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class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Animals"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Animals</span> </div> </a> <ul id="toc-Animals-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Mammals" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Mammals"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Mammals</span> </div> </a> <button aria-controls="toc-Mammals-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Mammals subsection</span> </button> <ul id="toc-Mammals-sublist" class="vector-toc-list"> <li id="toc-Humans" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Humans"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Humans</span> </div> </a> <ul id="toc-Humans-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Other_organisms" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Other_organisms"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Other organisms</span> </div> </a> <ul id="toc-Other_organisms-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Photoperiodism</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" 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Available in 41 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-41" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">41 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%81%D8%AA%D8%B1%D8%A9_%D8%B6%D9%88%D8%A6%D9%8A%D8%A9" title="فترة ضوئية – Arabic" lang="ar" hreflang="ar" data-title="فترة ضوئية" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Fotoperiodizm" title="Fotoperiodizm – Azerbaijani" lang="az" hreflang="az" data-title="Fotoperiodizm" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%86%E0%A6%B2%E0%A7%8B%E0%A6%95%E2%80%8C%E2%80%8C%E0%A6%AA%E0%A6%B0%E0%A7%8D%E0%A6%AF%E0%A6%BE%E0%A6%AC%E0%A7%83%E0%A6%A4%E0%A7%8D%E0%A6%A4%E0%A6%BF" title="আলোক‌‌পর্যাবৃত্তি – Bangla" lang="bn" hreflang="bn" data-title="আলোক‌‌পর্যাবৃত্তি" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Fotoperiodizam" title="Fotoperiodizam – Bosnian" lang="bs" hreflang="bs" data-title="Fotoperiodizam" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Fotoperiodisme_(bot%C3%A0nica)" title="Fotoperiodisme (botànica) – Catalan" lang="ca" hreflang="ca" data-title="Fotoperiodisme (botànica)" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Fotoperiodismus" title="Fotoperiodismus – Czech" lang="cs" hreflang="cs" data-title="Fotoperiodismus" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Photoperiodismus" title="Photoperiodismus – German" lang="de" hreflang="de" data-title="Photoperiodismus" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Fotoperiodism" title="Fotoperiodism – Estonian" lang="et" hreflang="et" data-title="Fotoperiodism" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A6%CF%89%CF%84%CE%BF%CF%80%CE%B5%CF%81%CE%B9%CE%BF%CE%B4%CE%B9%CF%83%CE%BC%CF%8C%CF%82" title="Φωτοπεριοδισμός – Greek" lang="el" hreflang="el" data-title="Φωτοπεριοδισμός" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Fotoperiodicidad" title="Fotoperiodicidad – Spanish" lang="es" hreflang="es" data-title="Fotoperiodicidad" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Fotoperiodismo" title="Fotoperiodismo – Esperanto" lang="eo" hreflang="eo" data-title="Fotoperiodismo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/Fotoperiodikotasun" title="Fotoperiodikotasun – Basque" lang="eu" hreflang="eu" data-title="Fotoperiodikotasun" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AF%D9%88%D8%B1%D9%87_%D9%86%D9%88%D8%B1%DB%8C" title="دوره نوری – Persian" lang="fa" hreflang="fa" data-title="دوره نوری" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Photop%C3%A9riodisme" title="Photopériodisme – French" lang="fr" hreflang="fr" data-title="Photopériodisme" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/F%C3%B3taithr%C3%A9imhseacht" title="Fótaithréimhseacht – Irish" lang="ga" hreflang="ga" data-title="Fótaithréimhseacht" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Fotoper%C3%ADodo" title="Fotoperíodo – Galician" lang="gl" hreflang="gl" data-title="Fotoperíodo" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EA%B4%91%EC%A3%BC%EA%B8%B0%EC%84%B1" title="광주기성 – Korean" lang="ko" hreflang="ko" data-title="광주기성" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D4%BC%D5%B8%D6%82%D5%BD%D5%A1%D5%BA%D5%A1%D6%80%D5%A2%D5%A5%D6%80%D5%A1%D5%AF%D5%A1%D5%B6%D5%B8%D6%82%D5%A9%D5%B5%D5%B8%D6%82%D5%B6" title="Լուսապարբերականություն – Armenian" lang="hy" hreflang="hy" data-title="Լուսապարբերականություն" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A4%95%E0%A4%BE%E0%A4%B6%E0%A4%95%E0%A4%BE%E0%A4%B2%E0%A4%BF%E0%A4%A4%E0%A4%BE" title="प्रकाशकालिता – Hindi" lang="hi" hreflang="hi" data-title="प्रकाशकालिता" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Fotoperiodisme" title="Fotoperiodisme – Indonesian" lang="id" hreflang="id" data-title="Fotoperiodisme" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Fotoperiodismo" title="Fotoperiodismo – Italian" lang="it" hreflang="it" data-title="Fotoperiodismo" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A4%D7%95%D7%98%D7%95%D7%A4%D7%A8%D7%99%D7%95%D7%93%D7%99%D7%96%D7%9D" title="פוטופריודיזם – Hebrew" lang="he" hreflang="he" data-title="פוטופריודיזם" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%96%D0%B0%D1%80%D1%8B%D2%9B%D0%BA%D0%B5%D0%B7%D0%B5%D2%A3%D0%B4%D1%96%D0%BA" title="Жарықкезеңдік – Kazakh" lang="kk" hreflang="kk" data-title="Жарықкезеңдік" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Fotoperiodizmus" title="Fotoperiodizmus – Hungarian" lang="hu" hreflang="hu" data-title="Fotoperiodizmus" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%AB%E0%B5%8B%E0%B4%9F%E0%B5%8D%E0%B4%9F%E0%B5%8B%E0%B4%AA%E0%B5%80%E0%B4%B0%E0%B4%BF%E0%B4%AF%E0%B5%8B%E0%B4%A1%E0%B4%BF%E0%B4%B8%E0%B4%82" title="ഫോട്ടോപീരിയോഡിസം – Malayalam" lang="ml" hreflang="ml" data-title="ഫോട്ടോപീരിയോഡിസം" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Fotoperiodisme" title="Fotoperiodisme – Malay" lang="ms" hreflang="ms" data-title="Fotoperiodisme" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Fotoperiodiciteit" title="Fotoperiodiciteit – Dutch" lang="nl" hreflang="nl" data-title="Fotoperiodiciteit" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E5%85%89%E5%91%A8%E6%80%A7" title="光周性 – Japanese" lang="ja" hreflang="ja" data-title="光周性" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Fotoperiodizm" title="Fotoperiodizm – Uzbek" lang="uz" hreflang="uz" data-title="Fotoperiodizm" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Fotoperiodyzm" title="Fotoperiodyzm – Polish" lang="pl" hreflang="pl" data-title="Fotoperiodyzm" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Fotoperiodismo" title="Fotoperiodismo – Portuguese" lang="pt" hreflang="pt" data-title="Fotoperiodismo" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A4%D0%BE%D1%82%D0%BE%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4%D0%B8%D0%B7%D0%BC" title="Фотопериодизм – Russian" lang="ru" hreflang="ru" data-title="Фотопериодизм" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Fotoperiodizmus" title="Fotoperiodizmus – Slovak" lang="sk" hreflang="sk" data-title="Fotoperiodizmus" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Fotoperiodizem" title="Fotoperiodizem – Slovenian" lang="sl" hreflang="sl" data-title="Fotoperiodizem" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/Fotoperiodizam" title="Fotoperiodizam – Serbian" lang="sr" hreflang="sr" data-title="Fotoperiodizam" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Valojaksoisuus" title="Valojaksoisuus – Finnish" lang="fi" hreflang="fi" data-title="Valojaksoisuus" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%92%E0%AE%B3%E0%AE%BF%E0%AE%95%E0%AF%8D%E0%AE%95%E0%AE%BE%E0%AE%B2%E0%AE%A4%E0%AF%8D%E0%AE%A4%E0%AF%81%E0%AE%B5%E0%AE%AE%E0%AF%8D" title="ஒளிக்காலத்துவம் – Tamil" lang="ta" hreflang="ta" data-title="ஒளிக்காலத்துவம்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%82%E0%B8%9F%E0%B9%82%E0%B8%95%E0%B9%80%E0%B8%9E%E0%B8%AD%E0%B8%A3%E0%B8%B4%E0%B9%82%E0%B8%AD%E0%B8%94%E0%B8%B4%E0%B8%8B%E0%B8%B6%E0%B8%A1" title="โฟโตเพอริโอดิซึม – Thai" lang="th" hreflang="th" data-title="โฟโตเพอริโอดิซึม" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Fotoperiyodizm" title="Fotoperiyodizm – Turkish" lang="tr" hreflang="tr" data-title="Fotoperiyodizm" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A4%D0%BE%D1%82%D0%BE%D0%BF%D0%B5%D1%80%D1%96%D0%BE%D0%B4%D0%B8%D0%B7%D0%BC" title="Фотоперіодизм – Ukrainian" lang="uk" hreflang="uk" data-title="Фотоперіодизм" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%85%89%E9%80%B1%E6%9C%9F%E7%8F%BE%E8%B1%A1" title="光週期現象 – Chinese" lang="zh" hreflang="zh" data-title="光週期現象" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q259028#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet 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.mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-Lead_too_short plainlinks metadata ambox ambox-content ambox-lead_too_short" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Wiki_letter_w.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/6/6c/Wiki_letter_w.svg/40px-Wiki_letter_w.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/6/6c/Wiki_letter_w.svg/60px-Wiki_letter_w.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/6/6c/Wiki_letter_w.svg/80px-Wiki_letter_w.svg.png 2x" data-file-width="44" data-file-height="44" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article's <a href="/wiki/Wikipedia:Manual_of_Style/Lead_section#Length" title="Wikipedia:Manual of Style/Lead section">lead section</a> <b>may be too short to adequately <a href="/wiki/Wikipedia:Summary_style" title="Wikipedia:Summary style">summarize</a> the key points</b>.<span class="hide-when-compact"> Please consider expanding the lead to <a href="/wiki/Wikipedia:Manual_of_Style/Lead_section#Provide_an_accessible_overview" title="Wikipedia:Manual of Style/Lead section">provide an accessible overview</a> of all important aspects of the article.