Sperm Supply Research Articles

Knowledge, Perception, and Acceptability of Vasectomy among Adult Males at University of Nigeria, Enugu Campus

Background: Vasectomy is a minimally invasive surgical procedure involving the severing of the vas deferens, effectively cutting off the supply of sperm to the semen so that the ejaculated semen is devoid of sperm cells. Howbeit, despite its high efficacy and minimal invasiveness, it remains underutilised in sub-Saharan Africa. Aim: This study assessed knowledge, perception, and acceptability of vasectomy among adult males at the University of Nigeria, Enugu Campus. Methods and Materials: A cross-sectional survey design was employed among 106 men attending St Mulumba Chaplaincy and Chapel of Redemption UNEC. A researcher-developed questionnaire was used to collect data, which was analysed using descriptive and inferential statistics with the aid of (SPSS) version 25 and Microsoft Excel. Results: The mean age and standard deviation of the respondents was 43.08±9.12. A greater percentage (n=70, 66%) had poor knowledge about vasectomy. The majority (n=74, 69.85%) had a negative perception of vasectomy. Only 1.9% (n=2) of the men have undergone vasectomy. Of those who have not had a vasectomy, only 6.7% (n=7) reported that they would consider it. The overall acceptability of vasectomy was 8.5% (n=9) and was not significantly associated with knowledge (p = .268). Conclusion: Overall, there was poor knowledge, negative perception, and low acceptability of vasectomy among the respondents. Although acceptability was not dependent on knowledge, there is still a need for healthcare workers to carry out educational programs, especially geared towards religious and cultural beliefs, engage community leaders, and train peer educators to improve the knowledge and acceptability of vasectomy among men. Keywords: Vasectomy, Acceptability, Adult men, Knowledge, Perception.

The Role of Retinoic Acid in Spermatogenesis and Its Application in Male Reproduction.

Spermatogenesis in mammalian testes is essential for male fertility, ensuring a continuous supply of mature sperm. The testicular microenvironment finely tunes this process, with retinoic acid, an active metabolite of vitamin A, serving a pivotal role. Retinoic acid is critical for various stages, including the differentiation of spermatogonia, meiosis in spermatogenic cells, and the production of mature spermatozoa. Vitamin A deficiency halts spermatogenesis, leading to the degeneration of numerous germ cells, a condition reversible with retinoic acid supplementation. Although retinoic acid can restore fertility in some males with reproductive disorders, it does not work universally. Furthermore, high doses may adversely affect reproduction. The inconsistent outcomes of retinoid treatments in addressing infertility are linked to the incomplete understanding of the molecular mechanisms through which retinoid signaling governs spermatogenesis. In addition to the treatment of male reproductive disorders, the role of retinoic acid in spermatogenesis also provides new ideas for the development of male non-hormone contraceptives. This paper will explore three facets: the synthesis and breakdown of retinoic acid in the testes, its role in spermatogenesis, and its application in male reproduction. Our discussion aims to provide a comprehensive reference for studying the regulatory effects of retinoic acid signaling on spermatogenesis and offer insights into its use in treating male reproductive issues.

Age‐related changes in male ant sperm quality

AbstractSperm cells age during storage in the male reproductive organs, which can lead ejaculate quality to decline dramatically over time. Such may pose a particular concern in species with constrained sperm supplies, where adult males cannot replenish their sperm reserves. In eusocial hymenopterans (i.e. ants, bees and wasps with permanent castes), males typically reach adulthood with a limited quantity of sperm, and their testes deteriorate shortly thereafter. In adult life, both sexes mate during a single reproductive event. While males die quickly after copulation, they persist posthumously via sperm stored in their mates' spermatheca, sometimes for decades. As a result of this mating system, males should experience intense selection pressure to produce and transfer high‐quality sperm. Using the black garden ant (Lasius niger) as a model system, we investigated whether the duration of storage in the accessory testes before copulation affected sperm quality. We found that there was no impact of male age on sperm number or viability and that sperm DNA fragmentation decreased rather that increased with age. These results highlight the extent to which male ants, and possibly other taxa with constrained sperm supplies, have evolved extremely specialized strategies to ensure reproductive performance.

