Female Sperm Research Articles

On the relative effect of spawning asynchrony, sperm quantity, and sperm quality on paternity under sperm competition in an external fertilizer

How much of a fitness benefit is obtained by dominant males of external fertilizers from releasing ejaculates in synchrony with female egg-release when engaging in sperm competition, and what is the most important sperm trait for paternity in these situations? The Arctic charr (Salvelinus alpinus) is an external fertilizer experiencing intense male-male competition over reproductive opportunities including sperm competition. To compensate for their disadvantage the sneaker males, which often spawn out of synchrony with the female, produce more and faster sperm than the guarding males. We used controlled in vitro fertilization trials with experimentally produced dominant and subordinate, sneaker males to test what effect relative synchrony in gamete release, sperm quality (i.e., motility and velocity) and sperm quantity have on a male’s fertilization success in pair-wise sperm competitions. When the sneaker males released ejaculates after the guarding male there was no overall difference in fertilization success. The quality (i.e., motility and velocity) of a male’s sperm relative to that of the competing male was the best predictor of male fertilization success regardless of their mating tactic and spawning synchrony. The relative number of sperm cells also had an effect on fertilization success, but mainly when the dominant and sneaker male ejaculated synchronously. Our close imitation of natural sperm competition in charr shows that the sneaker males of external fertilizing species may fully compensate for their disadvantaged mating role by producing ejaculates of higher quality - an adjustment strangely not met by dominants.

Sperm whales (Physeter macrocephalus), found stranded along the Adriatic coast (Southern Italy, Mediterranean Sea), as bioindicators of essential and non-essential trace elements in the environment

In September 2014, a pod of seven sperm whales (Physeter macrocephalus) was stranded along the Adriatic coast of Southern Italy. Concentrations of 20 essential and non-essential trace elements were quantified in the brain, muscle, liver and kidneys of three female sperm whales, which died in this event.The essential elements copper, iron, manganese and zinc showed low ranges of variability, suggesting a homeostatic physiological control, while selenium concentrations were associated with age. Molybdenum, nickel and chromium showed low ranges of concentrations and no evidence of preferential accumulation in selected organs. Very low concentrations of the non-essential elements cadmium, lead, tin and vanadium were detected in all tissues, suggesting a minor impact of these pollutants on the sperm whale populations of the Mediterranean Sea. Aluminum was revealed to have relatively high concentrations, together with a high variability between tissues and individuals, reaching the highest values in the kidneys and muscle of the oldest female, which was pregnant; the rare earth elements – lanthanum and cerium – were also detected in the kidneys of this female, indicating that pregnancy probably influenced metal concentrations in body tissues.

Maxillary teeth in sperm whales, Physeter macrocephalus (Cetacea: Physeteridae)

AbstractSperm whales, Physeter macrocephalus Linnaeus, 1758, have 18 to 28 pairs of well developed conical mandibular teeth, but maxillary teeth are vestigial and supposedly rare. The aim of this study is to report a new case of erupted maxillary teeth in P. macrocephalus, the first description for Brazil. On 29 October 2008 a female sperm whale was found stranded in Campina's Beach (06° 46' S, 34° 55' W), Paraíba state, northeastern Brazil. Inspection on the gums revealed three upper teeth on the right maxilla, corresponded to mandibular teeth 9 to 11 in a rostrocaudal sequence. The maxillary teeth were nearly straight, strongly worn in the tip and had no pulp cavity remaining. Most literature states that maxillary teeth are absent or rarely present, somewhat questionable, since other authors never failed to expose them by an incision in the gum. Data show that upper teeth have been overlooked, and its real frequency can only be determined by thorough dissections. This is important, since the study of maxillary teeth can provide information about evolution, functional morphology and age determination in sperm whales.

Male burying beetles extend, not reduce, parental care duration when reproductive competition is high.

Male parents spend less time caring than females in many species with biparental care. The traditional explanation for this pattern is that males have lower confidence of parentage, so they desert earlier in favour of pursuing other mating opportunities. However, one recent alternative hypothesis is that prolonged male parental care might also evolve if staying to care actively improves paternity. If this is the case, an increase in reproductive competition should be associated with increased paternal care. To test this prediction, we manipulated the level of reproductive competition experienced by burying beetles, Nicrophorus vespilloides (Herbst, 1783). We found that caregiving males stayed for longer and mated more frequently with their partner when reproductive competition was greater. Reproductive productivity did not increase when males extended care. Our findings provide support for the increased paternity hypothesis. Extended duration of parental care may be a male tactic both protecting investment (in the current brood) and maximizing paternity (in subsequent brood(s) via female stored sperm) even if this fails to maximize current reproductive productivity and creates conflict of interest with their mate via costs associated with increased mating frequency.