</span> <span class="date-container"><i>(<span class="date">October 2023</span>)</i></span></div></td></tr></tbody></table> <p><b>Photoperiod</b> is the change of day length around the seasons. The rotation of the earth around its axis produces 24 hour changes in light (day) and dark (night) cycles on earth. The length of the light and dark in each phase varies across the seasons due to the tilt of the earth around its axis. The photoperiod defines the length of the light, for example a summer day the length of light could be 16 hours while the dark is 8 hours, whereas a winter day the length of day could be 8 hours, whereas the dark is 16 hours. Importantly, the seasons are different in the northern hemisphere than the southern hemisphere. </p><p><b>Photoperiodism</b> is the physiological reaction of organisms to the length of light or a dark period. It occurs in <a href="/wiki/Plant" title="Plant">plants</a> and <a href="/wiki/Animal" title="Animal">animals</a>. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods. They are classified under three groups according to the photoperiods: short-day plants, long-day plants, and day-neutral plants. </p><p>In animals photoperiodism (sometimes called seasonality) is the suite of physiological changes that occur in response to changes in day length. This allows animals to respond to a temporally changing environment associated with changing seasons as the earth orbits the sun. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Plants">Plants</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=1" title="Edit section: Plants"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Photoperiodism_in_plants.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Photoperiodism_in_plants.jpg/220px-Photoperiodism_in_plants.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Photoperiodism_in_plants.jpg/330px-Photoperiodism_in_plants.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Photoperiodism_in_plants.jpg/440px-Photoperiodism_in_plants.jpg 2x" data-file-width="960" data-file-height="720" /></a><figcaption>Pr converts to Pfr during the day time and Pfr slowly reverts to Pr during the night time. When nights are short, an excess amount of Pfr remains in the day time and during long nights, most of the Pfr is reverted to Pr.</figcaption></figure> <p><span class="anchor" id="In_plants"></span> </p><p>In 1920, W. W. Garner and H. A. Allard published their discoveries on photoperiodism and felt it was the length of daylight that was critical,<sup id="cite_ref-mauseth_1-0" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-GA_2-0" class="reference"><a href="#cite_note-GA-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> but it was later discovered that the length of the night was the controlling factor.<sup id="cite_ref-h1_3-0" class="reference"><a href="#cite_note-h1-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-h2_4-0" class="reference"><a href="#cite_note-h2-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Photoperiodic flowering plants are classified as <i>long-day plants</i> or <i>short-day plants</i> even though night is the critical factor because of the initial misunderstanding about daylight being the controlling factor. Along with long-day plants and short-day plants, there are plants that fall into a "dual-day length category". These plants are either long-short-day plants (LSDP) or short-long-day plants (SLDP). LSDPs flower after a series of long days followed by short days whereas SLDPs flower after a series of short days followed by long days.<sup id="cite_ref-Taiz_5-0" class="reference"><a href="#cite_note-Taiz-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Each plant has a different length critical photoperiod, or critical night length.<sup id="cite_ref-mauseth_1-1" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>Many <a href="/wiki/Flowering_plant" title="Flowering plant">flowering plants</a> (angiosperms) use a <a href="/wiki/Circadian_rhythm#In_plants" title="Circadian rhythm">circadian rhythm</a> together with <a href="/wiki/Photoreceptor_protein" title="Photoreceptor protein">photoreceptor protein</a>, such as <a href="/wiki/Phytochrome" title="Phytochrome">phytochrome</a> or <a href="/wiki/Cryptochrome" title="Cryptochrome">cryptochrome</a>,<sup id="cite_ref-mauseth_1-2" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> to sense seasonal changes in night length, or photoperiod, which they take as signals to flower. In a further subdivision, <i>obligate</i> photoperiodic plants absolutely require a long or short enough night before flowering, whereas <i>facultative</i> photoperiodic plants are more likely to flower under one condition. </p><p><a href="/wiki/Phytochrome" title="Phytochrome">Phytochrome</a> comes in two forms: P<sub>r</sub> and P<sub>fr</sub>. Red light (which is present during the day) converts phytochrome to its active form (P<sub>fr</sub>) which then stimulates various processes such as germination, flowering or branching. In comparison, plants receive more <a href="/wiki/Far-red" class="mw-redirect" title="Far-red">far-red</a> in the shade, and this converts phytochrome from P<sub>fr</sub> to its inactive form, P<sub>r</sub>, inhibiting germination. This system of P<sub>fr</sub> to P<sub>r</sub> conversion allows the plant to sense when it is night and when it is day.