Oxidative stress and DNA fragmentation in frozen/thawed common Carp Cyprinus carpio sperm with and without supplemental proteins

Using cryopreservation techniques can increase the effectiveness of reproducing cultured fish species by ensuring a dependable supply of sperm, although the quality of the sperm could be impacted by the procedures involved. The goal of this study was to investigate the effect of purified seminal plasma transferrin (Tf), bovine serum albumin (BSA), and antifreeze protein (AFP) types I and III at 1 µg mL−1 on relevant characteristics of cryopreserved sperm from common carp Cyprinus carpio. We compared oxidative stress indices, antioxidant activity, and DNA fragmentation of fresh sperm to that frozen with extender only or with Tf, BSA, or AFP types I and III. Fresh sperm had significantly lower levels of thiobarbituric acid reactive substances (TBARS) compared to samples that underwent cryopreservation without protein treatment, which resulted in 0.54 ± 0.06 nmol/108 cells of TBARS. Carbonyl derivatives of proteins (CP) decreased significantly (ANOVA; P > 0.05) in carp sperm with addition of Tf, AFPI, and AFPIII. Significant differences in superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) activity were seen in sperm supplemented with Tf, BSA, AFPI, and AFPIII from those without. Significantly less DNA damage, expressed as percent tail DNA (11.56 ± 1.34) and olive tail moment (0.59 ± 0.13), was recorded in samples cryopreserved with Tf. The findings indicated that addition of Tf, BSA, AFPI, or AFPIII to cryopreservation medium is beneficial to sperm preservation. The mechanisms through which these proteins act positively on sperm need to be further investigated.

Aging and sperm signals alter DNA break formation and repair in the C. elegans germline.

Female reproductive aging is associated with decreased oocyte quality and fertility. The nematode Caenorhabditis elegans is a powerful system for understanding the biology of aging and exhibits age-related reproductive defects that are analogous to those observed in many mammals, including dysregulation of DNA repair. C. elegans germline function is influenced simultaneously by both reproductive aging and signals triggered by limited supplies of sperm, which are depleted over chronological time. To delineate the causes of DNA repair defects in aged C. elegans germlines, we assessed both DNA double strand break (DSB) induction and repair during meiotic prophase I progression in aged germlines which were depleted of self-sperm, mated, or never exposed to sperm. We find that germline DSB induction is dramatically reduced only in hermaphrodites which have exhausted their endogenous sperm, suggesting that a signal due specifically to sperm depletion downregulates DSB formation. We also find that DSB repair is delayed in aged germlines regardless of whether hermaphrodites had either a reduction in sperm supply or an inability to endogenously produce sperm. These results demonstrate that in contrast to DSB induction, DSB repair defects are a feature of C. elegans reproductive aging independent of sperm presence. Finally, we demonstrate that the E2 ubiquitin-conjugating enzyme variant UEV-2 is required for efficient DSB repair specifically in young germlines, implicating UEV-2 in the regulation of DNA repair during reproductive aging. In summary, our study demonstrates that DNA repair defects are a feature of C. elegans reproductive aging and uncovers parallel mechanisms regulating efficient DSB formation in the germline.

Sperm Limitation Produces Male Biased Offspring Sex Ratios in the Wasp, Nasonia vitripennis (Hymenoptera: Pteromalidae)

Haplo-diploid sex determination in the parasitoid wasp, Nasonia vitripennis (Walker), allows females to adjust their brood sex ratios. Females influence whether ova are fertilized, producing diploid females, or remain unfertilized, producing haploid males. Females appear to adjust their brood sex ratios to minimize ‘local mate competition,’ i.e., competition among sons for mates. Because mating occurs between siblings, females may optimize mating opportunities for their offspring by producing only enough sons to inseminate daughters when ovipositing alone, and producing more sons when superparasitism is likely. Although widely accepted, this hypothesis makes no assumptions about gamete limitation in either sex. Because sperm are used to produce daughters, repeated oviposition could reduce sperm supplies, causing females to produce more sons. In contrast, if egg-limited females produce smaller broods, they might use fewer sperm, making sperm limitation less likely. To investigate whether repeated oviposition and female fertility influence gamete limitation within females, we created two treatments of six mated female wasps, which each received a series of six hosts at intervals of 24 or 48 h. All females produced at least one mixed-sex brood (63 total broods; 3,696 offspring). As expected, if females became sperm-limited, in both treatments, brood sex ratios became increasingly male-biased with increasing host number. Interhost interval did not affect brood size, total offspring number, or sex ratio, indicating females did not become egg limited. Our results support earlier studies showing sperm depletion affects sex allocation in N. vitripennis¸ and could limit adaptive sex ratio manipulation in these parasitoid wasps.

