maximum or from rapid recolonization from few refugia. Analysis of nuclear microsatellites suggests two major groups: (1) central coastal California and (2) Sierra Nevada/Klamath/southern Oregon and an area of admixture in north coastal California. The low level of nuclear differentiation is likely to be due to pollen gene flow among populations during postglacial range expansion.     

Phytogeographical relations of the Andean dry valleys of Bolivia

Aim The objective of this study is to examine the phytogeographical affinities of the Andean dry valleys of Bolivia in order to contribute to a better understanding of the Andean dry flora's distribution, origin and diversity. Particular emphasis is given to the analysis of the floristic connections of this flora with more austral parts of South America. Location The dry valleys of Bolivia are located in the Andes of the southern half of the country, at elevations between 1300 and 3200 m. Methods An extensive floristic list compiled by the author to evaluate plant diversity in these Andean regions was used as the base for this study. To accomplish this, all recorded genera and species were assigned, respectively, to 11 and 12 phytogeographical elements established previously by the author. Two phytogeographical spectra were thus obtained and analysed. Results At the genus level, the Andean dry valleys of Bolivia are clearly dominated by genera that have widespread distributions (cosmoplitan and subtropical genera). Many of these reached the Andes from the lowland region of the Chaco. At species level, Andean elements constitute more than 60% of the species total, most of which are restricted to the central‐southern Andes. This suggests that Chaco‐related and Andean genera had considerable levels of speciation in these valleys. Many genera and more than half the species have their northernmost distribution in the dry valleys of Bolivia, thereby underlining strong relationships with central‐southern South America (mainly Argentina, Paraguay and southern Brazil). The data supports the belief of the existence, in central‐southern Peru, of a floristic disjunction in dry to arid environments that separates a tropical dry flora north of this limit from a dry subtropical/warm temperate flora south of it. Main conclusions The Andean dry valleys of Bolivia are diverse plant communities with high levels of endemism (c. 18% of the species). The species of this region are more related to those present in central‐southern South America than to the flora of northern South America that ranges southwards to Peru. Many of the species have restricted distributions in the dry Andes of Bolivia and Argentina, and many genera of these dry valleys have their northernmost distribution in Bolivia/southern Peru, too. The data point to high levels of speciation also in the central Andes.     

Structure and genetic diversity in Colliguaja odorifera Mol. (Euphorbiaceae), a shrub subjected to Pleisto-Holocenic natural perturbations in a mediterranean South American region

Aim Colliguaja odorifera Mol., a Euphorbiaceous shrub of central Chile, inhabits the matorral formation, growing at low altitudes on both Andean and coastal mountain range slopes. In the recent geological past, this region was subjected to climatic changes and geological disturbances that most probably caused population shrinkages on the Andean mountain slopes. This study tested the hypothesis that under such a scenario, existing populations should show lower genetic diversity in the Andean than in the coastal areas; these coastal populations being the potential source populations for recolonization. Location The study was carried out in central Chile by comparing the genetic diversity between the Andean and coastal areas, each represented by five localities distributed from 32°30′ S to 34° S. Methods Genetic diversity was estimated by DNA analysis using 18 dominant multilocus Random Amplified Polymorphic DNA (RAPD) loci, characterizing 73 genetic phenotypes. Results The comparison of the two matorral areas showed that Andean populations of C. odorifera have a subset of the genetic diversity found in the coastal populations. Andean populations also show a consistently lower genetic diversity, lower genetic distances and higher genetic structure, coincident with expectations based on the Pleisto‐Holocenic perturbation regime. Main conclusions This first genetic analysis for South American mediterranean populations confirms the findings of previous floristic and palynological studies that identified refuge zones in the coastal mountain range of central Chile, a situation analogous with that occurring during periods of inter‐glacial northward migration in Southern Europe.     