<sup id="cite_ref-Fankhauser2001_6-0" class="reference"><a href="#cite_note-Fankhauser2001-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> P<sub>fr</sub> can also be converted back to P<sub>r</sub> by a process known as dark reversion, where long periods of darkness trigger the conversion of P<sub>fr</sub>.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> This is important in regards to plant flowering. Experiments by Halliday et al. showed that manipulations of the red-to far-red ratio in Arabidopsis can alter flowering. They discovered that plants tend to flower later when exposed to more red light, proving that red light is inhibitory to flowering.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Other experiments have proven this by exposing plants to extra red-light in the middle of the night. A short-day plant will not flower if light is turned on for a few minutes in the middle of the night and a long-day plant can flower if exposed to more red-light in the middle of the night.<sup id="cite_ref-Chamovitz2013_9-0" class="reference"><a href="#cite_note-Chamovitz2013-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p><p>Cryptochromes are another type of photoreceptor that is important in photoperiodism. Cryptochromes absorb blue light and UV-A. Cryptochromes entrain the circadian clock to light.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> It has been found that both cryptochrome and phytochrome abundance relies on light and the amount of cryptochrome can change depending on day-length. This shows how important both of the photoreceptors are in regards to determining day-length.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>Modern biologists believe<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> that it is the coincidence of the active forms of phytochrome or cryptochrome, created by light during the daytime, with the rhythms of the <a href="/wiki/Circadian_clock" title="Circadian clock">circadian clock</a> that allows plants to measure the length of the night. Other than flowering, photoperiodism in plants includes the growth of stems or roots during certain seasons and the loss of leaves. Artificial lighting can be used to induce extra-long days.<sup id="cite_ref-mauseth_1-3" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Long-day_plants">Long-day plants</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=2" title="Edit section: Long-day plants"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Long_Day_Plants.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Long_Day_Plants.jpg/220px-Long_Day_Plants.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Long_Day_Plants.jpg/330px-Long_Day_Plants.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Long_Day_Plants.jpg/440px-Long_Day_Plants.jpg 2x" data-file-width="720" data-file-height="541" /></a><figcaption></figcaption></figure> <p>Long-day plants flower when the night length falls below their critical photoperiod.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> These plants typically flower during late spring or early summer as days are getting longer. In the northern hemisphere, the longest day of the year (summer solstice) is on or about 21 June.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> After that date, days grow shorter (i.e. nights grow longer) until 21 December (the <a href="/wiki/Winter_solstice" title="Winter solstice">winter solstice</a>). This situation is reversed in the southern hemisphere (i.e., longest day is 21 December and shortest day is 21 June).<sup id="cite_ref-mauseth_1-4" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-GA_2-1" class="reference"><a href="#cite_note-GA-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Some long-day obligate plants are: </p> <ul><li><a href="/wiki/Dianthus_caryophyllus" title="Dianthus caryophyllus">Carnation</a> (<i>Dianthus</i>)</li> <li><a href="/wiki/Hyoscyamus_niger" title="Hyoscyamus niger">Henbane</a> (<i>Hyoscyamus</i>)</li> <li><a href="/wiki/Oat" title="Oat">Oat</a> (<i>Avena</i>)</li></ul> <p>Some long-day facultative plants are: </p> <ul><li><a href="/wiki/Pea" title="Pea">Pea</a> (<i>Pisum sativum)</i></li> <li><a href="/wiki/Barley" title="Barley">Barley</a> (<i>Hordeum vulgare</i>)</li> <li><a href="/wiki/Lettuce" title="Lettuce">Lettuce</a> (<i>Lactuca sativa</i>)</li> <li><a href="/wiki/Wheat" title="Wheat">Wheat</a> (<i>Triticum aestivum</i>)</li></ul> <div class="mw-heading mw-heading3"><h3 id="Short-day_plants">Short-day plants</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=3" title="Edit section: Short-day plants"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Short_Day_Plants.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Short_Day_Plants.jpg/220px-Short_Day_Plants.jpg" decoding="async" width="220" height="163" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Short_Day_Plants.jpg/330px-Short_Day_Plants.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/64/Short_Day_Plants.jpg/440px-Short_Day_Plants.jpg 2x" data-file-width="914" data-file-height="678" /></a><figcaption></figcaption></figure> <p>Short-day (also called long-night) plants flower when the night lengths exceed their critical photoperiod.