The Protective Role of Melatonin in Sperm Cryopreservation of Farm Animals and Human: Lessons for Male Fish Cryopreservation.

Simple SummaryIn recent years, cryopreservation of fish sperm has been a rapidly evolving technique that contributes both to the improvement of genetic reproduction programs and the proper management of broodstock as well as to ensuring the viability of endangered species. However, this technique can cause significant damage to sperm, making the use of cryoprotectants and antioxidants in cryopreservation solutions imperative. The hormone melatonin has demonstrated positive effects on the cryopreservation of sperm in both farm animals and humans. Therefore, the plethora of research that has been conducted on animals and humans could be expanded to fish cryopreservation, making melatonin potentially a very promising alternative cryoprotectant.Cryopreservation is a technique that offers various advantages, especially in fish, among others, that makes the reproduction of species easier through a constant supply of sperm, synchronization of the gamete availability of both sexes, storage of semen for genetic improvement programs, reduction in the cost by eliminating the need to maintain male broodstock, and conserving the gametes of endangered species. However, freezing and warming procedures for cryopreservation lead to a reduction in the quality and viability of cryopreserved sperm because of oxidative stress. For this reason, the enrichment of extender media with antioxidants is a common method of cryopreservation of the semen of several fish species. Recently, many studies have been published for the protective role of antioxidants and especially of melatonin on male fertility preservation both in farm animals and humans, demonstrating the beneficial effects of melatonin as a sperm cryoprotectant. On the other hand, very few studies were conducted using melatonin as an antioxidant in different male fish species for semen cryopreservation. We conclude that the use of moderate concentrations of melatonin are beneficial to semen preservation, and the mechanisms through which melatonin acts positively on spermatozoa need to be further investigated to establish improvement protocols for cryopreservation in fish species.

The reproductive system of Ceracis cornifer (Mellié) and first description of sperm structure in a minute tree-fungus beetle (Tenebrionoidea: Ciidae)

Studies on the spermatogenesis of Tenebrionidae beetles (Tenebrionoidea) have shown an unusual organization of spermatozoa, in which they are arranged antiparallelly within the testicular cysts. Despite such works, many taxa of Tenebrionoidea remain to be studied, including the minute tree-fungus beetles (Ciidae). Among the challenges in the study of the internal morphology of ciids is their small body size (about 2 mm or less), which makes dissections and comparisons extremely arduous. Here, we provide, for the first time, an anatomical and histological study of the reproductive system (female and male) and a description of sperm structure of Ceracis cornifer Mellié (Ciidae), under light and transmission electron microscopes. We pointed out the growth of a single oocyte at a time in females, aside of evidences toward a constant copulatory activity that can provide a continuous supply of sperm in their small spermatheca. In males, sperm have an antiparallel organization within the cysts, a condition observed so far only in members of Tenebrionoidea. Furthermore, we observed sperm dimorphism in C. cornifer. We described, for the first time, this characteristic in a Tenebrionoidea taxon, and discussed the possible relationship between sperm dimorphism and antiparallel organization of sperm.

Non-programmable cryopreservation of sperm from industrial-farmed Murray cod (Maccullochella p peelii)

