Dynamics of seminal fluid replenishment after mating

Seminal fluid proteins (SFPs) play vital roles for optimizing reproductive success in diverse animals. Underlining their significance, SFP production and transfer are highly plastic, e.g., depending on the presence of rivals or mating status of partners. However, surprisingly little is known about replenishing SFPs after mating. It is especially relevant in multiple mating species, as they would continuously produce and use SFPs throughout their reproductive life. Here we examined the expression pattern of SFP genes after mating in the great pond snail, Lymnaea stagnalis. Our results show that three out of the six SFP genes investigated here were up-regulated after mating, indicating that L. stagnalis replenishes seminal fluid in a protein-specific manner. In addition, we suggest that SFP replenishment is plastic depending on the mating history of female-acting snails. Our results shed light on unexplored aspects of SFP replenishment, thereby expanding the understanding of reproductive strategies in animals.

Multiple Mating of Aphelinus asychis Enhance the Number of Female Progeny but Shorten the Longevity

The Aphelinus asychis female adult is an important arrhenotocous parthenogenesis parasitoid of Myzus persicae, and its reproductive mode is beneficial for the population continuation of A. asychis by way of multiple mating and backcross. To explore the effect of mating on the population fitness and control efficiency of A. asychis, its mating frequency and backcross were observed under laboratory conditions. The results showed that most matings in A. asychis involved four distinct stages: courtship, pre-copulatory, copulation, and post-copulatory behaviours. Only the duration of courtship increased significantly with an increase in copulation frequency for females, and the courtship duration of A. asychis females mated with different males were significantly shorter than those mated with the same male at the same mating times, which suggested that A. asychis females might prefer to mate with different males to enrich the genotype of their offspring. The total number of mummified aphids and the female and male longevity decreased significantly with an increase in mating frequency. On the contrary, female progenies increased significantly with an increase of mating frequency, suggesting that sperm limitation might occur in females when they only mated once. These results imply that females might prefer to receive more sperm by mating multiple times in their life span. In addition, we found that the intrinsic rate of increase (r) of A. asychis of the control group (0.2858 d−1) was significantly greater than that in the backcross treatment (0.2687 d−1). The finite killing rate (θ) of A. asychis of the control group was similar to that in the backcross treatment, which showed that this treatment had a negligible negative effect on the control efficiency of A. asychis. In conclusion, the results showed that multiple mating increased the number and proportion of A. asychis female progenies but shortened the longevity of female and male adults, while the negative effect of backcross on the control efficiency of A. asychis was negligible.

Evolution of nuptial gifts and its coevolutionary dynamics with male-like persistence traits of females for multiple mating

Background Many male animals donate nutritive materials during courtship or mating to their female mates. Donation of large-sized gifts, though costly to prepare, can result in increased sperm transfer during mating and delayed remating of the females, resulting in higher paternity. Nuptial gifting sometimes causes severe female-female competition for obtaining gifts (i.e., sex-role reversal in mate competition) and selection on females to increase their mating rate, changing the intensity of sperm competition and the resultant paternity gains. We built a theoretical model to simulate such coevolutionary feedbacks between nuptial gift size (male trait) and propensity for multiple mating (female trait). Donation of nuptial gifts sometimes causes development of female persistence trait for gift acquisition. We also analyzed the causes and consequences of this type of traits, taking double receptacles for nutritious seminal gifts, which are known to occur in an insect group with a “female penis” (Neotrogla spp.), as an illustrative example. Results Our individual-based simulations demonstrated that female-female competition for male-derived nutrients always occur when the environment is oligotrophic and mating costs are low for females. However, a positive correlation between donated gift size and the resultant paternity gain was a requisite for the co-occurrence of large gifts and females’ competitive multiple mating for the gifts. When gift donation satisfied female demands and thus resulted in monandry, exaggeration of nuptial gift size also occurred under the assumption that the last male monopolizes paternity. The evolution of double slots for gift acquisition and digestion (female persistence trait) always occurred when males could not satisfy the demands of females for gifts. However, through coevolutionary reduction in male gift size, fixation of this trait in a population drastically reduced the average female fitness. Conclusion Sperm usage patterns, which have rarely been examined for animals with nuptial gifts, can be a critical factor for determining the extent of exaggeration in nuptial gifting. Sex-role reversals in mate competition, as a result of donation of nuptial gifts from males to females, can involve the evolution of male-like, persistent traits in females that reduce population productivity, as is the case with persistence traits in males.

Effects of operational sex ratio, mating age, and male mating history on mating and reproductive behavior in Grapholita molesta

The short-lived polygamous moth Grapholita molesta (Busck) is an important fruit pest worldwide. Trapping males by synthetic female sex pheromones is not an effective reproductive control strategy. It is important to improve this technology by understanding the mating system of G. molesta. This study investigated mating opportunities and fertile egg production by altering the operational sex ratio, mating age, and male mating history in repeated single mating and multiple mating in the two sexes. Our results showed that the mating and reproductive parameters of virgin males were affected by the number and age of virgin females. Males preferred a female number ≤three-fifths of the male number or ≤2-day-old females, while they discriminated against a female number ≥three times of the male number or ≥5-day-old females. On the other hand, the mating and reproductive parameters of virgin females were affected by repeated single mating and especially multiple mating under different male mating histories. Females preferred once-mated males and discriminated against virgin males. These results indicated that mating systems including more and older virgin females for virgin males and different virgin males for virgin females may be suitable for suppressing G. molesta populations. Hence, these results revealed that preventing mating of virgin adults by synthetic female sex pheromones should be most effective in controlling G. molesta.

