HION ACCESANONE w nace cured The sex of an organism is typically determined genetically, but environmental factors can also play a role Scientists examined the roles of genes and environmental temperature in the sex determination of a lizard species. Individuals with a ZW pair of chromosomes are always female (ZW), while individuals with a ZZ pair of chromosomes can be either male (ZZm) or female ( 72) Scientists mated ZWE or ZZI females with ZZm males and incubated the eggs produced in 20 clutches at temperatures ranging from 23C to 36 C. When the young hatched, the scientis determined their sexes (Table 1). Among the eggs that did not hatch, the mortality of embryonic lizards was approximately the same for both males and females Table 1. Fraction of female progeny produced as a function of egg Incubation temperature Zzan x ZWY Crosses: Fraction of Female Progeny +25 Egg Incubation Temperature (C) 23 0.5.08 24 0.5.02 26 05.07 28 0.5.03 30 0.5.01 32 0.5.03 33 0.58.03 34 35 36 (a) If a particular gene is located 22m x 221 Crosses: Fraction of Female Progeny 2SE 0 0 0 0.03.01 0.2.02 0.52.05 0.74.04 0.93.03 1.00.0 0.88.04 0.970.2 1.0 0.0