Dr Nadiah Kristensen
LightNews LightNews
banner
nadiah.bsky.social
Dr Nadiah Kristensen
@nadiah.bsky.social
2.3K followers 1.1K following 530 posts
modeller of ecology, evolution, and cooperation | she/her | 🤘 | 🐘 fediscience.org/@nadiah | nadiah.org
Posts Replies Media Videos
nadiah.bsky.social
Why is altruism more common in nature than spite? This new paper gives a general mathematical explanation: the degree of negative assortment that can be achieved is constrained in a way that positive assortment is not, particularly in unbalanced populations.

www.sciencedirect.com/science/arti...
Multi panel figure illustrating the following intuition for why group structures favoring altruism might be more common than those favoring spite. It considers the example scenarios with pairs of individuals. When the population is evenly split between 100 actors (altruistic or spiteful) and 100 non-actors, maximum positive assortment produces all same-type pairs (50 pairs actor+actor, 50 pairs actor+nonactor) and maximum negative assortment produces all opposite-type pairs (100 pairs actor+nonactor). Therefore, maximum assortativity produces equally group structures most favorable to altruism and group structures most favorable to spite. However, when actors outnumber non-actors (140 actors, 60 nonactors), positive and negative assortment have asymmetric effects on group structure. Maximum positive assortment still produces all same-type pairs (70 pairs actor+actor, 30 pairs actor+nonactor); however, maximum negative assortment cannot achieve all opposite-type pairs due to the surplus of actors – some same-type pairs (actor–actor) must remain (60 pairs actor+nonactor, 40 pairs actor+actor, ). Therefore, the maximum achievable positive assortment promotes altruism more effectively than the maximum negative assortment promotes spite. A similar asymmetry arises when non-actors outnumber actors (60 actors, 140 nonactors). Maximum positive assortment again produces all same-type pairs (30 pairs actor+actor, 70 pairs actor+nonactor), but maximum negative assortment cannot achieve all opposite-type pairs due to the surplus of non-actors – some same-type pairs (non-actor– non-actor) necessarily remain (60 pairs actor+nonactor, but 40 pairs nonactor+nonactor). Thus, once again, the maximum achievable positive assortment promotes altruism more effectively than the maximum negative assortment promotes spite.
November 25, 2025 at 6:47 AM
nadiah.bsky.social
Analytic solution for the stationary distribution of actions taken in iterated games with implementation errors, and code to automate the solution in SymPy.

nadiah.org/2025/11/18/a...
Analytic solution for the stationary distribution in an iterated game with implementation errors
For the past year, I’ve been working in my spare time through a very interesting paper by Kleshnina et al. (2023). The paper concerns an evolutionary game theory model where individuals play an iterat...
nadiah.org
November 19, 2025 at 11:23 PM
nadiah.bsky.social
I wrote a blog post about an unpublished paper with a surprising result -- unequal sharing can promote cooperation.

nadiah.org/2025/06/01/c...
Cooperation among unequals
In an unpublished paper, Staab et al. (2002) studied the effects of heterogeneity in endowments and productivities on cooperation. They were particularly interested in the effect of allowing players t...
nadiah.org
October 30, 2025 at 7:04 AM
nadiah.bsky.social
Quite the opening sentence from the Discussion:-

"Repeated interactions alone cannot explain the evolution of one-shot cooperation because they cannot explain the evolution of repeated cooperation."

www.nature.com/articles/s41...
Super-additive cooperation - Nature
Models show that human cooperation cannot evolve reliably under repeated interactions or under intergroup competitions, but combining the two mechanisms predicts a distinctive strategy, observed exper...
www.nature.com
October 16, 2025 at 2:22 AM
nadiah.bsky.social
Congratulations to my office-mate, Zach Carter, for making the cover of Nature Ecology & Evolution 🎉
natecoevo.nature.com Nature Ecology & Evolution @natecoevo.nature.com · Oct 8
Our October issue is now live: www.nature.com/natecolevol/...

Featuring research on: 🧪

💧Wetland carbon sequestration
🌊Starfish diversity in the deep sea
🧬Genetic architecture of reproductive success

Cover shows a colony of king penguins, from Carter et al. www.nature.com/articles/s41...
Cover image of the October issue of Nature Ecology & Evolution showing a colony of king penguins. The headline reads "Antarctic challenges"
October 10, 2025 at 6:08 AM
nadiah.bsky.social
Watching “Animal Pride” hosted by Queer FoS at QUT
A screen showing a movie. It’s an underwater shot of two Orcas.
September 26, 2025 at 6:09 AM
Reposted by Dr Nadiah Kristensen
simoncolumbus.bsky.social
Turns out Alexander Magazinov has a long blog post about these guys (pretty sure it's the same paper mill): forbetterscience.com/2025/07/02/s...
Salesmen of Green Economy Bullshit
“This bullshit is a form of greenwashing, as policymakers might believe that with growing amount of “research” we are making progress. Except we are heading nowhere.” &#8211…
forbetterscience.com
August 29, 2025 at 7:28 PM
nadiah.bsky.social
The plot thickens! I just found what seems to be the original version of the paper. It wasn’t just AI generated, it was plagiarised.

www.sciencedirect.com/science/arti...
August 26, 2025 at 9:10 AM
nadiah.bsky.social
Check out the graphical abstract for a paper recently published in Ecological Modelling.