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> They cannot flower under short nights or if a pulse of artificial light is shone on the plant for several minutes during the night; they require a continuous period of darkness before floral development can begin. Natural nighttime light, such as moonlight or lightning, is not of sufficient brightness or duration to interrupt flowering.<sup id="cite_ref-mauseth_1-5" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-GA_2-2" class="reference"><a href="#cite_note-GA-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Short-day plants flower as days grow shorter (and nights grow longer) after September 21st in the northern hemisphere, which is during summer or fall. The length of the dark period required to induce flowering differs among species and varieties of a species. </p><p>Photoperiodism affects flowering by inducing the shoot to produce floral buds instead of leaves and lateral buds. </p><p>Some short-day facultative plants are:<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p> <ul><li><a href="/wiki/Kenaf" title="Kenaf">Kenaf</a> ( <i>Hibiscus cannabinus</i>)</li> <li><a href="/wiki/Marijuana" class="mw-redirect" title="Marijuana">Marijuana</a> (<i>Cannabis</i>)</li> <li><a href="/wiki/Cotton" title="Cotton">Cotton</a> (<i>Gossypium</i>)</li> <li><a href="/wiki/Rice" title="Rice">Rice</a> (<i>Oryza</i>)</li> <li><a href="/wiki/Sorghum_bicolor" class="mw-redirect" title="Sorghum bicolor">Sorghum</a> (<i>Sorghum bicolor</i>)</li> <li><a href="/wiki/Green_gram" class="mw-redirect" title="Green gram">Green gram</a> (Mung bean, <i>Vigna radiata</i>)</li> <li><a href="/wiki/Soybean" title="Soybean">Soybeans</a><sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> (<i>Glycine max</i>)</li></ul> <div class="mw-heading mw-heading3"><h3 id="Day-neutral_plants">Day-neutral plants</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=4" title="Edit section: Day-neutral plants"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Day-neutral plants, such as <a href="/wiki/Cucumber" title="Cucumber">cucumbers</a>, <a href="/wiki/Rose" title="Rose">roses</a>, <a href="/wiki/Tomato" title="Tomato">tomatoes</a>, and Ruderalis (<a href="/wiki/Autoflowering_cannabis" title="Autoflowering cannabis">autoflowering cannabis</a>) do not initiate flowering based on photoperiodism.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> Instead, they may initiate flowering after attaining a certain overall developmental stage or age, or in response to alternative environmental stimuli, such as <a href="/wiki/Vernalisation" class="mw-redirect" title="Vernalisation">vernalisation</a> (a period of low temperature).<sup id="cite_ref-mauseth_1-6" class="reference"><a href="#cite_note-mauseth-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-GA_2-3" class="reference"><a href="#cite_note-GA-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Animals">Animals</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=5" title="Edit section: Animals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><span class="anchor" id="In_animals"></span> Daylength, and thus knowledge of the season of the year, is vital to many animals. A number of biological and behavioural changes are dependent on this knowledge. Together with temperature changes, photoperiod provokes changes in the color of fur and feathers, <a href="/wiki/Animal_migration" title="Animal migration">migration</a>, entry into <a href="/wiki/Hibernation" title="Hibernation">hibernation</a>, <a href="/wiki/Animal_sexual_behavior" class="mw-redirect" title="Animal sexual behavior">sexual behaviour</a>, and even the resizing of organs. </p><p>In <a href="/wiki/Insect" title="Insect">insects</a>, sensitivity to photoperiod has been proven to be initiated by photoreceptors located in the brain.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-pmid6592591_20-0" class="reference"><a href="#cite_note-pmid6592591-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> Photoperiod can affect insects at different life stages, serving as an environmental cue for physiological processes such as <a href="/wiki/Diapause" title="Diapause">diapause</a> induction and termination, and seasonal morphs.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> In the water strider <i>Aquarius paludum</i>, for instance, photoperiod conditions during nymphal development have been shown to trigger seasonal changes in wing frequency and also induce diapause, although the threshold critical day lengths for the determination of both traits diverged by about an hour.