26Evolutionary theory proposes that maternal inheritance of mitochondria will facilitate the 27 accumulation of mitochondrial DNA (mtDNA) mutations that are harmful to males but benign 28 or beneficial to females. Furthermore, mtDNA haplotypes sampled from across a given species 29 distribution are expected to differ in the number and identity of these "male-harming" 30 mutations they accumulate. Consequently, it is predicted that the genetic variation that 31 delineates distinct mtDNA haplotypes of a given species should confer larger phenotypic 32 effects on males than females (reflecting mtDNA mutations that are male-harming, but female-33 benign), or sexually antagonistic effects (reflecting mutations that are male-harming, but 34 female-benefitting). These predictions have received support from recent work examining 35 mitochondrial haplotypic effects on adult life history traits in Drosophila melanogaster. Here, 36 we explore whether similar signatures of male-bias or sexual antagonism extend to a key 37 physiological trait -metabolic rate. We measured the effects of mitochondrial haplotypes on 38 the amount of carbon dioxide produced by individual flies, controlling for mass and activity, 39 across 13 strains of D. melanogaster that differed only in their mtDNA haplotype. The effects 40 of mtDNA haplotype on metabolic rate were larger in males than females. Furthermore, we 41 observed a negative intersexual correlation across the haplotypes for metabolic rate. Finally, 42 we uncovered a male-specific negative correlation, across haplotypes, between metabolic rate 43 and longevity. These results are consistent with the hypothesis that maternal mitochondrial 44 inheritance has led to the accumulation of a sex-specific genetic load within the mitochondrial 45 genome, which affects metabolic rate and that may have consequences for the evolution of sex-46 differences in life history. 47 48 Keywords: mitochondrial DNA; pleiotropy; rate of living; sex specific selective sieve; sexual 49 conflict; sexually antagonistic selection 50 Background 51Mitochondrial genes encode products that are key to the regulation of oxidative 52 phosphorylation. Given the pivotal importance of oxidative phosphorylation in the conversion 53 of chemical energy in eukaryotes, it was traditionally assumed that intense purifying selection 54 would prevent the accumulation of non-neutral (i.e. functional) genetic variants within the 55 coding sequence of the mitochondrial DNA (mtDNA). This assumption has, however, been 56 challenged over the past two decades by studies harnessing experimental designs able to 57 partition mitochondrial from nuclear genetic contributions to phenotypic expression [1][2][3][4]. 58These studies have generally shown that mtDNA haplotypes routinely harbour functional 59 polymorphisms that affect the expression of physiological and life history traits [5, 6]. 60Furthermore, several studies have reported that levels of mitochondrial genetic variation 61 underpinning phenotypic expression are often sex-spec...

Humans are lighting the night-time environment with ever increasing extent and intensity, resulting in a variety of negative ecological effects in individuals and populations. Effects of light at night on reproductive fitness traits are demonstrated across taxa however, the mechanisms underlying these effects are largely untested. One possible mechanism is that light at night may result in perturbed reactive oxygen species (ROS) and oxidative stress levels. Here, we reared Drosophila melanogaster under either dim (10 lx) light or no light (0 lx) at night for three generations and then compared mating and lifetime oviposition patterns. In a second experiment, we explored whether exposure to light at night treatments resulted in variation in ROS levels in the heads and ovaries of six, 23- and 36-day-old females. We demonstrate that dim light at night affects mating and reproductive output: 10 lx flies courted for longer prior to mating, and female oviposition patterns differed to 0 lx females. ROS levels were lower in the ovaries but not heads, of 10 lx compared with 0 lx females. We suggest that reduced ROS levels may reflect changes in ovarian physiology and cell signaling, which may be related to the differences observed in oviposition patterns. Taken together, our results indicate negative consequences for invertebrates under more stressful, urban, lit conditions and further investigation into the mechanisms driving these changes is warranted to manage invertebrate communities in a brighter future.

