Looking for a PhD student to study population genomics of rapid evolution

Details on how to apply (deadline 27th January 2021):

As part of a collaborative project with Isabell Hensen and Christoph Rosche (among others) at the Martin Luther University Halle-Wittenberg (Germany), we are looking for a PhD student to study rapid evolution using genomic data of a wide-spread invasive plant species. This project is in cooperation with the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig:

“Harnessing the power of RADseq data to achieve a more mechanistic understanding of rapid evolution”

This integrative project will apply RADseq analyses to identify molecular mechanisms of rapid evolution in native and non-native Conyza canadensis populations. Landscape genomics will unravel adaptive and non-adaptive drivers of the global genomic structure of this cosmopolitan weed. Available common garden data will allow studying genomic associations for intraspecific trait variation for phenotypic (competitive ability) and metabolomic data (root exudate profiles). The project will be supervised by the iDiv members Isabell Hensen (MLU Halle), Walter Durka (UFZ Halle) and Renske E. Onstein (iDiv Leipzig).

Tasks:
• Performing population genomic lab work and data analyses
• Publishing scientific papers in peer-reviewed journals
• Presenting results at national and international conferences
• Interactions with molecular and evolutionary ecologist at MLU, UFZ and iDiv
• Travelling for interactions with collaborators from the University of Montana
• Active participation in the yDiv graduate school
• Qualification goal: PhD in population genomics

Requirements:
• M.Sc. or equivalent scientific university degree in a project-related field (e. g., population genetics, plant
genomics, population ecology, plant ecology and evolution, invasion biology)
• Statistical skills, experience with R
• Expertise and experience in population genetics are advantageous
• Experience in working with data pipelines is also advantageous

Get in touch if you have any questions!

Looking for a technical assistant to join the group

Details on how to apply can be found here: 174_iDiv_Tech_Assistant_EA_REO_engl (deadline 12th of August 2020).

Technical assistant Evolution & Adaptation group at iDiv (Leipzig, Germany)

Limited until 30 September 2021. 100% of a full-time position. Salary: Entgeltgruppe 6 TV-L. Workplace: Leipzig.

The Evolution & Adaptation research group focuses on the interchange between (macro-) ecology and evolution, to understand the global distribution of genetic, taxonomic and functional diversity. We therefore generate genetic (genomic) data (e.g. from plants from Madagascar), and build databases of biodiversity data (such as functional traits) to investigate the link between genes and phenotype. Understanding these links is important for predicting how adaptable biodiversity is to current and future global change.

Tasks:

  • Combining (botanical) data sources (such as monographs and floras) to build databases for biodiversity data (using Access/PROTEUS or SQL)
  • Measuring functional plant traits from herbaria or fresh sample material
  • Collecting and cleaning plant species occurrence data from online data sources/herbaria
  • General laboratory organization and maintenance
  • Planning and conducting basic molecular techniques
  • Analysis of generated data and preparation of suitable presentations

Requirements:

  • Professional qualification as a Biological-Technical Assistant or an equivalent degree (e.g. BSc or MSc in Biology)
  • Hands-on experience with basic molecular techniques (e.g., DNA/RNA isolation, PCR, real-time PCR, gel electrophoresis) preferable
  • Experience in building databases preferable
  • Very good computer skills (MS Windows, MS Office, R, etc.)
  • Very good spoken and written English
  • Strong team player also able to work independently
  • Very well organized and reliable
  • Experience with working in interdisciplinary and international teams

For questions, contact me on onsteinre@gmail.com!

Looking for two PhD students to join iDiv!

Application details for both positions are now available – see below!

I am looking for two new PhD students to join the Evolution & Adaptation group at iDiv in Leipzig (Germany) from October 2020 onwards. The positions are fully funded (65% of a full time employment, Salary: Entgeltgruppe 13 TV-L) and for 3 + 1 years. There is a budget available for consumables to perform fieldwork, lab work, sequencing, visit conferences, herbaria, collaborators and take courses. The PhD students will become part of the yDiv graduate school. iDiv is a very international place to work in and learn about Biodiversity science more generally, with weekly seminars, and Leipzig is a lovely city with lots of green space and a cultural history to live in.

