Changes in life‐history traits in an expanding moss species: phenotypic plasticity or genetic differentiation? A reciprocal transplantation experiment with Pogonatum dentatum

A transplant experiment was performed to investigate whether differences in life-history traits of the bryophyte Pogonatum dentatum that recently expanded its distribution range, were genetically or environmentally determined, or a combination of both. Plants were transplanted reciprocally between the original mountain area and a recently colonised lowland area. Vegetative biomass of annual segments and branches tended to be higher in the mountain area than in the lowland area. Reproductive investment was higher for plants transplanted to the lowland area, and lowland shoots tended to produce larger sporophytes than mountain shoots when placed in the same environment. Age of reproducing shoots showed no consistent pattern.
Native shoots were often outperformed by non-native shoots transplanted into the same site. Non-native shoots grew larger and produced larger sporophytes than native shoots. Much of the observed variation was at the site level instead of between mountain and lowland areas, with both genetic origin and environmental effects contributing together. Range expansion of P. dentatum may have taken place by dispersal from populations with shoots whose growth is plastic. Such shoots grow larger and potentially produce more spores for dispersal.     

THE HERITABLE BASIS OF VARIATION IN LARVAL DEVELOPMENTAL PATTERNS WITHIN POPULATIONS OF THE WOOD FROG (RANA SYLVATICA)

This study compares the heritable basis of variation in larval developmental patterns of mountain and lowland populations of the wood frog, Rana sylvatica. Additive genetic variances, heritabilities, and genetic correlations for larval developmental time and size at metamorphosis are estimated from half-sib and full-sib crosses. Considerable additive-genetic variances and high heritabilities are revealed for developmental time in both the mountain and the lowland population. There was a high level of additive-genetic variance and high heritability for body size at metamorphosis in the mountain population, but these were very low in the lowland population. The genetic correlations between developmental rate and larval body size are negative for the mountain population and near zero for the lowland population. It is argued that the differences in genetic structure between these two populations reflect differences in the selective regimes of their respective environments.     

Floral adaptation to local pollinator guilds in a terrestrial orchid

Background and Aims

Studies of local floral adaptation in response to geographically divergent pollinators are essential for understanding floral evolution. This study investigated local pollinator adaptation and variation in floral traits in the rewarding orchid Gymnadenia odoratissima, which spans a large altitudinal gradient and thus may depend on different pollinator guilds along this gradient.

Methods

Pollinator communities were assessed and reciprocal transfer experiments were performed between lowland and mountain populations. Differences in floral traits were characterized by measuring floral morphology traits, scent composition, colour and nectar sugar content in lowland and mountain populations.

Key Results

The composition of pollinator communities differed considerably between lowland and mountain populations; flies were only found as pollinators in mountain populations. The reciprocal transfer experiments showed that when lowland plants were transferred to mountain habitats, their reproductive success did not change significantly. However, when mountain plants were moved to the lowlands, their reproductive success decreased significantly. Transfers between populations of the same altitude did not lead to significant changes in reproductive success, disproving the potential for population-specific adaptations. Flower size of lowland plants was greater than for mountain flowers. Lowland plants also had significantly higher relative amounts of aromatic floral volatiles, while the mountain plants had higher relative amounts of other floral volatiles. The floral colour of mountain flowers was significantly lighter compared with the lowland flowers.

Conclusions

Local pollinator adaptation through pollinator attraction was shown in the mountain populations, possibly due to adaptation to pollinating flies. The mountain plants were also observed to receive pollination from a greater diversity of pollinators than the lowland plants. The different floral phenotypes of the altitudinal regions are likely to be the consequence of adaptations to local pollinator guilds.     

Factor interaction influencing the distribution of the freshwater “shrimp” Gammarus

Summary The enormous variation in the environmental factors of south-eastern Norway makes this area particularly suitable for field studies on the relationship between environmental factors and fauna. Lakes are abundant, from 1 to 1,837 m a.s.l., and the geology of the surroundings as well as acid precipitation influence their chemical characteristics. In lowland areas the distribution of Gammarus lacustris is related to how rich in lime the lakes are. Populations found in mountain lakes tolerate much lower levels of calcium and higher H⁺ concentrations than populations inhabiting lowland lakes. The lowland populations probably have a higher calcium demand when stressed by high temperature. We predict that factor interaction may be used to explain the distribution patterns of the species also in other parts of Europe.     

