MASTER THESIS PROJECTS
Patterns of morphometric variation and taxonomy of the bryophyte genus Plagiothecium in southern Sweden
(Bryophytes, Plagiothecium)

TThe genus Plagiothecium (Sv.: sidenmossor) is taxonomically problematic since the different species currently recognized mainly differ in size and a few other morphological characters. It may even appear as if there is a continuum of variation from the smallest to the largest species. Between 7 and 10 species are recognized as occuring in southern Sweden in different recent floras and at least some of these appear to differ with respect to distribution and choice of habitat. However, there is no consensus as to how many species may be recognized or how they should be circumscribed and delimited. During the ongoing inventory of the bryophyte flora of the province of Skåne, a large and representative material of this genus has been collected making it possible to thoroughly analyse the pattern of variation by means of multivariate statistical tools. The aim of this project is thus to obtain data about all characters traditionally used to differentiate taxa in this genus and use various multivariate statistical methods to analyse to what extent the variation in different characters correlate, and if there are any discontinuities in the pattern of variation that may be used to differentiate between the species. A basic question will be to find out how many species may be recognized and what frequency and distribution they have in the province of Skåne. A pilot study with molecular markers may optionally be added to this project with the aim of assessing to what extent the morphometric variation correlates with the pattern of molecular variation, but without prior knowledge of a suitable molecular marker system for this particular bryophyte genus the odds for finding a marker system that may reveal suitable levels and patterns of variation may be rather high.

Supervisor - Museum curator Torbjörn Tyler

Department of Biology, Botanical collections, Lund University

Phone: +46 46 222 4234
E-mail: torbjorn.tyler@biol.lu.se
Personal website

Patterns of morphometric variation and infra-specific taxonomy of a highly polymorphic Nordic vascular plant species
(Composits, Asteraceae)

In the Nordic countries, the infra-specific taxonomy and variation of polymorphic but common and widespread plant species have not received much attention in recent years. As a consequence, there are several species within which two or more infraspecific taxa are currently recognized in standard floras but for which the infraspecific taxonomy has never been thoroughly investigated. The aim of this group of projects is to select one of the polymorphic species briefly described below, measure a set of variable characters and map their distribution throughout the Nordic countries based on herbarium specimens in the public herbaria, use various multivariate statistical methods to analyse to what extent the variation in different morphological characters correlate, and, ultimately, try to find out which (if any) combinations of characters that may be used for defining and circumscribing geographical or ecological races that may deserve to be recognized taxonomically. Pilot studies with molecular markers may optionally be added to these projects with the aim of assessing to what extent the morphometric variation correlates with the pattern of molecular variation, but without prior knowledge of a suitable molecular marker system for these particular plant species the odds for finding a marker system that may reveal suitable levels and patterns of variation may be rather high.

– Scorzoneroides (Leontodon) autumnalis (Sv.: höstfibbla). This species occurs more or less throughout the Nordic countries and is common in a wide range of grassland habitats including seashores and alpine habitats as well as roadsides and wastelands. In the current Swedish checklist, four varieties are accepted within this species, mainly based on variation in the indumentum of the phyllaries and the dentation of the leaves, but additional infra-specific taxa with different ranks have been described in the past and there are many additional polymorphic characters in this species. Two of the varieties are believed to be predominantly arctic-alpine, one is believed to dominate in the lowlands and one is believed to be confined to seashores, but abbarent morphotypes that don’t fit into these taxa are quite commonly found and both their circumscription and distribution is largely uncertain. No thorough taxonomic revision or morphometric analysis of these taxa has ever been made.

– Erigeron acris (Sv.: gråbinka). This species has scattered occurencies throughout most of the Nordic area and is found in a variety of different dry and open habitats including sandy heathlands, steep and rocky sites, exposed subalpine habitats and ruderal lowland habitats. The species is highly polymorphic with respect to multiple morphological characters (e.g. indumentum, branching pattern and pigmentation) and it has been suggested that parts of this variation is due to introgression from related species and/or repeated immigration from different isolated glacial refugia. In the current Swedish checklist, 6 subspecies are accepted within this species, mainly based on a Finnish study from the 1950’s, but their geographic distribution in the Nordic countries is largely unknown and while some of these subspecies appear very difficult to keep separated some others appear so distinct that it is difficult to understand why they should not deserve the rank of independent species. Thus, a thorough morphometric study is much needed to evaluate the status of these taxa and their geographic distribution needs to be clarified.

– Cirsium arvense (Sv.: åkertistel). This common species occurs both on seashores and in various ruderal and agricultural habitats almost throughout the Nordic countries. Within the species there is a pronounced polymorphism with respect to the dentation and spinyness of the leaves. In addition to this there is one morphotype with almost glabrous lower leaf surfaces and another type whose leaves are densely grayish-whooly below. Three varietes within this species are currently recognized in the checklist of Swedish species and there is an obvious geographic and ecological component in this variation with one variety mainly found on seashores, one variety dominating in agricultural habitats in the southwestern parts of the area and another dominating further to the north and east. However, to what extent the pattern of variation in the above mentioned characters correlate with variation in other characters is generally unexplored and the precise geographic distribution of the varieties is still largely unknown as they have not got much attention in recent floristic inventories.