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> In <i><a href="/wiki/Gerris_buenoi" title="Gerris buenoi">Gerris buenoi</a></i>, another water strider species, photoperiod has also been shown to be the cause of wing <a href="/wiki/Polyphenism" title="Polyphenism">polyphenism</a>,<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> although the specific daylengths changed between species, suggesting that <a href="/wiki/Phenotypic_plasticity" title="Phenotypic plasticity">phenotypic plasticity</a> in response to photoperiod has evolved even between relatively closely related species. </p><p>The singing frequency of birds such as the <a href="/wiki/Domestic_Canary" class="mw-redirect" title="Domestic Canary">canary</a> depends on the photoperiod. In the spring, when the photoperiod increases (more daylight), the male canary's testes grow. As the testes grow, more androgens are secreted and song frequency increases. During autumn, when the photoperiod decreases (less daylight), the male canary's testes regress and androgen levels drop dramatically, resulting in decreased singing frequency. Not only is singing frequency dependent on the photoperiod but the song repertoire is also. The long photoperiod of spring results in a greater song repertoire. Autumn's shorter photoperiod results in a reduction in song repertoire. These behavioral photoperiod changes in male canaries are caused by changes in the song center of the brain. As the photoperiod increases, the <a href="/wiki/High_vocal_center" class="mw-redirect" title="High vocal center">high vocal center</a> (HVC) and the robust nucleus of the <a href="/wiki/Archistriatum" class="mw-redirect" title="Archistriatum">archistriatum</a> (RA) increase in size. When the photoperiod decreases, these areas of the brain regress.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Mammals">Mammals</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=6" title="Edit section: Mammals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In mammals, daylength is registered in the <a href="/wiki/Suprachiasmatic_nucleus" title="Suprachiasmatic nucleus">suprachiasmatic nucleus</a> (SCN), which is informed by <a href="/wiki/Photosensitive_ganglion_cell" class="mw-redirect" title="Photosensitive ganglion cell">retinal light-sensitive ganglion cells</a>, which are not involved in vision. The information travels through the <a href="/wiki/Retinohypothalamic_tract" title="Retinohypothalamic tract">retinohypothalamic tract</a> (RHT). In most species the hormone <a href="/wiki/Melatonin" title="Melatonin">melatonin</a> is produced by the <a href="/wiki/Pineal_gland" title="Pineal gland">pineal gland</a> only during the hours of darkness, influenced by the light input through the RHT and by innate <a href="/wiki/Circadian_rhythm" title="Circadian rhythm">circadian rhythms</a>. This hormonal signal, combined with outputs from the SCN inform the rest of the body about the time of day, and the length of time that melatonin is secreted is how the time of year is perceived. </p><p>Many mammals, particularly those inhabiting temperate and polar regions, exhibit a remarkable degree of seasonality in response to changes in daylight hours(photoperiod). This seasonality manifests in a broad spectrum of behaviors and physiology, including hibernation, seasonal migrations, and coat color changes. A prime example of the adaptation to photoperiods is the seasonal coat color (SCC) species.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> These animals undergo molting, transforming from dark summer fur to white coat in winter, that provides crucial camouflage in snowy environments. </p> <div class="mw-heading mw-heading3"><h3 id="Humans">Humans</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=7" title="Edit section: Humans"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The view has been expressed that humans' seasonality is largely believed to be <a href="/wiki/Evolutionary_baggage" title="Evolutionary baggage">evolutionary baggage</a>.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Writing_better_articles#Stay_on_topic" title="Wikipedia:Writing better articles"><span title="The material near this tag may contain information that is not relevant to the article's main topic. (April 2018)">relevant?</span></a></i>]</sup>. Human <a href="/wiki/Birth_rate" title="Birth rate">birth rate</a> varies throughout the year, and the peak month of births appears to vary by latitude.<sup id="cite_ref-Kevin_M_2013_27-0" class="reference"><a href="#cite_note-Kevin_M_2013-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> Seasonality in human birth rate appears to have largely decreased since the industrial revolution.<sup id="cite_ref-Kevin_M_2013_27-1" class="reference"><a href="#cite_note-Kevin_M_2013-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Other_organisms">Other organisms</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=8" title="Edit section: Other organisms"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Photoperiodism has also been demonstrated in other organisms besides plants and animals. The fungus <a href="/wiki/Neurospora_crassa" title="Neurospora crassa">Neurospora crassa</a> as well as the dinoflagellate <a href="/wiki/Lingulodinium_polyedra" title="Lingulodinium polyedra">Lingulodinium polyedra</a> and the unicellular green alga <a href="/wiki/Chlamydomonas_reinhardtii" title="Chlamydomonas reinhardtii">Chlamydomonas reinhardtii</a> have been shown to display photoperiodic responses.