Hypothesis/Prediction:

Sex promotes fixation of beneficial mutations by mitigating clonal interference and preventing  fixation of hitchhiking deleterious mutations

(Fisher-Muller and Muller's ratchet effects)

Sex increased fitness and reduces the number of mutations fixed

Most mutations that fixed were genic and nonsynonymous

in asexual reproduction, mutations are correlated and may become extinct after temporarily increasing in frequency

Correlations between mutations is stronger in asexual reproduction  

Mutations in both sexual and asexual reproduction are more correlated than chance

Deleterious mutations will not fix in sexual reproduction even when averaged across backgrounds

Discussion

4 out of 6 sexual populations developed an adherent phenotype coexisting with the wild type.

The adherent phenotype has a loss of function mutation in the ergosterol pathway "which is maintained by balancing selection".

How can supposedly deleterious mutations fix in sexual reproduction?  Perhaps because deleterious is a function of fitness and fitness seems difficult to predict: That is, despite being "deleterious" in the wild type, mutations can increase fitness in certain genetic and environmental backgrounds, and may allow the colonization of a different environment.  

Does the general claim that most mutations are deleterious need further qualifiers? Our explanations of evolution are not far from circular descriptions. This is supported by the fact that even in very simple setups predictions are surprisingly difficult.