The Pleistocene demography of an alpine juniper of the Qinghai‐Tibetan Plateau: tabula rasa,cryptic refugia or something else?

Aim Numerous palaeoecological and genetic studies have shown that different tree species responded in very different ways to Pleistocene climatic oscillations. Some were forced into small refugia far from their current range, while others were able to survive in small refugia close to, or even within, their current natural range. In this study we examine the Pleistocene demography of a juniper species (Juniperus przewalskii, Cupressaceae) from the Qinghai‐Tibetan Plateau. Location The Qinghai‐Tibetan Plateau (QTP). Methods Eight nuclear loci were sequenced in 141 individuals from 20 natural populations distributed across the entire natural range of J. przewalskii, and coalescent analysis was used to test demographic hypotheses. Results The overall nucleotide diversity in the sample was low (π_sil = 0.0029), with few rare alleles and pronounced population genetic structure (F_ST = 0.181). We detected a division previously found using chloroplast DNA markers: all segregating sites in populations from the central part of the QTP appear to be a subset of those found around the edge of the plateau, confirming the relatively young age of the former. In contrast to the middle Pleistocene bottlenecks detected in boreal tree species, the coalescent‐based analyses failed to reject the standard neutral model for the juniper species considered here. Main conclusions Juniperus przewalskii did not undergo marked changes in population sizes during the Pleistocene, although this species seems to have experienced recent, post‐glacial expansion. This finding is largely consistent with the limited number of previous studies on conifer species of the QTP, but contradicts findings of studies on boreal species. These findings have wide implications for understanding plant species’ responses to past climatic oscillations on the high‐elevation QTP.     

Past,present, and future geographic range of the relict Mediterranean and Macaronesian Juniperus phoenicea complex

AimThe aim of this study is to model the past, current, and future distribution of J. phoenicea s.s., J. turbinata, and J. canariensis, based on bioclimatic variables using a maximum entropy model (Maxent) in the Mediterranean and Macaronesian regions.LocationMediterranean and Macaronesian.TaxonCupressaceae, Juniperus.MethodsData on the occurrence of the J. phoenicea complex were obtained from the Global Biodiversity Information Facility (GBIF.org), the literature, herbaria, and the authors’ field notes. Bioclimatic variables were obtained from the WorldClim database and Paleoclim. The climate data related to species localities were used for predictions of niches by implementation of Maxent, and the model was evaluated with ENMeval.ResultsThe potential niches of Juniperus phoenicea during the Last Interglacial period (LIG), Last Glacial Maximum climate (LGM), and Mid‐Holocene (MH) covered 30%, 10%, and almost 100%, respectively, of the current potential niche. Climate warming may reduce potential niches by 30% in RCP2.6 and by 90% in RCP8.5. The potential niches of Juniperus turbinata had a broad circum‐Mediterranean and Canarian distribution during the LIG and the MH; its distribution extended during the LGM when it was found in more areas than at present. The predicted warming in scenarios RCP2.6 and RCP8.5 could reduce the current potential niche by 30% and 50%, respectively. The model did not find suitable niches for J. canariensis during the LIG and the LGM, but during the MH its potential niche was 30% larger than at present. The climate warming scenario RCP2.6 indicates a reduction in the potential niche by 30%, while RCP8.5 so indicates a reduction of almost 60%.Main conclusionsThis research can provide information for increasing the protection of the juniper forest and for counteracting the phenomenon of local extinctions caused by anthropic pressure and climate changes.     

Ecological status of the Mediterranean Juniperus phoenicea L. Relicts in the desert mountains of North Sinai,Egypt

