Relative Effectiveness of Mating Success and Sperm Competition at Eliminating Deleterious Mutations in Drosophila melanogaster

Condition-dependence theory predicts that sexual selection will facilitate adaptation by selecting against deleterious mutations that affect the expression of sexually selected traits indirectly via condition. Recent empirical studies have provided support for this prediction; however, their results do not elucidate the relative effects of pre- and postcopulatory sexual selection on deleterious mutations. We used the Drosophila melanogaster model system to discern the relative contributions of pre- and postcopulatory processes to selection against deleterious mutations. To assess second-male ejaculate competition success (P2; measured as the proportion of offspring attributable to the experimental male) and mating success, mutant and wild-type male D. melanogaster were given the opportunity to mate with females that were previously mated to a standard competitor male. This process was repeated for males subjected to a diet quality manipulation to test for effects of environmentally-manipulated condition on P2 and mating success. While none of the tested mutations affected P2, there was a clear effect of condition. Conversely, several of the mutations affected mating success, while condition showed no effect. Our results suggest that precopulatory selection may be more effective than postcopulatory selection at removing deleterious mutations. The opposite result obtained for our diet manipulation points to an interesting discrepancy between environmental and genetic manipulations of condition, which may be explained by the multidimensionality of condition. Establishing whether the various stages of sexual selection affect deleterious mutations differently, and to what extent, remains an important issue to resolve

Constancy of the bilayer splitting as a function of doping in Bi2Sr2CaCu2O8+δBi_{2}Sr_{2}CaCu_{2}O_{8+δ}

Using high energy resolution angle resolved photoemission spectroscopy, we have resolved the bilayer splitting effect in a wide range of dopings of the bilayer cuprate $Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta}$. This bilayer splitting is due to a nonvanishing intracell coupling $t_{\perp}$, and contrary to expectations, it is not reduced in the underdoped materials. This has implications for understanding the increased c-axis confinement in underdoped materials

An intrinsic peak-dip-hump and strong coupling effects in Bi2Sr2CaCu2O8+δBi_{2}Sr_{2}CaCu_{2}O_{8+δ} ARPES data near (π,0)(π,0)

A well-known peak-dip-hump structure exists near $(\pi, 0)$ in superconducting state ARPES spectra of $Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta}$ (Bi2212). Here we report results on optimal and overdoped Bi2212 samples indicating the traditional peak-dip-hump structure observed near $(\pi,0)$ is largely due to bilayer splitting. However a separate, much weaker peak-dip hump (PDH) structure distinct from bilayer splitting can be detected near $(\pi, 0)$. This new PDH structure is consistent with electronic coupling to the magnetic resonance mode in Bi2212. Both the dispersion and line shape signatures indicate strong coupling to this mode

An intrinsic peak-dip-hump and strong coupling effects in Bi2Sr2CaCu2O8+δBi_{2}Sr_{2}CaCu_{2}O_{8+δ} ARPES data near (π,0)(π,0)

A well-known peak-dip-hump structure exists near $(\pi, 0)$ in superconducting state ARPES spectra of $Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta}$ (Bi2212). Here we report results on optimal and overdoped Bi2212 samples indicating the traditional peak-dip-hump structure observed near $(\pi,0)$ is largely due to bilayer splitting. However a separate, much weaker peak-dip hump (PDH) structure distinct from bilayer splitting can be detected near $(\pi, 0)$. This new PDH structure is consistent with electronic coupling to the magnetic resonance mode in Bi2212. Both the dispersion and line shape signatures indicate strong coupling to this mode