Below I briefly describe both projects. Feel free to get in touch (onsteinre@gmail.com) to find out more, if you are interested in applying to one of them:

1. Macroecology and macroevolution of plant – frugivore trait matching in the tropics

Application details available from here: 113_iDiv_P3_REO_engl and 112_general_announcement__4thFlexPoolcall_engl. Deadline for application: 10th July 2020.

Background: Mutualistic interactions between fleshy-fruited plants and frugivorous animals are prominent in tropical rainforests. These interactions are facilitated by the evolution of matching traits in both plants and frugivores, such as fruit size and frugivore gape width. Due to ongoing global change (e.g., defaunation) trait matching may have been distorted in certain places, such as highly disrupted regions, leading to co-extinction or rapid evolutionary change in plants/animals that relied on these locally extinct interaction partners. However, which places harbour such mismatches in traits is unknown. Furthermore, it is unclear when these interaction-relevant traits evolved, and whether they have influenced the past diversification dynamics of plants and frugivores. In this PhD project, we aim to understand the impact of frugivory-related plant and disperser trait origin and extinction on the macroecology and macroevolution of fruit-frugivore trait matching, by addressing three main questions: (1) Do frugivory-related plant and animal dispersal syndromes (i.e., sets of correlated traits) differ among biogeographical realms, or mainland/island systems? (2) Is the spatial distribution of frugivory-related plant traits matched by the corresponding animal disperser traits (e.g., fruit size ~ gape width), or are there mismatches due to Late Quaternary extinctions of particular mammalian, avian or reptilian functional groups? (3) Has there been trait matching or mismatching during particular geological time periods, leading to increased (co-)speciation or extinction? To answer these questions, we will focus on three plant clades that are keystone resources for frugivores in the tropics: Arecaceae (palms), Annonaceae (custard apples) and Fabaceae – Mimosoideae (legumes). Furthermore, we will match the plant data to frugivore data, primarily focusing on frugivorous birds and mammals. We will integrate phylogenetic, distribution and functional trait data for these clades and apply macroecological and macroevolutionary methods to answer the research questions. This project will shed light on the biogeography of plant-frugivore interactions to be able to identify places and lineages prone to ongoing (co-)extinctions of their interaction partners. This project is supervised by me, Ingolf Kühn, Isabell Hensen and Irene Bender, but the student will work with several more collaborators for the specific datasets and their expertise on the plant and animal clades.

Tasks:

  • Developing specific research questions and hypotheses within the scope of the project;
  • Assembling/cleaning plant and animal frugivory-related traits, phylogenetic and distribution data from online databases, literature, monographs and herbarium visits (partly already done);
  • Applying macroecological and macroevolutionary methods to test the specific hypotheses;
  • Writing and publishing scientific papers in peer-reviewed journals;
  • Presenting results at national and international conferences;
  • Participation in iDiv’s PhD training program yDiv.

Requirements: Applicants should hold a Master’s or equivalent degree in a related field of research (e.g., biosystematics, (macro-)ecology, (macro-)evolution, environmental sciences). The successful candidate should be innovative, able to work on his or her own initiative, have expertise and experience in phylogenetics or working with phylogenetic data, interest and ability in handling spatial data and functional traits and strong statistical skills (in R). Candidates should be team-oriented and have strong organizational skills, in order to manage this collaborative research project within an international consortium. Excellent English communication skills (speaking and writing) are required. We seek candidates with an independent mind and the ambition to publish in internationally leading journals.

2. Adaptive evolution of plant-frugivore interactions on Madagascar

Application details available from here: 142_iDiv_PhD_Onstein_EA_engl. Deadline for application: 20th July 2020.

Background: Madagascar harbours exceptional biodiversity, but this tropical hotspot also faces increasing threat from human activities and climate change. Plants with large, ‘megafaunal’ fruits are common across the flora of Madagascar, especially within the palm (Arecaceae) family. However, Pleistocene-Holocene extinctions of large-bodied ‘megafaunal’ fruit-eating and seed-dispersing animals (such as giant lemurs) may have hindered the dispersal of taxa with megafaunal fruits. In this project we aim to investigate the molecular, micro- to macroevolutionary consequences of dispersal limitation in palms, specifically focusing on adaptive evolution of a megafaunal-fruited palm, Hyphaene coriacea, using a comparative framework of Madagascar (all megafauna extinct) and mainland Africa (where H. coriacea is still frequently dispersed by elephants). Specifically, we aim to (i) identify candidate genes for fruit and seed traits important for plant-frugivore interactions, (2) pick up genetic traces of selection or adaptation in relation to dispersal by smaller-bodied frugivores, and (3) evaluate the macroevolution of candidate genes or gene families across the palm family. This project integrates the fields of plant evolution, molecular evolution and plant-frugivore interaction ecology. It will be in collaboration with researchers from Hohenheim University (Prof. Philipp Schlüter) and University of Miami (Prof. Mauro Galetti), among others.

