{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T16:50:17Z","timestamp":1791996617601,"version":"4.4.0"},"reference-count":45,"publisher":"Wiley","issue":"19","license":[{"start":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T00:00:00Z","timestamp":1790899200000},"content-version":"vor","delay-in-days":1,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Molecular Ecology"],"published-print":{"date-parts":[[2026,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Natural variation in circadian clock genes provides a powerful framework for understanding how organisms respond to environmental heterogeneity. The\n                    <jats:italic>Clock<\/jats:italic>\n                    (\n                    <jats:italic>Clk<\/jats:italic>\n                    ) gene encodes a core transcriptional regulator of circadian rhythms and contains a polymorphic polyglutamine (polyQ) tract whose evolutionary significance remains unclear. Here, we integrate population genomic, behavioural, and molecular analyses to investigate the functional and geographic patterns of\n                    <jats:italic>Clk<\/jats:italic>\n                    polyQ variation in\n                    <jats:styled-content style=\"fixed-case\">\n                      <jats:italic>Drosophila melanogaster<\/jats:italic>\n                    <\/jats:styled-content>\n                    . Using data from 127 European populations, we identify 11\n                    <jats:italic>Clk<\/jats:italic>\n                    polyQ alleles and find that their frequencies are geographically structured, most consistently along an east\u2013west gradient: the Q25 and Q27 alleles show robust clines in longitude and in a bioclimatic axis of continentality, whereas latitudinal and altitudinal trends are weaker. Behavioural assays of near\u2010isogenic lines revealed that polyQ length modulates circadian function under thermal challenge: most alleles maintained stable free\u2010running periods across temperatures, whereas the intermediate\u2010length Q25 allele showed the strongest, though modest, temperature sensitivity. Circadian phase showed pronounced allele\u2010specific sensitivity to elevated temperature in laboratory assays, although phase variation did not display a consistent relationship with geographic variables. At the molecular level, luciferase reporter assays showed that longer polyQ alleles exhibited higher transcriptional activity, linking polyQ length to CLK\u2010mediated gene expression. Together, these results demonstrate that natural variation in\n                    <jats:italic>Clk<\/jats:italic>\n                    polyQ length has measurable functional consequences for circadian regulation and is geographically structured in patterns consistent with underlying climatic variation, highlighting the potential for low\u2010complexity regions to modulate clock function in a context\u2010dependent manner across environmental gradients.\n                  <\/jats:p>","DOI":"10.1111\/mec.70554","type":"journal-article","created":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T04:52:32Z","timestamp":1791003152000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Natural Variation in\n                    <i>Drosophila melanogaster Clock<\/i>\n                    <scp>PolyQ<\/scp>\n                    Length: Geographic Gradients and Functional Properties"],"prefix":"10.1111","volume":"35","author":[{"given":"Maya","family":"Yair","sequence":"first","affiliation":[{"name":"Department of Evolutionary and Environmental Biology, and Institute of Evolution University of Haifa  Haifa Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bettina","family":"Fishman","sequence":"additional","affiliation":[{"name":"Department of Evolutionary and Environmental Biology, and Institute of Evolution University of Haifa  Haifa Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3810-0504","authenticated-orcid":false,"given":"Martin","family":"Kapun","sequence":"additional","affiliation":[{"name":"Naturhistorisches Museum Wien  Wien Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4018-6535","authenticated-orcid":false,"given":"Eran","family":"Tauber","sequence":"additional","affiliation":[{"name":"Department of Evolutionary and Environmental Biology, and Institute of Evolution University of Haifa  Haifa Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,10,2]]},"reference":[{"key":"e_1_2_11_2_1","doi-asserted-by":"publisher","DOI":"10.1515\/BC\u20102011\u2010252"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1038\/nrm.2017.7"},{"key":"e_1_2_11_4_1","doi-asserted-by":"publisher","DOI":"10.1038\/nrg1633"},{"key":"e_1_2_11_5_1","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pgen.1004775"},{"key":"e_1_2_11_6_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.2410680121"},{"key":"e_1_2_11_7_1","doi-asserted-by":"publisher","DOI":"10.1098\/rspb.1992.0128"},{"key":"e_1_2_11_8_1","doi-asserted-by":"publisher","DOI":"10.1038\/srep05601"},{"key":"e_1_2_11_9_1","doi-asserted-by":"publisher","DOI":"10.1111\/febs.17317"},{"key":"e_1_2_11_10_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.280.5369.1599"},{"key":"e_1_2_11_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/joc.5086"},{"key":"e_1_2_11_12_1","doi-asserted-by":"crossref","unstructured":"Fu J. K. A.Murphy M.Zhou et\u00a0al.2016.\u201cCodon Usage Affects the Structure and Function of theDrosophilaCircadian Clock Protein 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