What is the major difficulty posed by each new generation being a combination of DNA copies from two pre-existing individuals?

The major difficulty posed by each new generation being a combination of DNA copies from two pre-existing individuals lies in the potential accumulation of harmful genetic variations. While sexual reproduction enhances genetic diversity, it also introduces the risk of inheriting deleterious mutations from both parents. These mutations may be recessive and, when paired, result in genetic disorders or reduced fitness. Additionally, the recombination of genes during meiosis can lead to unexpected combinations that may be disadvantageous in specific environments. This complexity poses challenges for natural selection to act efficiently in removing detrimental variations, as it relies on the presence of a dominant selective advantage. Despite these challenges, sexual reproduction’s benefits, such as increased adaptability and the ability to weed out harmful mutations over generations, generally outweigh these difficulties, contributing to the long-term evolutionary success of species.