I have papers published in Ecological Modelling. Never again, I guess.
A diagram titled "Ecological Network Optimisation" with attractive landscapes and networks and very clear AI-generation artifacts.
August 25, 2025 at 11:05 PM
nadiah.bsky.social
I got a lot out of last semester's Christian Nationalism course, so if you're interested in learning about climate action, direct action, and/or socially aware sci fi, check them out.
darktimesacademy.bsky.social Dark Times Academy @darktimesacademy.bsky.social · Aug 15
Good news everybody!

Dark Times Academy’s September courses are here!

This term's courses are about action and imagination in dark times, focusing on climate action, resistance, and creating vision – with a stellar lineup of guest lecturers.

darktimesacademy.co....
August 16, 2025 at 4:03 AM
Reposted by Dr Nadiah Kristensen
bacpop.org
My PhD student @leonielorenz.bsky.social (with Eva Geissen) has made this nice (free) online course to introduce mathematical modelling for biology:
www.ebi.ac.uk/training/onl...

Including both molecular and epidemiological examples
Mathematical modelling for biologists - Modelling concepts in biological research
Mathematical modelling for biologists - Modelling concepts in biological research
www.ebi.ac.uk
August 15, 2025 at 10:39 AM
nadiah.bsky.social
I'm interested in this online seminar next week.

If you want to sign up for this seminar series, which is timed to suit researchers in Asia and Oceania, there's a Google form here -- forms.gle/WSnJS3bNK1b4... -- or you can follow @courtgt.bsky.social for updates.
Online seminar: PopBio on the Dark Side Joe Wan National Taiwan University Thursday 31st July 1 pm AEST UTC+10 **A unified theory of community structure** Much of our theoretical understanding of biodiversity, including well-established tools such as coexistence theory, focuses on the identity and number of coexisting species. Yet even when species coexist, they may show stark differences in abundance. Though such differences in community structure determine ecosystem function, we lack general quantitative tools linking interactions to abundance patterns in complex communities. In this seminar, I will address this gap by proposing a theoretical framework uniting coexistence with community structure and function. Beginning with the classic niche–fitness framework and canonical models of small communities, I illustrate simple links between species' fitness (as measured by invasion growth rates) and abundance (or more generally, their contributions to total function). New quantitative tools generalize these relationships to non-additive competitive interactions and high species richness, providing a general way to predict the structure and function of complex communities. This extends foundational theories of coexistence to new questions of community structure and function: a functional coexistence theory which, as I show using plant and microbial case studies, provides tractable insight into both theoretical models and empirical systems. **Footer**: Add your email to the above google form to receive the zoom link and future seminar announcements!
July 24, 2025 at 2:29 AM
Reposted by Dr Nadiah Kristensen
plosbiology.org
From student to researcher, a #career in #science can come with a high price tag. @drcraigmc.bsky.social ‬explores how wealth shapes opportunity in #STEM and proposes structural changes to support #equity and inclusion. 🧪
plos.io/4edGlY4
Too poor to science: How wealth determines who succeeds in STEM
From student to researcher, a career in science can come with a high price tag. This Perspective explores how persistent financial barriers limit who can succeed in science, revealing how wealth shape...
plos.io
June 25, 2025 at 2:39 PM
nadiah.bsky.social
I keep getting academic spam saying my recent paper has won the 'Best Research Paper Award'.

Sucks to be them, though, I have low self-esteem, so I'd never fall for that.

Here's the paper that didn't win an award.
Many-strategy games in groups with relatives and the evolution of coordinated cooperation
Humans often cooperate in groups with friends and family members with varying degrees of genetic relatedness. Past kin selection can also be relevant …
www.sciencedirect.com
June 18, 2025 at 11:00 PM
nadiah.bsky.social
Binmore's flair 🖤

"the community of spirit [of] modern communitarians and ancient moralists alike actually operates ... we are not bound together by iron shackles of duty and obligation, but by common understandings and conventions that propagate through societies like fungus through a rotten log"
May 31, 2025 at 8:20 AM
nadiah.bsky.social
@carlo-h.bsky.social has finished OCR-ing the Antarctic Treaty System documents, and he also indulges my dork-nostalgia for games like Myst, excessive adjectives and archaic prose.
An image resembling the text pop-up of an adventure game from the late 1990s. It reads: *Journal Entry Found* Dearest Dr Kristensen; At long last - and not without the eldritch whisper of unseen forces pressing at the frayed edges of my resolve - the Antarctic Documents have yielded to my labours and now lie assembled, murmuring with the strange energies of the austral post. They are ready. There is a sense, almost a tremor in the veil, as though by unearthing them we have disturbed something older than mere time. [Access the sealed archive] Yours at the threshold, Dr C. Hamalainen Scribe of the Forgotten Latitude
May 21, 2025 at 11:00 PM
nadiah.bsky.social
biorxiv is down, in case anyone else has revisions due today. Either that or something has happened to my user account :-(

