Promiscous female Euxesta eluta derive nutrients for ovarian development by expelling and consuming ejaculates

Seminal gifts range from important material donations to items that provide little direct benefit to females. Promiscuous, female silk corn flies Euxesta eluta expel and consume male ejaculates immediately after mating. The evolution and function of this peculiar behavior are currently unknown. We performed a series of experiments aimed to: determine if females under different dietary regimes derive nutrients or water for survival and/or reproduction from ejaculate consumption, if males suffer a fitness cost from supplying females with ejaculates, and if females prefer to mate and/or are more likely to store sperm from well fed than nutritionally stressed presumably inferior males. Experiments revealed that protein deprived E. eluta females derive nutrients for ovarian development through consumption of ejaculates of protein fed males. No seminal products affecting survival appear to be transferred in the consumed ejaculate. However, ovarian development, in contrast to testes growth, occurs in detriment of longevity. Females preferred to mate with protein fed males, yet sperm retention in spermathecae was extremely rare after a single mating. This finding suggests that females could be exerting post copulatory control. A key question that remained to be addressed for the understanding of this puzzling and promiscuous mating system is what ecological factors or male traits drive females to retain sperm from one or several males in order to achieve and/or maximize fertilization potential.     

Sperm competition,but not major histocompatibility divergence,drives differential fertilization success between alternative reproductive tactics in Chinook salmon

Post‐copulatory sexual selection processes, including sperm competition and cryptic female choice (CFC), can operate based on major histocompatibility (MH) genes. We investigated sperm competition between male alternative reproductive tactics [jack (sneaker) and hooknose (guard)] of Chinook salmon (Oncorhynchus tshawytscha). Using a full factorial design, we examined in vitro competitive fertilization success of paired jack and hooknose males at three time points after sperm activation (0, 15 and 60 s) to test for male competition, CFC and time effects on male fertilization success. We also examined egg‐mediated CFC at two MH genes by examining both the relationship between competitive fertilization success and MH divergence as well as inheritance patterns of MH alleles in resulting offspring. We found that jacks sired more offspring than hooknose males at 0 s post‐activation; however, jack fertilization success declined over time post‐activation, suggesting a trade‐off between sperm speed and longevity. Enhanced fertilization success of jacks (presumably via higher sperm quality) may serve to increase sneaker tactic competitiveness relative to dominant hooknose males. We also found evidence of egg‐mediated CFC (i.e. female × male interaction) influencing competitive fertilization success; however, CFC was not acting on the MH genes as we found no relationship between fertilization success and MH II β₁ or MH I α₁ divergence and we found no deviations from Mendelian inheritance of MH alleles in the offspring. Our study provides insight into evolutionary mechanisms influencing variation in male mating success within alternative reproductive tactics, thus underscoring different strategies that males can adopt to attain success.     

Isolation and culture of protoplasts from young sporophytes ofSalvinia natans aseptically obtained by co-culture of female and male gametophytes

Sporophytes were aseptically obtained by co-culture of female and male gametophytes derived from two types of spores (megaspores and microspores) of the heterosporous fernSalvinia natans All. Protoplasts isolated enzymatically from juvenile leaflets of sporophytes were cultured in a 1/10 Murashige and Skoog's medium containing 2.2 M naphthalene acetic acid, 2.2 M 6-benzyl-aminopurine, 0.35 M mannitol, and 0.05 M sucrose. Cell division took place within 6 days of culture, and cell-clusters composed of 9–10 cells were observed after 30 days of culture.Abbreviations BA 6-benzyl-aminopurine - MS Murashige and Skoog - NAA naphthaleneacetic acid     

Sex-dependent correlation between survival and expression of genes related to the circadian oscillator in patients with colorectal cancer