Altitudinal distribution of chytrid (Batrachochytrium dendrobatidis) infection in subtropical Australian frogs

The disappearance of amphibian populations from seemingly pristine upland areas worldwide has become a major focus of conservation efforts in the last two decades, and a parasitic chytrid fungus, Batrachochytrium dendrobatidis, is thought to be the causative agent of the population declines. We examined the altitudinal distribution of chytrid infections in three stream‐dwelling frog species (Litoria wilcoxii, L. pearsoniana and L. chloris) in southeast Queensland, Australia, and hypothesized that if B. dendrobatidis were responsible for the disappearance of high‐altitude frog populations, infection prevalence and intensity would be greatest at higher altitudes. Overall, 37.7% of the 798 adult frogs we sampled were infected with B. dendrobatidis, and infections were found in all the populations we examined. Contrary to our initial hypothesis, we found no consistent evidence that high‐altitude frogs were more likely to be infected than were lowland frogs. Further, the intensity of fungal infections (number of zoospores) on high‐altitude frogs did not differ significantly from that of lowland frogs. Batrachochytrium dendrobatidis appears to be capable of infecting frogs at all altitudes in the subtropics, suggesting that all populations are at risk of decline when conditions favour disease outbreaks. We did find evidence, however, that chytrid infections persist longer into summer in upland as compared with lowland areas, suggesting that montane amphibian populations remain susceptible to disease outbreaks for longer periods than do lowland populations. Further, we found that at high altitudes, temperatures optimal for chytrid growth and reproduction coincide with frog metamorphosis, the life‐stage at which frogs are most susceptible to chytrid infections. While these altitudinal differences may account for the differential population‐level responses to the presence of B. dendrobatidis, the reason why many of southeast Queensland's montane frog populations declined precipitously while lowland populations remained stable has yet to be resolved.     

Alien flora of mountains: global comparisons for the development of local preventive measures against plant invasions

Aim We use data from 13 mountain regions and surrounding lowland areas to identify (1) the origins, traits and cultural uses of alien plant species that establish in mountains, (2) the alien species that are most likely to be a threat and (3) how managers might use this information to prevent further invasions. Location Australia, Canada, Chile, India, New Zealand, South Africa, Spain, Switzerland, USA. Methods Lists of alien species were compiled for mountains and their surrounding or nearby lowlands. Principal co‐ordinates analysis was performed on a matrix of similarities created using presence/absence data for alien species. The significance of differences between means for (1) similarity metrics of lowland and mountain groups and (2) species traits of lowland and mountain alien floras was determined using t‐tests. In seven of the 13 mountain regions, lists of alien species undergoing management were compiled. The significance of differences between proportions of traits for species requiring and not requiring management input was determined with chi‐square tests. Results We found that the proximal lowland alien flora is the main determinant of a mountain region’s alien species composition. The highest similarities between mountain floras were in the Americas/Pacific Region. The majority of alien species commonly found in mountains have agricultural origins and are of little concern to land managers. Woody species and those used for ornamental purposes will often pose the greatest threat. Main conclusions Given the documented potential threat of alien species invading mountains, we advise natural resource managers to take preventive measures against the risk of alien plant invasion in mountains. A strategy for prevention should extend to the surrounding lowland areas and in particular regulate the introduction of species that are already of management concern in other mountains as well as climatically pre‐adapted alien mountain plants. These may well become more problematic than the majority of alien plants currently in mountains.     

Genetic variation in lowland and mountain populations of Tofieldia calyculata and their ability to survive within low levels of genetic diversity

Loss of genetic diversity is expected to be a reason behind the decline of populations of many rare species. To what extent this is true for populations at the range periphery remains to be explored. Alpine species with peripheral lowland populations are an ideal but little-known model system to address this issue. We used 17 microsatellite markers to investigate the genetic diversity and structure of populations of Tofieldia calyculata, a common species in central European mountains, but highly endangered in lowlands. We showed that lowland populations have lower genetic diversity than mountain populations and that the two groups of populations are not clearly differentiated genetically. The species probably survived the last glaciation in refugia in the margins of the Alps and the western Carpathians and some lowland populations likely originated by postglacial colonisation. Some lowland populations may be relictual, but our data did not unequivocally confirm this. Low genetic diversity of lowland populations is likely the result of the reduction of population sizes, limited gene flow, and selfing. Based on data from herbarium specimens from extinct lowland populations, within-population genetic diversity has not changed over the last century suggesting that, under suitable habitat conditions, these populations are able to survive with low levels of genetic diversity. This idea is also supported by the presence of large viable extant populations with very low genetic diversity. Comparisons between modern and historic collection also showed that a large proportion of genetic diversity was lost, due mainly to the extinction of whole populations. Our results provided detailed insight into the recent past of the populations of Tofieldia calyculata, but the genetic diversity of the populations before the twentieth century remains unknown due to the poor quality of old DNA from herbaria samples. Overall, the study indicates that despite reduced genetic diversity, the lowland populations harbour some unique alleles and, with the current levels of genetic diversity, have a chance to survive in the long-term, and thus deserve conservation.

