The high performance of Au-CeO 2 and Au-TiO catalysts in the water-gas shift (WGS) reaction (H O + CO→H CO ) relies heavily on direct participation oxide catalytic process. Although clean Au(111) is not catalytically active for WGS, gold surfaces that are 20 to 30% covered by ceria or titania nanoparticles have activities comparable those good WGS such as Cu(111) Cu(100). In TiO 2- x /Au(111) CeO /Au(111), water dissociates vacancies nanoparticles, adsorbs Au sites located nearby, subsequent...

Using information from physics, biomechanics and evolutionary biology, we explore the implications of physical constraints on sperm performance, review empirical evidence for links between length competition (where two or more males compete to fertilize a female's eggs). A common theme in literature is that selection increased performance polyandrous species will favour evolution longer, therefore faster swimming, sperm. This argument based assumption swimming velocity directly related...

The rewards of promiscuity for males are undisputed. But why should a female mate promiscuously, particularly when her partners offer no resources other than sperm and increase chances succumbing to predation or disease? This question has been hotly debated but at present remains largely unresolved [Jennions, M. D. & Petrie, (2000) Biol. Rev. 75, 21–64]. One possibility is that females exploit postcopulatory mechanisms, such as competition, both the quality quantity their offspring. In...

Previous work (Reynolds and Gross 1992) has demonstrated that mate choice enables female guppies, Poecilia reticulata, to obtain heritable benefits ('good genes') for their offspring. It is not yet known whether males also signal functional fertility, is, viability as fathers, guppies. Our study tested the hypothesis a male's behaviour reveals characteristics of his ejaculate. We uncovered strong correlation between display rate sperm number in male guppies derived from two wild Trinidadian...

In guppies (Poecilia reticulata) precopulatory sexual selection (via female choice) and post-copulatory sperm competition) both favour males with relatively high levels of carotenoid (orange) pigmentation, suggesting that colourful produce more competitive ejaculates. Here we test whether there is a positive association between male orange pigmentation quality. Our analysis quality focused on swimming speeds (using CASA: computer-assisted to estimate three parameters velocity in vitro),...

Sperm competition is expected to favour the evolution of traits that influence performance sperm when they compete fertilize a female's eggs. While there considerable evidence selection favours increases in numbers, much less known about how quality contributes towards competitive fertilization success. Here, we determine whether variation influences success green swordtail Xiphophorus helleri, highly promiscuous livebearing fish. We use artificial insemination as method controlled delivery...

In 1992, David Houle showed that measures of additive genetic variation standardized by the trait mean, CVA (the coefficient variation) and its square (IA), are suitable evolvability. has been used widely to compare patterns variation. However, use CVAs for comparative purposes relies critically on correct calculation this parameter. We reviewed a sample quantitative studies, focusing sire models, found 45% studies incorrect methods calculating practices render these coefficients meaningless...

Cryptic female choice (CFC) refers to female‐mediated processes occurring during or after copulation that result in biased sperm use favor of preferred compatible males. Despite recent empirical support for this hypothesis, evidence CFC contributes towards the evolution male body ornaments, same way precopulatory does, is currently lacking. Here, we tested possibility selects increased attractiveness guppy Poecilia reticulata, a freshwater fish exhibiting internal fertilization....

Numerous studies have reported that females benefit from mating with multiple males (polyandry) by minimizing the probability of fertilization genetically incompatible sperm. Few, however, directly attributed variation in female reproductive success to fertilizing capacity In this study we report on two experiments investigated benefits polyandry and interacting effects at free-spawning Australian sea urchin Heliocidaris erythrogramma. first experiment used a paired (split clutch)...

Despite its widespread occurrence in animals, sperm competition has been studied a limited range of taxa. Among the most neglected groups this respect are internally fertilizing fish which virtually nothing is known about dynamics competition. In study, we examined outcome when virgin female guppies mated with two males. Behavioural cues were used to ensure that each male once (with cooperation) and successfully inseminated at copulation. Two polymorphic microsatellite loci estimate...

In nonresource based mating systems females are thought to derive indirect genetic benefits by with high-quality males. Such can be due either the intrinsic quality of sires or beneficial interactions between maternal and paternal haplotypes. Animals external fertilization no parental care offer unrivaled opportunities address these hypotheses. With systems, cross-classified breeding designs in vitro used disentangle sources environmental variance offspring fitness. Here, we employ...

According to the good-genes hypothesis, females choose among males ensure inheritance of superior paternal genes by their offspring. Despite increasing support for this prediction, in some cases differential (non-genetic) maternal effects may obscure or amplify relationship between attractiveness and offspring quality. Artificial insemination controls such because it uncouples mate choice from copulation, therefore denying opportunity assessing male attractiveness. We adopted technique...

Polyandry, where females mate with multiple males, means that a male's reproductive success will depend both on his ability to acquire mates and the of sperm compete effectively for fertilizations. But, how do males partition their investment between these two episodes selection? Theory predicts increases in ejaculate come at cost other traits. Although evidence revealing such trade-offs is accumulating, we know little about genetic basis. Here, I report patterns (co)variation range traits...

Synchrotron-based in situ time-resolved x-ray diffraction and absorption spectroscopies were used to study the behavior of nanostructured {Au+AuO(x)}-CeO(2) catalysts under water-gas shift (WGS) reaction. At temperatures above 250 degrees C, a complete AuO(x)-->Au transformation was observed with high catalytic activity. Photoemission results for oxidation reduction Au nanoparticles supported on rough ceria films or CeO(2)(111) single crystal corroborate that cationic Au(delta+) species...

In numerous species, egg chemoattractants play a critical role in guiding sperm towards unfertilized eggs (sperm chemotaxis). Until now, the known functions of chemotaxis include increasing effective target size eggs, thereby promoting sperm–egg encounters, and facilitating species recognition. Here, we report that broadcast spawning mussel, Mytilus galloprovincialis , may an unforeseen sexual selection by enabling to effectively ‘choose’ between different conspecific females. initial...

Abstract In many species, females mate with multiple partners, meaning that sexual selection on male traits operates across a spectrum encompasses the competition for mates (that is, before mating) and fertilizations (after mating). Despite being inextricably linked, pre- postcopulatory are typically studied independently, we know almost nothing about how this divide. Here bridge knowledge gap using livebearing fish Poecilia reticulata . We show both selective episodes, as well their...

It is often assumed that longer sperm, by virtue of their increased swimming speed, have a fertilization advantage over shorter sperm when in competition to fertilize eggs. However, there surprisingly little evidence for positive correlation between length and speed. Here we use an approach accounts within-male variation traits examine the relationships speed across broad range species, including three internally fertilizing species externally species. Our results reveal correlations size...

Sperm chemoattraction, where sperm locate unfertilized eggs by following a concentration gradient of egg-derived chemoattractants, has been widely documented across numerous taxa. While marine invertebrates are favoured models for understanding the underlying mechanisms evolutionary forces underpinning process remain enigmatic. Here, we show that in mussels ( Mytilus galloprovincialis ), chemically moderated gamete preferences promote assortative fertilizations between genetically compatible...