Juniperus phoenicea L. is listed as threatened tree by IUCN Red List. In Egypt, J. phoenicea L. is the only conifer tree that is restricted to the three mountains of northern Sinai: Gabal El-Halal, Gabal El-Maghara and Gabal Yelleq. As a Mediterranean relict it has been included in a national list as target for conservation and management. To provide baseline information for the development of a conservation strategy, the present study aims at comparing the isolated populations of J. phoenicea and their associated plant composition and diversity at the three mountains. The application of TWINSPAN and DCA analysis techniques has resulted in identifying of four vegetation types associated with juniper, and each could be related to a specific geomorphologic habitat on a topographic gradient. Chiliadenus montanus and Zygophyllum dumosum characterized the slopes of smooth-faced rock outcrops in Wadi Abu Seyal (at 350–470 m altitude of Gabal El-Halal), Deverra tortuosa, Ephedra aphylla and Gymnocarpos decander inhabited together with the target species the soil pockets of north-facing slope in Neqeb Abu Hamam (at 600–700 m altitude of Gabal El-Halal), Stachys aegyptiaca and Moricandia nitens characterized the juniper occurrences in the runnels of Wadi Arar (at 450–560 m altitude of Gabal El-Maghara), and Artemisia herba-alba, Atriplex halimus and Reaumuria hirtella represent the stands on slope runnels (at 900–960 m) of Gabal Yelleq. The two vegetation types recognized at Gabal El-Halal had, on average, the highest species diversity, juniper density and cover. Juniper shows generally poor conditions of vitality at higher elevation (600–960 m) with a higher proportions of old and recent dead trees, and with the predominance of male individuals, as compared with the populations of Gabal El-Maghara and Gabal Yelleq. In contrast, the juniper populations at lower elevation (350–470 m) of Gabal El-Halal proved to be in best condition with mostly living foliage and reproductive branches. The differences in rock types and elevation among the three mountains reflect serious limitation on recruitment of J. phoenicea due to moisture availability. The results of this study showed that J. phoenicea is an endangered species and its conservation in northern Sinai mountains is a priority. For a successful conservation of this community it is highly recommended to preserve in particular the suitable habitats at Gabal El-Halal, but also the other stands merit conservation measures.     

Genetic Diversity and Population Structure of Juniperus rigida (Cupressaceae) and Juniperus coreana

Enzyme electrophoresis was used to estimate genetic diversity and population structure of Juniperus rigida (Cupressaceae) and Juniperus coreana in Korea. In J. rigida, 16 of the 22 loci (72.7%) showed detectable polymorphism. Genetic diversity (0.224) was higher than average values for species with similar life history traits. The endemic species (J. coreana) was found to have fewer alleles per locus (1.39 vs. 1.61), fewer alleles per polymorphic locus (2.42 vs. 2.63), lower percent polymorphic locus (54.6 vs. 72.7%), and lower diversity (0.199 vs. 0.224) than J. rigida. These genetic diversity parameters indicated that J. coreana was genetically depauperate relative to its presumptive progenitor, J. rigida. Analysis of fixation indices showed a substantial deficiency of heterozygotes relative to Hardy–Weinberg expectations suggesting inbreeding in J. coreana. The G _ST values of J. rigida and J. coreana were 0.173 and 0.118 respectively. The indirect estimate of gene flow based on mean G _ST was moderate (Nm = 1.19 for J. rigida and 1.86 for J. coreana). This revised version was published online in July 2006 with corrections to the Cover Date.     

Re-evaluation of morphological and chloroplast DNA variation in Juniperus osteosperma Hook and Juniperus occidentalis Torr. Little (Cupressaceae) and their putative hybrids

Relationships between variation in cpDNA and morphology were examined to test the hypothesis of hybridization between Juniperus osteosperma and Juniperus occidentalis. Principal components analysis of 11 taxonomically-important characters distinguished individuals collected from eastern Nevada and Utah from those of southern Oregon. In contrast, many individuals collected from sympatric populations in western Nevada were morphologically intermediate to these two groups. Comparative sequencing of the trnS-trnG intergenic spacer and restriction site analysis of a trnL-trnF PCR product revealed nine haplotypes, and examination of haplotype-morphology associations allowed identification of species-specific genetic markers as well as those that transcend species limits. The confinement of morphological intermediacy and transcendent haplotypes to zones of sympatry, the discovery of haplotypes characteristic of one species in the morphological background of the other, and determination that the character intermediacy encountered is of the type expected under interspecific gene flow are marshaled in support of introgressive hybridization between J. osteosperma and J. occidentalis.     