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=9" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Chronobiology" title="Chronobiology">Chronobiology</a></li> <li><a href="/wiki/Circadian_clock" title="Circadian clock">Circadian clock</a></li> <li><a href="/wiki/Circadian_rhythm" title="Circadian rhythm">Circadian rhythm</a></li> <li><a href="/wiki/Florigen" title="Florigen">Florigen</a></li> <li><a href="/wiki/Photobiology" title="Photobiology">Photobiology</a></li> <li><a href="/wiki/Seasonal_breeder" title="Seasonal breeder">Seasonal Breeder</a></li> <li><a href="/wiki/Scotobiology" title="Scotobiology">Scotobiology</a></li> <li><a href="/wiki/Epigenetics_of_plant_growth_and_development#Photoperiodism" title="Epigenetics of plant growth and development">Epigenetics of plant growth and development § Photoperiodism</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=10" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-mauseth-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-mauseth_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-mauseth_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-mauseth_1-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-mauseth_1-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-mauseth_1-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-mauseth_1-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-mauseth_1-6"><sup><i><b>g</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and 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Retrieved <span class="nowrap">2010-05-28</span></span>. <q>...we have the evolutionary baggage of showing seasonality but we're not entirely sure what the mechanism is.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Science+Show&rft.atitle=Extra-retinal+photo+receptors&rft.date=2009-12-05&rft.aulast=Foster&rft.aufirst=R&rft.au=Williams%2C+R&rft_id=http%3A%2F%2Fwww.abc.net.au%2Frn%2Fscienceshow%2Fstories%2F2009%2F2762261.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotoperiodism" class="Z3988"></span></span> </li> <li id="cite_note-Kevin_M_2013-27"><span class="mw-cite-backlink">^ <a href="#cite_ref-Kevin_M_2013_27-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Kevin_M_2013_27-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMartinez-BakkerBakkerKingRohani2014" class="citation journal cs1">Martinez-Bakker, Micaela; Bakker, Kevin M.; King, Aaron A.; Rohani, Pejman (2014-05-22). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3996592">"Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics"</a>. <i>Proceedings of the Royal Society B: Biological Sciences</i>. <b>281</b> (1783): 20132438. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1098%2Frspb.2013.2438">10.1098/rspb.2013.2438</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0962-8452">0962-8452</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3996592">3996592</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/24695423">24695423</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+Royal+Society+B%3A+Biological+Sciences&rft.atitle=Human+birth+seasonality%3A+latitudinal+gradient+and+interplay+with+childhood+disease+dynamics&rft.volume=281&rft.issue=1783&rft.pages=20132438&rft.date=2014-05-22&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC3996592%23id-name%3DPMC&rft.issn=0962-8452&rft_id=info%3Apmid%2F24695423&rft_id=info%3Adoi%2F10.1098%2Frspb.2013.2438&rft.aulast=Martinez-Bakker&rft.aufirst=Micaela&rft.au=Bakker%2C+Kevin+M.&rft.au=King%2C+Aaron+A.&rft.au=Rohani%2C+Pejman&rft_id=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC3996592&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotoperiodism" class="Z3988"></span></span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWehr2001" class="citation journal cs1">Wehr, Thomas A. (August 2001). <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="http://journals.sagepub.com/doi/10.1177/074873001129002060">"Photoperiodism in Humans and Other Primates: Evidence and Implications"</a></span>. <i>Journal of Biological Rhythms</i>. <b>16</b> (4): 348–364. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1177%2F074873001129002060">10.1177/074873001129002060</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0748-7304">0748-7304</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/11506380">11506380</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:25886221">25886221</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Biological+Rhythms&rft.atitle=Photoperiodism+in+Humans+and+Other+Primates%3A+Evidence+and+Implications&rft.volume=16&rft.issue=4&rft.pages=348-364&rft.date=2001-08&rft.issn=0748-7304&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A25886221%23id-name%3DS2CID&rft_id=info%3Apmid%2F11506380&rft_id=info%3Adoi%2F10.1177%2F074873001129002060&rft.aulast=Wehr&rft.aufirst=Thomas+A.&rft_id=http%3A%2F%2Fjournals.sagepub.com%2Fdoi%2F10.1177%2F074873001129002060&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotoperiodism" class="Z3988"></span></span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text">Tan Y, Merrow M, Roenneberg T. Photoperiodism in Neurospora crassa. J Biol Rhythms. 2004 Apr;19(2):135-43. <a rel="nofollow" class="external free" href="https://doi.org/10.1177/0748730404263015">https://doi.org/10.1177/0748730404263015</a>. PMID 15038853.