Laboratory of Plant Ecology Master thesis subjects 2012-2013

Laboratory of Plant EcologyMaster thesis subjects 2012-2013

1. Genetic diversity and survival chances of the last remaining

populations of Broad-Leaved Thyme (Thymus pulegioides) in Flanders

HagelandSupervisor: Olivier Honnay & Joachim Mergeay

Aims:

- Quantify population genetic diversity in remnant populations using SNPs- Quantify population fitness based on seed viability- Quantify Soil chemical composition (N, P, C, pH)- Statistically relate genetic diversity with degree of habitat fragmentation, fitness and local habitat chracateristicsInfer gene flow (pollen and seeds) among populations

- Provide guidelines for conservation

2. Genomic diversity and local adaptation in Frangula alnus

(Sporkehout)

Supervisor: Hanne De Kort

General objectiveExamine both adaptive and neutral genetic variation between Belgian and foreign (Italian, Swedish and French) populations.Basically, our most important research questions are:• Is Frangula alnus adapted to its local growing

conditions?

• How genetically diverged are Frangula populations, and are the observed patterns different in Flanders than abroad?

Methodology• Measurement of seedling characteristics in a common

garden • Measurement of seedling characteristics in

transplant sites• Apply single nucleotide polymorphism (SNP) analysis,

and calculate genetic diversity parameters.

• Compare morphological variation among seedling characteristics (Qst) with genetic marker (SNP) variation (Fst) to detect natural selection (Qst-Fst)

3. The impact of sex ratio on genetic diversity and differentiation in the

gynodioecious Saxifraga granulata

Gynodioecy is a special sexual system in which populations consist of female and hermaphroditic plants.

Gynodioecy can only exist if female plants have a reproductive advantage relative to hermaphroditic plants.

Females need pollen from hermaphrodites for seed production

AimsIn this study you will

investigate the relationship between sex ratio and:◦ genetic diversity◦ population size◦ population differentiation◦ gene flow

in Saxifraga granulata (Knolsteenbreek)

Practical

Fieldwork Leaf sampling of females and hermaphrodites (Dijle Valley)

Labwork Genetic analysis of polymorphic loci(SSRs)

Statistics Analysis of results

4. The taste of nectar: Effects of nectar amino acids on pollinator behavior

To increase reproductive success, many plants produce nectar to attract insect pollinators.

Very little is known about the role of amino acids in nectar. Amino acid concentration is expected to be an important source of nitrogen for pollinators but also composition could be of importance since aa can influences the taste of nectar.

The aim of the project is to test the effect of changes in amino acid concentration and composition on the behavior of butterflies pollinating the orchid Gymnadenia conopsea.

Supervisor: Pieter Gijbels

Practical:

◦ Select pairs of individuals and enrich the nectar of one individual of each pair

◦ Determine nectar aa composition of both enriched and control individuals using HPLC

◦ Monitor pollinator behavior on individuals with control and enriched nectar.

◦ Collect and dissect flowers of all individuals and determine the number of pollinaria removed and deposited.

◦ Statistically compare the different elements of pollinator behavior, pollen removal and pollen deposition between treatments

5. Impact of coffee forest management on AMF diversity of coffee in Southwest

Ethiopia Coffee is the most important economic export

product of Ethiopia. More than 15 million Ethiopians depend on it for their main income. Arbuscular mycorrhiza are important for sustainable and organic cofee cultivation. A high diversity of AMF on coffee roots can be expected to have a broad functionality.

supervisor: Matthias De Beenhouwer

What is the effect of forest management intensity of coffee forests on the diversity of AMF in coffee roots? Does the age of the coffee shrub affect AMF diversity?

practicalSampling campaign in Ethiopia

(Jimma region) summer 2012DNA extraction soil samples454 sequencingBioinformaticsStatistical analysis of AMF

diversity vs. forest stand characteristics

Functioneren ecosysteem

Niveau van biodiversiteit

6. Effects of plant trait diversity on the stability of functioning of Dutch dune

grasslands

Supervisor: Nils Van Rooijen

With Joop Schaminee (Nijmegen University)

• Species richness• Species diversity• Species evenness

• Trait diversity• Trait richness• Functional species groups

• Continous trait measures• Hypervolumes• Dendrograms

Homogene vegetatie = RS MODIS pixel

Kwantificeren van plantendiversiteit

Vegetatie-opname

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Taxonomische diversiteit

Funcionele diversiteit

7. Adaptive evolution in floral traits in response to changes in pollinator composition

across the distribution range of a distylous forest herb

Geographic ranges of plants and their pollinators do not always entirely overlap. A shift in pollinator composition from specialized pollinators in the centre of the plant species’ range to more generalist insect species in the periphery and introduced populations may lead to adaptation of the floral morphology and mating system.

Supervisor: Sofie Meeus

Specialists Generalists

Practical:◦ Floral measurements of

12 traits on flowers collected in spring 2012 from populations within the range (Germany) and outside the range (Flanders) of P. officinalis

◦ Statistics of floral variation with differences in pollinator composition in the three regions

8. Factors affecting natural regeneration of pedunculate oak, implications for

sustainable forestry? Forest policy increasingly promotes a sustainable forest management in which natural regeneration plays an important role (FAO 2011).