Supervisor - Museum curator Torbjörn Tyler

Department of Biology, Botanical collections, Lund University

Phone: +46 46 222 4234
E-mail: torbjorn.tyler@biol.lu.se
Personal website

Molecular systematics of Clitellata
(Annelida, segmented worms)

The overall aim of our research is to establish a classification of Clitellata (or Oligochaeta) that is congruent with a well-supported set of hypotheses of the clitellate Tree of life, including its deep as well as terminal nodes.

The big picture deals with the phylogenetic position of Clitellata within the Annelida and the basal evolutionary history of the clitellate families and other higher taxa, such as Crassiclitellata (the earthworms). At the other end of the spectrum are the delimitation and identification of separately evolving metapopulation lineages (=species), primarily using a combination of rapidly evolving mitochondrial and nuclear genes.

A number of widely distributed morphospecies of Clitellata, showing preliminary evidence of cryptic speciation are studied, and the amount of genetic within and between lineages will be analyzed. Morphological variation and ecological differences are also be evaluated when possible or necessary (as in the case of asexual species).

We can offer a number of Masters projects (30, 45 or 60 credit points) dealing with taxonomy and phylogeny of selected groups of terrestrial, freshwater or marine clitellates.

Supervisor - Professor Christer Erséus

Department of Biological and Environmental Sciences University of Gothenburg

Phone: +46 - 31 - 786 36 45
E-mail: christer.erseus@bioenv.gu.se
Personal website

Species delimitation in wild Dahlias
Focal taxa: Dahlia coccinea & allies (Asteraceae)

The genus Dahlia comprises about 35 species in Central and South America, with a centre of diversity in Mexico. Over 10,000 cultivars are known today and widely cultivated worldwide. The tubers of some species are used as starch source and consumed locally. Despite a tremendous variation in the cultivated forms, they are all believed to have originated from the crossing between 2 wild species, including Dahlia coccinea.

This project aims at using NGS data to i) testing whether D. coccinea constitutes a monophyletic clade (is a ‘good species’); ii) assessing whether naturally occurring colour variants are phylogenetically clustered (form ‘natural groups’); and iii) estimating the environmental requirements of the species and assessing whether it will expand or contract under future climate change. Sampling of living specimens will be done from living collections at the Botanical gardens in Gothenburg, Copenhagen and Hamburg.

To be conducted with the Botany building research group.

Supervisor - Alexandre Antonelli

Department of Biological and Environmental Sciences University of Gothenburg

Phone: +46 - 703 - 98 95 70
E-mail: alexandre.antonelli@bioenv.gu.se
Personal website

Supervisor - Mari Källersjö

Department of Biological and Environmental Sciences University of Gothenburg

Phone: +46 - 703 - 61 39 88
E-mail: mari.kallersjo@vgregion.se
Personal website

Evolution of hummingbird pollination in tetraploid Silene spp.
Focal taxa: North American Silene spp. (Caryophyllaceae)

We have in previous studies found that the large variation in e.g., ecology, morphology, and pollination exhibited by North American Silene species probably all stems back to a single polyploidization event in the Quarternary. However, reconstruction of the the species phylogeny was comprimised by the polyploidy.

We now have developed a model to cope with this, and in this project you will specifically trace the origins of hummingbird pollination syndrome in the group. For calibration of the timescale, we will try to use fossil DNA sampled from permafrost. You will collaborate various aspects with scientists from USA, Germany, Scotland, and Norway.

To be conducted with the Botany building research group.

Supervisor - Professor Bengt Oxelman

Department of Biological and Environmental Sciences University of Gothenburg

Phone: +46 - 31 - 786 26 78
E-mail: bengt.oxelman@bioenv.gu.se
Personal website

What is Gentianella baltica (Murb.) Börner?
Focal taxa: Gentianella baltica, G. campestris (Gentianaceae)

Gentianella baltica is a red-listed plant occurring at some locations on the Swedish westcoast. It is very similar to G. campestris, and differs mainly by being annual and flowering late in the season,instead overwintering as a rosette.

You will test the genetic distictiveness using next-generation sequence data from several populations, and also from other closely related taxa. You will collect G. baltica in the field during September-October, and also use herbarium material.

To be conducted with the Botany building research group.

Supervisor - Professor Bengt Oxelman

Department of Biological and Environmental Sciences University of Gothenburg

Phone: +46 - 31 - 786 26 78
E-mail: bengt.oxelman@bioenv.gu.se
Personal website

Testing species boundaries in Mediterranean mediks
Focal taxa: Medicago intertexta complex (Fabaceae)

Photo Credit: Ron Frumkin

The Medicago intertexta complex is a group of annual medik species with four names generally applied (M. ciliaris, M. granadensis, M. intertexta and M. muricoleptis). However, there are two pairs of taxa that are very difficult to distinguish from one another, suggesting that the species boundaries as currently used may not reflect biological reality. These taxa are found distributed around the Mediterranean basin, from North Africa, southern Europe and to the margins of the Middle East.

This project aims to generate NGS gene tree and codominant marker data from several dozen loci to test (a) the species boundaries, and (b) possible hybridisation where these taxa appear to overlap in their distributions. Sampling will be done using existing collections housed in public seed banks that have been made from across the range of the group. The student will participate in generating the data and undertake population genetic and phylogenetic analyses using methods based on the coalescent.

To be conducted with the Botany building research group.

Supervisor - Bernard Pfeil

Department of Biological and Environmental Sciences University of Gothenburg

Phone: +46 - 31 - 786 26 01
E-mail: bernard.pfeil@bioenv.gu.se
Personal website