Jørgen Søraker

@jorgensoraker.bsky.social

DPhil student at the Edward Grey Institute, University of Oxford

@egioxford.bsky.social Oct 13, 2026, 7:21 AMReposted by @jorgensoraker.bsky.social

Pleased to announce first EGI seminar of 2026-27 with @erikpostma.bsky.social from @uniexecec.bsky.social talking about Evolutionary Dynamics & Constraints on Avian Reproductive Effort. Abstract in ALT-text. Erik's seminar is at 3.30 in LT2 in LaMB @biology.ox.ac.uk. All welcome; also streamed ⬇️

Seminar poster abstract: In search of the evolutionary forces and constraints that shape the dynamics of reproductive effort
Although central to life-history theory and a potentially powerful evolutionary constraint, the predicted trade-off between reproduction and survival remains remarkably elusive. Here I will build upon the so-called Y-model that emphasises the roles of variation in resource acquisition vs. allocation in shaping life-history correlations. In particular, I will distinguish between genetic and environmental sources of variation in resource allocation and acquisition, and between phenotypic and genetic patterns of covariance on the one hand, and the trade-off function that describes the relationship between resource allocation to, for example, reproduction versus survival, on the other. I will illustrate this using empirical studies of three species—humans, quails and great tits—in which we quantified the lifespan-cost of reproduction. Using complementary approaches, I will show how women reproducing when resources are scarce, great tits genetically predisposed to lay large clutches, and quails artificially bred to invest more in reproduction all live shorter lives. Thereby I will provide empirical evidence for a lifespan-cost of reproduction across a range of life-history strategies, and highlight its role in shaping the evolutionary dynamics of reproductive effort.

@jorgensoraker.bsky.social Oct 4, 2026, 1:21 PM

Social network analysis offers a powerful tool for understanding the social aspects of an animal’s life. Here, (soon-to-be Dr.) Daisy Abraham from the @egioxford.bsky.social takes me through what social networks have taught us about divorce and windowing in birds

m.youtube.com/watch?v=5Q9_...

@devisatarkar.bsky.social Sep 23, 2026, 6:25 PMReposted by @jorgensoraker.bsky.social

Heavier great tit nestlings 🐥 usually end up as heavier adults 🐦. Is this always a strong correlation?

Our new preprint shows that the strength of this 'silver-spoon' association shifts continuously with environmental context, and is stronger in harsh conditions!

www.biorxiv.org/content/10.6...

14-day old great tit (Parus major) nestling in hand. Bird handled under appropriate BTO licence.

Adult great tit (Parus major) in hand. Bird handled under appropriate BTO licence.

@egioxford.bsky.social Sep 10, 2026, 6:53 PMReposted by @jorgensoraker.bsky.social

New paper in @animalecology.bsky.social led by @davididiaquez.bsky.social published today. We document a reduction of ~5% in body mass of adult great tits at Wytham (>1 sd!) over ~45 years and show best explained by natal environment carry-over
besjournals.onlinelibrary.wiley.com/doi/10.1111/...

@rona-learmonth.bsky.social Aug 28, 2026, 10:37 AMReposted by @jorgensoraker.bsky.social

Excited to share this joint first-author paper with @andreaestandia.bsky.social, now out in @royalsocietypublishing.org!
We combined translocations, common garden experiments and genomic analyses to test for local adaptation to individual tree phenology in winter moths 🌳🐛
doi.org/10.1098/rspb...

@jorgensoraker.bsky.social May 1, 2026, 10:22 AM

New paper out in Biological Reviews📝🚨
When trying to explain why female birds engage in extra-pair copulations/paternity, we mostly focus on the benefits.

But what about the costs? Should we not consider the downsides of the behavior we try to understand? 🧵
onlinelibrary.wiley.com/doi/10.1002/...

onlinelibrary.wiley.comThe costs of extra‐pair behaviours in birdsExtra-pair behaviours – reproductive behaviours, including those related to copulation and paternity of offspring, amongst animals outside of a social pair bond – have long intrigued behavioural ecol...