BioND Lab

3 Dec 2024

There is now a starter pack with our group members available: go.bsky.app/4aYCsai

arxiv.orgNutrient Competition as a General Mechanism of Regulation in PhotosymbiosisNitrogen limitation is a key mechanism regulating the mutualism between photosymbiotic cnidarians and their algal symbionts. Algal-derived photosynthate facilitates host assimilation of inorganic nitr...

Paper Alert! New preprint by @limnivorous.bsky.social, @radecker.bsky.social , @ibaums.bsky.social , and @thilogross.bsky.social that offers mechanistic insights into photosymbiotic stability by analyzing the role of nitrogen competition in corals. arxiv.org/abs/2609.37826

symbiont density must positively couple to host ammonium assimilation via photosynthate translocation. Bifurcation analyses show that an unregulated influx of external nitrogen can destabilize the interaction, leading to population oscillations or system collapse.

This metabolic feedback loop offers a general ecological mechanism explaining both the maintenance of partner abundance and the repeated evolutionary origin of photosymbiosis across diverse taxa.

Nitrogen competition acts as an autonomous negative feedback loop, regulating symbiont density without requiring external density-dependent mechanisms. At low host nitrogen assimilation rates,

stability is driven primarily by intraspecific symbiont competition for ammonium. As host assimilation increases, the system transitions toward interspecific host-symbiont competition. To maintain dynamic stability under strong interspecific competition,

How do cnidarian-algal symbioses maintain ecological stability without relying on host sanctions? Using a generalized modeling framework we show that host-symbiont competition for inorganic nitrogen (ammonium) is sufficient on its own to dynamically stabilize symbiont population.

Great work! Last week Juliane Entzian (@j-entz.bsky.social) and Melanie Habermann (@mhab.bsky.social) represented our group at the Topic 6 Symposium 2026 at GEOMAR. Topic 6 is one branch of the Helmholtz research area 'Changing Earth - Sustaining our Future' with focus on Marine and Polar Life.

Both approaches identify important parts of food webs but through different perspectives: one (Juliane) by looking at the network as a whole and the other (Melanie) by considering it's small building blocks.

The insights are important for prioritization in marine governance and nature conservation but can be applied to every system that is representable as a network (basically all) from power grids to epidemic transmission.

Juliane had a poster about her work on how to identify key species in a food web, including a dynamic predator-prey system.

Melanie gave a talk on her paper Functional Motifs in Food Webs and Networks (see previous post: bsky.app/profile/bion...), in which she showed how reactivity can be used to determine the influence of subgraphs on system behavior.

besjournals.onlinelibrary.wiley.comComplexity promotes stability in mutualistic networks through weaker mutualistic dependencies: Insights from Generalized ModellingWe show that complexity, but not nestedness or modularity, increase dynamical stability of mutualistic networks, mainly through a weakening in mutualistic dependencies with complexity.

10 Sept

Paper Alert! New paper out together with Timo Metz (@timometz.bsky.social), Jan Timo Bachmann and Nico Blüthgen.

Thilo Gross@thilogross.bsky.social

New Paper: An ecological model of plant polinator network shows how dynamical stability depends on network properties. besjournals.onlinelibrary.wiley.com/doi/full/10....

journals.aps.orgDiffusion-driven pattern formation in an opinion dynamical network modelThe spatial organization of individuals and their interactions in communities are important factors known to preserve diversity in many complex systems. Inspired by metapopulation models from ecology,...

11 June

Paper alert! Very proud to announce, that our PhD student Tim (@timmauch.bsky.social) got his first paper published. He introduces a meta-community opinion model via a reaction-diffusion system on networks. 1/3

Tim Mauch@timmauch.bsky.social

My master's thesis got published in Physical Review E🥳! Thanks to @thilogross.bsky.social for the supervision. We develop a meta-community opinion model and use a master stability function approach to find conditions where pattern formation facilitates diversity. Read here: arxiv.org/abs/2508.15377

11 June

The study uncovers conditions where structural properties allow an "inferior" opinion to achieve local dominance, preventing global homogenization. Analytical insights on #OpinionDynamics #NetworkScience #ComplexSystems #StatisticalPhysics #AppliedMath journals.aps.org/pre/abstract... 2/3

arxiv.orgDiffusion-driven pattern formation in an opinion dynamical network modelThe spatial organization of individuals and their interactions in communities are important factors known to preserve diversity in many complex systems. Inspired by metapopulation models from ecology,...