The high price of larvae is a major constraint for the expansion of Murray cod (Maccullochella p peelii) aquaculture. Sperm cryopreservation creates a ready supply of sperm for the production of larvae, reduces the number of males required by hatcheries and contributes to preserving desirable genetic traits for breeding programmes. For hatchery application, there is a requirement for easy-to-implement cryopreservation protocols. Important factors for the development of a practical non-programmable sperm cryopreservation method for industrial-farmed Murray cod were evaluated. The results showed that Murray cod sperm can be successfully cryopreserved using dimethyl sulfoxide (Me2SO), propylene glycol (PG) and methanol (MeOH) as cryoprotectant additives (CPAs). In 0.5 mL straws, 10% PG proved to be the most effective CPA (post-thaw motility 75 ± 7%), followed by 10% MeOH (62 ± 7%). At the same time, in 2 mL cryovials, 10% PG was significantly more effective than 10% MeOH at three chosen heights (P<0.05). In 0.5 mL straws, cooling rates of 11–22 °C/min from 20 °C to −5 °C provided better results than cooling rates of 4–6 °C/min in 2 mL cryovials. Post-thaw motility was greater, regardless of CPA, without a 5.0 min equilibration period (Me2SO, from 8 to 34%; PG, from 25 to 75%; MeOH, from 19 to 62%). Toxicity tests indicated a marked loss of sperm motility following dilution with cryoprotectants; MeOH was less toxic than Me2SO and PG and the toxicity of either Me2SO or PG increased according to exposure duration. Therefore, the results suggest that on-site non-programmable sperm cryopreservation with 10% PG is effective and efficient for industrial-farmed Murray cod, yielding an acceptable percentage of post-thaw motile sperm. However, minimising equilibration time before cooling and maintaining cooling rates of ~11 °C/min between 20 °C and − 5 °C may be crucial for reducing CPA-associated toxicity. Further research is required in order to confirm that the recovered sperm motilities which are shown in this study translate into fertility during the process of in vitro fertilisation.

A unique reproductive strategy in the mushroom coral Fungia fungites

The vast majority of scleractinian corals are either simultaneous hermaphrodites or gonochoric. Exceptions to these are rare. Nevertheless, species belonging to the family Fungiidae are known to exhibit a wide variety of reproductive strategies. We examined the reproductive ecology of the mushroom coral Fungia fungites in Okinawa. Our study was conducted as part of a long-term, wide-ranging project (2009–2010 and 2013–2017) which explored the unique reproductive strategies of several species belonging to the family Fungiidae. Here we report the co-occurrence of males, females, and hermaphrodite individuals in a long-term monitored population of the reproductively atypical brooder coral F. fungites within the family Fungiidae. F. fungites status as a single-polyped solitary coral, was used to perform manipulative experiments to determine the degree of dependence of an individual coral on its conspecific neighbors for reproduction, and examined whether a constant sperm supply is obligatory for the continuous production of planulae. Isolated females of F. fungites exhibited a distinctive reproductive strategy, expressed in continuously releasing planulae also in the absence of males. Observations conducted on a daily basis for 2.5 months (throughout the reproductive season of 2015) revealed that some of these individuals released planulae continuously, often between tens and hundreds every day. In an effort to explain this phenomenon, three hypotheses are discussed: (1) Self-fertilization; (2) Asexual production of planulae (i.e., parthenogenetic larvae); and (3) Extended storage of sperm. Finally, we emphasize the importance of continuous and long-term monitoring of studies of coral reproduction; through further genetic studies of coral populations representing a broad range of species and their larval origin.

A perfect storm of intervention? Lesbian and cisgender queer women conceiving through Australian fertility clinics

ABSTRACT Amendments to various state laws have made it easier for cisgendered lesbian, bisexual and queer (LBQ) women to access Australian fertility clinics. When women conceive through clinics, they generally use intrauterine insemination (IUI) or in vitro fertilisation (IVF). IUI is cheaper and requires less invasive medical intervention than IVF. A recent survey found that almost 60% of Australian cisgendered LBQ women who conceived with clinical assistance did so using IVF, despite most presenting to clinics without a diagnosis of infertility and seeking donor sperm only. In this paper, based on 20 interviews with Australian clinicians who treat LBQ patients seeking pregnancy, we explore potential explanations for why over half of LBQ women using Australian fertility clinics to conceive used IVF rather than IUI. A ‘perfect storm’ of factors appears to converge in this tendency. Although some LBQ women are purposefully choosing IVF to achieve biological relatedness for two mothers, other pressures toward high intervention conceptions include the distinction between ‘social’ and ‘clinical’ infertility by Medicare (the Australian national health insurance scheme), the relative profitability of IVF procedures and issues with the supply and quality of donor sperm. Accessing sperm from clinics appears to set some Australian women without male partners on a potentially unnecessary path to a high intervention and costly conception.

