Ve z\u00e1p\u011bst\u00edch na\u0161ich ope\u0159en\u00fdch p\u0159\u00e1tel se odv\u00edj\u00ed fascinuj\u00edc\u00ed evolu\u010dn\u00ed p\u0159\u00edb\u011bh. P\u0159ed miliony let se po Zemi proh\u00e1n\u011bli dinosau\u0159i s robustn\u00edmi z\u00e1p\u011bst\u00edmi uzp\u016fsoben\u00fdmi k nesen\u00ed jejich v\u00e1hy. Nicm\u00e9n\u011b jak se n\u011bkte\u0159\u00ed dinosau\u0159i vyv\u00edjeli v dvounoh\u00e9 tvory, jejich z\u00e1p\u011bst\u00ed se st\u00e1vala jemn\u011bj\u0161\u00ed a ztr\u00e1cela n\u011bkolik kost\u00ed, v\u010detn\u011b hrachu.<\/p>\n\n
Kdy\u017e maso\u017erav\u00ed dinosau\u0159i dobyli oblohu, jejich p\u0159edn\u00ed kon\u010detiny prod\u011blaly pozoruhodnou p\u0159em\u011bnu. Z\u00e1p\u011bst\u00ed se stala flexibiln\u011bj\u0161\u00ed, co\u017e umo\u017enilo p\u0159ikl\u00e1d\u00e1n\u00ed k\u0159\u00eddel k t\u011blu. V tomto p\u0159echodu vznikla nov\u00e1 kost na stejn\u00e9m m\u00edst\u011b jako ztracen\u00fd hr\u00e1\u0161ek a poskytovala k\u0159\u00eddlu oporu. Anatomov\u00e9 p\u016fvodn\u011b v\u011b\u0159ili, \u017ee tato kost je novou strukturou, loketn\u00ed kost\u00ed.<\/p>\n\n
Po stalet\u00ed v\u011b\u0159ili biologov\u00e9 Dollovovu z\u00e1konu, kter\u00fd uv\u00e1d\u011bl, \u017ee jakmile se struktura v evoluci ztrat\u00ed, nelze ji znovu z\u00edskat. Objev loketn\u00ed kosti v\u0161ak toto dogma zpochybnil. V\u00fdzkumn\u00edci si uv\u011bdomili, \u017ee loketn\u00ed kost nebyla v\u016fbec novou kost\u00ed, ale sp\u00ed\u0161e op\u011btovn\u00fdm objeven\u00edm hrachu.<\/p>\n\n
Studium embryon\u00e1ln\u00edho v\u00fdvoje vrh\u00e1 sv\u011btlo na zvratnost evoluce. V embry\u00edch modern\u00edch pt\u00e1k\u016f, v\u010detn\u011b ku\u0159at, holub\u016f a papou\u0161k\u016f, lze pozorovat stopy p\u0159edkov\u00fdch znak\u016f. P\u0159\u00edtomnost t\u011bchto znak\u016f nazna\u010duje, \u017ee potenci\u00e1l pro op\u011btovn\u00fd v\u00fdvoj ur\u010dit\u00fdch struktur z\u016fst\u00e1v\u00e1 v genetick\u00e9m k\u00f3du ne\u010dinn\u00fd.<\/p>\n\n
Dollo\u016fv z\u00e1kon byl zpochybn\u011bn i v jin\u00fdch p\u0159\u00edpadech. N\u011bkte\u0159\u00ed rozto\u010di se vr\u00e1tili ke sv\u00e9mu voln\u011b \u017eij\u00edc\u00edmu zp\u016fsobu existence pot\u00e9, co po tis\u00edcilet\u00ed \u017eili na \u017eivo\u010di\u0161n\u00fdch hostitel\u00edch. Podobn\u011b stromov\u00e1 \u017e\u00e1ba z Ji\u017en\u00ed Ameriky ztratila sv\u00e9 doln\u00ed zuby, jen aby je o miliony let pozd\u011bji znovu vytvo\u0159ila.<\/p>\n\n
Zvratnost evoluce vyvol\u00e1v\u00e1 zaj\u00edmav\u00e9 ot\u00e1zky o potenci\u00e1lu anatomick\u00fdch zm\u011bn u lid\u00ed. Kostr\u010d, mal\u00e1 kost na z\u00e1kladn\u011b p\u00e1te\u0159e, je poz\u016fstatkem na\u0161\u00ed evolu\u010dn\u00ed minulosti jako ocasat\u00fdch tvor\u016f. Bylo by mo\u017en\u00e9, aby tato kost v budoucnu znovu vytvo\u0159ila ocas, pokud by se lid\u00e9 p\u0159izp\u016fsobili \u017eivotn\u00edmu stylu, kter\u00fd by to vy\u017eadoval?<\/p>\n\n
Studium pta\u010d\u00edch z\u00e1p\u011bst\u00ed a dal\u0161\u00edch p\u0159\u00edklad\u016f evolu\u010dn\u00ed zvratnosti nazna\u010duje, \u017ee ztr\u00e1ta struktury nutn\u011b neznamen\u00e1 jej\u00ed trval\u00e9 vymizen\u00ed. Genetick\u00fd potenci\u00e1l pro danou strukturu naopak m\u016f\u017ee z\u016fstat ne\u010dinn\u00fd a \u010dekat na vhodn\u00e9 podm\u00ednky prost\u0159ed\u00ed, kter\u00e9 spust\u00ed jej\u00ed op\u011btovn\u00e9 objeven\u00ed. Tento koncept otev\u00edr\u00e1 nov\u00e9 cesty zkoum\u00e1n\u00ed p\u0159izp\u016fsobivosti a odolnosti \u017eivotn\u00edch forem na na\u0161\u00ed planet\u011b.<\/p>","protected":false},"excerpt":{"rendered":"
Evoluce pta\u010d\u00edch z\u00e1p\u011bst\u00ed: P\u0159\u00edb\u011bh zvratnosti Ztracen\u00e1 kost Ve z\u00e1p\u011bst\u00edch na\u0161ich ope\u0159en\u00fdch p\u0159\u00e1tel se odv\u00edj\u00ed fascinuj\u00edc\u00ed evolu\u010dn\u00ed p\u0159\u00edb\u011bh. P\u0159ed miliony let se po Zemi proh\u00e1n\u011bli dinosau\u0159i s robustn\u00edmi z\u00e1p\u011bst\u00edmi uzp\u016fsoben\u00fdmi k…<\/p>\n","protected":false},"author":1,"featured_media":24638,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[244],"tags":[1647,3022,740,15642,136,188,584,137],"class_list":["post-11565","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-natural-history","tag-adaptation","tag-anatomy","tag-biology","tag-dollos-law","tag-evolution","tag-genetics","tag-ornithology","tag-paleontology"],"_links":{"self":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/11565","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/comments?post=11565"}],"version-history":[{"count":2,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/11565\/revisions"}],"predecessor-version":[{"id":24639,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/11565\/revisions\/24639"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/media\/24638"}],"wp:attachment":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/media?parent=11565"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/categories?post=11565"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/tags?post=11565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}