Range-wide phylogeography of the European temperate-montane herbaceous plant Meum athamanticum Jacq.: evidence for periglacial persistence

Aim  The aim of this study is to analyse the genetic population structure of Meum athamanticum Jacq. in order to explore the alternative hypotheses (1) that the central and northern highland populations are the result of post-glacial recolonization from southern refugia, and the disjunct distribution of M. athamanticum can be explained by modern ecological conditions, or (2) that extant populations north of the Alps and Pyrenees persisted in situ during glacial periods.
Location  Europe.
Methods  Variation of amplified fragment length polymorphisms (AFLPs) was analysed for 23 populations from the entire range of the species. We used band-based approaches and methods based on allele frequencies to measure genetic diversity and to identify population structure.
Results  Our analyses reveal a north–south differentiation within M. athamanticum . High levels of genetic diversity, as well as private fragments, are found in populations both north and south of the Alps. Differentiation among populations is lower in the northern than in the southern population group, and significant isolation-by-distance is found only in the latter group.
Main conclusions  Our results indicate that M. athamanticum survived the last ice age in multiple refugia throughout its contemporary range and did not expand into areas north of the Alps from southern refugia. We found evidence that regional-scale migration in northern, formerly periglacial, parts of the species range has resulted in the intermingling of populations. In contrast, southern populations are characterized by long-term isolation. The south-west Alps represent an area where immigration and mixing of populations from northern and southern refugia appears to have taken place.     

Postglacial recolonization in a cold climate specialist in western Europe: patterns of genetic diversity in the adder (Vipera berus) support the central–marginal hypothesis

Understanding the impact of postglacial recolonization on genetic diversity is essential in explaining current patterns of genetic variation. The central–marginal hypothesis (CMH) predicts a reduction in genetic diversity from the core of the distribution to peripheral populations, as well as reduced connectivity between peripheral populations. While the CMH has received considerable empirical support, its broad applicability is still debated and alternative hypotheses predict different spatial patterns of genetic diversity. Using microsatellite markers, we analysed the genetic diversity of the adder (Vipera berus) in western Europe to reconstruct postglacial recolonization. Approximate Bayesian Computation (ABC) analyses suggested a postglacial recolonization from two routes: a western route from the Atlantic Coast up to Belgium and a central route from the Massif Central to the Alps. This cold‐adapted species likely used two isolated glacial refugia in southern France, in permafrost‐free areas during the last glacial maximum. Adder populations further from putative glacial refugia had lower genetic diversity and reduced connectivity; therefore, our results support the predictions of the CMH. Our study also illustrates the utility of highly variable nuclear markers, such as microsatellites, and ABC to test competing recolonization hypotheses.     

Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

Aim The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post‐glacial history of many high‐mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems – the Alps and the Carpathians. Location Alps and Carpathians. Methods The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results Neighbour joining and principal coordinate analyses revealed three well‐supported phylogeographical groups of populations corresponding to three disjunct geographical regions – the Alps and the western and south‐eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within‐population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region‐diagnostic markers than those from the south‐eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south‐western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south‐eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long‐term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps.     

Niche shifts and range expansions along cordilleras drove diversification in a high‐elevation endemic plant genus in the tropical Andes

The tropical Andes represent one of the world's biodiversity hot spots, but the evolutionary drivers generating their striking species diversity still remain poorly understood. In the treeless high‐elevation Andean environments, Pleistocene glacial oscillations and niche differentiation are frequently hypothesized diversification mechanisms; however, sufficiently densely sampled population genetic data supporting this are still lacking. Here, we reconstruct the evolutionary history of Loricaria (Asteraceae), a plant genus endemic to the Andean treeless alpine zone, based on comprehensive population‐level sampling of 289 individuals from 67 populations across the entire distribution ranges of its northern Andean species. Partly incongruent AFLP and plastid DNA markers reveal that the distinct genetic structure was shaped by a complex interplay of biogeography (spread along and across the cordilleras), history (Pleistocene glacial oscillations) and local ecological conditions. While plastid variation documents an early split or colonization of the northern Andes by at least two lineages, one of which further diversified, a major split in the AFLP data correlate with altitudinal ecological differentiation. This suggests that niche shifts may be important drivers of Andean diversification not only in forest–alpine transitions, but also within the treeless alpine zone itself. The patterns of genetic differentiation at the intraspecific level reject the hypothesized separation in spatially isolated cordilleras and instead suggest extensive gene flow among populations from distinct mountain chains. Our study highlights that leveraging highly variable markers against extensive population‐level sampling is a promising approach to address mechanisms of rapid species diversifications.