     

Variability in the developmental life history of the genus Gorilla

Life history is influenced by factors both intrinsic (e.g., body and relative brain size) and extrinsic (e.g., diet, environmental instability) to organisms. In this study, we examine the prediction that energetic risk influences the life history of gorillas. Recent comparisons suggest that the more frugivorous western lowland gorilla shows increased infant dependence, and thus a slower life history, than the primarily folivorous mountain gorilla to buffer against the risk of starvation during periods of food unpredictability. We further tested this hypothesis by incorporating additional life history data from wild western lowland gorillas and captive western lowland gorillas with the assumption that the latter live under ecological conditions of energetic risk that more closely resemble those of mountain gorillas and thus should show faster life histories than wild members of the species. Overall, we found captive western lowland and wild mountain gorillas to have faster developmental life histories than wild western lowland gorillas, weaning their infants approximately a year earlier and thus reducing interbirth intervals by a year. These results provide support that energetic risk plays an important role in determining gorilla life history. Unlike previous assertions, gorillas do not have substantially faster life histories, at least at the genus level, than other great apes. This calls for a re‐evaluation of theories concerning comparative ape life history and evolution and highlights the need for data from additional populations that vary in energetic risk. Am J Phys Anthropol 152:165–172, 2013. © 2013 Wiley Periodicals, Inc.     

Ecomorphological and genetic divergence between lowland and montane forms of the Pieris napi species complex (Pieridae, Lepidoptera)

The present study aimed to investigate the morphological and genetic differentiation of lowland and montane populations of the Pieris napi species complex in Norway and to make inferences about the subspecific status of Pieris napi adalwinda and Pieris napi napi . We measured 22 morphological characters on 228 individuals from eight populations in Central Norway (20–1100 m a.s.l.). In addition, lowland and mountain animals were reared at a high altitude locality. Half the animals from either locality were reared on mountain plant, and the other half on a lowland plant. Finally, a fragment of the mitochondrial cytochrome b gene was sequenced for individuals from Central and South-eastern Norway and Germany. Principal component analysis of morphological characters showed a zone of abrupt change from lowland to mountain morphological character states between populations at 506 m and 730 m a.s.l., respectively. The transplant experiment showed that the morphological differences have a genetic basis and that food plants have no impact on morphology. Limited, but significant, molecular genetic differentiation was found between lowland and mountain animals, but the phylogenetic analysis, however, showed that the lowland form ( P. n. napi ) is paraphyletic and the montane form ( P. n. adalwinda ) is monophyletic. Further study is required before taxonomic recognition can be applied.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 727–745.     

Isozyme polymorphisms provide evidence of clinal variation with elevation in Nothofagus pumilio

Variable physical conditions along elevational gradients strongly influence patterns of genetic differentiation in tree species. Here, the hypothesis is tested that different growth forms of Nothofagus pumilio, which characterizes the subalpine forests in the southern Andes, will display continuous genetic variation with elevation. At each of four elevational strips in three different mountain ranges, fresh leaf tissue was sampled from 30 randomly selected individuals to be analyzed by protein electrophoresis. Allelic frequencies were used to test for heterogeneity across populations and to classify populations into different elevational strips by discriminant analysis. The degree of population divergence was estimated by F(ST). Clinical variation on within-population genetic characteristics was analyzed by linear regressions against elevation. Seven enzyme systems coded for 14 putative isozyme loci, 57% of which were polymorphic in at least one population. Allele frequencies significantly varied with elevation and discriminant analysis separated populations at different elevational strips. Among-population divergence within any mountain range was small, but greater than among different mountain ranges. Overall, low-elevation populations were more variable than high-elevation populations, and regression analyses suggested continuous variation in populations of N. pumilio 100 m apart. Marked stepwise phenological differences on mountain slopes are most probably responsible for the isolation of nearby populations.     

