{"id":14228,"date":"2016-12-01T11:26:35","date_gmt":"2016-12-01T08:26:35","guid":{"rendered":"http:\/\/109.232.216.219\/~bilimvegelecek\/?p=14228"},"modified":"2018-02-08T16:24:32","modified_gmt":"2018-02-08T13:24:32","slug":"kelebek-etkisi-modern-genetigin-soyledikleri-ve-biston-betularianin-renk-evrimi","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2016\/12\/01\/kelebek-etkisi-modern-genetigin-soyledikleri-ve-biston-betularianin-renk-evrimi","title":{"rendered":"Kelebek etkisi:\u00a0Modern geneti\u011fin s\u00f6yledikleri ve Biston betularia\u2019n\u0131n renk evrimi"},"content":{"rendered":"

\u201cSanayi melanizminin\u201d B.betularia\u2019daki evriminin alt\u0131nda yatan geni ve gendeki Carbonaria mutasyonunun 19. y\u00fczy\u0131lda ortaya \u00e7\u0131k\u0131\u015f\u0131n\u0131 b\u00fcy\u00fck do\u011frulukla saptayan ke\u015fifler heyecan verici. Dahas\u0131, Carbonaria varyant\u0131n\u0131n olu\u015fma sebebinin gene girmi\u015f olan bir transpozondan kaynaklan\u0131yor olmas\u0131, hareketli genetik elementlerle evrimsel yeniliklerin ortaya \u00e7\u0131k\u0131\u015f\u0131n\u0131n da \u00e7ok \u00e7arp\u0131c\u0131 bir \u00f6rne\u011fini olu\u015fturuyor. <\/em><\/p>\n

Ge\u00e7ti\u011fimiz ayki yaz\u0131m\u0131zda, do\u011fal se\u00e7ilimle evrimle\u015fmenin parlak bir \u00f6rne\u011fini olu\u015fturan Biston betularia<\/em>\u2019daki farkl\u0131 v\u00fccut renklerinin y\u00fczy\u0131l\u0131 a\u015fk\u0131n evriminin nam\u0131 di\u011fer \u201csanayi melanizmi\u201dnin \u00f6yk\u00fcs\u00fcn\u00fc \u00f6zetlemi\u015ftik. \u0130ngiliz vah\u015fi sanayile\u015fmesinin h\u0131zla d\u00f6n\u00fc\u015ft\u00fcrd\u00fc\u011f\u00fc \u015fehirlerin ormanl\u0131k-koruluk b\u00f6lgelerindeki \u00e7evresel kirlenme sonucunda, B.betularia<\/em>\u2019n\u0131n o zamana de\u011fin s\u0131kl\u0131\u011f\u0131 \u00e7ok d\u00fc\u015f\u00fck olan siyah (Carbonaria) formunun y\u00fczy\u0131l\u0131 a\u015fan bir art\u0131\u015f\u0131n\u0131, ku\u015flarla avlanmadan korunmas\u0131 \u00e7er\u00e7evesinde izah eden bilimsel bulgulardan ve bu bulgular\u0131n genel yorumuna yap\u0131lan itirazlardan s\u00f6z etmi\u015f ve evrimsel biyolojinin bu locus classicus\u2019unun mevcut durumunu bu ayki yaz\u0131m\u0131za b\u0131rakm\u0131\u015ft\u0131k. \u015eimdi kald\u0131\u011f\u0131m\u0131z yerden devam edelim.<\/p>\n

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Biston betularia\u2019n\u0131n renk varyantlar\u0131: A) tipik, B) insularia, C) carbonaria.<\/figcaption><\/figure>\n