A novel method of quantifying sperm to determine the potential for sperm depletion in male American lobstersHomarus americanus(H. Milne Edwards, 1837) (Decapoda: Astacidea: Nephropidae)

AbstractSperm limitation is a concern for a number of heavily fished decapods; however, work to assess this concern is sometimes hampered by a lack of simple techniques to quantify sperm transferred during reproduction. Our primary goal was to determine if DNA measurements could be used to quantify the sperm content of spermatophores and thus facilitate investigations of sperm limitation in American lobsters (Homarus americanus H. Milne Edwards, 1837). This was achieved by measuring the amount of DNA in a sample and then calibrating those values by using flow cytometry to count the number of individual sperm present in the sample. Our results show that the DNA quantification technique provides a fast and accurate way to quantify sperm. We then demonstrated the utility of the method by using it to examine the rate at which males can produce sperm under simulated conditions of repeated mating events, a situation that might lead to a reduction in the number of sperm per spermatophore. While spermatophores obtained from male lobsters at three-day intervals varied substantially in the number of sperm they contained (range 427,090–5,028,996; mean 2,306,473), there was no clear decline in sperm count over time. These results suggest that male lobsters replenish their sperm supplies rapidly, and that sperm recharge rate is unlikely to be a factor that could lead to sperm limitation in American lobster populations.

Be prudent if it fits you well: male mate choice depends on male size in a golden orb-weaver spider

Male preference for high-quality females is expected to evolve when male reproductive potential is restricted. However, when there is competition among males, some models predict the evolution of assortative male mate choice, in which good competitors choose high-quality females while poor competitors choose lower quality females to avoid competition. In Trichonephila clavipes spiders, males have limited sperm supply and fight for access to females. We tested whether female quality and male size (a proxy of fighting ability) influence male decisions in T. clavipes. We used field experiments in which males could choose between two available females in a scenario free of competition. We found that males choose their mates based on both female size and female recent pairing status (whether the female was accompanied by a male before the experiment). Importantly, male mate choice was plastic, and varied with male size, as large males preferred larger females that were recently unpaired, medium-sized males showed no preference and small males preferred smaller, recently paired females. Because all females appear to attract males, we predict that variation in male mate choice attenuates sexual selection on females. Our findings confirm the prediction of variable male mate choice when there is male–male competition and male reproductive potential is restricted, a pattern that may be common, but hard to detect.

Male performance and associated costs in successive sexual encounters in a polygynous web wolf spider

Polygynous males increase their reproductive success by fertilizing as many females as possible. However, this strategy can lead to costs for the males. This study focused on an atypical wolf spider that lives in webs, Aglaoctenus lagotis. Previous studies report polyandrous females, but little is known about the mating strategy of males and its potential associated costs. Our goals were to determine the potential polygyny and the changes in sexual behaviour, body condition and physiology of males throughout successive matings. Males were expected to mate with multiple females; males’ body condition was expected to decrease and male mating performance, including sperm transfer, was expected to decrease over successive matings. Males were exposed to successive virgin females every 3 days until the male did not court, was cannibalized or died of natural causes. Agreeing with our predictions, males were capable of multiple matings, showing an average of 5 ± 2 matings (range 3–11). Their mating performance decreased in successive matings and, although no changes were found in the behavioural patterns during the courtship over successive matings, the number of palpal insertions decreased. Unexpectedly, overall body condition did not decrease and males did not deplete their sperm supply. We found that 44% of the males were victims of sexual cannibalism after their third mating. The females that attacked or cannibalized males had less sperm stored in their spermathecae than those that did not. We discuss hypotheses that may clarify this scenario and the role of the cryptic female choice mechanism.