</span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text">Suzuki, L., Johnson, C. Photoperiodic control of germination in the unicell Chlamydomonas. Naturwissenschaften 89, 214–220 (2002). <a rel="nofollow" class="external free" href="https://doi.org/10.1007/s00114-002-0302-6">https://doi.org/10.1007/s00114-002-0302-6</a></span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text">Ivonne Balzer, Rüdiger Hardeland ,Photoperiodism and Effects of Indoleamines in a Unicellular Alga, Gonyaulax polyedra.Science253,795-797(1991).<a rel="nofollow" class="external free" href="https://doi.org/10.1126/science.1876838">https://doi.org/10.1126/science.1876838</a></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Photoperiodism&action=edit&section=11" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin" style=""> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFosket1994" class="citation book cs1">Fosket DE (1994). <i>Plant Growth & Development, A Molecular Approach</i>. San Diego: Academic Press. p. 495.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Plant+Growth+%26+Development%2C+A+Molecular+Approach.&rft.place=San+Diego&rft.pages=495&rft.pub=Academic+Press&rft.date=1994&rft.aulast=Fosket&rft.aufirst=DE&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotoperiodism" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFThomasVince-Prue1997" class="citation book cs1">Thomas B, Vince-Prue D (1997). <i>Photoperiodism in plants</i> (2nd ed.). Academic Press.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Photoperiodism+in+plants&rft.edition=2nd&rft.pub=Academic+Press&rft.date=1997&rft.aulast=Thomas&rft.aufirst=B&rft.au=Vince-Prue%2C+D&rfr_id=info%3Asid%2Fen.wikipedia.org%3APhotoperiodism" class="Z3988"></span></li></ul> </div> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul 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aria-labelledby="Biological_rhythms" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="3"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini 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title="Special:EditPage/Template:Biological rhythm"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Biological_rhythms" style="font-size:114%;margin:0 4em"><a href="/wiki/Biological_rhythm" title="Biological rhythm">Biological rhythms</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Internal rhythms</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Circadian_rhythm" title="Circadian rhythm">Circadian rhythm</a></li> <li><a href="/wiki/Infradian_rhythm" title="Infradian rhythm">Infradian rhythm</a></li> <li><a href="/wiki/Ultradian_rhythm" title="Ultradian rhythm">Ultradian rhythm</a></li> <li><a href="/wiki/Lunar_effect" title="Lunar effect">Lunar rhythm</a></li> <li><a href="/wiki/Season" title="Season">Annual rhythm</a></li></ul> </div></td><td class="noviewer navbox-image" rowspan="4" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/File:Light_Ethology.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Light_Ethology.svg/150px-Light_Ethology.svg.png" decoding="async" width="150" height="60" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Light_Ethology.svg/225px-Light_Ethology.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Light_Ethology.svg/300px-Light_Ethology.svg.png 2x" data-file-width="512" data-file-height="205" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">External cycles</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Diurnality" title="Diurnality">Diurnality</a> <ul><li><a href="/wiki/Diurnal_cycle" title="Diurnal cycle">Diurnal cycle</a></li></ul></li> <li><a href="/wiki/Nocturnality" title="Nocturnality">Nocturnality</a></li> <li><a href="/wiki/Cathemerality" title="Cathemerality">Cathemerality</a></li> <li><a href="/wiki/Crepuscular_animal" title="Crepuscular animal">Crepuscular</a> <ul><li><a href="/wiki/Matutinal" title="Matutinal">Matutinal</a></li> <li><a href="/wiki/Vespertine_(biology)" title="Vespertine (biology)">Vespertine</a></li></ul></li> <li><a href="/wiki/Season" title="Season">Seasonality</a></li> <li><a class="mw-selflink selflink">Photoperiodism</a></li> <li><a href="/wiki/Vernalization" title="Vernalization">Vernalization</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fields</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Behavioral_ecology" title="Behavioral ecology">Behavioural ecology</a></li> <li><a href="/wiki/Chronobiology" title="Chronobiology">Chronobiology</a></li> <li><a href="/wiki/Ethology" title="Ethology">Ethology</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronotype" title="Chronotype">Chronotype</a></li> <li><a href="/wiki/Diel_vertical_migration" title="Diel vertical migration">Diel vertical migration</a></li> <li><a href="/wiki/Light_pollution" title="Light pollution">Light pollution</a></li> <li><a href="/wiki/Solunar_theory" title="Solunar theory">Solunar theory</a></li> <li><a href="/wiki/Template:Parts_of_a_day" title="Template:Parts of a day">Parts of a day</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"><style data-mw-deduplicate="TemplateStyles:r1038841319">.mw-parser-output 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