COHABITACIÓN SEXUAL Y RIESGO DE PREECLAMPSIA

Objetivo: Determinar si existe asociación entre el número de contactos sexuales en los cuales ocurre libre depósito de semen en el tracto genital femenino antes de la concepción y la presentación o no de la preeclampsia en el embarazo subsecuente. MATERIAL Y MÉTODO: Estudio caso-control en el Hospital General Nacional Arzobispo Loayza. Se estudió 85 preeclámpticas y 85 controles no preeclámpticas mediante entrevista directa. Para los cálculos estadísticos se utilizó los programas SPSS for MS Windows Release 6,1 y Epi Info 6. RESULTADOS. Se encontró 23 veces más riesgo de hacer preeclampsia en gestantes que tuvieron menos de 6 relaciones sexuales sin métodos anticonceptivos de barrera (exposiciones) y riesgo mínimo por debajo de las 6,3 exposiciones (1) < 0, 0001). El riesgo fue 3 veces mayor cuando se tuvo menos de 18 meses de cohabitación sexual (p < 0,00247). El riesgo de, presentar preeclampsia severa fue mayor conforme el menor el número de exposiciones. CONCLUSIÓN. El uso de métodos anticonceptivos de barrera, los cuales limitan la exposición del tracto genital femenino a los antígeno presentes en el semen del esposo, así como un tiempo de cohabitación sexual corto anterior a lo concepción, serian factores de riesgo para el desarrollo de preeclampsia y seueridad de la misma, en mujeres posteriormente embarazadas.

Patterns of Sperm Transfer in the Golden Orb‐Weaver Nephila edulis

AbstractSperm competition studies typically identify copulation duration as an important predictor of paternity as it may determine the quantity of sperm transferred and thus paternity success. This study explores the relationship between copulation duration, male body size, male age and sperm transfer in the golden orb‐weaving spider, Nephila edulis. Paternity in this species is strongly associated with the relative frequency and duration of copulation, which is also influenced by male size. We determined the number of sperm transferred during copulation, by performing sperm counts in both the male copulatory organs (palps) and female sperm receptacle (spermatheca) of recently mated pairs. The total number of sperm recorded (the sum in the male palps and female spermathecae) was greater for younger males than older males, but did not vary with male body size. In general, younger males transferred more sperm and a greater proportion of their sperm supplies than older males and, among these younger males, larger individuals transferred more sperm. However, there were no significant size effects for older males. More sperm was transferred with longer copulations, but in contrast with previous studies, we found that larger males copulated for longer. The rate of sperm transferred was negatively correlated with the duration of copulation, suggesting that the variation in copulation duration in N. edulis may represent strategic investment by males to alter patterns of paternity, in addition to transferring additional sperm.

Sperm Economy between Female Mating Frequency and Male Ejaculate Allocation

Why females of many species mate multiply is a major question in evolutionary biology. Furthermore, if females accept matings more than once, ejaculates from different males compete for fertilization (sperm competition), which confronts males with the decision of how to allocate their reproductive resources to each mating event. Although most existing models have examined either female mating frequency or male ejaculate allocation while assuming fixed levels of the opposite sex's strategies, these strategies are likely to coevolve. To investigate how the interaction of the two sexes' strategies is influenced by the level of sperm limitation in the population, we developed models in which females adjust their number of allowable matings and males allocate their ejaculate in each mating. Our model predicts that females mate only once or less than once at an even sex ratio or in an extremely female-biased condition, because of female resistance and sperm limitation in the population, respectively. However, in a moderately female-biased condition, males favor partitioning their reproductive budgets across many females, whereas females favor multiple matings to obtain sufficient sperm, which contradicts the predictions of most existing models. We discuss our model's predictions and relationships with the existing models and demonstrate applications for empirical findings.