On the plus side, guess I get to go home now :-)
A screenshot of the downforeveryoneorjustme website saying biorxiv.org is down.
May 15, 2025 at 8:08 AM
nadiah.bsky.social
I really enjoyed the session I attended this morning from Brisbane, and there is another on in about 8 hours that you can still enrol to attend.
danielcooney1.bsky.social Daniel Cooney @danielcooney1.bsky.social · May 8
We have now posted the schedule of talks on the workshop website. The workshop will run in two sessions:

Thursday, May 8: 1pm to 5:30pm (EDT / UTC - 4)
Friday, May 9: 8am to 12:50pm (EDT/ UTC -4)

sites.google.com/d/1eSIOaNYu-...
May 9, 2025 at 4:15 AM
nadiah.bsky.social
Well, that's something new that's never happened to me before -- my blog just got cited in a paper!

journals.plos.org/plosone/arti...
Extraordinary siblings: Mole rats, marmosets, and Radcliffe-Brown
According to the theory of kin selection, an organism that shows some level of altruism toward her kin – lowering her own fitness, raising that of a close genetic relative – may enjoy an evolutionary ...
journals.plos.org
May 8, 2025 at 12:11 AM
Reposted by Dr Nadiah Kristensen
danielcooney1.bsky.social
I am really happy to share information about the 2nd Workshop on Modeling and Applications of Evolutionary Game Theory, which will be held virtually on Thursday, May 8, and Friday, May 9.

sites.google.com/view/2nd-evo...

I enjoyed organizing this workshop with Olivia Chu and Alex McAvoy.
Workshop on Modeling and Applications of Evolutionary Game Theory
Dates: May 8-9, 2025 Location: Held virtually via Zoom
sites.google.com
April 25, 2025 at 12:17 PM
nadiah.bsky.social
Thanks, past self, that's exactly what I was looking for!
A snippet of code. It reads: # NOTE to future self - commented code is a more elegant way to find attractors and basins """ # find the attractors and their full basins of attraction # --- idx_2_attractor = {
April 28, 2025 at 10:35 PM
nadiah.bsky.social
PopBio on the Dark Side Seminar this week - "Predicting Ecosystem Responses to Perturbations via a Geometric Approach" by @akshitg.bsky.social

Thursday 1pm AEST, UTC +10 April 24.

Our students chose to do a project on this topic this semester, so very interested to hear Akshit's talk!
Advert for the seminar with abstract: How ecosystems respond to environmental perturbations is a fundamental question in ecology, made especially challenging due to the strong coupling between species and their environment. Here, we introduce a theoretical framework for calculating the steady-state response of ecosystems to environmental perturbations in generalized consumer-resource. Our construction is applicable to a wide class of systems, including models with non-reciprocal interactions, cross-feeding, and non-linear growth/consumption rates. Within our framework, all ecological variables are embedded into four distinct vector spaces and ecological interactions are represented by geometric transformations between these spaces. We show that near a steady state, such geometric transformations directly map environmental perturbations - in resource availability and mortality rates - to shifts in niche structure. We illustrate these ideas in a variety of settings including a minimal model for pH-induced toxicity in bacterial denitrification. We end by discussing the biological implications of our framework. In particular, we show that it is extremely difficult to distinguish cooperative and competitive interactions by measuring species' responses to external perturbations.
April 21, 2025 at 10:53 PM
Reposted by Dr Nadiah Kristensen
jeffsharlet.bsky.social
The student paper at the college at which I teach reports a "tsunami of takedown requests" from international students terrified of being targeted for innocuous, legitimate op-eds & opinions.. Many ask in person--leave no trace in writing. Reminds me of my father's account of studying in the USSR.
April 15, 2025 at 5:37 PM
nadiah.bsky.social
Carlo Hamalainen has been doing an amazing job using LLMs for OCR on early Antarctic Treaty System documents.
A window with two columns. On the left-hand side is a scanned document. On the right-hand side is the text that was extract. It reads: --- INTRODUCTION The time is past now, when a yacht's arrival at an Antarctic base was the cause of marvel and admiration. That era, short though it was, is over - despite the still as yet un-cruised waters of most of Antarctica's coastline. Yachts and cruise ships, scientists and support personnel, all have contributed in these past few years to the opening up of Antarctica. We must be careful that this increasing familiarity with the Antarctic does not dull the emotions or lessen the respect that did so often transform the lives of earlier visitors, that enticed them back again and again, stimulating others to go, until visitors today must be numbered in their thousands every year. Because few visitors will be familiar with the Antarctic environment, or the way in which the various nations occupying bases here operate, these guidelines have been drawn up to help you and your crew during your season South. Above all, an understanding and appreciation of the Antarctic as a very special and fragile environment will go a long way to lessening the ... ---
April 13, 2025 at 9:10 PM