Population genetic evidence for complex evolutionary histories of four high altitude juniper species in the Qinghai-Tibetan Plateau

Population genetics data based on multiple nuclear loci provide invaluable information to understand demographic, selective, and divergence histories of the current species. We studied nucleotide variation at 13 nuclear loci in 53 populations distributed among four closely related, but morphologically distinct juniper species of the Qinghai-Tibetan Plateau (QTP). We used a novel approach combining Approximate Bayesian Computation and a recently developed neutrality test based on the maximum frequency of derived mutations to examine the demographic and selective histories of individual species, and isolation-with-migration analyses to study the joint history of the species and detect gene flow between them. We found that (1) the four species, which diverged in response to the extensive QTP uplifts, have different demographic histories; (2) two loci, Pgi and CC0822, depart significantly from neutrality in one species and Pgi, is also marginally significant in another; and (3) shared polymorphisms are common, indicating both incomplete lineage sorting and gene flow after species divergence. In addition, the detected unidirectional gene flow provides indirect support for the theoretical prediction that introgression should mostly take place from local to invading species. Our results, together with previous studies, underscore complex evolutionary histories of plant diversification in the biodiversity-hotspot QTP.     

Late Pleistocene climate change promoted divergence between Picea asperata and P. crassifolia on the Qinghai–Tibet Plateau through recent bottlenecks

Divergence during the early stage of speciation can be driven by a population bottleneck via reduced gene flow and enhanced lineage sorting. In this study, we aimed to examine whether such bottlenecks occurred during the initial speciation of two closely related spruce species Picea asperata and P. crassifolia occurring on the Qinghai–Tibet Plateau (QTP). We analyzed sequences of three chloroplast, two mitochondrial DNA fragments and a further 13 nuclear loci from 216 individuals of the two species. Both species showed a low level of genetic diversity in contrast to other congeners occurring in the QTP and adjacent regions. The estimated population sizes of P. asperata and P. crassifolia are less than the ancestral population size before splitting. These results together with multiple statistical tests (Tajima's D, Fu and Li's D* and F*) suggest that these two species underwent recent bottlenecks. Based on approximate Bayesian computation (ABC), we also determined that the period of the population shrinkage was consistent with the interspecific divergence during the late Pleistocene. The reduced population sizes and the divergent selection may together have triggered the initial divergence under high gene flow between these two species. Our results therefore highlight the importance of climatic oscillations during the late Pleistocene in promoting speciation through changing demographic sizes of the ancestral species on the QTP and in adjacent regions.     

Demographic and spatial analysis of a population of Juniperus oxycedrus L. in an abandoned grassland

A study of the structural, dynamic, and space occupancy characteristics of a prickly juniper (Juniperus oxycedrus) population developed on an abandoned secondary grassland of the Central Apennines (Italy), is presented here. The data were collected from a permanent plot, limited by mixed deciduous woods dominated by Ostrya carpinifolia Scop. by a plantation of Pinus nigra Arnold, and by a forest road, and consisting of 1744 prickly juniper individuals, as well as other pre-forest and forest species. The age and sex distributions of this population were assessed. With these data, the age pyramid was constructed, within which three developmental phases of the population became apparent, as confirmed by a study of the logistic curve of development of the population. Based on an estimate of the intensity function of the spatial distribution of the prickly juniper individuals, the hypothesis of complete randomness has to be rejected. On the other hand, the correlation between sex and population density was significant. The mode of space occupancy of the prickly juniper population was investigated also with respect to the other populations of shrubs and forest species. It was shown to spread out in all directions, following lines of diffusion that could be randomly determined. Finally, the presence, within the plot, of some pasture areas not occupied by prickly juniper may be derived from lack of germination of the fruits, or development of the seedlings owing to unfavourable micro-environmental conditions.     

The colonization history of Juniperus brevifolia (Cupressaceae) in the Azores Islands

Background

A central aim of island biogeography is to understand the colonization history of insular species using current distributions, fossil records and genetic diversity. Here, we analyze five plastid DNA regions of the endangered Juniperus brevifolia, which is endemic to the Azores archipelago.

Methodology/Principal Findings

The phylogeny of the section Juniperus and the phylogeographic analyses of J. brevifolia based on the coalescence theory of allele (plastid) diversity suggest that: (1) a single introduction event likely occurred from Europe; (2) genetic diversification and inter-island dispersal postdated the emergence of the oldest island (Santa Maria, 8.12 Ma); (3) the genetic differentiation found in populations on the islands with higher age and smaller distance to the continent is significantly higher than that on the younger, more remote ones; (4) the high number of haplotypes observed (16), and the widespread distribution of the most frequent and ancestral ones across the archipelago, are indicating early diversification, demographic expansion, and recurrent dispersal. In contrast, restriction of six of the seven derived haplotypes to single islands is construed as reflecting significant isolation time prior to colonization.

