Unraveling the genetic basis of bird migration: insights from the Common Yellowthroat

Post by Luz Estela Zamudio-Beltrán 

A recent study pub­lished in Evol­u­tion Let­ters invest­ig­ates the genet­ic under­pin­nings of migrat­ory beha­vi­or in birds using pop­u­la­tions of the Com­mon Yel­low­throat. Author Luz Zamu­dio tells us more about this work:

Migra­tion is one of nature’s most inspir­ing phe­nom­ena, with count­less anim­als under­tak­ing long jour­neys each year. Among these, birds have cap­tiv­ated sci­ent­ists due to their remark­able abil­ity to travel vast dis­tances. Ques­tions such as “What drives some birds to migrate across con­tin­ents while oth­ers remain in one place?” and “Do the same genet­ic mech­an­isms drive migra­tion across dif­fer­ent pop­u­la­tions and spe­cies?” have been cent­ral to research on this topic.

Fig­ure 1. Illus­tra­tion of a Com­mon Yel­low­throat, Geothlypis trichas, by Erica Robertson.

In our study, we exam­ine the genet­ic basis of migra­tion in the Com­mon Yel­low­throat, a small and brightly colored North Amer­ic­an migrat­ory song­bird. This spe­cies is an ideal mod­el for migra­tion research because east­ern and west­ern clades with­in the spe­cies inde­pend­ently evolved both migrat­ory and non-migrat­ory forms. By com­par­ing the genet­ic dif­fer­ences with­in and between these groups, we aim to identi­fy genes asso­ci­ated with migra­tion and assess how con­sist­ent they are across populations.

To invest­ig­ate this, we con­duc­ted genet­ic ana­lyses on 196 indi­vidu­als from 22 loc­a­tions across the spe­cies’ breed­ing range in the United States and Canada. We searched for genet­ic sig­nals that might explain why some birds migrate while oth­ers do not, focus­ing on “can­did­ate genes” known to play import­ant roles in migra­tion-related traits like energy meta­bol­ism and timing.

Fig­ure 2. Pop­u­la­tion struc­ture res­ults obtained with Admix­Pipe per­formed for each main group: West and East (A). Geo­graph­ic dis­tri­bu­tion of pop­u­la­tion struc­ture (B). Evol­u­tion­ary rela­tion­ships inferred with Tree­m­ix ©. The let­ter codes rep­res­ent dif­fer­ent sampled loc­al­it­ies, and dif­fer­ent col­ors rep­res­ent main clusters found. Res­id­ent pop­u­la­tions are rep­res­en­ted inside dot­ted circles. Fig­ure and cap­tion taken from the paper, cour­tesy of the authors. 

Inter­est­ingly, we found that while cer­tain genes appeared repeatedly in both east­ern and west­ern pop­u­la­tions, the spe­cif­ic genet­ic changes were not identic­al. This sug­gests two phe­nom­ena at play: par­al­lel evol­u­tion, where dif­fer­ent pop­u­la­tions evolve sim­il­ar traits res­ult­ing from the same genet­ic changes, and con­ver­gent evol­u­tion that occurs when dif­fer­ent pop­u­la­tions evolve sim­il­ar traits inde­pend­ently but through dif­fer­ent genet­ic pathways.

One of the most intriguing find­ings was the prom­in­ence of can­did­ate genes linked to bio­lo­gic­al time­keep­ing in explain­ing the dif­fer­ences between migrant and res­id­ent forms. These genes are believed to help with fine-tun­ing the pre­cise tim­ing of migra­tion in response to chan­ging sea­sons. Our study uncovered evid­ence that sim­il­ar genes were con­sist­ently under selec­tion in both migrat­ory groups, emphas­iz­ing their pivotal role in orches­trat­ing the remark­able jour­neys of long-dis­tance migrat­ory movements.

Fig­ure 3. Illus­tra­tion of a Com­mon Yel­low­throat, Geothlypis trichas, by Erica Robertson.

Over­all, this work sheds light on the com­plex inter­play of genet­ic factors in shap­ing anim­al move­ment and offers cru­cial insights into how spe­cies like the Com­mon Yel­low­throat may adapt—or struggle to adapt—to rap­idly chan­ging envir­on­ment­al con­di­tions in the future.

Luz Estela Zamu­dio-Beltrán is a postdoc­tor­al research­er in the Depart­ment of Evol­u­tion­ary Bio­logy at the Uni­ver­sid­ad Nacion­al Autónoma de México. The ori­gin­al art­icle is freely avail­able to read and down­load from Evol­u­tion Letters.

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