11 June

If you don't have access to the journal, you can find the paper also on arXiv: arxiv.org/abs/2508.15377 3/3

22 May

Mind the gap! Next stop: Biodiversity Theory Our working group just digitized our research landscape using a classic London Tube map design. Every line is a team member; every station is a core topic or application we tackle. Check it out and see where our work interconnects!

doi.orgCounting chemical isomers with multivariate generating functions | Network Science | Cambridge CoreCounting chemical isomers with multivariate generating functions - Volume 14

21 Apr

Paper alert! Did you ever think that counting the many different structures you can get from the chemical composition is hard? We've got the paper that shows you how to do it. Here's the newest publication by Rana Shojaei (@ranashj.bsky.social) and Thilo Gross (@thilogross.bsky.social).

Rana Shojaei@ranashj.bsky.social

Very excited to share that our paper with @thilogross.bsky.social , “Counting Chemical Isomers with Multivariate Generating Functions,” has been published in Network Science. doi.org/10.1017/nws.... #network_structure #multivariate_generating_function #Pólya’s_theorem #symmetry #moleculardiversity

17 Mar

Paper alert! Great use of generalized modeling to learn about bacteria. It's Jana's (@janamassing.bsky.social) final paper from her time in our group. Highly recommended!

This post is unavailable.

12 Mar

If you're at dpg today: Our PhD student Tim Mauch (@timmauch.bsky.social) will give his talk about "Jacobian Reconstruction from Time-Series of an Opinion Dynamical Network Model and its Applicability as an Early Warning Signal for Tipping Points" 🕧 12:30 PM 📌 GÖR/0226

12 Mar

At dpg this week? Then you don't want to miss Bernd Fernengel's talk about "Linear Dynamics on Infinite Networks". 11:45 AM, ZEU/0118

doi.orgFunctional motifs in food webs and networks | PNASWhen studying a complex system, it is often useful to think of the system as a network of interacting units. One can then ask if some properties of...

1 Feb

Paper alert! Our study about functional motifs is out in PNAS. We use food webs as an example to discuss how small subgraphs drive the dynamics in complex systems. While motifs that determine overall stability are rare, when it comes to reactivity, we show that small groups dominate system behavior.

Ashkaan K. Fahimipour@akfbio.bsky.social

New paper with @mhab.bsky.social @jdyeakel.bsky.social and @thilogross.bsky.social out now in @pnas.org! We show when and why you can know something about an entire network, just by knowing the behavior of it's building blocks: doi.org/10.1073/pnas...

Time to introduce a new group member: Juliane Entzian joined us as a new postdoc! "Don’t we all want to improve the world for at least just a tiny bit? And is there a more comfortable way in doing so than just telling decision-makers what should be done – ... 1/5

... I’m absolutely grateful for the opportunity to extensively dive into network analysis here, and for finding an application in biodiversity and food web research that contributes to the wide-ranging IMAPP project." 4/5

hifmb.deJuliane Entzian - HIFMB OldenburgVita 2025 – heute Postdoktorandin am HIFMB, Oldenburg 2020 – 2024 PhD im Bereich Angewandte Mathematik mit Schwerpunkt Numerik/ Approximationen, Universität Hamburg 2012 – 2019 Diplom in Mathema...

Find out more about Juliane and her publications here: hifmb.de/de/personen/... www.researchgate.net/scientific-c... 5/5

... without having to deal with the (often pretty complicated) implementation? I barely think so. Still, evidence-based decisions are crucial when it comes to successful implementation. In order to be able to explore, improve, and further develop methods and models that provide ... 2/5

... such evidence and facts, I started studying Mathematics in Leipzig with a focus on PDEs, continued giving attention to numerics/approximations during my PhD in Hamburg and finally joined the Biodiversity Theory group at HIFMB as a PostDoc. ... 3/5

4 Sept 2025

Don't miss Tom Clegg's (@cleggtom.bsky.social) poster today at EcoNet 2025 with the title "Cross-feeding networks create tipping points in microbiome diversity" where he tries to answer the question how biodiversity of microbiomes emerges from interactions between populations.

3 Sept 2025

If you’re attending EcoNet 2025, don’t miss Jordan Gault’s (@jagault.bsky.social) poster presentation: “Dissimilarity analysis based on diffusion maps.” His work highlights how diffusion maps, a manifold learning approach, provide powerful new tools to track community change across space and time.