Conclusions/Significance

Our phylogeographic reconstruction points to the sequence of island emergence as the key factor to explain the distribution of plastid DNA variation. The reproductive traits of this juniper species (anemophily, ornithochory, multi-seeded cones), together with its broad ecological range, appear to be largely responsible for recurrent inter-island colonization of ancestral haplotypes. In contrast, certain delay in colonization of new haplotypes may reflect intraspecific habitat competition on islands where this juniper was already present.     

Genetic structure and seed-mediated dispersal rates of an endangered shrub in a fragmented landscape: a case study for Juniperus communis in northwestern Europe

Background

Population extinction risk in a fragmented landscape is related to the differential ability of the species to spread its genes across the landscape. The impact of landscape fragmentation on plant population dynamics will therefore vary across different spatial scales. We quantified successful seed-mediated dispersal of the dioecious shrub Juniperus communis in a fragmented landscape across northwestern Europe by using amplified fragment length polymorphism (AFLP) markers. Furthermore we investigated the genetic diversity and structure on two spatial scales: across northwestern Europe and across Flanders (northern Belgium). We also studied whether seed viability and populations size were correlated with genetic diversity.

Results

Unexpectedly, estimated seed-mediated dispersal rates were quite high and ranged between 3% and 14%. No population differentiation and no spatial genetic structure were detected on the local, Flemish scale. A significant low to moderate genetic differentiation between populations was detected at the regional, northwest European scale (PhiPT = 0.10). In general, geographically nearby populations were also genetically related. High levels of within-population genetic diversity were detected but no correlation was found between any genetic diversity parameter and population size or seed viability.

Conclusions

In northwestern Europe, landscape fragmentation has lead to a weak isolation-by-distance pattern but not to genetic impoverishment of common juniper. Substantial rates of successful migration by seed-mediated gene flow indicate a high dispersal ability which could enable Juniperus communis to naturally colonize suitable habitats. However, it is not clear whether the observed levels of migration will suffice to counterbalance the effects of genetic drift in small populations on the long run.     

Preference and performance of Lepidoptera varies with tree age in juniper woodlands

1. As trees age, they undergo significant physiological and morphological changes. Nevertheless, tree ontogeny and its impacts on herbivores are often overlooked as determinants of plant–herbivore population dynamics and the strength of plant–herbivore interactions. 2. Juniperus (Cupressaceae) is a dominant, long‐lived conifer that serves as the sole host to a specialised assemblage of caterpillars. Over the past 150 years, several juniper species in western North America have expanded their geographic occupancy at local and regional scales, which has resulted in an increase in the number of immature trees on the landscape. Using assays in the laboratory, the effects of tree ontogeny on caterpillar performance and oviposition preference for two juniper specialist caterpillars, Callophrys gryneus (Lycaenidae) and Glena quinquelinearia (Geometridae), were examined. The study considered whether responses to tree ontogeny were consistent across caterpillar species and juniper host species. 3. Tree age was found to be a reliable predictor of caterpillar performance, with caterpillars developing more quickly and growing larger when fed foliage from young trees. Differences in the phytochemical diversity between foliage from trees of different ages might help to explain observed differences in caterpillar performance. Interestingly, the specialist butterfly, C. gryneus, displayed an oviposition preference for foliage from old‐growth Juniperus osteosperma trees, despite the fact that larvae of this species performed poorly on older trees. 4. It is concluded that young juniper trees are an important resource for the specialised Lepidopteran community and that tree ontogeny is an important component of intraspecific variation, which contributes to the structure of plant–herbivore communities.     

Can the site conditions required for successful natural regeneration of juniper (Juniperus communis L.) be determined from a single species survey?

Background: Ecological surveys often aim to inform biodiversity conservation policy and practice. Survey types differ; all require clear aims and good design. A survey in Scotland was carried out to measure the distribution and health of juniper (Juniperus communis) and potential for its natural regeneration.

Aims: Explore if one-off national surveys can inform conservation action by examining, as an example, the Scottish juniper data set to: (1) determine site conditions favourable for juniper regeneration, (2) provide recommendations for site management for regeneration.