ABSTRACT

Recent evidence supports the important role of the circadian system in cancer progression in humans. The aim of the present study is to evaluate clock (cry1, cry2 and per2) and clock-controlled (vascular endothelial growth factor-a, early growth response protein 1 and estrogen receptor β) gene expression in colorectal cancer and adjacent tissue and identify a possible link between survival of patients and expression of above mentioned genes. The study includes 64 patients of both sexes with previously diagnosed colorectal cancer. RNA was extracted from the tumor tissue and adjacent parts of the resected colon, and real-time PCR was used for detection of clock gene expression. Expression of cry2 and per2 was significantly downregulated in tumor tissue compared to adjacent tissues. After splitting of the cohort according to sex, we detected downregulated levels of cry2 and per2 in male patients, but not in females. Splitting of male and female sub-cohorts according to presence of metastases revealed significant donwregulation of cry2 expression in female patients without distant metastasis. Better survival rate was associated with low expression of cry2 in female patients. Moreover, we observed an increase in cry1 expression in female patients with distant metastases in tumor compared to adjacent tissue. Accordingly, women with high expression of cry1 in tumor tissue displayed worse survival, which was not observed in men. Taken together, expression of clock and clock-controlled genes in tumors of males and females clustered according to presence of distant metastases correlated with survival analysis. Studied clock-controlled genes also showed sex-dependent changes. Low expression of vegf-a in tumor correlated with better survival in men but not in women. High expression of estrogen receptor β mRNA was related to better survival in women but not in men. Low expression of vegf-a, egr1 and estrogen receptor β was associated with worse survival in women compared to men. Our data indicate sex-dependent associations between clock and clock-controlled gene expression in cancer tissue and patient’s survival prognosis.     

Secretion of Spodoptera littoralis female reproductive system on deposited egg masses that possibly acts as oviposition deterring substance for conspecific females

Egg masses laid by Spodoptera littoralis mated female moths were extracted by petroleum ether (PE), ethanol (E) and Ringer's solution (RS). Egg-wash extracts were evaporated and the weights of crude materials were obtained. Different aqueous concentrations were made. The amount of extracted material increased as the weight of eggs used increased and vice versa. Coating Nerium oleander leaves with aqueous egg-wash extracts prepared from S. littoralis egg-masses deterred the mated conspecific female moths from ovipositing their eggs on treated leaves, as well as causing a decrease in the total number of deposited eggs per female during the moth's life span. The highest deterrent effect on conspecific female moths to oviposit their eggs was obtained after treatment of N. oleander leaves with PE or E egg-wash extract. The deterrent effects of the tested egg-wash extracts was concentration dependant; an increase in the concentration of any extract caused an obvious decrease in the number of deposited egg-masses and the total number of laid eggs on the treated N. oleander leaves.     

Photoperiodic regulation of gametogenesis in a North Atlantic sea star,Asterias vulgaris

Summary

Individuals of the sea star Asterias vulgaris from New Hampshire were maintained under two contrasting regimes of seasonally changing photoperiod. In one regime the lights turned on and off in phase with local sunrise and sunset; in the other, the daily photoperiod was kept 6 months out of phase with ambient photo- period. When dissected after being maintained for 18 months, the gametogenic condition of the out-of-phase animals was found to be 6 months out of phase with that of the in-phase animals. This experiment demonstrates that photoperiodic regulation of reproduction is important even in marine animals that normally experience marked seasonal changes in sea temperature.     

Dynamic properties of the advertisement calls of gray tree frogs: patterns of variability and female choice

We assessed the potential for several acoustic properties ofthe advertisement calls of male gray tree frogs to affect relativemating success by relating patterns of variation in these propertiesto minimum differences required to elicit female choice. Dynamicproperties (pulse number, PN; call rate, CR; and duty cycle,DC, the ratio of call duration to call period) varied much morewithin bouts of calling than a static property (dominant frequency,DF) but nevertheless exhibited significant between male variationin three of four breeding seasons. Many multiply recorded malesconsistently produced calls with values substantially aboveor below mean values of males recorded on the same nights. Nightlyranges of variation in PN and CR were often greater than theminimum differences required to elicit female preferences inthe laboratory. In most experiments, females chose high-PN orfast-CR calls over low-PN or slow-CR alternatives, respectively,even if the preferred stimuli were farther away or 6-10 dB lowerin sound pressure level (SPL), provided that differences inPN or CR were 100%. Consistent with these results, females didnot always choose the closer of two calling males in the field.Nightly ranges of variation in DF rarely equaled the minimumdifference required to elicit SPL independent preferences. Femalespreferred a stimulus of high-PN and slow-CR over an alternativeof low-PN or fast-CR with the same acoustic on-time; in twoexperiments, females chose calls of high-PN over low-PN alternativeseven though the playback of the high-PN call was interruptedand the low-PN call was broadcast continuously. Thus, femalepreferences were not merely based on the total time of acousticstimulation. Responses of females tested twice in the same experimentsuggest that phenotypic variation in preference was limitedin our study populations.     