Psychoactive pollutants, such as antidepressants, are increasingly detected in the environment. Mounting evidence suggests that such pollutants can disrupt the behaviour of non-target species. Despite this, few studies have considered how the response of exposed organisms might be mediated by social context. To redress this, we investigated the impacts of two environmentally realistic concentrations of a pervasive antidepressant pollutant, fluoxetine, on foraging behaviour in fish ( Gambusia holbrooki ), tested individually or in a group. Fluoxetine did not alter behaviour of solitary fish. However, in a group setting, fluoxetine exposure disrupted the frequency of aggressive interactions and food consumption, with observed effects being contingent on both the mean weight of group members and the level of within-group variation in weight. Our results suggest that behavioural tests in social isolation may not accurately predict the environmental risk of chemical pollutants for group-living species and highlight the potential for social context to mediate the effects of psychoactive pollutants in exposed wildlife.

Recent studies have demonstrated that modifications to the ratio of dietary macronutrients affect longevity in a diverse range of species. However, the degree to which levels of natural genotypic variation shape these dietary effects on longevity remains unclear. The mitochondria have long been linked to the aging process. The mitochondria possess their own genome, and previous studies have shown that mitochondrial genetic variation affects longevity in insects. Furthermore, the mitochondria are the sites in which dietary nutrients are oxidized to produce adenosine triphosphate, suggesting a capacity for dietary quality to mediate the link between mitochondrial genotype and longevity. Here, we measured longevity of male and female fruit flies, across a panel of genetic strains of Drosophila melanogaster, which vary only in their mitochondrial haplotype, when fed one of the two isocaloric diets that differed in their protein-to-carbohydrate ratio. The mitochondrial haplotype affected the longevity of flies, but the pattern of these effects differed across the two diets in males, but not in females. We discuss the implications of these results in relation to an evolutionary theory linking maternal inheritance of mitochondria to the accumulation of male-harming mitochondrial mutations, and to the theory exploring the evolution of phenotypic plasticity to novel environments.

In metazoans, the expression of key phenotypic traits is sensitive to two- and three-way interactions between variation in mitochondrial DNA, nuclear DNA and the external environment. Whether gene- by -environment interactions affect phenotypes in single-celled eukaryotes is poorly studied, except in a few species of yeast and fungi. We developed a genetic panel of the unicellular slime mould, Physarum polycephalum containing strains differing in mitochondrial and nuclear DNA haplotypes. The panel also included two strains harbouring a selfishly replicating mitochondrial-fusion (mF) plasmid that could affect phenotype expression. We assayed movement and growth rate differences among the strains across two temperature regimes: 24° and 28°C. We found that the slime mould's growth rate, but not movement, is affected by G × G × E interactions. Predictably, mtDNA × nDNA interactions significantly affected both traits. The inter-trait correlation across the strains in each temperature regime was positive. Surprisingly, the mF plasmid had no negative effects on our chosen traits. Our study is the first to demonstrate genetic regulation of phenotype expression in a unicellular slime mould. The genetic effect on phenotypes manifests via epistatic interactions with the thermal environment, thus shedding new light on the role of G × G × E interactions in trait evolution in protists.

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A new Streptomyces sp. IF 5 was isolated from the feather dumped soil and found to have a tremendous keratinase activity. The strain enabled the degradation of the chicken feathers very effectively in 60 h. The 16S rRNA sequence of 1474 bp long was submitted to the National centre for Biotechnological information. The keratinolytic activity in the culture medium was 1181 U/ml. The release and analyses of sulphydryl groups in the culture medium evident the degradation activity by the Streptomyces sp. IF 5. The idea of the present study was to use the degraded chicken feathers as the substrate for the growth and cultivation of microorganisms. We have designed a very economical culture medium that includes the usage of some basal salts alone and degraded chicken feathers (10 g/l). The results of the specific growth rate of the tested microbes confirm the usage of the new designed medium for microbial culturing.

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