Impact on Pregnancy of Gross and Microscopic Vasal Fluid during Vasectomy Reversal

We compared fertility outcomes with gross and microscopic fluid findings at vasectomy reversal at a high volume vasectomy reversal center. A retrospective study of a prospective database was performed. All vasectomy reversals were performed by a single surgeon (EFF) between 1978 and 2011. The clinical pregnancy rate was self-reported or determined via patient mailers. Patient and operative findings were determined through database review. We classified vasal fluid as opalescent, creamy, pasty or clear. Intraoperative light microscopy was used to determine if sperm or sperm parts were present and if they were motile. Multivariate analysis was performed evaluating patient age, partner age, years after vasectomy, type of surgery, and gross and microscopic fluid analysis. A total of 2,947 microsurgical vasectomy reversals were reviewed after we excluded reversals performed for post-vasectomy pain. We determined the pregnancy status of 902 (31%) cases. On univariate analysis with respect to pregnancy the presence of motile sperm at vasovasostomy neared statistical significance (p=0.075) and there was no difference between bilateral vs unilateral motile sperm. Gross fluid appearance was not statistically significant but we found the order of pregnancy success to be opalescent, creamy, clear then pasty fluid. On multivariate analysis only female partner age and sperm heads only or no sperm seen on light microscopy had statistical significance (p <0.05). The presence of motile sperm at vasectomy reversal approaches statistical significance on univariate analysis as a factor that affects clinical pregnancy rates. On multivariate analysis female partner age and microscopic findings of sperm heads only or no sperm are inversely related to pregnancy rates. These data will help counsel couples after vasectomy reversal and reinforce the importance of female partner age.

Timing associated with oviductal sperm storage and release after artificial insemination in domestic hens

Female birds store sperm in sperm storage tubules (SSTs) in the uterovaginal junction of their reproductive tract for days or weeks (depending on species) before fertilization. Sperm are transported from the SSTs to the infundibulum where fertilization occurs immediately after ovulation of each ovum. The timing of sperm release from the SSTs relative to ovulation is unknown for any bird. Here, we show that, after artificial insemination of domestic fowl Gallus domesticus, sperm are not accepted into any region of the oviduct before sexual maturity. Once hens reach maturity, there is a temporal shift in the distribution of sperm throughout the oviduct. Sperm are first accepted into and accumulate in the SSTs 6 to 8 days before ovulation but are at this point significantly less numerous in the infundibulum. From 1 to 6 days before ovulation, approximately 10-fold more sperm (235 × 103 sperm) populate the infundibulum than at 6 to 8 days before ovulation (26 × 103 sperm; P < 0.001). Our results suggest that the mechanisms underlying sperm acceptance and release in the oviduct are under fine temporal control, most likely mediated by female hormones.

Island survivors: population genetic structure and demography of the critically endangered giant lizard of La Gomera, Gallotia bravoana.

BackgroundThe giant lizard of La Gomera (Gallotia bravoana), is an endemic lacertid of this Canary Island that lives confined to a very restricted area of occupancy in a steep cliff, and is catalogued as Critically Endangered by IUCN. We present the first population genetic analysis of the wild population as well as of captive-born individuals (for which paternity data are available) from a recovery center. Current genetic variability, and inferred past demographic changes were determined in order to discern the relative contribution of natural versus human-mediated effects on the observed decline in population size.ResultsGenetic analyses indicate that the only known natural population of the species shows low genetic diversity and acts as a single evolutionary unit. Demographic analyses inferred a prolonged decline of the species for at least 230 generations. Depending on the assumed generation time, the onset of the decline was dated between 1200–13000 years ago. Pedigree analyses of captive individuals suggest that reproductive behavior of the giant lizard of La Gomera may include polyandry, multiple paternity and female long-term sperm retention.ConclusionsThe current low genetic diversity of G. bravoana is the result of a long-term gradual decline. Because generation time is unknown in this lizard and estimates had large credibility intervals, it is not possible to determine the relative contribution of humans in the collapse of the population. Shorter generation times would favor a stronger influence of human pressure whereas longer generation times would favor a climate-induced origin of the decline. In any case, our analyses show that the wild population has survived for a long period of time with low levels of genetic diversity and a small effective population size. Reproductive behavior may have acted as an important inbreeding avoidance mechanism allowing the species to elude extinction. Overall, our results suggest that the species retains its adaptive potential and could restore its ancient genetic diversity under favorable conditions. Therefore, management of the giant lizard of La Gomera should concentrate efforts on enhancing population growth rates through captive breeding of the species as well as on restoring the carrying capacity of its natural habitat.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-014-0121-8) contains supplementary material, which is available to authorized users.

