Like most animals , bearded dragons have a hereditary sexuality found on chromosomes . Rather than mammalian ' X and Y chromosomes , these reptiles have Z and W — a ZZ chromosome pairing unremarkably makes a male , and ZW a female person . However , ina 2007 lab discipline , scientists found that temperature - induced changes — a rare but recognized feature of some reptilian — could override a lounge lizard ’s inherited sex . At an brooding temperature over 32 ° C ( 90 ° F ) , all the eggs hatch female , even those that had ZZ chromosomes . It was unreadable if this just happened to be a fluke affiliate with the laboratory surround , or if the same weather condition would affect sex out in the wild .
A squad of Australian researchers led by Clare E. Holleley specify out to look into this phenomenon for a paper publish recently inNature . With very little fright of humanity , the lizard were promiscuous to outflank up and analyze , with scientists checking for provable sex , as well as chromosomal penning .
Of the 131 lizards the team studied , research lab tests register that 11 females had no W chromosome , meaning they were primitively male whose sex had change in response to temperature pressures . astonishingly , these ZZ female person were not only fertile , they laid almost twice as many eggs as ZW mothers . Having matte up with ZZ males these redundant fecund ZZ female laid ball that had only zed chromosome .
" They ’ve completely lost a whole chromosome in one propagation , " Holleley toldNew Scientist . The Z generation are technically all genetically virile but their genetically male mothers seem to have passed on a propensity for sex change . Their " sons " switched sex at even slightly low temperatures than they themselves had .
This discovery represents the first known clip that two form of sex determination have coexisted in the wilderness . This finical moment in bearded dragon evolution is notable because with climate change create ever warmer weather , temperature determination could change more and more males into ZZ females , driving the species towards extinction .