Why Do Floral Perfumes Become Different? Region-Specific Selection on Floral Scent in a Terrestrial Orchid

Geographically structured phenotypic selection can lead to adaptive divergence. However, in flowering plants, such divergent selection has rarely been shown, and selection on floral signals is generally little understood. In this study, we measured phenotypic selection on display size, floral color, and floral scent in four lowland and four mountain populations of the nectar-rewarding terrestrial orchid Gymnadenia odoratissima in two years. We also quantified population differences in these traits and pollinator community composition. Our results show positive selection on display size and positive, negative, or absence of selection on different scent compounds and floral color. Selection on the main scent compounds was consistently stronger in the lowlands than in the mountains, and lowland plants emitted higher amounts of most of these compounds. Pollinator community composition also differed between regions, suggesting different pollinators select for differences in floral volatiles. Overall, our study is the first to document consistent regional differences in selection on floral scent, suggesting this pattern of selection is one of the evolutionary forces contributing to regional divergence in floral chemical signaling.     

Population genetics of the East African White-eye species complex

The Eastern Afromontane biodiversity hotspot consists of isolated mountain massifs embedded within the dry lowland savannas of East Africa and of which the peaks and ridges are covered by cloud forest remnants. These cloud forests are home to the Mountain White-eye (Zosterops poliogaster), while three congeneric species (Abyssinian White-eye, Zosterops abyssinicus; Yellow White-eye, Zosterops senegalensis; Pemba White-eye, Zosterops vaughani) inhabit the adjacent lowland savannas. We sampled individuals of all four species across Kenya to analyse interspecific genetic relationships as well as intraspecific differentiation among mountain populations of Z. poliogaster. While the level of genetic differentiation among the four species was rather low, genetic differentiation within Z. poliogaster was very high, even between geographically neighbouring populations. Overall, levels of genetic variation varied strongly across all four species, with much higher diversity detected within the three lowland ones. The highland species was characterised by numerous private alleles that were geographically restricted at populations from single mountains, some of which showed evidence of recent population bottlenecks. We conclude that Z. poliogaster populations are both of high conservation value and conservation concern, given the high proportion of endemic alleles and the genetic signatures of high genetic drift and low gene flow that are typical for small and isolated populations.     

Invasion by Fallopia spp. in a French upland region is related to anthropogenic disturbances

Within Europe, mountain ecosystems are generally less invaded by exotic plant species than are lowland areas. This pattern is commonly attributed to climatic harshness, which limits invasive species presence, and higher propagule pressure and rates of disturbance in lowlands, which favours dissemination. However, the extent to which anthropogenic and natural disturbances contribute to invasive species presence in mountain and lowland environments remains unclear. We conducted field observations in a lowland and an upland region in France and measured environmental variables, estimated the natural and anthropogenic disturbance of plots invaded by Fallopia spp. and compared them to non-invaded plots. Based on generalised linear mixed models, the predictors of Fallopia spp. presence in the upland area only included anthropogenic elements such as the presence of a road or trail and frequentation by humans, whereas both anthropogenic parameters and natural components (light penetration, slope, presence of a road and of a watercourse) were retained as predictors for the lowland region. We calculated the odds of Fallopia spp. presence for the increase of one unit of each predictor. We conclude that the spread of Fallopia spp. in upland areas was mainly linked to human activity whereas dissemination of the species occurred both through humans and in natural ways in lowland areas, and this may be due to a more recent colonisation in the mountains. We therefore advise stakeholders to undertake actions in mountain areas to specifically limit the dissemination of exotic species by humans and to monitor areas of high invasion risk by exotic species, such as areas neighbouring trails and roads highly frequented by humans.     