Female sperm use and storage between fertilization events drive sperm competition and male ejaculate allocation

Sperm competition theory has traditionally focused on how male allocation responds to female promiscuity, when males compete to fertilize a single clutch of eggs. Here, we develop a model to ask how female sperm use and storage across consecutive reproductive events affect male ejaculate allocation and patterns of mating and paternity. In our model, sperm use (a single parameter under female control) is the main determinant of sperm competition, which alters the effect of female promiscuity on male success and, ultimately, male reproductive allocation. Our theory reproduces the general pattern predicted by existing theory that increased sperm competition favors increased allocation to ejaculates. However, our model predicts a negative correlation between male ejaculate allocation and female promiscuity, challenging the generality of a prevailing expectation of sperm competition theory. Early models assumed that the energetic costs of precopulatory competition and the level of sperm competition are both determined by female promiscuity, which leads to an assumed covariation between these two processes. By modeling precopulatory costs and sperm competition independently, our theoretical framework allows us to examine how male allocation should respond independently to variation in sperm competition and energetic trade-offs in mating systems that have been overlooked in the past.

Multiple paternity but no evidence of biased sperm use in female dumpling squid Euprymna tasmanica

Assessing the natural level of multiple paternity and sperm-use patterns provides important information regarding sperm competition and the potential for cryptic female mate choice. We developed 5 novel polymorphic microsatellites for the dumpling squid Euprymna tasmanica and used them to measure multiple paternity from both field- and laboratory-laid clutches. All clutches had multiple paternity, with a minimum of 2 to 4 sires per clutch, consistent with benefits to females of polyandry in this species, and indicating strong potential for sperm competition. We found a higher level of multiple paternity within field-laid eggs than in the first and second clutches from females that laid in the laboratory. The level of multiple paternity did not change over successive clutches from individual laboratory females and sperm from different males did not consistently dominate separate clutches, although individual females differed in patterns of sperm use. This suggests that spermatangia may be somewhat mixed within the female spermatheca at the time of fertilisation. Sperm competition is enhanced by high sperm longevity, and we found that viable sperm could be stored for up to 145 d in the laboratory. Overall, our results suggest strong potential for post-copulatory sexual selection in this species, due to the presence of sperm from multiple males in the female sperm storage organ competing for fertilisation of the female's eggs.

Characterization of rheotaxis of bull sperm using microfluidics.

We study rheotaxis of bull sperm inside microchannels to characterize the effects of flow and wall shape on sperm swimming behavior. We found that a large percentage of sperm cells, 80 to 84%, exhibited positive rheotaxis (sperm cells swimming against the flow) within flow velocities of 33 to 134 μm s(-1). Sperm cells were also found to reverse their swimming direction when the liquid flow direction was reversed. Time taken by sperm cells to reverse their swimming direction was inversely proportional to the flow velocity. Sperm behavior was significantly affected by the sperm position with respect to the channel wall. Sperm cells close to the channel wall moved upstream faster than sperm cells moving along the channel centerline. Shear stress, which is an indicator of velocity distribution, was found to play an important role in regulating rheotactic behavior of sperm cells. Side pockets were added to some microchannels to mimic storage sites in mucosal folds and pockets in the fallopian tube of the female reproductive system and sperm interaction with these pockets was monitored. We found that sperm cells tend to follow channel walls and enter these pockets without any chemical binding, which further confirms the wall tracking behavior of mammalian sperm cells. Our results confirm that sperm rheotaxis is a strong mechanism for guiding sperm cells towards the oocyte along the female genital tract.

