Phylogeography and population genetics of key steppe species: Artemisia frigida Willd. (Anthemideae, Asteraceae)

The present thesis elucidates facts about a prominent steppe plant’s evolutionary history (i.e., geographic origin, migration route, distribution of genealogical lineages and polyploidization events) and contemporary population divergence (i.e., genetic diversity and differentiation, impacts of abiotic and biotic factors). Artemisia frigida has been chosen as the target species, with Mongolia as the focus study region. Because A. frigida is widely distributed in the both New and Old Worlds, it was a suitable candidate for the phylogeographic study. Moreover, because of its dominance in many communities in Mongolian steppes and tolerance for cold, drought and mechanical disturbances (grazing), evaluating the effect of environmental factors and grazing pressures on its population genetics was profitable. The overall goal of this thesis was to assess the effects of paleo- and current climate, and land use changes on the distribution of A. frigida’s genealogical lineages and genetic variations. The thesis is divided into two main parts: (i) Chapter 3 focuses on Phylogeography. Within this, section 3.3 depicts a study on the phylogeography of A. frigida, covering samples from its distributional range across the northern hemisphere. The study resulted in Asia being the species’ main origination and diversification center, and the species spread northwards to the Russian Far East and eventually crossed the Bering Strait to North America. Among four geographical regions sampled, seven genetic lineages were found, with Middle Asia having the most diverse populations. According to our phylogenetic analysis, two populations of Kazakhstan in Middle Asia represented the most likely ancestral diploids, and subsequent polyploidization events have occurred on several occasions independently. The observed phylogeographic patterns of the species showed that paleoclimate, especially glaciation events of the Quaternary has predominantly affected species’ current distribution, along with the expansion and contraction of the Eurasian steppe. The second part (Chapter 4) is dedicated to Population genetics to reveal the effects of the current climate and land use on population genetic variation. Three studies were conducted at local and regional levels, focusing on Mongolia. The first study (Section 4.1- review of local literature) was done to offer background information about Mongolian steppes, and the effects of climate and grazing on the steppe vegetation. As a result, steppe vegetation responded to grazing in different ways, depending on the interplay of local environmental factors. In particular, an overall negative effect of grazing was found in desert, dry and high mountain steppes, but no or even positive effects in meadow and mountain steppes. The study highlighted the importance of the interaction effect of local environmental conditions and grazing in Mongolian steppe vegetation. The second study (Section 4.2) employed large scale climatic gradient and local scale grazing gradients to assess the effects of grazing and environmental factors on the population genetics of A. frigida. Precipitation gradient covered 110 – 300mm difference of mean annual precipitation from central to southern Mongolia. While three levels of grazing gradient, such as heavy, moderate, and least grazed sites were examined. According to the study, grazing in overall, had no substantial effect on the genetic diversity of A. frigida, while environmental factors, i.e., summer precipitation and soil phosphorous content, promoted high genetic diversity. Genetic differentiation among populations across large climatic gradients was extremely low, suggesting the existence of considerable gene flow among populations across the steppes of Mongolia. The third study (Section 4.3) employed grazing exclosures to evaluate the genuine effects of grazing. Because Mongolia has a long-term nomadic pastoralism history, and grazing of large herbivores is already an integral part of the steppe vegetation. Thus, we utilized reference site fences along the Trans-Mongolian Railway (TMR), where fences have been built and maintained since 1955, resulting in over 60 years of grazing exclusion. In addition, we supplemented this with data from Hustai National Park (HNP), where three fences were established in 2003. As a result, we found a significant positive impact of grazing on the genetic diversity of A. frigida, implying that a certain level of grazing is beneficial for the species. While no grazing effect on the population genetic differentiation was detected, but climatic and soil variables strongly influenced population genetic structure. In summary, this thesis provided an in-depth investigation of the phylogeography and population genetics of the species A. frigida, which can stand as an exemplar for other Eurasian steppe species. Paleoclimate had largely shaped the current distribution pattern of the species, while contemporary climate and environmental heterogeneity promoted species’ polyploidization and genetic variation. Grazing by large herbivores showed no detrimental effect, or even a positive impact on the genetic diversity of A. frigida. Artemisia frigida populations in Mongolia are thus apparently genetically ‘healthy’, in spite of pervasive grazing in the region. Climate variables and environmental heterogeneity had a substantial impact on the species’ both genetic diversity and differentiation, indicating its higher sensibility to climate change than to land use change. The findings of the thesis could be valuable in understanding species genetic variation under global land use and climate changes.:Summary 4 List of Abbreviations 6 Chapter 1. Introduction 8 Chapter 2. Material and methods 10 2.1. Study region: Mongolian steppe 10 2.2. Focus species: Artemisia frigida Willd. 11 2.3. Molecular markers 12 Chapter 3. Phylogeography 13 3.1. Eurasian steppe and its evolutionary history 13 3.2. Artemisia L. (Asteraceae) as model plant for phylogeography 16 3.3. A case study: Phylogeography of Artemisia frigida Willd. 19 Chapter 4. Plant population genetics under changing climate and grazing……. 40 4.1. Climate – grazing interactions in Mongolian steppe 41 4.2. Climate – grazing interactions on plant population genetics 59 4.3. Effect of grazing exclusion on plant populations genetics 83 Chapter 5. Overarching synthesis and discussion 101 5.1. Molecular markers: pros and cons 102 5.2. A review of phylogeographical studies on Eurasian steppe plants 104 5.3. A review on plant population genetic studies in Mongolia 109 5.4. Outlook 113 Acknowledgements 114 References 115 Curriculum vitae 137 Confirmation 14