Methods: Associations between site conditions and juniper occurrence were investigated with principal component analysis (PCA) and using species distribution modelling (SDM). To identify changes in site conditions over time, we compared degree of site suitability for natural regeneration (PCA distance) and population age structure.

Results: Twenty-one per cent of the sites showed juniper regeneration. Compared to all juniper sites, conditions at regenerating sites were different (e.g. climatically wetter, lower site fertility). Change over time in conditions was suggested by patterns in population age structure.

Conclusions: Following the establishment of a juniper population, site conditions may change, becoming unsuitable for natural regeneration. Historical site information to confirm this is lacking. We cannot answer fundamental questions about the causal mechanisms of the natural regeneration of juniper and question whether one-off survey data can inform conservation management.     

Diet breadth of mammalian herbivores: nutrient versus detoxification constraints

Two hypotheses, nutrient constraints and detoxification limitation, have been proposed to explain the lack of specialists among mammalian herbivores. The nutrient constraint hypothesis proposes that dietary specialization in mammalian herbivores is rare because no one plant can provide all requisite nutrients. The detoxification limitation hypothesis suggests that the mammalian detoxification system is incapable of detoxifying high doses of similar secondary compounds present in a diet of a single plant species. We experimentally tested these hypotheses by comparing the performance of specialist and generalist woodrats (Neotoma) on a variety of dietary challenges. Neotoma stephensi is a narrow dietary specialist with a single species, one-seeded juniper, Juniperus monosperma, comprising 85–95% of its diet. Compared with other plants available in the habitat, juniper is low in nitrogen and high in fiber, phenolics, and monoterpenes. The generalist woodrat, N. albigula, also consumes one-seeded juniper, but to a lesser degree. The nutrient constraint hypothesis was examined by feeding both species of woodrats a low-nitrogen, high-fiber diet similar to that found in juniper. We found no differences in body mass change, or apparent digestibility of dry matter or nitrogen between the two species of woodrats after 35 days on this diet. Moreover, both species were in positive nitrogen balance. We tested the detoxification limitation hypothesis by comparing the performance of the generalist and specialist on diets with and without juniper leaves, the preferred foliage of the specialist, as well as on diets with and without α-pinene, the predominant monoterpene in juniper. We found that on the juniper diet, compared with the specialist, the generalist consumed less juniper and lost more mass. Urine pH, a general indicator of overall detoxification processes, declined in both groups on the juniper diet. The generalist consumed half the toxin load of the specialist yet its urine pH was slightly lower. Moreover, the generalist consumed significantly less of the treatment with high concentrations of α-pinene compared to the control treatment, while the specialist consumed the same amount of food regardless of α-pinene concentration. For both groups, urine pH declined as levels of α-pinene in the diet increased. The generalist produced a significantly more acidic urine than the specialist on the treatment with the highest α-pinene concentration. Our results suggest that in this system, specialists detoxify plant secondary compounds differently than generalists and plant secondary compounds may be more important than low nutrient levels in maintaining dietary diversity in generalist herbivores. Received: 5 May 1999 / Accepted: 14 November 1999     