Experimental evidence that brighter males sire more extra‐pair young in tree swallows

Across taxa, extra‐pair mating is widespread among socially monogamous species, but few studies have identified male ornamental traits associated with extra‐pair mating success, and even fewer studies have experimentally manipulated male traits to determine whether they are related directly to paternity. As a consequence, there is little experimental evidence to support the widespread hypothesis that females choose more ornamented males as extra‐pair mates. Here, we conducted an experimental study of the relationship between male plumage colour and fertilization success in tree swallows (Tachycineta bicolor), which have one of the highest levels of extra‐pair mating in birds. In this study, we experimentally dulled the bright blue plumage on the back of males (with nontoxic ink markers) early in the breeding season prior to most mating. Compared with control males, dulled males sired fewer extra‐pair young, and, as a result, fewer young overall. Among untreated males, brighter blue males also sired more extra‐pair young, and in paired comparisons, extra‐pair sires had brighter blue plumage than the within‐pair male they cuckolded. These results, together with previous work on tree swallows, suggest that extra‐pair mating behaviour is driven by benefits to both males and females.     

What do men want? Re-examining whether men benefit from higher fertility than is optimal for women

Several empirical observations suggest that when women have more autonomy over their reproductive decisions, fertility is lower. Some evolutionary theorists have interpreted this as evidence for sexual conflicts of interest, arguing that higher fertility is more adaptive for men than women. We suggest the assumptions underlying these arguments are problematic: assuming that women suffer higher costs of reproduction than men neglects the (different) costs of reproduction for men; the assumption that men can repartner is often false. We use simple models to illustrate that (i) men or women can prefer longer interbirth intervals (IBIs), (ii) if men can only partner with wives sequentially they may favour shorter IBIs than women, but such a strategy would only be optimal for a few men who can repartner. This suggests that an evolved universal male preference for higher fertility than women prefer is implausible and is unlikely to fully account for the empirical data. This further implies that if women have more reproductive autonomy, populations should grow, not decline. More precise theoretical explanations with clearly stated assumptions, and data that better address both ultimate fitness consequences and proximate psychological motivations, are needed to understand under which conditions sexual conflict over reproductive timing should arise.     

Mate choice and the operational sex ratio: an experimental test with robotic crabs

The operational sex ratio (OSR: sexually active males: receptive females) predicts the intensity of competition for mates. It is less clear, however, under what circumstances, the OSR predicts the strength of sexual selection – that is, the extent to which variation in mating success is attributable to traits that increase the bearer's attractiveness and/or fighting ability. To establish causality, experiments that manipulate the OSR are required. Furthermore, if it is possible to control for any OSR‐dependent changes in the chosen sex (e.g. changes in male courtship), we can directly test whether the OSR affects the behaviour of the choosing sex (e.g. female choice decisions). We conducted female mate choice experiments in the field using robotic models of male fiddler crabs (Uca mjoebergi). We used a novel design with two females tested sequentially per trial. As in nature, the choice of the first female to mate therefore affected the mates available to the next female. In general, we detected significant sexual selection due to female choice for ‘males’ with larger claws. Importantly, the strength of sexual selection did not vary across five different OSR/density treatments. However, as the OSR decreased (hence the number of available males declined), females chose the ‘males’ with the largest claws available significantly more often than expected by chance. Possible reasons for this mismatch between the expected and observed effects of the OSR on the strength of sexual selection are discussed.