Coleoptera in the Altai Mountains (Mongolia): species richness and community patterns along an ecological gradient

The Altai Mountains located in western Mongolia comprise diverse habitats including forest, mountain steppe, dry steppe, semidesert, and desert. This study used advanced statistics to examine how diversity and species composition of beetle communities depend on vegetation pattern and environmental factors along an ecological gradient from steppe to desert. Our study included the beetle families Tenebrionidae, Carabidae, Curculionidae, and Coccinellidae, which account for the majority of the known beetle fauna in the area. The most abundant Coleoptera in all plots were Harpalus limbaris, Corsyra fusula, and Anatolica cellicola; otherwise, we caught a large number of rare species. The beta diversity of communities was correlated with distance between plots. Species richness of beetles was positively impacted by plant cover and correlated negatively with rising temperatures, whereas Shannon diversity of beetle communities was significantly higher in areas with higher precipitation. Distribution and community composition of Coleopterans were governed by environmental factors, especially plant diversity, mean annual temperature, and summer precipitation, as revealed by redundancy analysis

A new record of critically endangered Saussurea bogedaensis (Asteraceae) from Dzungarian Gobi, Mongolia

A species in the family Asteraceae, Saussurea bogedaensis, was newly described from Bogeda Mountain in Xinjiang, China and is a critically endangered species in China. Morphological and genetic characteristics confirm the presence of this species in Mongolia, as it was found in Baitag Bogd Mountain (in the Dzungarian Gobi). In addition, the distribution and conservation status of S. bogedaensis are provided

Predicting the current and future suitable habitats, species distribution, and conservation assessment of Fritillaria dagana (Liliaceae)

Fritillaria dagana Turcz. has a restricted global distribution, occurring only in southern Siberia and northern Mongolia. Concerning its restricted distribution and endangered conservation status, we aimed to forecast its current and future suitable habitats as well as distribution shifts for 2050 and 2080. The Maxent model with different scenarios (representative concentration pathway 4.5 and representative concentration pathway 8.5) was used to analyze 113 georeferenced records of F. dagana using 19 bioclimatic factors from the WorldClim database. As a result, the amount and variance of precipitation and temperature, together with elevation, were shown to be the most significant factors affecting the species' distribution. In particular, precipitation during the plant growing season had the greatest impact (55.2% variability) on the species distribution. Climate change was expected to cause a minor shift in the distribution of suitable habitats toward the north and an increase in habitat continuity, indicating that the climate will become more favorable for the growth of species and in the future. The species' highly suitable area will remain primarily concentrated in its current potential distribution area in central Siberia (around Lake Baikal). The species' conservation status was determined to be near threatened, emphasizing the great relevance of facilitating proper conservation measures for F. dagana

Phylogeography of Artemisia frigida (Anthemideae, Asteraceae) based on genotyping-by-sequencing and plastid DNA data: migration through Beringia

Artemisia frigida is a temperate grassland species that has the largest natural range among its genus, with occurrences across the temperate grassland biomes of Eurasia and North America. Despite its wide geographic range, we know little about the species' distribution history. Hence, we conducted a phylogeographical study to test the hypothesis that the species' distribution pattern is related to a potential historical migration over the 'Bering land bridge'. We applied two molecular approaches: Genotyping-by-Sequencing (GBS) and Sanger sequencing of the plastid intergenic spacer region (rpl32 - trnL) to investigate genetic differentiation and relatedness among 21 populations from North America, Middle Asia, Central Asia and the Russian Far East. Furthermore, we identified the ploidy level of individuals based on GBS data. Our results indicate that A. frigida originated in Asia, spread northwards to the Far East and then to North America across the Bering Strait. We found a pronounced genetic structuring between Middle and Central Asian populations with mixed ploidy levels, tetraploids in the Far East, and nearly exclusively diploids in North America except for one individual. According to phylogenetic analysis, two populations of Kazakhstan (KZ2 and KZ3) represent the most likely ancestral diploids that constitute the basally branching lineages, and subsequent polyploidization has occurred on several occasions independently. Mantel tests revealed weak correlations between genetic distance and geographical distance and climatic conditions, which indicates that paleoclimatic fluctuations may have more profoundly influenced A. frigida's spatial genetic structure and distribution than the current environment