Se\u00e7ilimle ya da se\u00e7ilim harici (\u00f6rne\u011fin genetik s\u00fcr\u00fcklenme ile) herhangi bir evrimle\u015fmenin birinci \u015fart\u0131, odak \u00f6zellikteki de\u011fi\u015fkenli\u011fin genetik de\u011fi\u015fkenlikle ili\u015fkili olmas\u0131d\u0131r ve dolay\u0131s\u0131yla B.betularia<\/em>\u2019daki renk de\u011fi\u015fkenli\u011finin geneti\u011fi ilk zamanlar\u0131ndan bu yana derin ilgi g\u00f6rm\u00fc\u015ft\u00fcr. Ayr\u0131nt\u0131l\u0131 genetik analizlerin ilk olarak ortaya koydu\u011fu, \u00f6rne\u011fin, siyah, beyaz\u0131ms\u0131 ve insularia (siyah benekli beyaz) formlar\u0131n\u0131n tek bir gendeki \u00fc\u00e7 genetik varyanttan kaynakland\u0131\u011f\u0131 ve bu varyantlar\u0131n etkilerini g\u00f6stermeleri bak\u0131m\u0131ndan bask\u0131nl\u0131k s\u0131ras\u0131n\u0131n Carbonaria>insularia>beyaz\u0131ms\u0131 \u015feklinde oldu\u011fudur ve ara formla (insularia) ili\u015fkili genetik varyant\u0131n beyaz\u0131ms\u0131 genetik varyant\u0131na belli bir oranda eksik bask\u0131nl\u0131k g\u00f6sterdi\u011fi de saptanm\u0131\u015ft\u0131r (1). Genetikte yayg\u0131n olarak kullan\u0131lan klasik haritalama y\u00f6ntemi ile Carbonaria formuyla ili\u015fkili kromozom b\u00f6lgesini saptayan bu \u00e7al\u0131\u015fmalar, bu b\u00f6lgedeki genin, dolay\u0131s\u0131yla da B.betularia<\/em>\u2019daki v\u00fccut rengi de\u011fi\u015fkenli\u011finin genetik kimli\u011finin saptanmas\u0131n\u0131n \u00f6n\u00fcn\u00fc a\u00e7maktayd\u0131lar.<\/p>\n

K\u0131sa s\u00fcre \u00f6nce de, g\u00fcn\u00fcm\u00fcz\u00fcn modern genetik ili\u015fkilendirme y\u00f6ntemini kullanan bir \u00e7al\u0131\u015fma, \u0130ngiltere\u2019nin ada co\u011frafyas\u0131n\u0131n d\u0131\u015f\u0131na ta\u015fm\u0131\u015f bu g\u00fcvedeki v\u00fccut rengi farkl\u0131l\u0131klar\u0131n\u0131 yaratan genetik sebepler hakk\u0131nda hayli \u00e7arp\u0131c\u0131 ve bir o kadar da s\u0131ra d\u0131\u015f\u0131 g\u00f6z\u00fcken sonu\u00e7lar\u0131 ortaya koymu\u015ftur. S\u00f6z konusu \u00e7al\u0131\u015fma, aralar\u0131nda aaNAT<\/em>, DOPA-decarboxylase<\/em>, ebony<\/em>, tan<\/em> ve yellow<\/em> gibi melanizasyon metabolizmas\u0131n\u0131n \u00f6nemli genlerinin de yer ald\u0131\u011f\u0131 tipik melanizasyon genlerinin Carbonaria formu ile birlikte kal\u0131t\u0131lmad\u0131\u011f\u0131n\u0131, bir bak\u015fa deyi\u015fle, carbonaria kromozom b\u00f6lgesinin bilinen melanizasyon genleriyle ili\u015fkili olmad\u0131\u011f\u0131n\u0131 g\u00f6stermektedir (2). V\u00fccut rengine ili\u015fkin ve temeli genetik olan bir de\u011fi\u015fkenli\u011fin v\u00fccut renginin olu\u015fumuna katk\u0131da bulunan genlerle ili\u015fkisinin bulunmamas\u0131ndan daha garip ne olabilir? Bu beklenmedik sonu\u00e7, ileri ara\u015ft\u0131rmalar\u0131 tetiklemi\u015f ve Carbonaria krozom b\u00f6lgesindeki genin\/genlerin kimli\u011finin saptanmas\u0131na varan yolu a\u00e7m\u0131\u015ft\u0131r.<\/p>\n

Yukardaki \u00e7al\u0131\u015fmadan hemen sonra, Carbonaria kromozom b\u00f6lgesindeki, Carbonaria formunu (siyah form) yaratan genetik varyant\u0131n ne zaman ortaya \u00e7\u0131kt\u0131\u011f\u0131n\u0131 ke\u015ffeden titiz \u00e7al\u0131\u015fmalara g\u00f6re, 200 kilobaz (200,000 DNA baz\u0131) uzunlu\u011fundaki Carbonaria genetik b\u00f6lgesi dizilendi\u011finde, sadece tek bir genle ili\u015fkilenmenin s\u00f6z konusu oldu\u011fu ve bu gende 19. y\u00fczy\u0131l\u0131n ilk \u00e7eyre\u011fi civar\u0131nda ger\u00e7ekle\u015fen bir mutasyonla Carbonaria genetik varyant\u0131n\u0131n ortaya \u00e7\u0131kt\u0131\u011f\u0131 saptanm\u0131\u015ft\u0131r. G\u00fc\u00e7l\u00fc bir \u015fekilde ger\u00e7ekle\u015fen pozitif do\u011fal se\u00e7ilim izi ta\u015f\u0131yan bu varyant, 19. y\u00fczy\u0131l\u0131n ortalar\u0131ndan itibaren g\u00f6sterdi\u011fi s\u0131kl\u0131k art\u0131\u015f\u0131 ile sanayile\u015fme ile ortaya \u00e7\u0131kan kirlili\u011fin ayak izlerini takip eden evrimsel ad\u0131mlar\u0131n bir i\u015faretidir adeta (3).<\/p>\n