Egg production in relation to paternal weight in a freshwater caridean shrimp (Decapoda)

AbstractIn diverse invertebrate species, sperm quantity and quality are positively correlated with male size, egg fertilization rates being consequently affected by paternal weight. This factor may also have an indirect effect on egg quality, because females could adjust the quantity of yolk stored in oocytes before spawning according to their partner attractiveness. The objective of this study was to determine whether paternal weight influences egg production in a freshwater crustacean with external egg fertilization, the caridean shrimp Neocaridina davidi. Virgin females weighing 60–100 mg were paired with virgin males weighing 20–50 mg. The number (total and fertilized), size (volume, wet and dry weight) and carotenoid content of eggs were recorded for each pair. Paternal weight was not associated to any of the evaluated egg variables, while maternal weight showed a positive correlation with egg number and a negative correlation with egg carotenoid content. The percentage of fertilized eggs was similar and near 100% for all paternal sizes, which indicates that small mature males provided enough good‐quality sperm to fertilize almost all the oocytes laid by females, similarly to larger males. The relatively low fecundity of N. davidi females may explain, at least in part, the absence of sperm limitation even under a hypothetical decrease in sperm supply by smaller males. In addition, paternal weight had no effect on egg volume, weight and carotenoid content, which suggests that females do not modulate the total amount of biochemical reserves allocated to the maturing ovary as a function of their partner size. Present results are the starting point for a future evaluation of sperm production, in terms of quantity and quality, in males of different size and physiological condition.

Sperm-limited males continue to mate, but females cannot detect the male state in a parasitoid wasp

Female mating frequency and male ejaculate allocation are likely to interact. Females may adjust their propensity for remating based on the amount of provided sperm to ensure a sufficient sperm supply, and males may determine sperm allocation based on female availability and female mating frequency. In this study, I investigated male and female mating behaviors in the parasitoid wasp Anisopteromalus calandrae. The wasp exhibits the haplo-diploid sex determination, in which sperm-depleted females are constrained to produce only sons by laying unfertilized eggs. The first experiment showed that a rapid succession of male mating decreased the production of daughters (fertilized eggs) by the inseminated females, suggesting that sperm-limited males provided an insufficient amount of sperm to the females. Although the males appeared to replenish their sperm store after 6 h, they mated upon encountering females despite their sperm shortage. The second experiment showed that copulation reduced the subsequent mating receptivity of the inseminated females irrespective of whether the females received a sufficient amount of sperm. Moreover, although approximately 26% of females accepted a second mating and recovered a certain degree of daughter production, remating was independent of the mating status of their first mating partner or the social environment. These results suggest that sperm-limited males may benefit from continuing to mate because their copulation prevents competing males from reproducing with their mates. Females incur a cost from not remating depending on the amount of sperm provided, which may result from weak environmental selection pressure or manipulation by the initial mate.Significance statementMale and female mating strategies are likely to evolve interdependently. Specifically, in species that produce limited numbers of sperm, the mating behavior of males and females is likely to be influenced by sperm transfer. The results of the present study suggest that males of the parasitoid wasp Anisopteromalus calandrae can replenish their sperm stores over time. However, sperm-limited males that encounter a potential mating partner mate rather than wait for sperm recovery. Females do not discriminate the male state before copulation, and those that mate with sperm-limited males suffer from sperm shortage. Although females can augment their sperm supply by remating, only a portion of females do so, regardless of sperm supply. The lack of a female facultative response suggests weak environmental selection on the species or the existence of sexual conflict over sperm transfer.

The effects of male age, sperm age and mating history on ejaculate senescence

Abstract In polyandrous species, a male’s reproductive success depends on his ability to fertilize females, which, in turn, depends on his mating ability and his ability to produce competitive ejaculates. In many species, sperm traits differ between old and young males in ways that are likely to decrease the sperm competitiveness and fertility of older males. This age–ejaculate quality relationship is attributed to male ageing (i.e., senescence). In a natural setting, male age and mating history are usually confounded: older males have usually mated and replenished their sperm supplies more often, so they have made a greater lifetime reproductive effort. In principle, the costs of reproduction, independent of any causal effect of male age, could generate an age‐related decline in ejaculate quality. To date, only a handful of studies have determined how male age, reproductive effort or their interaction affect ejaculate quality. Here, we experimentally manipulated the long‐term mating history of 209 adult male mosquitofish (Gambusia holbrooki) over 14 weeks (N = 1,118 sperm samples). Males either had direct access to females and could mate freely, or had only visual and olfactory access to females. We documented the effect of mating history, adult male age (3, 9 and 14 weeks post‐maturation) and their interaction on sperm velocity, sperm reserves and the rate of sperm replenishment. For sperm velocity, we additionally examined the effects of sperm age, because when older males mate less (or more) often than younger males there will be a correlation between mean sperm age and male age. Sexually active males produced fewer sperm and replenished their sperm at a lower rate, and their sperm had lower velocity than males prevented from mating. Though older males produced more sperm, the rate of replenishment and velocity of their sperm was lower than the sperm of younger males. We also tested for a difference in the velocity of recently replenished (&lt;24 hr) and older sperm (i.e., post‐meiotic sperm senescence). There was no evidence that male age or mating history affects the extent of sperm senescence, but older sperm swam faster than recently produced sperm. Crucially, complex interactions are evident between male age and male mating history with respect to sperm number and the proportion of sperm that are replenished. These results suggest that male age and mating history will interact to determine the reproductive success of a male under sperm competition. They reveal a complex relationship between a male’s age and his ejaculate quality. We suggest that both mating history and sperm age should be controlled for when measuring the intrinsic rate of senescence for male reproductive traits if the goal is to isolate effects that are solely attributable to a male’s chronological age. A plain language summary is available for this article.

