Tomorrow will be a good day for birding.

What does this mean for plumage introgression? We may have caught this situation as gene flow is temporarily slowed at the river before continuing. Or it could point to geographic variation in female preference or some other unusual scenario. Either would be pretty interesting.

Finally, we ran demographic models to estimate gene flow and found a similar result. Higher gene flow upriver than downriver. But in both areas, there is plenty of gene flow across the river.

Second, population structure showed a river effect, but only downriver where the Changuinola is widest. Upriver, there was hardly any population structure. This general pattern mirrors findings from some of the world’s largest rivers, but on a much smaller scale.

What did we find? First, across all sites there was an isolation-by-distance effect, but opposite-bank populations were significantly more divergent than expected given their distance.

We used RADseq data from ~200 birds along the river to look at population structure and gene flow, testing the hypothesis that the river is a strong barrier, thus preventing introgression.

I posted a thread on the genetic basis of the trait last year (see below). Now we wanted to look at a longstanding mystery: if it is selected for, why has it not crossed the river? Color forms are almost completely restricted to opposite riverbanks.

Manakins are under strong sexual selection for male traits, and in Panama, female white-collared manakins seem to prefer the yellow plumage of golden-collared manakins. That has led to one-way introgression of yellow plumage, but only as far as the Changuinola River.

The study species: manakins in the genus Manacus. They do acrobatic courtship dances to woo females.

New paper published! How does a mid-size river impact gene flow and population structure, including when there is an adaptive sexual trait present on one bank but not the other? With Peri Bolton, @robb_brumfield, Jerry Wilkinson, and Mike Braun.

RT @Geoffrey_E_Hill: After decades of creeping along, carotenoid honest signaling research is moving at warp speed.CYP2J19 & BDH1L localize….

. except by me who watched it on mute and celebrated while trying to rock a baby to sleep.

RT @Jente_O: ✍️ New story on the Avian Hybrids blog!. Fruit resources explain the courtship dynamics at White-bearded Manakin leks. https://….

RT @Geoffrey_E_Hill: And now we need to find the House Finch ketolase.

RT @Geoffrey_E_Hill: A new paper with big news in the world of red carotenoid ornamentation: House Finches do not utilize CYP2J19/BDH1L to….

RT @weiss_hadas: how it feels to recommend "minor revisions"

Nice writeup in Smithsonian Voices about our recent manakin work with Mike Braun, along with papers from @kmlong7 and @verntasco.

Bonus video of dancing manakins!

This project was a huge effort and relied on the work of many dedicated scientists. Huge thanks to everyone who helped make it happen!

There's more meat to the paper beyond this, including interesting microstructural modifications to colorful feathers and our speculation about how they might affect fitness.

So we looked for evidence of past gene flow between golden-collared and orange-collared manakins. Surprise! The same region of BCO2 shows evidence of past introgression from orange-collared to golden-collared manakins.