Phylogeography

Genetic structure of Androsace helvetica

Edraianthus glisicii (photo: M. Sonnleitner)

Pleistocene climate fluctuations had major impacts on the distribution and evolution of organisms. We are interested in inferring past and current range connectivity among and within European high mountain ranges (from the Iberian to the Balkan Peninsula) and beyond (especially with the Arctic), identifying patterns of Pleistocene range shifts (e.g., latitudinal versus altitudinal) including the location of refugia (e.g., nunataks) and their role for (re)colonization of formerly uninhabited regions, as well as addressing niche dynamics (niche conservatism versus niche evolution) in association with range shifts. To this end, we are employing varied molecular marker systems (DNA sequencing, AFLP fingerprinting, RADseq data) and ecological niche modeling and analyze those using state-of-the-art tools.

A group we have been intensively studying over the last years are European rock jasmines (Androsace sect. Aretia, Primulaceae). Its two dozen species, which are morphologically well-defined and share similar dispersal abilities and floral syndromes, show numerous biogeographic patterns, including widespread versus restricted or continuous versus disjoint distribution areas, rendering this group particularly suitable for investigating disjunctions on several geographical scales. Although each species or species-group has a highly idiosyncratic history, a few commonalities emerge, including the relevance of long distance dispersal sometimes involving counter-intuitive connections, high incidence of both ancient and current gene flow, and a decoupling of the degree of range fragmentation and its age.

Current research includes comparative phylogeography and niche evolution in selected species of sedges (Carex, Cyperaceae) and louseworts (Pedicularis, Orobanchaceae) from the eastern Alps to test whether ecological niches stay constant over time (niche conservatism) or not (niche evolution) and whether species of similar ecological requirements (e.g., Carex firma and Pedicularis rosea from wind-exposed limestone ridges; C. ferruginea and P. rostrato-spicata from sheltered snow-covered alpine swards) rather than species with similar pollination and dispersal biology (i.e., all Carex species versus all Pedicularis species) show similar phylogeographic patterns.

Selected Publications

  • Surina B, Schneeweiss GM, Glasnović P, Schönswetter P (2014) Testing the efficiency of nested barriers to dispersal in the Mediterranean high mountain plant Edraianthus graminifolius (Campanulaceae). Molecular Ecology 23: 2861–2875
  • Escobar García P, Winkler M, Flatscher R, Sonnleitner M, Krejčiková J, Suda J, Hülber M, Schneeweiss GM, Schönswetter P (2012) Extensive range persistence in peripheral and interior refugia characterizes Pleistocene range dynamics in a widespread Alpine plant species (Senecio carniolicus, Asteraceae). Molecular Ecology 21: 1255–1270
  • Winkler M, Tribsch A, Schneeweiss GM, Brodbeck S, Gugerli F, Holderegger R, Abbott RA, Schönswetter P (2012) Tales of the unexpected: Phylogeography of the arctic-alpine model plant Saxifraga oppositifolia (Saxifragaceae) revisited. Molecular Ecology 21: 4618–4630
  • Schneeweiss GM, Schönswetter P (2010) The wide but disjunct range of the European mountain plant Androsace lactea L. (Primulaceae) reflects late Pleistocene range fragmentation and post-glacial distributional stasis. Journal of Biogeography 37: 2016–2025
  • Dixon C, Schönswetter P, Vargas P, Ertl S, Schneeweiss GM (2009) Bayesian hypothesis testing supports long-distance Pleistocene migrations in a European high mountain plant (Androsace vitaliana, Primulaceae). Molecular Phylogenetics and Evolution 53: 580–591

Polyploid Evolution

Fieldwork (photo: M. Sonnleitner)

Senecio carniolicus s. str. (photo: M. Sonnleitner)

Polyploidy is a major driver of plant diversification and speciation, and alpine plants are no exception. While we have studied the origin of polyploids in a number of alpine plant groups, such as rock jasmines (Androsace sect. Aretia, Primulaceae) or leopard's-banes (Doronicum, Asteraceae), our focus in recent years has been in the Carniolian ragwort (Senecio carniolicus s. l. [syn. Jacobaea carniolica s. l.], Astercaeae). In the eastern European Alps, this complex comprises four species: two allopatric diploids, the western S. insubricus and the eastern S. noricus; the tetraploid S. disjunctus with a strongly disjoint distribution range, and the most widespread hexaploid S. carniolicus s. str. In many parts of the Alps, two (most often one of the diploid species, S. insubricus or S. noricus, and the hexaploid S. carniolicus s. str.) or even three species (as before, but additionally with S. disjunctus) are growing in close proximity. Apart from defining these species both morphologically and genetically (including inference of the origin of the polyploids), we investigated factors responsible for the maintenance of species integrity in areas of sympatry, focusing on habitat differentiation and crossability (fruit set, germination rates).

Cytotype diversity is common in Alpine plants and in many cases under-appreciated. A recent survey focusing on two narrowly endemic diploid eyebright species (Euphrasia inopinata, E. sinuata) revealed that diploid cytotypes are also present in E. minima, a widespread mostly tetraploid species (presumably of allotetraploid origin). More extensive cytotype screening as well as molecular studies are on the way to clarify this taxonomically and evolutionarily intriguing polpyloid complex.