Seminal receptacle of the pill box crab Limnopilos naiyanetri Chuang and Ng, 1991 (Brachyura: Hymenosomatidae)

We used an histological approach to describe the female sperm storage organ (seminal receptacle) of the freshwater crab Limnopilos naiyanetri Chuang and Ng, 1991. The crescent-shaped sclerotized ventral part of the vagina (towards the gonopore) with attached abductor muscles displays structures that are similar to thoracotreme crabs. The oviduct opens into the basal (ventral) part of the receptacle. We found a secondary, additional sperm storage organ (‘bursa’) between the sclerotized ventral and the un-sclerotized dorsal part of the vagina, a feature rarely found in other brachyurans. The bursa is lined with cuticle and lacks a glandular epithelium, but is filled with free spermatozoa. We hypothesize that muscles attached to the female genital ducts could allow females to selectively permit male ejaculates access to the seminal receptacle, or direct the ejaculate into the bursa (cryptic female choice). Sperm stored in the bursa is distant from the site of fertilization, i.e., the entrance point of the oviduct into the seminal receptacle, and so differential treatment of ejaculates could translate into differential male reproductive success.

Factors influencing paternity in multiply mated female red-sided garter snakes and the persistent use of sperm stored over winter

In some species, sperm is stored within the female reproductive tract for months to years, and yet remains viable to fertilize eggs and produce offspring. Female red-sided garter snakes store sperm for over 7 months of winter dormancy. In previous work, we demonstrated that these stored sperm account for an average of 25 % paternity of a litter when the female mates with a male at spring emergence. Here, we tested whether last-male sperm precedence was prevalent when a female mates with two males during the spring. On average, paternity was shared equally among the first (P1 proportion of paternity of the first male to mate) and second males (P2) to mate in the spring, and stored sperm (Pss), but the variance in paternity was high. Thus, last male sperm precedence may diminish when a female has more than two mates. Male size did not affect paternity, but, as the interval between matings increased, P1 increased at the expense of Pss. Interestingly, as the second spring male’s copulation duration increased, P1 also increased at the expense of P2. This result suggests that female influence over sperm and/or copulatory plug transfer during matings may also affect which male fathers her offspring in response to coercive matings as we assisted females to mate for their second mating. Finally, all females were spring “virgins”; consequently, sperm stored from autumn matings (and/or previous spring matings) remain competitive even when faced with two rivals in sperm competition and is likely the driver of the evolution of sperm longevity.

Mating and genital coupling in the primitive earwig species Echinosoma denticulatum (Pygidicranidae): implications for genital evolution in dermapteran phylogeny

Dermaptera (earwigs) shows much diversity in the genital structures, the presence of either one or two male intromittent organs (penes) being one striking aspect. The members of several groups (Karschiellidae, Eudermaptera, Arixeniina, and Hemimerina) possess a single functional penis, while others have a pair of penes. The latter condition is considered to be plesiomorphic in Dermaptera. Despite its importance for inferring the phylogeny of Dermaptera, it is presently unclear how the ancestor of earwigs acquired paired penes. To estimate the mode of mating and sperm transfer in the common ancestor of extant earwigs, this study examines the mating behavior and genital coupling of the primitive earwig species Echinosoma denticulatum Hincks, 1959 as a representative of Pygidicranidae, one of the basal-most assemblages of earwigs. Staged mating experiments, including surgical manipulation of male penes revealed the following characteristics for this species: (1) males use only one of the paired penes for a single genital coupling; (2) both penes are likely functional; (3) there are no consistent biases in usage of the penes; (4) laterality of the penis-use pattern is not related to the direction of rotation of the male abdomen to establish genital coupling; (5) sperm are transferred directly into the spermatheca, a female sperm storage organ; (6) the spined area of the penis inflicts wounds on the vagina around the spermathecal opening, which bears many setae, during copulation. Characteristics (1)–(4) are considered to be plesiomorphic and may represent the condition of the common ancestor. Traumatic penetration during copulation is reported for earwigs for the first time. Together with intermittent acceptance of courting males by females only after a certain interval, these results suggest sexual conflict over mating in this species.

Influence of male courtship intensity and male-male competition on paternity distribution in Hermann's tortoise,Testudo hermanni hermanni(Chelonia: Testudinidae)