Contribution to the knowledge on the flora of Munkhkhairkhan mountain area, Mongolia

The Munkhkhairkhan mountain area is a unique highland ecosystem with a diverse regional alpine flora. This mountain habitat is located at the overlap of different floristic regions: on its western side KazakhstanâTuran flora is dominating, and on the eastern side East Asian flora is observed. It is known that the whole area has a large number of endemics and rare plant species, because of its specific, harsh habitat conditions. Therefore, the flora of different habitats in the Munkhkhairkhan mountain needs to be investigated and properly protected. Munkhkhairkhan National Park has been founded in 2006, and our survey concentrated on the protected area as well as the surrounding areas of the mountains. All recorded species in this study were based on the collected voucher specimens. Conservation status for remarkable species was also reviewed based on the literature. As a result, we recorded 40 families, 150 genera, and 267 species of vascular plants, including four endemic and 34 subendemic species and 15 species' new distribution notes. Around the Munkhkhairkhan mountain, 16 very rare, 21 rare, eight endangered, and two near threatened species are growing, indicating the high conservation value of this area and the necessity for research. Keywords: Conservation status, Mongolia, Munkhkhairkhan national park, Vascular flor

Updated checklist of vascular plants endemic to Mongolia

The aim of the present study is to update the checklist of vascular plants endemic to Mongolia using previous checklists, publications, herbarium collections, and field observations. The revised checklist includes 102 endemic taxa (95 species, five subspecies, and two nothospecies) from 43 genera and 19 families. The majority of endemic taxa were distributed in western and central Mongolia, and high endemic species richness was identified in four phytogeographical regions, namely Mongolian Altai, Khangai, Dzungarian Gobi, and Gobi Altai, wich harbor 49, 27, 20, and 16 endemic taxa, respectively. For each endemic taxon, we compiled information about growth form, conservation status (if already assessed), phytogeographical distribution, and voucher specimens. Data on each taxon`s type specimen were also collected, and the majority of the type specimens were assessioned at the LE (58 taxa), MW (20 taxa), and UBA (7 taxa) herbaria

Flora of Mongolia: annotated checklist of native vascular plants

In this study, we critically revised and updated the checklist of native vascular plants of Mongolia. The checklist comprises 3,041 native vascular plant taxa (2,835 species and 206 infraspecific species) from 653 genera and 111 families, including 7 lycophytes, 41 ferns, 21 gymnosperms, and 2,972 angiosperms. In the angiosperms, we identified the 14 families with the greatest species richness, ranging from 50 to 456 taxa. Species endemism is also noted here; 102 taxa are endemic to Mongolia, and 275 taxa are sub-endemic that co-occur in adjacent countries. Since 2014, a total of 14 taxa have been described new to science based on morphological evidences. Moreover, five genera and 74 taxa were newly added to the flora of Mongolia. Based on our critical revisions, names of three families, 21 genera, and 230 species have been changed in comparison to the previous checklist, “Conspectus of the vascular plants of Mongolia” (2014)

Flora of Mongolia: annotated checklist of native vascular plants

In this study, we critically revised and updated the checklist of native vascular plants of Mongolia. The checklist comprises 3,041 native vascular plant taxa (2,835 species and 206 infraspecific species) from 653 genera and 111 families, including 7 lycophytes, 41 ferns, 21 gymnosperms, and 2,972 angiosperms. In the angiosperms, we identified the 14 families with the greatest species richness, ranging from 50 to 456 taxa. Species endemism is also noted here; 102 taxa are endemic to Mongolia, and 275 taxa are sub-endemic that co-occur in adjacent countries. Since 2014, a total of 14 taxa have been described new to science based on morphological evidences. Moreover, five genera and 74 taxa were newly added to the flora of Mongolia. Based on our critical revisions, names of three families, 21 genera, and 230 species have been changed in comparison to the previous checklist, “Conspectus of the vascular plants of Mongolia” (2014)