Tasks:

  • Collecting genetic samples from H. coriacea individuals and populations on Madagascar and mainland Africa, and measuring their functional traits (part of these samples have already been collected);
  • Collecting ecological information about the seed dispersal effectiveness (e.g., using camera traps) and demography of H. coriacea in the study areas;
  • Using novel genomic and transcriptomic techniques (e.g., RAD-seq, RNA-seq) to infer candidate genes for functional traits and evaluate traces of selection;
  • Writing and publishing of scientific papers in peer-reviewed journals;
  • Presentation of results at international conferences;
  • Participation in iDiv’s PhD training program yDiv.

Requirements: Applicants should hold a Master’s or equivalent degree in a related field of research (e.g. molecular biology, genetics, phylogenetics, population genomics, ecology and evolution). The successful candidate should be innovative, able to work on his or her own initiative, and willing to spend several months in the field (Madagascar/mainland Africa). Therefore, prior experience with tropical natural history, fieldwork and basic living conditions is advantageous. Furthermore, the successful candidate should have prior experience using molecular techniques, preferably with transcriptomics or bioinformatics, incl. the basics of scripting/programming for handling and statistically analysing large genetic/genomic datasets. Candidates should be team-oriented and have strong organizational skills, in order to manage this collaborative research project within an international consortium. Excellent English communication skills (speaking and writing) are required. We seek candidates with an independent mind and the ambition to publish in internationally leading journals.

 

 

PalmTraits 1.0

Functional traits are characteristics of individuals, populations and species that determine their fitness, via their impacts on growth, survival and reproduction. Examples are leaf size, leaf thickness, fruit size, wood density…. Traits are great proxies for the ecology of species, and used extensively in macroecological and macroevolutionary research. PalmTraits 1.0 provides species-level trait data for all ca. 2500 palm (Arecaceae) species worldwide. The database is available from Dryad. The article in which we present the data was published in Scientific Data.

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PalmTraits 1.0, Figure from the publication in the journal Scientific Data

What else did we (I and my collaborators) do with these data? For example, using average fruit size of palm species, we asked questions such as: Do large fruits co-occur with large-bodied animals that disperse these fruits? And: Does fruit size influence speciation rates via the interaction between fruits and fruit-eating and seed-dispersing animals? What happened to palms with large, ‘megafaunal’ fruits since the Quaternary extinctions of large-bodied animals?

Answers to these questions can be found in these publications:

Onstein, R.E. , Baker,W.J., Couvreur, T.L.P. , Faurby, S., Herrera-Alsina, L., Svenning, J.-C. & Kissling, W.D. (2018). “To adapt or go extinct? The fate of megafaunal palm fruits under past global change”. Proceedings of the Royal Society B 285: 20180882. [ABSTRACT] [PRESS RELEASE]

OnsteinR.E. , Baker,W.J., Couvreur, T.L.P. , Faurby, S. , Svenning, J.-C. & Kissling, W.D. (2017). “Frugivory-related traits promote speciation of tropical palms”. Nature Ecology & Evolution 1:1903–1911. [ABSTRACT] [DATA & CODE] [PRESS RELEASE] [BLOG]

However, the data can be used to answer many more questions, related to the ecology and evolution of palms. Species differ not only in their fruit sizes, but also in, for example, fruit colours, leaf structures and sizes, the presence or absence of spines, growth forms, plant height. In combination with distribution data and a phylogeny, we can now answer questions such as: when did these traits evolve? Where do species with these traits occur? Where do we find the most colourful fruits, and why? Where do species occur that have spines? Etcetera…

Beyond climate: why are there so many species of flowering plants in mediterranean-type ecosystems?