Selected Publications

  • Sonnleitner M, Hülber K, Flatscher R, Escobar García P, Winkler M, Suda J, Schönswetter P, Schneeweiss GM (2016) Ecological differentiation of diploid and polyploid cytotypes of Senecio carniolicus s.l. (Asteraceae) is stronger in areas of sympatry. Annals of Botany 117: 269–276
  • Pachschwöll C, Escobar García P, Winkler M, Schneeweiss GM, Schönswetter P (2015) Polyploidisation and geographic differentiation drive diversification in a European high mountain plant group (Doronicum clusii aggregate, Asteraceae). PLoS ONE 10(3): e0118197
  • Sonnleitner M, Weis B, Flatscher R, Escobar García P, Suda J, Krejčiková J, Schneeweiss GM, Winkler M, Schönswetter P, Hülber K (2013) Parental ploidy strongly affects offspring fitness in heteroploid crosses among three cytotypes of autopolyploid Jacobaea carniolica (Asteraceae). PLoS ONE 8(11): e78959
  • Weiss-Schneeweiss H, Blöch C, Turner B, Villaseñor JL, Stuessy TF, Schneeweiss GM (2012) The promiscuous and the chaste: frequent allopolyploid speciation and its genomic consequences in American daisies (Melampodium sect. Melampodium; Asteraceae). Evolution 66: 211–228
  • Dixon CJ, Schönswetter P, Suda J, Wiedermann MM, Schneeweiss GM (2009) Reciprocal Pleistocene origin and postglacial range formation of an allopolyploid and its sympatric ancestors (Androsace adfinis group, Primulaceae). Molecular Phylogenetics and Evolution 50: 74–83

Phylogeny and Taxonomy

Phylogeny of Phyteuma (photos: C. Pachschwöll)

Understanding evolution requires a solid phylogenetic framework that ideally would be translated into a taxonomic system. Consequently, much of our research in alpine plants has a strong phylogenetic and taxonomic component. For instance, studies in Alpine rock-jasmines (Androsace sect. Aretia, Primulaceae) focusing on phylogeography included establishing their phylogeny and the recognition of new taxa (species and subspecies). Likewise, studying factors responsible for the maintenance of mixed-ploidy populations of the Carniolian ragwort (Senecio carniolicus aggregate, Asteraceae) resulted in the taxonomic recognition of four species instead of one. Further studied groups include purple saxifrages (Saxifraga oppositifolia and relatives, Saxifragaceae), rampions (Phyteuma, Campanulaceae), or leopard's banes (Doronicum, Asteraceae).

Selected Publications

  • Flatscher R, Escobar García P, Hülber K, Sonnleitner M, Winkler M, Saukel J, Schneeweiss GM, Schönswetter P (2015) Underestimated diversity in one of the world's best studied mountain ranges: The polyploid complex of Senecio carniolicus (Asteraceae) contains four species in the European Alps. Phytotaxa 213: 1–21
  • Schönswetter P, Magauer M, Schneeweiss GM (2015): Androsace halleri subsp. nuria Schönsw. & Schneew. (Primulaceae), a new taxon from the eastern Pyrenees (Spain, France). Phytotaxa 203: 227–232
  • Schneeweiss GM, Pachschwöll C, Tribsch A, Schönswetter P, Barfuss MHJ, Esfeld K, Weiss-Schneeweiss H, Thiv M (2013) Molecular phylogenetic analyses identify Alpine differentiation and dysploid chromosome number changes as major forces for the evolution of the European endemic Phyteuma (Campanulaceae). Molecular Phylogenetics and Evolution 69: 634–652
  • Winkler M, Tribsch A, Schneeweiss GM, Brodbeck S, Gugerli F, Holderegger R, Schönswetter P (2013) Strong nuclear differentiation contrasts with widespread sharing of plastid DNA haplotypes across taxa in European purple saxifrages (Saxifraga sect. Porphyrion subsect. Oppositifoliae). Botanical Journal of the Linnean Society 173: 622–636
  • Schneeweiss GM, Schönswetter P, Kelso S, Niklfeld H (2004) Complex biogeographic patterns in Androsace (Primulaceae) and related genera: evidence from phylogenetic analyses of nuclear ITS and plastid trnL-F sequences. Systematic Biology 53: 856–876

Areas of Endemism in the Iranian High Mountain Flora

Endemics in Iranian high mountains

Veronica paederotae (photo: J. Noroozi)

Areas of endemism, i.e., areas of non-random distributional congruence among different taxa, are fundamental entities of analysis in evolutionary biogeography, as they are the units compared in the investigation of earth history according to biological patterns. Biogeographers and evolutionary biologists are interested in explaining the causes for the occurrence of areas of endemism, such as ecological factors or historical reasons (e.g., vicariance, speciation in isolation); ecologists are interested in areas of endemism due to their importance in devising conservation priorities.

In a current research project (funded by the Austrian Science Fund, FWF), we aim at identifying areas of endemism and their ecological and/or historical correlates in the Iranian high-mountain flora as the basis for a better understanding of its fate under global change and for determining the habitats with conservation priorities. Specifically, using several complementary techniques for identifying areas of endemism (Endemicity Analysis; Sympatry Inference and Network Analysis; Delimitation of Biogeographic Regions Using Fuzzy Logic), we are assessing number and location of the areas of endemism of the Iranian alpine flora as well as the roles of historical, physical and/or ecological factors in shaping those areas of endemism, which jointly will help in identifying areas of endemism with conservation priorities.

By assembling data on Iranian alpine endemics and their publication in appropriate online databases, we will provide the necessary (publicly available) basis for recognition and prioritization of conservation areas and their distinguishing species. Furthermore, knowledge on areas of endemism provides a valuable basis for future research on the phylogeography of the thus far grossly understudied Iranian biodiversity hotspot. Finally, because analyses including some of the newer and conceptually different approaches for inferring areas of endemism are at best rare, this project is expected to be of broader interest for the biogeography and the evolutionary biology community.