Methuselah's daughters: Paternal age has little effect on offspring number and quality in Cardiocondyla ants.

Male age may directly or indirectly affect the fitness of their female mating partners and their joint progeny. While in some taxa of insects, old males make better mates and fathers, young males excel in others. Males of most social Hymenoptera are relatively short lived and because of testis degeneration have only a limited sperm supply. In contrast, the wingless fighter males of the ant Cardiocondyla obscurior live for several weeks and produce sperm throughout their lives. Wingless males engage in lethal combat with rival males and the winner of such fights can monopolize mating with all female sexuals that emerge in their nests over a prolonged timespan. Here, we investigate if male age has an influence on sperm quality, the queen's lifespan and productivity, and the size and weight of their offspring. Queens mated to one‐week or six‐week‐old males did not differ in life expectancy and offspring production, but the daughters of young males were slightly heavier than those of old males. Our data suggest negligible reproductive senescence of C. obscurior males even at an age, which only few of them reach. This matches the reproductive strategy of Cardiocondyla ants, in which freshly emerging female sexuals rarely have the option to mate with males other than the one present in their natal nest.

Перспективи збереження лебединської породи

В статті вивчений сучасний стан племінних стад лебединської породи, її кількісний та якісний склад. Досліджено генеалогічна структура племінних стад. Встановлено, що значна частина маточного поголів’я корів племінних стад лебединської породи одержана від імпорттованих плідників або спермопродукції бугаїв швіцької породи зарубіжної селекції. Рівень молочної продуктивності корів лебединської породи знаходиться в межах 3000 – 7000 кг молока. Проаналізована наявність спермопродукції бугаїв-плідників лебединської породи. Встановлено, що в банках генетичних ресурсів та селекційних центрах створено достатній запас сперми плідників у глибоко охолодженому стані. В чотирьох підприємствах зберігається сперма більше 15 бугаїв-плідників лебединської породи та їх помісей з швіцькою породою. Авторами розроблені перспективні заходи щодо збереження популяції лебединської породи.

Individual- and ejaculate-specific sperm traits in ant males

Sperm cells are the most morphologically diverse cells across animal taxa. Within species, sperm and ejaculate traits have been suggested to vary with the male’s competitive environment, e.g., level of sperm competition, female mating status and quality, and also with male age, body mass, physiological condition, and resource availability. Most previous studies have based their conclusions on the analysis of only one or a few ejaculates per male without investigating differences among the ejaculates of the same individual. This masks potential ejaculate-specific traits. Here, we provide data on the length, quantity, and viability of sperm ejaculated by wingless males of the ant Cardiocondyla obscurior. Males of this ant species are relatively long-lived and can mate with large numbers of female sexuals throughout their lives. We analyzed all ejaculates across the individuals’ lifespan and manipulated the availability of mating partners. Our study shows that both the number and size of sperm cells transferred during copulations differ among individuals and also among ejaculates of the same male. Sperm quality does not decrease with male age, but the variation in sperm number between ejaculates indicates that males need considerable time to replenish their sperm supplies. Producing many ejaculates in a short time appears to be traded-off against male longevity rather than sperm quality.