Have you ever wondered why – evolutionary speaking – the mediterranean floras of the world are so species-rich (e.g. the Cape of South Africa and Western Australia)? And why species look so similar in these systems (small, fibrous leaves adapted to deal with drought and low nutrient soils)?

We (Peter Linder and I) may give you a clue in a recently published study: “Beyond climate: convergence in fast evolving sclerophylls in Cape and Australian Rhamnaceae predates the mediterranean climate” in Journal of Ecology.

Although the very similar climatic conditions among mediterranean-type ecosystems were previously thought to drive this patterns of morphological ‘convergence’, it may not be the only important factor.  Furthermore, it seems that these typical morphological characteristics of the plants (i.e. sclerophyllous leaves) may also have influenced their evolutionary fate: well-adapted leaves may reduce your chance to go extinct. Some groups of plants may therefore have evolved a whole bunch of species – all with similar functional traits – and so contributed to the extraordinary species diversity in these mediterranean-type ecosystems.

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Mediterranean-type ecosystem in the Cape of South Africa

A week with Shipley

 

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Wageningen University, credit: JD Santillana-Ortiz

Last week I traveled back to my scientific roots (Wageningen University) to participate in a course on Structural Equation Modeling (SEM) given by Bill Shipley (he is particularly well known from his book on ‘Cause and Correlation in Biology‘). Structural Equation Models can be used to evaluate the sequence of variables affecting each other, and whether the underlying data supports such a sequence of events (also called path-models). For example – ecosystem functions (e.g. productivity and decomposition) can be affected by the biomass of the vegetation, and this can be affected again by the age of the plot (e.g. during succession) (Lohbeck et al. 2015).

P1110855

some notes…

As an evolutionary ecologist I was a  bit of a misfit in the group. The group was dominated by Dutch PhD students and professors working in ecology (e.g. functional ecology, community assembly, soil science). They often collect data from plots; data which fit perfectly well in a structural equation model. My data did not – for a couple of reasons. My ‘plots’ are fossil assemblages (species richness = count data, problem 1), collected during the Cenozoic (different time scales, problem 2) and the variables we have are often not assemblage-specific but biased by time, and not normally distributed (e.g. CO2 concentration, temperature, latitude). On the positive side – I have a large sample size (N=666), which is necessary to have enough power to run these SEMs. So how can I test what factors directly and indirectly affect biodiversity (species richness)?

The solution. There is a solution. If your data is spatially, or phylogenetically biased, if your variables are not normally distributed, if you deal with binary/categorical/count data, if you have a nested design… The solution is the d-separation test. (d-sep cannot deal with ‘latent’ variables, e.g. unmeasured variables which may be important for the model).

d-separation in 6 steps:

  1. your hypothetical model (DAG: “Directed Acyclic Graph” avoid feedback loops in the model!) (for simplicity: A<- B <- C)
  2. write down each pair not connected by an arrow (in our example only AC)
  3. causal parents of these? (i.e. causal parent of A = B and of B = C. In our example of AC there is just one causal parent: B)
  4. run a suitable linear model/generalized linear model/PGLS/mixed model in which you test the effect of your pair variables, conditioned on the parent variables, in our example, of C on A conditioned on B (A ~ B + C)
  5. sum the probabilities (p values) of the slope coefficients of the regressions (in this case only one regression model was run, and we asses the coefficient of C and it’s p-value)
  6. calculate the C-statistic: -2 * ln (the sum calculated in step 5) and compare this to a Chi-square distribution. The degrees of freedom are calculated by 2* the number of regressions run (in our case 2 degrees of freedom). If p>0.05, you cannot reject you hypothesized model. If p<0.05 your data do not support the model.

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    All analyses can be performed in R using packages ggm and lavaan. credit: JD Santillana-Ortiz

Thanks to the d-separation test we, evolutionary biologist, can still test for causal relationships in our data, even if these data are far from ‘perfect’ or complete. It provides great potential for the field of phylogenetic comparative methods. But how exactly I’m not sure yet….

Reference

Madelon Lohbeck, Lourens Poorter, Miguel Martínez-Ramos, and Frans Bongers 2015. Biomass is the main driver of changes in ecosystem process rates during tropical forest succession. Ecology 96:1242–1252. http://dx.doi.org/10.1890/14-0472.1