The suggestion that reproduction always creates individuals with adaptive traits is not correct. Reproduction produces offspring that inherit traits from their parents, but these traits are not always adaptive. Some traits may be neutral or even maladaptive depending on the environment. Adaptation results from natural selection favoring individuals with traits that confer a reproductive advantage in a specific environment, but reproduction itself does not guarantee all offspring will have adaptive traits. Non-adaptive traits can still be passed down and appear in offspring.
Why reproduction doesn't always create adaptive traits
- Traits are inherited from parents, but genetic variation means offspring may have a range of traits, some adaptive and some not, depending on environmental context.
- Adaptive traits increase fitness by improving survival or reproduction, but many traits are simply variations that may not provide an advantage.
- Natural selection works over generations to increase the frequency of adaptive traits, but each reproductive event does not automatically produce adaptive offspring.
Supporting evidence from simulations and theory
- Simulations show that offspring can inherit non-adaptive traits from parents, and populations contain a mix of adaptive and non-adaptive traits at any time.
- Adaptive traits become more common over time because individuals with those traits reproduce more successfully.
- The concept of adaptation involves testing whether traits increase fitness, rather than assuming all traits produced by reproduction are adaptive.
In summary, reproduction generates variation; some of that variation includes adaptive traits favored by natural selection, but not all reproductive events yield only adaptive traits. Adaptation is a process driven by selection acting on this variation, not a guaranteed outcome of reproduction itself.