Biston betularia<\/em>\u2019daki v\u00fccut rengi varyasyonuna ili\u015fkin do\u011fal se\u00e7ilimin tek bir gendeki, yak\u0131n tarihli mutasyondan kaynakland\u0131\u011f\u0131n\u0131 g\u00f6steren bu \u00e7al\u0131\u015fmay\u0131, do\u011fal olarak, bu genin ne oldu\u011funa odaklanan ara\u015ft\u0131rmalar takip etmi\u015ftir. Bu \u00e7er\u00e7evedeki ilk heyecan verici ke\u015fif, carbonaria varyant\u0131n\u0131 veren gen b\u00f6lgesindeki mutasyonu yaratan etkenin hareketli bir genetik element yani bir transpozon oldu\u011fudur. Cortex<\/em> adl\u0131 genin ilk intronuna yani proteine \u00e7evrilmemesine kar\u015f\u0131n genden sentezlenen protein miktar\u0131n\u0131 belirleyen gen k\u0131sm\u0131na giren bu transpozonun, genetik analizlere g\u00f6re, 1859 y\u0131l\u0131 civar\u0131nda cortex<\/em> geninin bu k\u0131sm\u0131na girdi\u011fi ve b\u00f6ylece carbonaria ad\u0131n\u0131 alan siyah formu olu\u015fturdu\u011fu anla\u015f\u0131l\u0131yor (4). Cortex<\/em> geninin Biston betularia\u2019daki v\u00fccut renginden sorumlu gen olarak ortaya \u00e7\u0131kmas\u0131 ise tesad\u00fcf g\u00f6z\u00fckm\u00fcyor zira bir di\u011fer b\u00fcy\u00fck kelebek cinsi Heliconus<\/em>\u2019ta da kanat deseni ve renklenmesinden sorumlu genin cortex<\/em> oldu\u011fu, geni\u015f bir h\u00fccre d\u00f6ng\u00fcs\u00fc kontrol genleri ailesinin bir \u00fcyesi olan cortex<\/em>\u2019in pulcuk h\u00fccrelerinin geli\u015fimini d\u00fczenleyerek v\u00fccut ve kanat renklenmesini sa\u011flayabilece\u011fi de saptanm\u0131\u015f durumda (5).<\/p>\n

Bu son derece yak\u0131n tarihli ve modern genetik-genombilimi tekniklerini kullanarak \u201csanayi melanizminin\u201d B.betularia<\/em>\u2019daki evriminin alt\u0131nda yatan geni ve gendeki Carbonaria mutasyonunun 19. y\u00fczy\u0131lda ortaya \u00e7\u0131k\u0131\u015f\u0131n\u0131 b\u00fcy\u00fck do\u011frulukla saptayan ke\u015fiflerin olduk\u00e7a heyecan verici olduklar\u0131 ku\u015fkusuz. Dahas\u0131, Carbonaria varyant\u0131n\u0131n olu\u015fma sebebinin gene girmi\u015f olan bir transpozondan kaynaklan\u0131yor olmas\u0131, hareketli genetik elementlerle evrimsel yeniliklerin ortaya \u00e7\u0131k\u0131\u015f\u0131n\u0131n da \u00e7ok \u00e7arp\u0131c\u0131 bir \u00f6rne\u011fini olu\u015fturuyor. Cortex<\/em> genindeki ve onu \u00e7evreleyen b\u00f6lgedeki pozitif do\u011fal se\u00e7ilim izleri de sanayi melanizminin do\u011fal se\u00e7ilimle evrimle\u015fmi\u015f bir olgu oldu\u011funu net bi\u00e7imde ifade ediyor. Bununla birlikte, do\u011fal se\u00e7ilimin B.betularia<\/em>\u2019daki v\u00fccut rengi de\u011fi\u015fkenli\u011fini bi\u00e7imlendirirken, i\u015f g\u00f6ren se\u00e7ilimsel etkenin ne oldu\u011fu konusunda bu \u00e7ok \u00f6nemli genetik ke\u015fiflerin s\u00f6yledi\u011fi bir \u015fey de bulunmuyor.<\/p>\n

