I finally finished reading Walden! In many places a frustrating, but also an interesting, occasionally funny, and often beautiful read. A few favourites of mine: the excited ant war report, the excessively detailed description of different kinds of ice, and this pictured passage... (1/2)

Map of areas meeting thresholds for butterfly observation count & species sampling coverage in 2001–2010. I find this fascinating. I expected the good coverage in western and parts of northern Europe, but, knowing little about south-eastern Europe, I didn't expect Serbia to be a data hotspot. (1/3)

While all didn’t go quite as planned (e.g. butterflies not mating, sun-fried pupae, and uninvited guests), I’m really happy with how this turned out – largely thanks to my coauthors Matthew Nielsen (co-first author), ‪@bsiemers.bsky.social‬, Magne Friberg, and Karl Gotthard (PhD supervisor)! (12/12)

We also highlight that, together with my earlier studies, we now have lab and field tests of evolution in all our studied traits. Our conclusions differ from what they would be from either lab or field experiments alone. Combined lab and field experiments are laborious but powerful. (11/12)

But how was winter survival? Equal among populations and between the southernmost and the range margin site, but plummeting at the beyond-range site, 100 km north of the range margin. Thus, winter sets the limit and will continue to do so, as there’s no local adaptation to different winters. (9/12)

Caterpillars from northern populations grew faster, at all field sites. But this counter-gradient variation didn’t help caterpillars survive winter – survival was as poor for big as for small caterpillars. For this trait, we think selection acts only on the LATE part of the generation. (7/12)

We scored diapause decisions and weighed caterpillars in October. Despite previously shown genetic differences in daylength thresholds for diapause induction (see paper linked above), virtually all caterpillars, regardless of descent and rearing site, entered diapause at an appropriate time! (5/12)

So, we collected butterflies from two populations in the species’ core range and two at the range margin. In August, we put eggs form all four populations out in cages at three field sites: one in the range interior, one at the range margin, and one north of the species’ current range. (4/12)

We wanted to know 1) whether local adaptations to unfamiliar conditions have evolved at the northern range margin, 2) whether local adaptations to the range margin also facilitate survival beyond the current range, and, as part of that, 3) what (climatic) features limit the expansion. (3/12)

I finally managed to find a copy of this crucial, but out of print, Estonian language learning material! 🤩 Brilliant folk/bluegrass band & special guest's children's album – released together with a song- and colouring book! Lovely idea & great music.

Ever seen an entomologist at a conference about soil microorganisms? Now's your chance! And, yeah, there's a poster about stuff I've been doing this spring. #ESM2025

Blind-tasting Estonian alcohol-free beers! We started with lagers, and only four kinds so we'd be able to actually finish them. We chose three from A.LeCoq because they're brewed 500 metres from our home. Saku (near Tallin) is another big brewery.