[..] the infamous ‘two-fold’ cost may be reduced or, perhaps more accurately, more easily balanced in K-selected species. The ‘cost of males’ is with respect to reproduction. Abugov (1985) argued from life history theory principles that the two-fold cost of sex might be easier to pay with K-selection. The two-fold fecundity advantage of asexual reproduction is always a two-fold fitness advantage, regardless of whether it is in a K- or r-selected environment. However, a survival advantage is worth more under K-selection than under r-selection. Consequently, it is easier to balance the two-fold cost under K-selection if sexually derived genotypes have a survival advantage.
I think that k-selection, k-selected environment and stable environment describe (more or less) the same kind of environment. Let me know if this sounds wrong to you. Here is wiki for r/K selection theory
From the same article K-selection is defined as:
K-selection might favour slower development, greater competitive ability, delayed reproduction, higher survival rates, lower resource thresholds, leading to ‘efficiency’ (rather than productivity) and constant population sizes at or near carrying capacity of the environment.
It sounds really strange to me. Can you please help me to understand why the two-fold cost of sex is lower in stable environment than in unstable environment?.