Honest-advertisement models of sexual selection suggest that condition-dependent male secondary sexual characters could function as reliable signals of male quality, enabling females to discriminate among potential partners, both in the pre- and post-copulatory phases. In this context, many studies have revealed the importance of promiscuous mating systems and female sperm storage in determining the occurrence of such a model of sexual selection. By contrast, few studies have investigated the presence and extent of post-copulatory female choice in chelonian species. The present study aimed to investigate the effect of male size, male–male competition, and courtship intensity on paternity distribution in Testudo hermanni hermanni, combining behavioural and genetic data. We created experimental groups composed of two males of different sizes and three or four randomly selected females. Observations conducted during social interactions between males revealed that a hierarchy, unrelated to male size, was soon established: Alpha males were more aggressive towards competitors and courted females more intensively. Alpha males also achieved a higher mounting success than Beta males. Paternity analysis performed on hatchlings produced from experimental females revealed that male reproductive success was not correlated with male–female size ratio. Finally, despite the higher mounting success of Alpha males, paternity analysis revealed that male reproductive success did not differ between Alpha and Beta males. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 656–667. ADDITIONAL KEYWORDS: assignment – female choice – intrasexual competition – reproductive success – sperm storage.

Differences in sperm whale codas between two waters off Japan: possible geographic separation of vocal clans

The sperm whale (Physeter macrocephalus) clan is a social unit that shares a similar repertoire of vocalizations called codas. Coda repertoires and clan structure are well studied in sperm whales of the eastern tropical Pacific, but information is limited in the western North Pacific. We compared sperm whale codas recorded from female and immature sperm whales in 2 areas near Japan, off the Kumano Coast and off the Ogasawara Islands, to determine whether different clans exist in these waters. Repertoires of coda types were different between the 2 areas, and the lengths of codas consisting of the same number of clicks were longer in duration near Kumano than near Ogasawara. Our results suggest that different vocal clans inhabit in these 2 areas. Such clear geographic structure of clans is not known in other waters in the Pacific and distinct environmental features may favor a clan in which members share a specific foraging strategy and coda repertoire, both of which likely are transmitted through social learning.

Strong, convergent male mate choice along two preference axes in field populations of black widow spiders

Strong male mate preferences have been documented in species with otherwise conventional sex roles in the laboratory, and across taxa, male preferences generally focus on indicators of female fecundity and sperm competition risk. However, the few field studies of male choice rarely show equally strong effects. This suggests that costs of choice in nature may make the expression of preferences unlikely, or that interacting assessment cues may lead to unpredictable and variable outcomes in the wild. Field studies are therefore critical for testing whether or not male mate choice is sufficiently strong to exert sexual selection on females. Here we examine male choice in nature in response to two experimentally manipulated cues of female reproductive value. We recorded the attraction of male black widow spiders, Latrodectus hesperus, to females in a field enclosure and in a unconstrained natural setting. Stimulus females varied in two ways: sperm competition risk (low–unmated; high–mated) and fecundity (high–fed; low–unfed). Females and their silk were caged to prevent behavioural interactions while allowing the spread of airborne pheromones that attract males. Males in both experiments showed strong, nearly unanimous choice for unmated, well-fed females. In field enclosures, 80% of males made this choice, and wild males made the same choice in 94% of trials. We conclude that male choice in L. hesperus is mediated by detection of airborne pheromones, is strong and consistent despite natural costs of mate searching, and is not affected by natural interactions between (sometimes conflicting) cues of female reproductive value. Thus, universal mate choice may exist among males in nature. We propose general features of systems in which this may be likely and discuss implications for the study of sexual selection on females under conventional sex roles.

Duration of sperm storage in the simultaneous hermaphrodite Lymnaea stagnalis

Reproductive success is a crucial variable to understand the action of sexual selection, but its quantification is not straightforward because several factors cause nonrandom fertilization success. One of these factors is female sperm storage, which leads to prolonged paternity gain ( paternity longevity). In particular, knowledge about paternity longevity is crucial in simultaneous hermaphrodites, since their ability to self-fertilize adds a further layer of complexity to the quantification of male reproductive success. Here, we investigated the pattern of outcrossing over time after a single mating in a freshwater snail, Lymnaea stagnalis, using a microsatellite marker. We found that offspring are produced from stored sperm for a little over 2 months on average. Furthermore, the pattern of paternity indicates an active role for the female reproductive system in the transport of received sperm to the sperm storage organ. To quantify paternity longevity in a sperm-storing mating system, we propose to use the time when half the offspring are sired by a focal donor (Paternity Longevity 50; PL50), in addition to total storage duration. Intriguingly, we reveal that overall body size is positively correlated with paternity longevity. Although the exact mechanism of sperm storage and its contribution to male reproductive success remain to be revealed, this study provides useful information and new perspectives on sperm storage and sexual selection in this simultaneous hermaphrodite.