Organisms who have trait variations that are advantageous are more likely to survive and reproduce, while organisms who have disadvantageous traits are less likely to survive and reproduce. This is because advantageous traits provide the organism with an increased ability to compete for resources, avoid predators, and adapt to changing environments. Organisms with disadvantageous traits are less able to compete for resources, and may be more vulnerable to predation or environmental pressures.
For example, consider a population of gazelles. If some gazelles have longer legs that allow them to run faster and escape predators more easily, these individuals are more likely to survive and pass on their advantageous trait to their offspring. On the other hand, if some gazelles have a genetic mutation that makes them more prone to disease, they may be less likely to survive and reproduce.
Over time, natural selection favors advantageous traits and weeds out disadvantageous traits, resulting in the evolution of populations better adapted to their environments. This is a fundamental principle of evolution and helps explain the diversity of life on Earth.