1 Sept 2025

If you're at CCS 2025 this week: Tues, Sep 2nd, 12:15 pm, Room 15, Melanie (@mhab.bsky.social) will present her work on functional motifs in foodwebs and networks. Same day, Room 14, Tim (@timmauch.bsky.social) talks about diffusion-driven pattern formation in an opinion dynamical network model.

Paper alert! See the new pre-print up on arXiv by Tim Mauch (@timmauch.bsky.social) and Thilo Gross (@thilogross.bsky.social) on opinion formation: arxiv.org/abs/2508.15377 The paper discusses the very nice results of Tim's master thesis, so let's get into the details, shall we? 1/5

These dynamics lead to bistable conditions where either one of the two opinions can be dominant across all communities. Tipping points can lead to an abrupt switch of the dominant opinion. However, the minority opinion is not doomed totally... 4/5

Using a master stability function approach, we show conditions where opinions distribute heterogeneously across the network, resulting in communities where the majority of agents hold the minority opinion. These regions can be seen as local hubs where minority views can thrive and develop. 5/5

Opinions form the basis of how individuals make decisions. We change our opinions through interactions with others along the complex social networks that structure societies. In our paper we ask how these interaction networks shape opinion formation. 2/5

We build a network model where nodes are communities of interacting agents with two competing opinions, and links represent avenues of migration. Agents can either flip their opinion spontaneously, change their opinion under the influence of others or leave to a more like-minded community. 3/5

1 July 2025

Great opportunity 👇

HIFMB@hifmb.de

Hallo artist community, this one is for you! Together with @hanse-ias.bsky.social we are looking for an artist in residence in early 2026. Please share! #artscience #artistinresidence #marinebiodiversity

Meet our group members! Next one up is Fabian Moye: "Hi, I am Fabian, a postdoc in the Biodiversity Theory group at HIFMB and the Eco-Evolutionary Genomics group at AWI, Bremerhaven. I am interested in the formation, fate and function of diversity from chemistry (chemodiversity) ... 1/5

... The focus of my postdoc is on genome size and cell size of unicellular marine plankton within environmental and evolutionary constraints that may form tipping points in biodiversity. Cell size is a major trait that links individuell fitness with ecosystem function. ... 4/5

biond.orgBioND | Fabian Moye

... Using field data and theoretical models I want to answer: How will cell size of unicellular plankton develop in a future ocean?" Find out more about him here: biond.org/people/profi... hifmb.de/people/fabia... 5/5

... to ecology (biodiversity). Sources, sinks and transformation of marine dissolved organic matter (DOM) control the storage of carbon in the ocean for thousands of years. During my PhD, I used mass spectrometry and data science ... 2/5

doi.orgFrom Retention Time to Functional Group Assignment: A Chemical Database‐Driven Approach for High‐Resolution Mass Data of Marine Dissolved Organic MatterRationale The high chemodiversity of marine dissolved organic matter (DOM) has challenged identification of singular DOM components. To infer chemical structure features of DOM with accurately deter...

... to unravel the extreme complex molecular composition of DOM (doi.org/10.1002/rcm....) to better understand the marine carbon cycle. ... 3/5

5 June 2025

Another talk at #NetSci2025 @netsciconf.bsky.social you shouldn't miss: Thilo Gross @thilogross.bsky.social will give a talk in the Ecological Networks session at 12:45 pm today. 📄Functional Motifs in Food Webs and Networks 📌0.04 Brussels

arxiv.orgFunctional Motifs in Foodwebs and NetworksWhen studying a complex system it is often useful to think of the system as a network of interacting units. One can then ask if some properties of the entire network are already explained by a small p...

5 June 2025

Find out more about the topic in the paper corresponding arxiv.org/abs/2503.14093

4 June 2025

At #NetSci2025 @netsciconf.bsky.social today and searching for something to do in the lunch break? Then good news! Why not take a look at Rana Shojaei's ( @ranashj.bsky.social ) poster in the lobby? 📄Counting Molecular Structures with Multi-variate Generating Functions 📌Biology, poster no. 20

4 June 2025

If you're at #NetSci2025 @netsciconf.bsky.social today, don't miss the talk by Thomas Clegg @cleggtom.bsky.social in the Biological Networks session at 11:30 am! 📄: Cross-feeding Creates Tipping Points in Microbiome Diversity 📌: 0.04 Brussels