These XXXXX XXXXXXXXX XX tural XXXXXXXXX or in XXXXX XXXXX, XXXXXXXX of the fittest. Only the species XXXX XXX XXXX desirable traits XXX able to XXXXXXX to pass XX XXXXX XXXXXX in XXX next generations while those with undesirable XXXXXX will XXXXXX. Environmental XXXXXXX XXXX an XXXXXXXXX role XX XXXX XXXXXX XXX XXXXXXXXX for XXXXXXXX. XX XXXX example XX have the XXXXXXXX moth whose XXXXX XXXXXX XXXX XXXX XXX pre-industrial revolution trees. This trait XXX beneficial at the time XXXXXXX it allowed the XXXX XX XXXX from predators. The XXXXX XXXX survived were able to XXXX XXXXX traits XX XX the next generation. XXXX XXX XXXXXXXXXX XXXXXXXXXX XXXXXXXX in XXXXXXX, the XXXX trunks XXXXXX a darker color. XXXXX XXXXX colors were XXXXXXX were easily seem XX XXXXX XXXXXXXXX XXX XXXXXXXX XXXX their XXXXXX XXXX XXX passed on XX XXX XXXX XXXXXXXXXX. XXXXX who XXX a darker color XXXX able XX XXXX XXXX XXXXX predators thus XXXX were able XX pass XXXX XXXXX XX to XXX next generations. XXXX XX an example of XXXXXXXXX XXXXXXXX against a particular phenotype, in XXXX XXXX, against XXX XXXXX-XXXXXXX XXXXX. XXX XXXXXXXXX XXXXXXXX against XXX XXXXX-colored XXXXXXXXX disrupts XXX ratio which favors the XXXX-colored phenotype. XXX loss of individuals with XXX XXXXX-XXXXXXX phenotype lowers XXX chances of XXXXXXX XXX trait XX XX XXX next generations. XX this continues, the light-XXXXXXX XXXXXXXXX would XX XXXX and only the dark-XXXXXXX phenotype will XXXXXXX XXXXXX acted XXXX XXXXX by an XXXXXXX XXXXX.