Molek\u00fcler d\u00fczeydeki bilginin, biyolojik \u00f6zelliklerin tarihsel bi\u00e7imleni\u015fine ili\u015fkin nedenselli\u011fin, \u00f6nemli olmakla birlikte, yaln\u0131zca bir b\u00f6l\u00fcm\u00fcne kar\u015f\u0131l\u0131k geldi\u011fini bir kez daha, B.betularia<\/em> \u00f6rne\u011finde, g\u00f6rm\u00fc\u015f oluyoruz. Nedensellik resminin di\u011fer par\u00e7alar\u0131n\u0131 tamamlamak i\u00e7in ise, evrimsel biyolojinin \u00e7oklu \u00f6l\u00e7ekli metodolojisinin izd\u00fc\u015f\u00fcm\u00fcn\u00fc takip etmemiz gerekiyor. B.betularia<\/em>\u2019n\u0131n renk de\u011fi\u015fkenli\u011finin evrimini anlamak i\u00e7in avc\u0131 ku\u015flar\u0131n se\u00e7ici avc\u0131l\u0131\u011f\u0131n\u0131n h\u00e2l\u00e2 do\u011fru bir ba\u015flang\u0131\u00e7 noktas\u0131 olu\u015fturduklar\u0131n\u0131 s\u00f6ylemek m\u00fcmk\u00fcn m\u00fcd\u00fcr? Bu sorunun yan\u0131t\u0131n\u0131, \u00f6n\u00fcm\u00fczdeki ayki yaz\u0131m\u0131zda, pop\u00fclasyon ekolojisi ve evriminin \u00f6l\u00e7e\u011fine yeniden y\u00fckselerek vermeye \u00e7al\u0131\u015faca\u011f\u0131z.<\/p>\n

Kaynaklar<\/strong><\/p>\n

1) D. R. Lees ve E. R. Creed, The genetics of the insularia forms of te peppered moth, Biston betularia<\/em>. Heredity<\/em> 39: 67-73, 1977.<\/p>\n

2) Arjen E. van\u2019t Hof ve Ilik J. Saccheri, Industrial melanism in the peppered moth is not associated with genetic variation in canonical melanisation gene candidates. PLoS ONE<\/em> 5(5): e10889. doi:10.1371\/journal.pone.0010889, 2010.<\/p>\n

3) Arjen E. van\u2019t Hof, Nicola Edmonds, Martina Dal\u00edkov\u00e1, Franti\u0161ek Marec ve Ilik J. Saccheri; Industrial melanism in British peppered moths has a singular and recent mutational origin. Science <\/em>332: 958-960, 2011.<\/p>\n

4) Arjen E. van\u2019t Hof, Pascal Campagne, Daniel J. Rigden, Carl J. Yung, Jessica Lingley, Michael A. Quail, Neil Hall, Alistair C. Darby ve Ilik J. Saccheri; The industrial melanism mutation in British peppered moths is a transposable element. Nature <\/em>534: 102-105, 2016.<\/p>\n

5) Nicola J. Nadeau, Carolina Pardo-Diaz, Annabel Whibley, Megan A. Supple, Suzanne V. Saenko, Richard W. R. Wallbank, Grace C. Wu, Luana Maroja, Laura Ferguson, Joseph J. Hanly, Heather Hines, Camilo Salazar, Richard M. Merrill,Andrea J. Dowling, Richard H. ffrench-Constant, Violaine Llaurens, Mathieu Joron, W. Owen McMillan ve Chris D. Jiggins; The gene cortex <\/em>controls mimicry and crypsis in butterflies and moths. Nature<\/em> 534: 106-113, 2016.<\/p>\n","protected":false},"excerpt":{"rendered":"

\u201cSanayi melanizminin\u201d B.betularia\u2019daki evriminin alt\u0131nda yatan geni ve gendeki Carbonaria mutasyonunun 19. y\u00fczy\u0131lda ortaya \u00e7\u0131k\u0131\u015f\u0131n\u0131 b\u00fcy\u00fck do\u011frulukla saptayan ke\u015fifler heyecan verici. Dahas\u0131, Carbonaria varyant\u0131n\u0131n olu\u015fma sebebinin gene girmi\u015f olan bir transpozondan kaynaklan\u0131yor olmas\u0131, hareketli genetik elementlerle evrimsel yeniliklerin ortaya \u00e7\u0131k\u0131\u015f\u0131n\u0131n da \u00e7ok \u00e7arp\u0131c\u0131 bir \u00f6rne\u011fini olu\u015fturuyor. Ge\u00e7ti\u011fimiz ayki yaz\u0131m\u0131zda, do\u011fal se\u00e7ilimle evrimle\u015fmenin parlak bir \u00f6rne\u011fini […]<\/p>\n","protected":false},"author":67,"featured_media":14229,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[191,1475,21,32],"tags":[200,292,1610,1109,1494],"class_list":["post-14228","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-154-sayi","category-bilim-ve-tarih","category-biyoloji","category-evrim","tag-evrim","tag-genetik","tag-kelebek","tag-renk","tag-secilim"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t