Institut für Evolution und Ökologie

Upcoming theses (MSc and BSc) opportunities starting in 2020

Here you will find a description and further details for each of the proposed theses themes.

T1. Evolution of heterocarpic plants

T1.1 - Along a gradient of environmental unpredictability (i.e. an aridity gradient in Israel), the ratio of far vs. short dispersing seeds should change: more seeds with high dormancy should be produced towards the arid. There should be a trade-off with dispersal, i.e. dispersal distance and seed dormancy should be inversely related. This hypothesis will be tested using a collection seeds from of annual heterocarpic species. They will be grown in Winter 2020/21. Start: Sept-Nov 2020 (preparation), peak work March-May 2021 (i.e. between Nov and March there is time for taking courses).

T1.2 - Plasticity should be more pronounced for plants coming from more variable (i.e. arid environments). Thus we assume that plants will plastically change the ratio between the two seed morphs more when coming from arid sites. This hypothesis will be tested with growing several species of annual plants from an aridity gradient under drought and well-watered conditions. Start: Sept-Nov 2020 (preparation), peak work March-May 2021 (i.e. between Nov and March there is time for taking courses).

T2. Competition intensity and relatedness

In an equilibrium world, coexistence requires that plants differ from each other. Therefore, competition should be stronger between plants that are very similar. Thus, competition intensity should increase along a gradient of relatedness, ranging from between regions, between family within a region, between species within a family, between individuals within a species from different climates, between individuals from same climate and species, between sibling plants. relatedness should also affect symmetry of interactions and should be more symmetric on an intraspecific level.
This topic is more relevant for an MSc level and will be tested with the collection of Israeli annuals, i.e. this is again a winter topic.

Contact Maja Majekova

Ma1. Asynchrony and stability of winter annual communities along a steep environmental gradient in the Eastern Mediterranean Basin

Master project; start any time, no field work involved, good command of R required
Background: What determines stability of populations and communities remains one of the most debated questions in both theoretical and applied ecology. An important factor affecting the stability of communities over time is the degree of synchrony in fluctuations of individual species populations that coexist within a community.
Aim and Methods: Here we will investigate the crucial question whether deviations from perfect synchrony (asynchrony) lead to more stable communities. For this, we will use a long-term dataset on winter annuals assembled along a steep gradient of aridity and intensity of environmental fluctuations in the Eastern Mediterranean Basin in Israel. The dataset encompasses four sites (arid, semi-arid, Mediterranean and mesic-Mediterranean) and climate change manipulations (increased drought and increased precipitation) within two of them.
What you should know: You should have a good command of R to handle the big dataset (packages tidyr, dplyr, ggplot2). You can start any time, and duration will depend on your speed in handling the data. There is no field work involved, but as a member of our Plant Ecology group, you are welcomed to join us in the 2020 spring and summer field work in the Schwabische Alb forests and grasslands. In early March 2020, there will be a two-week student excursion to Israel organized by Katja Tielborger, and you are encouraged to join to see the system you will be working with.

Contact Maxi Herberich

Scientific evidence is concurrent in that the anthropogenic-induced climate change will continuously intensify the magnitude and frequency of climate extremes such as severe drought. The topic below is embedded in a climate change experiment on the Swabian Alb which mimics extreme drought.

H1. Role of seed dormancy to mitigate extreme drought in temperate plant communities

Dormancy and thus, seed bank demography, is one of the classical bet-hedging mechanisms to mitigate highly variable water availability in arid and semi-arid plant communities. Most species of plant communities in temperate environments have a persistent seed banks as well. In difference to arid communities, dormancy in temperate plant communities is a function of light and space availability not strategy to mitigate against unfavorable water conditions. However, it has never been tested explicitly whether dormancy might be anyway be beneficial under extreme drought. This might especially hold for temperate plant communities originating from habitats with naturally high variability in soil water. To test this, we compare the germination fraction of seeds collected from the Swabian Alb from more and less variable soil water conditions in a drought experiment.
Field work: Seed collection in September 2020; Greenhouse work: Beginning of October

Contact Anubhav Mohiley

Mo1. Can competition induce clonal sharing and foraging for metals in plants?

Plants can respond to competition in a myriad of physiological or morphological changes. Competition has also been shown to affect the root foraging decisions of plants. However, a completely unexplored idea is that competition might also affect plants foraging for specific chemicals required for inhibiting the growth of their competitors. As we could show that metal hyperaccumulation trait is related to neighbour inhibition. We aim to examine the way simulated competition affects both clonal foraging and sharing of metal in the metal-hyperaccumulating plant Arabidopsis halleri, which uses heavy metals (e.g. Cadmium, Zinc) for neighbour inhibition. In addition, we will study if these responses vary between A. halleri ecotypes originating from non-metalliferous soils and metalliferous soils. The experiment will be performed in the green house. We will use green filters to simulate competition and have different treatments to study clonal foraging and sharing between ramets.
Starting Flexible, 3 – 4 months of experiment approximately (BSc or MSc; in English)

Mo2. Can metal hyperaccumulation increase drought tolerance?

Metal hyperaccumulation is an intriguing trait found in very few plant species. Hyperaccumulation has been hypothesized to perform several functions in hyperaccumulator species. We did in previous studies show that this trait is likely related to defence against herbivores and competitors. Another hypothesis suggested in the literature is that plants hyperaccumulate heavy metal to withstand drought. Evidence bearing on this hypothesis is scarce. Hence in this study we hypothesize that metal hyperaccumulation (e.g. Cadmium, Zinc) will enhance drought tolerance of metal hyperaccumulating plant Arabidopsis halleri. Does this response differ between plants from metalliferous and non-metalliferous origin of A. halleri. The experiment will be performed in the green house. We will combine drought and metal in a full factorial experiment.
Starting Flexible, 3 – 4 months of experiment approximately (BSc or MSc; in English)