Evolution of Animal Mating Systems

Animal mating systems are fascinating and diverse, and their evolution is central to evolutionary biology. A mating system describes patterns and processes of how females and males mate and reproduce successfully, and how this relates to their reproductive ecologies, including demographic and environmental factors. One of the more stimulating challenges in biology is to provide a comprehensive explanation for the evolution of mating adaptations among animals. In the course of sexual reproduction, animals engage in a dizzying array of traits, behaviors, and strategies. Such diversity simultaneously requires and eludes categorization: it is required for a general understanding, but at once confounds any rigorous classification because an almost inexhaustible supply of animal examples disrupt otherwise neatly ordered systems (see Classifications of Animal Mating Systems). Historically, mating with a single partner was thought to be a common mating system among animals. However, increasing observations of multiple mating by both sexes, supported by genomic evidence of mixed parentage within families, has since revealed that strict genetic monogamy is rare. In this bibliography, the selected literature highlights a compelling diversity and flexibility among animal mating systems, and sexual selection emerges both as a contributing cause and consequence of this variation. Sexual selection plays a central role in animal mating system evolution, and key references provide insights into its operation before and after mating, and describe how it leads to the expression of secondary sexual traits and sexual conflicts. Efforts to explain diversity in animal mating systems have often focused on how acquiring mates or matings relates to variance in reproductive success. This variation and diversity can be approached at the level of an individual, among individuals in a population, or between species. However, a preoccupation with the mean or average pattern often leads to generalizations that obscure important diversity crucial to evolutionary understanding. To avoid unnecessary categorization, the presentation here focus`es on variation in mating patterns and contrasts multiple mating with mating with a single partner. Furthermore, it considers the wider effects of animal mating systems, and includes associations with patterns of parental care. The aim with this bibliography is to provide key citations demonstrating that animal mating systems evolve from diverse, interactive, complex and dynamic processes resulting in a variety of adaptive mating strategies in females and males. A grateful acknowledgment is given to C. Kvarnemo and D. Gwynne for insightful comments.

Unprecedented dynamics of seminal fluid replenishment after mating

Seminal fluid proteins (SFPs) play vital roles for optimizing reproductive success in diverse animals. Underlining their significance, SFP production and transfer are highly plastic, e.g., depending on the presence of rivals or mating status of partners. However, surprisingly little is known about replenishing SFPs after mating. It is especially relevant in multiple mating species, as they would continuously produce and use SPFs throughout their reproductive life. Here we examined the expression pattern of SFP genes after mating in the great pond snail, Lymnaea stagnalis. Our results show that only two of the six SFP genes investigated here were up-regulated after mating, indicating that L. stagnalis replenishes seminal fluid in a protein-specific manner. In addition, we suggest that SFP replenishment is plastic depending on the mating history of female-acting snails. Our results shed light on unexplored aspects of SFP replenishment, thereby expanding the understanding of reproductive strategies in animals.

Mechanisms that ensure monogamous mating in Saccharomyces cerevisiae

Haploid cells of the budding yeast Saccharomyces cerevisiae communicate using secreted pheromones and mate to form diploid zygotes. Mating is monogamous, resulting in the fusion of precisely one cell of each mating type. Monogamous mating in crowded conditions, where cells have access to more than one potential partner, raises the question of how multiple-mating outcomes are prevented. Here we identify mutants capable of mating with multiple partners, revealing the mechanisms that ensure monogamous mating. Before fusion, cells develop polarity foci oriented towards potential partners. Competition between these polarity foci within each cell leads to disassembly of all but one focus, thus favoring a single fusion event. Fusion promotes the formation of heterodimeric complexes between subunits that are uniquely expressed in each mating type. One complex shuts off haploid-specific gene expression, and the other shuts off the ability to respond to pheromone. Zygotes able to form either complex remain monogamous, but zygotes lacking both can re-mate.

Polyandry in the Fruit Fly Bactrocera dorsalis Hendel (Diptera: Tephritidae)

The Oriental fruit fly, Bactrocera dorsalis (Hendel) is a global pest of a wide variety fruits. Due to its importance, the sterile insect technique (SIT) has raised attention as a safe and sustainable solution to this pest. Successful SIT programs require a comprehensive understanding on the mating behavior of this species. Females of oriental fruit flies are known monandrous which implies that females only mate once with one male. This experiment aimed to confirm that female flies were able to mate more than once with the same (multiple mating) or different males (polyandry) in certain period of time. Four different experiments were conducted to test the hypothesis: receptivity a female to the same male (1) and different males (2) in a cage for 11 days; receptivity a mated female with the same male (3) and different males (4) in a cage for 14 days after the first mating. Results indicated that a part of the female oriental fruit flies was capable to mating more than once with the same or different males.