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

• Published in: Conservation Genetics
• Main Author: Khurelpurev, Oyundelger
• Other Authors: Wesche, Karsten, Ritz, Christiane M., Technische Universität Dresden
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2020
• Subjects: population genetics; phylogeography; Mongolia; Artemisia frigida; info:eu-repo/classification/ddc/570; ddc:570; Bering Strait
• Online Access: https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa2-823706; https://tud.qucosa.de/id/qucosa%3A82370; https://tud.qucosa.de/api/qucosa%3A82370/attachment/ATT-0/

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 ...