Which observation does not support sexual selection as a major cause of speciation?

Sexual selection plays a significant role in speciation by influencing which individuals reproduce and pass on their genes. The observation of high variation in mate choice preferences highlights the diversity in how individuals select partners based on specific traits, which can lead to divergent mating strategies over time. Competition for mates and variation in reproductive success are directly tied to sexual selection, as these factors can drive evolutionary changes.

Differential recombination rates between sexes, however, do not directly relate to sexual selection as a mechanism of speciation. While recombination can influence genetic variation within a population, it is a broader genetic process that doesn’t specifically connect to the dynamics of mate choice or competition. Therefore, this observation does not offer support for the idea that sexual selection is a major driver of speciation. Instead, it reflects general genetic processes that can occur irrespective of sexual selection pressures.