Influence of Juniper on Montezuma Quail Habitat Use in Texas

Montezuma quail (Cyrtonyx montezumae) inhabit oak (Quercus spp.)-juniper (Juniperus spp.) woodlands throughout Mexico and the southwestern United States. In Texas, USA, Montezuma quail occur in the Edwards Plateau and Trans-Pecos Mountains and Basins (Trans-Pecos), 2 ecoregions with contrasting juniper patterns. Ashe juniper (Juniperus ashei) dominates in the Edwards Plateau and has been increasing over decades, whereas alligator juniper (Juniperus deppeana) is a co-dominant in the Trans-Pecos and appears to have stable Montezuma quail populations. Our objectives were to compare between ecoregions the relative abundance and habitat use of Montezuma quail in relation to juniper and quantify the influence of juniper on key features of Montezuma quail habitat (grass height, grass cover, forb cover, and forb species richness). We conducted a study from March–August 2018‒2020 in the Edwards Plateau (Kinney and Edwards counties) and Trans-Pecos ecoregions (Jeff Davis County) to evaluate these objectives. We conducted call-back surveys to estimate relative abundance (number of detections/hr) of Montezuma quail and identify used locations. We collected vegetation data at a micro-scale (16-m) at used (n = 32–30 points) and random locations (n = 70–60 points) in each ecoregion. Relative abundance of Montezuma quail was considerably lower in the Edwards Plateau (0.06 ± 0.01 detections/survey hr; ± SE) than in the Trans-Pecos (1.10 ± 0.30 detections/survey hr). In addition, Montezuma quail selected areas of low Ashe juniper cover (<23% cover), density (<7 trees/80 m²), and height (<2 m) in the Edwards Plateau but selected areas of high alligator juniper cover (>18% cover), density (>4 trees/80 m²), and height (2–8 m) in the Trans-Pecos. Moreover, Ashe juniper cover had a significant, negative influence on herbaceous features, whereas alligator juniper exerted little to no influence. Our results suggest that these 2 juniper species have contrasting effects on Montezuma quail space use and their habitat, possibly as a result of the contrasting influence of these junipers on herbaceous understory. Creating habitat for Montezuma quail in the Edwards Plateau generally will involve the reduction of Ashe juniper and creating patches that possess juniper trees of small stature (<2 m) with low amounts of cover (<23%) and density (<7 trees/80 m²), whereas management in the Trans-Pecos will require site-specific assessments based on current alligator juniper influence. © 2021 The Wildlife Society.     

Dendroclimatological potential of three juniper species from the Turkestan range,northwestern Pamir-Alay Mountains,Uzbekistan

Key message

Intensity and magnitude of the growth-climate relationship depends on juniper species and sites. Juniperus seravschanica at low elevations shows highest potential for April–September drought reconstruction in the Turkestan range (Pamir-Alay), Uzbekistan.

Abstract

We present a detailed dendroclimatological study of three juniper species, Juniperus seravschanica Kom., Juniperus semiglobosa Regel and Juniperus turkistanica Kom., sampled at six sites of different elevation (2100–2700 m a.s.l.), exposition (west and south) and steepness (10°–30°) in the Zaamin National Park, Turkestan range, Pamir-Alay mountain system in eastern Uzbekistan. Simple correlation statistics and redundancy analyses were applied to detect species- and site-specific climate responses during the twentieth century, which were additionally investigated in the high-frequency domain by identifying extreme growth years. Our results show that tree-ring formation of J. seravschanica at our low-elevation site is strongly limited by April to September drought conditions, while J. semiglobosa inherits a weak and variable climate response with respect to elevation. J. turkistanica growth at high altitudes is positively associated with warm spring and summer temperatures. Species-specific growth extremes are triggered by incoming air masses from the Atlantic and Arctic, highlighting the connection of synoptic climate regimes across Eurasia. From a dendroclimatic perspective, J. seravschanica exhibits a high potential for reconstructing past drought and pluvials, but under sustained temperature rise also J. semiglobosa will likely increase its sensitivity to drought. Moreover, J. turkistanica at its distribution limit at the tree line is a suitable proxy of summer temperature. Our findings clearly demonstrate that a careful selection of the site, overall topography and elevation as well as the different juniper species are important for successfully reconstructing past climate in Uzbekistan.

     

Cryptic speciation between Juniperus deltoides and Juniperus oxycedrus (Cupressaceae) in the Mediterranean

Analyses of individuals classically treated as Juniperus oxycedrus L. var. oxycedrus from Morocco, Portugal, Spain, France, Italy, Greece and Turkey, using DNA sequencing of nrDNA (ITS 1, 5.8S, ITS 2) plus RAPDs, leaf terpenoids and morphology revealed that two cryptic, genetically distinct but morphologically almost identical species are present. These species, J. oxycedrus L. var. oxycedrus and Juniperus deltoides R.P. Adams, are about as different from each other as Juniperus navicularis and Juniperus macrocarpa are from J. oxycedrus var. oxycedrus. Examination of herbarium specimens revealed that the two species are largely allopatric with J. deltoides occurring from Italy eastward through Turkey into the Caucasus Mts. and Iran. J. oxycedrus var. oxycedrus appears to be largely concentrated west of Italy (France, Spain, Portugal, Morocco). Cryptic speciation is discussed.     