Southern Scandinavian lowland populations of Rhytidium rugosum (Hedw.) Kindb. (Bryophyta,Rhytidiaceae) differ significantly from those in the mountains

Abstract

Haplotype diversity patterns based on internal transcribed spacer (ITS) and gpd (glyceraldehyde 3-phosphate dehydrogenase) in Scandinavian Rhytidium rugosum were compared between four populations from the mountain range and two in the southern lowlands. The mountain populations differ from the southern lowland ones in haplotype composition and the lowland ones differ from each other, suggesting different histories. A coalescent-based analysis (LAMARC) indicated immigration into the population now found in the mountains from that represented in the lowlands. Because several factors argue against such a dispersal scenario within the relatively short postglacial period, it is proposed that these migration patterns are older than the postglacial period. It is suggested that the mountain range populations immigrated from a source population either in the north-east or within Scandinavia, whereas the lowland populations are likely to represent remains of the glacial population of lowland Europe. The highest haplotype diversity in Scandinavia was found in the Gudbrandsdalen area in southern Norway. This is probably explained by the fact that this is the only region in Europe where R. rugosum regularly reproduces sexually. The lowest diversity was found on the Great Alvar on the island of Öland off the Baltic coast of southern Sweden, and is most likely a result of gradual loss of haplotypes over time.     

The genetic basis of altitudinal variation in the wood frog Rana sylvatica II. An experimental analysis of larval development

Summary The variation in larval developmental patterns in the wood frog, Rana sylvatica, along an elevation gradient of 1,000 m was experimentally studied. Larval populations at high elevation ponds had lower growth rates, developmental rates and were larger at all stages (including metamorphic climax) than larval populations developing in low elevation ponds. There was considerable variation among ponds within each elevation in both the length of the larval period and size at metamorphic climax. Reciprocal transplant experiments and controlled laboratory experiments revealed that most of the observed variation between high and low elevation populations could be explained by the effects of temperature induction during ontogeny. Significant genetic differences in growth rates and non-genetic maternal effects on developmental rates between larvae of mountain origin and lowland origin were also demonstrated. Selection in both environments has acted to minimize the prevailing environmental effect of pond temperature on developmental rates, but has accentuated the prevailing environmental effects on larval body size. As a consequence mountain larvae were capable of completing metamorphosis sooner and at a larger size in all environments than lowland larvae.     

Changes in body melanisation and desiccation resistance in highland vs. lowland populations of D. melanogaster

Wild caught samples of Drosophila melanogaster from five highland localities showed parallel changes in melanisation and desiccation resistance in darker versus lighter phenotypes, i.e. darker flies (>45% melanisation) showed significantly higher desiccation resistance than lighter flies (<30% melanisation). In order to find an association between body melanisation and desiccation resistance, highland and lowland populations from tropical and subtropical regions (11.15-31.06 degrees N) of the Indian subcontinent were raised and investigated at 21 degrees C for four physiological traits, i.e. per cent body melanisation, desiccation resistance, rate of water loss and rate of water absorption. On the basis of mother-offspring regression, body melanisation and desiccation resistance showed higher heritability (0.58-0.68) and thus these traits are suitable for laboratory analyses. Significantly higher melanisation as well as desiccation resistance were observed in highland populations as compared with lowland populations. The rates of water loss as well as absorption were negatively correlated with body melanisation, i.e. darker flies from highlands showed a reduced rate of water loss as well as a lower rate of water absorption while the reverse trend was observed in lighter flies from lowlands. On the basis of multiple regressions, significant effects due to combined altitude and latitude were observed for all the four physiological traits. Local climatic conditions (i.e. annual average temperature and relative humidity) helped in explaining parallel changes in body melanisation and desiccation resistance in D. melanogaster.     

Leaf‐litter colonisation and breakdown in relation to stream typology: insights from Mediterranean low‐order streams

1. Scant information is available on leaf breakdown in streams of arid and semiarid regions, including the Mediterranean, where environmental heterogeneity can be high and the relationship between stream characteristics and leaf breakdown is poorly known. We tested the hypotheses that differences in leaf breakdown metrics would be substantially higher between mountain and lowland Mediterranean streams than among streams within each subregion and that variability among streams would be substantially higher in the lowlands, because permanent reaches in the semiarid lowland streams are rare and isolated. 2. We compared leaf breakdown and associated dynamics of nutrients, fungi and invertebrates in low‐order Mediterranean streams draining sub‐humid forests in the Sierra Nevada Mountains and nearby semiarid lowlands of south‐eastern Spain. Streams differed between the two subregions mainly in water ion content, temperature and riparian tree cover. We detected higher environmental heterogeneity among streams within the lowlands compared to the Sierra Nevada mountain range. In the lowlands, breakdown coefficients (k) of alder leaves spanned almost the entire range reported for this species from temperate streams, overlapping with less variable breakdown coefficients in the Sierra Nevada. 3. The high variability of k values among the lowland sites appeared to be caused primarily by variability in the composition and abundance of a few leaf‐consuming invertebrate taxa, particularly the snail Melanopsis praemorsa. Fungal and nutrient dynamics were less variable among sites within each subregion. 4. These results indicate that the critical condition for stream functional assessment of well‐constrained breakdown rates, or related metrics, could be met at reference sites within homogenous bio‐geo‐climatic regions such as the Sierra Nevada. By contrast, in heterogeneous areas such as the semiarid lowland streams, natural variability of breakdown rates can greatly exceed the magnitude of effects expected in response to anthropogenic disturbances.     