Besides the economical and ecological benefits, natural regeneration allows permanent natural selection on the regeneration, favoring well adapted progeny.

However, in many forest stands successful establishment of seedlings is limited or completely absent, jeopardizing a sustainable forestry .

Supervisor: Guy Vranckx

General objectiveThe general objective is to examine which environmental factors (vegetation, light, soil) affect natural regeneration of pedunculate oak (Quercus robur) in forest stands across Flanders. Methodology

Vegetation surveys in ca. 20 pedunculate oak stands across Flanders (Summer 2012)

Measurements of stand characteristics in 10 x10m plots:

Number and diameter adults and seedlings Health status trees (defoliation index),

tree mortality Analysis of light conditions (Leaf area

index (LAI) using a hemispherical lens) Measurements of soil water and thickness

of the Ah horizon Analysis of soil samples (pH, nitrogen,

organic matter content…)

Supervisor: Rein Brys & Hans Jacquemyn

Hybridization between species may be an important threat to the long-term viability of rare taxa. We will investigate the extent of hybridization between D. maculata and D. sphagnicola using both molecular and morphological analyses.

Pre- and post-zygotic mating barriers will estimated using controlled pollinations. This study involves both field work and laboratory analysis.

All field work will be conducted in the Hoge Venen Nature Reserve.

9. Hybridization between Dactylorhiza maculata and the rare D. sphagnicola:

implications for conservation

Methodology Assessment of prezygotic and

postzygotic reproductive barriers using controlled pollinations between the two study species.

Measurement of morphological traits in hybrid populations and pure populations of both D. maculata and D. sphagnicola.

Collection of leaf samples and genetic AFLP analysis of pure and hybrid populations.

Assessing the extent of hybridization and introgression using multivariate techniques and assignment analyses.

10. Changes in the soil seed bank during community assembly on the calcareous grasslands of the Viroin

valley.

Due to the LIFE-project “restoration of calcareous grasslands”, more than 100 ha calcareous grassland have been restored since 2002. This allows us to create establish a chronosequence of grasslands fragments of different age (and thus of different succession stage), making it possible to compare the seedbank composition of the restored fragments between different successional stages.

Supervisor: Kenny Helsen

Aim:◦ Look at the evolution of seed abundances and

species composition of the seed bank under calcareous grasslands of different restoration age using germination experiments. This allows us to reconstruct the succession within the seedbank.

Practical:◦ Sampling in the summer: taking

soil samples in the Viroin valley.◦ Doing vegetation surveys◦ Lab work: germination protocol

and identification of seedlings.◦ Statistical analysis (multivariate,

mixed models).

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Laboratory of Plant EcologySupervisor: Rein Brys & Hans Jacquemyn

Habitat fragmentation has been shown to affect the genetic constitution of populations in a large number of plant species, but the ecological consequences on plant and population viability are, however, often poorly understood. You will study the consequences of habitat fragmentation and the resulting genetic consequences on the process of reproduction, dispersal capacity and offspring fitness in the rare calcareous grassland plant, Cirsium acaule. This study involves both field work (in the Viroin valley) and experiments in the laboratory.

11. Impact of habitat fragmentation on reproductive success, dispersal capacity and offspring fitness in the rare Cirsium acaule

Methodology Investigation of successful pollination and

pollen limitation in the field, via comparisons of seeds set resulting from open vs. supplemental hand-pollinations in a large number of natural populations.

Measurement of seed quality, seed mass and dispersal traits (pappus size and width) in the laboratory.

Measurement of seed dispersal capacity under experimental conditions.

Common garden experiment to examine offspring fitness of each of the studied populations at the level of: germination rates, seedling survival, offspring fitness etc.

Statistical analysis (multivariate, mixed models)

Laboratory of Plant EcologySupervisor: Bruno Cachapa Bailarote

The ecology of many epiphytic orchid species is still poorly known, mainly due to their high diversity in tropical regions coupled to sampling difficulties due to their unusual lifestyle. In particular, little is known about the diversity and specificity of mycorrhizal associations in tropical epiphytic orchids, even though those symbiosis are crucial in determining their distribution and abundance. The aim of this study is to investigate the diversity and specificity of orchid mycorrhizal associations in a number of orchid species found in Cameroon and Gabon through field and laboratory work.

12. Mycorrhizal diversity in tropical epiphytic orchids: the case of orchid communities in

Cameroon and Gabon

Methodology Sampling of orchid roots and leaves on

the field in tropical rainforests in Atlantic Central Africa (Cameroon and Gabon). This include tree climbing with appropriate gears in order to get access to most of the local species.

DNA extraction of mycorrhizal fungi from orchid roots and identification using the 454 technology (next generation sequencing).

Determination of mycorrhizal specificity and spatial variation in mycorrhizal associations across different species and populations.