An enlarged right ventricle both increases oxygen intake and the risk of pulmonary hypertension. How can natural selection result in an adaptation that produces both positive and negative effects?
Natural selection can result in adaptations that have both positive and negative effects if the trait provides a survival advantage in certain environments or situations, but also comes with potential drawbacks. In the case of an enlarged right ventricle, individuals with this adaptation may have an increased capacity for oxygen intake, allowing them to thrive in high-altitude environments where oxygen levels are lower. This could provide a significant advantage in terms of survival and reproduction in these environments.
However, the enlarged right ventricle may also increase the risk of developing pulmonary hypertension, a condition that can be harmful to overall health. Despite this potential negative consequence, individuals with the enlarged right ventricle may still have higher overall fitness in their specific environment compared to individuals without this adaptation. As a result, natural selection may favor the trait, even though it comes with some negative effects.
Ultimately, adaptations that have both positive and negative consequences can persist in a population if the benefits outweigh the drawbacks in terms of overall reproductive success and survival. In the case of the enlarged right ventricle, the advantages of increased oxygen intake in certain environments may outweigh the risks of pulmonary hypertension, leading to the trait being maintained through natural selection.