渭河底栖动物性状和功能对空间尺度环境变量响应的生态区差异性

以我国中部渭河南部流域山区和平原生态区的底栖动物为研究对象,通过计算29个生物性状类别和7个功能多样性指数,比较了不同生态区的生物性状组成和功能与性状多样性指数差异性;应用综合RLQ和fourth-corner方法探索底栖动物生物性状组成与土地利用和理化变量的关系;通过广义线性模型(GLM)比较不同空间尺度环境变量对底栖动物功能与性状多样性指数影响的生态区差异性。研究发现,共18个底栖动物性状组成在山区和平原间存在显著差异性,其中具有无庇护所和以叶片为庇护所材料、外骨骼轻微骨化和骨化良好、草食性、捕食性等生物性状的底栖动物栖息于栖境状况较好的山区,体壁呼吸、虫体柔软、集食者等生物性状更多的集中在人类活动较严重的平原区。除了功能均匀度指数外,山区的性状和功能多样性指数均显著高于平原,说明平原环境干扰显著降低了底栖动物性状和功能多样性。综合RLQ和fourth-corner方法表明底栖动物生物性状对环境胁迫的响应存在可预测性。GLM模型结果表明,山区和平原生物性状和功能多样性指数受到不同空间尺度土地利用和理化环境变量的影响:流域尺度城镇用地、水温和TN含量是影响山区功能和性状多样性指数模型的重要环境变量,但平原区河段尺度农业用地面积百分比和平均水深是影响功能和性状多样性的主要因子。     

Age and size at maturity in mountain and lowland populations of the expanding moss <Emphasis Type="Italic">Pogonatum dentatum</Emphasis>

The moss Pogonatum dentatum has expanded its distribution in Fennoscandia from mountainous areas into the lowlands. This recent expansion appears to be associated with changes in important life-history parameters in female shoots. We examined shoot age and size at first production of sex organs and mature spores in P. dentatum to investigate this phenomenon. Female shoots produced mature spores for the first time in the lowlands in their second year but in their third year in the mountains. However, sex organs were produced by second year plants in both areas. There was no size difference between the mountain and lowland female shoots at the time of spore production. Among mountain females reproducing for the first time, 41% of the shoots branched, making them potentially ‘iteroparous’. Branching was not observed among lowland females. Male shoots showed no difference in production of sex organs, and were produced by second year shoots in both areas. Female shoots in the lowlands have earlier spore production and exhibit ‘semelparous’ behaviour by not producing branches. This suggests that the lowland phenotypes of P. dentatum are more ‘invasive’ than the mountain phenotypes. Earlier studies showing high rates of diaspore establishment in lowland areas also support this observation.     

Genetic variation and structure in the expanding moss Pogonatum dentatum (Polytrichaceae) in its area of origin and in a recently colonized area

Genetic variation in the expanding moss species Pogonatum dentatum was studied using intersimple sequence repeat (ISSR) markers. The genetic consequences of range expansion were studied by comparing source populations in a mountain area with populations from a recently colonized lowland area in Sweden. Indices of genetic variation show slightly lower number of alleles per locus in the lowlands and a similar gene diversity in both areas. Three of four lowland populations had evidence of a recently passed bottleneck. Considerably higher haplotype diversity was found in the recently colonized lowlands compared to source populations in the mountains. Patterns of allelic diversity suggest that P. dentatum experiences loss of genetic variation through founder effects and genetic drift when expanding its distribution range. Higher haplotypic diversity, less linkage disequilibrium, and fewer compatible loci indicate that sexual recombination is relatively more important in the lowlands compared to the mountains. A likely explanation is higher success of establishment from spores in the lowlands, while clonal propagation predominates in the mountains. Less genetic differentiation among lowland populations indicates more gene flow in the lowland area, involving more spores and/or fragments moving among populations.