Divergent adaptation to Qinghai-Tibetan Plateau implicated from transciptome study of Gymnocypris dobula and Schizothorax nukiangensis

The Schizothoracine fishes are widely distributed in the Qinghai-Tibetan Plateau (QTP) area and its peripheral regions, which provide a prime example of adaptation in highland aquatic environments. Recent progresses have revealed various genetic adaptations of these fishes by comparing to distantly related lowerland species, however, comparative studies on closely-related species of different altitudes are still lacking. In this study, we sequenced and annotated a primitive Schizothoracine fish Schizothorax nukiangensis Tsao and a highly specialized one Gymnocypris dobula. We performed evolutionary analyses to investigate the candidate genes and signaling pathways involved QTP highland adaptation in both Schizothoracine fishes. Analysis of the 11,007 one-copy orthologs to the primitive cyprinid species, Danio rerio, revealed that both G. dobula and S. nukiangensis showed elevated evolutionary rates. A large number of genes related to hypoxia, including genes involved metabolic processes and cardiovascular system development, exhibited signatures of positive selection in both Schizothoracine fishes, but very few positively selected genes were found overlapping among these Schizothoracines. Our results indicated divergent genetic adaptation to highland environment for aquatic species living in QTP.     

Characterization of highly polymorphic nuclear microsatellite loci in Juniperus communis L.

We developed five nuclear microsatellite markers in Juniperus communis L. using an enriched library method. Samples from 28 juniper individuals were collected in Spain, Germany and Slovakia and were analysed at the five loci. A high level of allelic diversity with values ranging from nine to 23 alleles was found. These highly polymorphic markers will be used in ongoing population genetic studies to evaluate the genetic resources and to contribute to the maintenance of genetic diversity of juniper in Middle Europe.     

Responses of plants to changes in Qinghai–Tibetan Plateau and glaciations: Evidence from phylogeography of a Sibiraea (Rosaceae) complex

The genetic structure and phylogeographical history of the alpine shrubs Sibiraea angustata (Rosaceae) and Sibiraea laevigata from the Qinghai–Tibetan Plateau (QTP) were investigated to identify alpine plant responses to changes in the QTP and glaciations. Fifty-five populations were analyzed using four chloroplast DNA (cpDNA) regions and (nuclear ribosomal internal transcribed spacer) nrITS sequence data. In all, 21 cpDNA haplotypes and 13 nrITS sequence types were detected. Analyses of the genetic diversity and phylogenetic relationships detected two rarely reported glacial refugia. One was the Yushu–Nangqian area, and the other consisted of the area from the Songpan Plateau to the southeastern margin of the QTP. Sibiraea species populations experienced divergent evolution and founder effects when they recolonized the QTP platform and adjacent high-altitude regions following glaciations. The divergence times of the main lineages and haplotypes were in the range of 1.60–2.58 Ma. The population size of Sibiraea species in the QTP decreased approximately 23-fold during the last 0.12 Ma, indicating that Sibiraea species were significantly affected by environmental changes in the QTP. Therefore, the rapid uplift of the QTP and subsequent glaciations likely played an important role in driving genetic divergence and population size changes of Sibiraea species in the QTP.     

Reproduction and genetic diversity of Juniperus squamata along an elevational gradient in the Hengduan Mountains

Elevation plays a crucial factor in the distribution of plants, as environmental conditions become increasingly harsh at higher elevations. Previous studies have mainly focused on the effects of large-scale elevational gradients on plants, with little attention on the impact of smaller-scale gradients. In this study we used 14 microsatellite loci to survey the genetic structure of 332 Juniperus squamata plants along elevation gradient from two sites in the Hengduan Mountains. We found that the genetic structure (single, clonal, mosaic) of J. squamata shrubs is affected by differences in elevational gradients of only 150 m. Shrubs in the mid–elevation plots rarely have a clonal or mosaic structure compared to shrubs in lower- or higher–elevation plots. Human activity can significantly affect genetic structure, as well as reproductive strategy and genetic diversity. Sub-populations at mid-elevations had the highest yield of seed cones, lower levels of asexual reproduction and higher levels of genetic diversity. This may be due to the trade-off between elevational stress and anthropogenic disturbance at mid-elevation since there is greater elevational stress at higher-elevations and greater intensity of anthropogenic disturbance at lower-elevations. Our findings provide new insights into the finer scale genetic structure of alpine shrubs, which may improve the conservation and management of shrublands, a major vegetation type on the Hengduan Mountains and the Qinghai-Tibet Plateau.