Tagyirpaziri baraksi irsiyat meboshad, vale bo on robitai zich dorad. Zero zarrachahoi irsi genho inkishofi in yo on alomatro muayyan mekunand. Agar tajdidi qolab (matritsa) – molekulai KDN hamesha daqiq surat megirift, pas hini afzoishi organizmho faqat alomathoi peshtara az nasl ba nasl meguzashtand va mutobiqati namudho ba tagyiroti sharoiti muhiti zist nomumkin megasht.
Az in ru, tagyirpaziri qobiliyati organizmho buda, bahri paydo kardani alomatu khosiyathoi nav meboshad va dar natijai tagyiryobii sokhtori mavodi irsi yo paydoishi genhoi navi kombinativi ba amal meoyad.
Tagyirpaziri baroi intikhobi tabii mavodi gunogun muhayyo mesozad, yane intikhobi fardhoe meboshad, ki ba sharoiti muhiti zist nagz mutobiq gashtaand. In ba paydo shudani shakl va namudhoi navi organizmho musoidat mekunad.