Variation In Sperm Precedence Research Articles

High variation in sperm precedence and last male advantage in the scorpionfly Panorpa germanica L. (Mecoptera, Panorpidae): Possible causes and consequences

In the last decades, many insect species have been studied in terms of sperm competition. Patterns of sperm use are often inferred from the mean species value of P 2, defined as the mean proportion of offspring sired by the second male in double-mating trials. In Panorpa germanica (Mecoptera, Panorpidae), P 2 largely depends on relative copulation durations of both males, but with the second male on average having some advantage over the first male. Estimating the presence of fertile sperm inside the female's reproductive tract in relation to time after copulation we conclude this partial last male sperm precedence not to be caused by natural death, loss, or depletion of first male sperm. Estimating sperm transfer rates of both mates of a female we, furthermore, found that the high intraspecific variance in P 2 that can be observed cannot solely be explained by variances in sperm transfer rates among P. germanica males. Other factors possibly causing the observed patterns of paternity success are discussed.

Sperm Precedence in Colorado Potato Beetle, <I>Leptinotarsa decemlineata</I> (Coleoptera: Chrysomelidae): Temporal Variation Assessed by Neutral Markers

Variation in sperm precedence was examined in the Colorado potato beetle, Leptinotarsa decemlineata Say, using neutral allozyme markers. Two temporal components were studied: (1) pairing duration and (2) time since initial pairing. We used two pairing protocols that differed in the time males and females were allowed to mate for first and second pairings. When pairings were limited to 8 h each for the first and second male, the proportion of offspring in the xth egg mass attributable to the second male, P2(x), rose from 68% in the first egg mass after pairing with the second male to 78% in the tenth egg mass. When pairing was extended so that the first male-female pair had time to produce three egg masses and the second male was allowed to remain with the female indefinitely, P2(x) rose from 44% in the first egg mass after pairing with the second male to nearly 100% in the third and subsequent egg masses. Observations that (1) multiple matings are necessary to fill the female’s spermatheca and (2) the last male accounts for a greater proportion of offspring with time, provide evidence for both the sperm mixing and sperm displacement hypotheses. These data also help to explain male-guarding behavior in Colorado potato beetle. Because the allozyme markers were shown to be neutral with respect to fitness, other aspects of mating behavior could be tested by establishing a similar series of unique lines.

'Sloppy' sperm mixing and intraspecific variation in sperm precedence (P2) patterns.

Sperm precedence patterns are typically highly variable within (and between) species. Intraspecific variation in sperm precedence (measured as P2, the proportion of progeny fathered by the last male to mate' is frequently seen as a candidate for adaptive interpretation through either male effects (e.g. body size), female effects (e.g. cryptic female choice) or an interaction between the two. Here we show, using computer simulation, that if ejaculates divide into a number of 'packets' and packets from two males mix randomly, then a variety of patterns of sperm precedence may result. We term this process 'sloppy' mixing. If ejaculates break into a small number of packets, bimodal P2 distributions are predicted. As the number of packets is increased, then a complex series of changes through multimodal and flat to unimodal distributions results. Sloppy mixing can thus result in many of the observed P2 distributions. Sloppy mixing is unlikely to change the predictions of adaptive models of sperm competition.

Females of the grasshopper Chorthippus parallelus (Zett.) do not remate for fresh sperm

The evolution of female multiple mating is still a largely debated field. Among the benefits that have been proposed to explain this risky behaviour is the replenishment of sperm reserves. Apart from an increase in total sperm number, it can be an expression of post-copulatory mate choice or can be directed towards the uptake of fresh sperm. Using fresh sperm for fertilization instead of sperm aged by storage in the female genital tract may avoid a lowered fertilization capacity, an increase in deleterious effects or a skewed offspring sex ratio. We investigated the influence of sperm age on female fitness in the grasshopper Chorthippus parallelus, a species where females mate multiply. After copulation, females store sperm over the course of weeks until fertilization. An average ejaculate of 250 000 spermatozoa exponentially declined with time within the female's spermatheca. The number of days since copulation better explained the variation in actual sperm number than the number of pods or eggs laid. We investigated differences in female fitness parameters in two treatments. In the first, females were mated only once, while in the second, females always had freshly ejaculated sperm available. Although in our experiment, multiply mated females had heavier offspring than singly mated females, egg number per pod, hatching and fertilization success, their composite effects and offspring sex ratio did not vary with respect to season or sperm age. We therefore reject the hypothesis that the reason for remating in females of this species is the uptake of fresh sperm.

Male genital traits and mating interval affect male fertilization success in the water strider Gerris lacustris

Parker's seminal work brought attention to the possibility of postmating sexual selection by non-random fertilization success. Mechanisms for these processes are still only partly understood and there is clearly a need for more studies of intraspecific variation in sperm precedence. Here, we report results from an experimental study of the variation in fertilization success between males of the water strider Gerris lacustris. Genital morphology, male body size, and copulation duration were examined as possible correlates of paternity. The significance of guarding duration was also analysed. Only male genital morphology was correlated to fertilization success. This is one of the first studies showing a relationship between male genital traits and fertilization success, supporting the view that sexual selection may be responsible for the rapid and divergent evolution of genital structures in animals with internal fertilization. The fertilization success of last males varied considerably after double matings with a short mating interval (10 min). Last-male priority ranged from 0 to 100% and usually one of the males involved fertilized almost all the eggs. After double matings with a short mating interval, the proportion of eggs fertilized by the last male averaged 0.68 and was greater than 0.5. In contrast, the average fertilization success was biased towards the first male when the matings were more spread out over time (24 h). These results do not support earlier suggestions of a widespread last-male sperm priority in water striders.

Predicting variation in sperm precedence

Sperm competition theory predicts that males are adapted for success in sperm competition by the production of large numbers of sperm. This is supported by both inter– and intraspecific studies showing that males mating under high sperm competition risk increase investment in sperm production. Such an increase in sperm production is an advantage if sperm mix randomly or if sperm displacement occurs. When two males mate with the same female, the measurement of the proportion of eggs fertilized by the second male to mate (termed P 2 ) has been used to help elucidate sperm competition mechanisms. P 2 is usually quoted as a mean value, with little attention being paid to its variance, although P 2 estimates are notoriously variable. By predicting an expected variance for P 2 , additional information on sperm competition mechanisms may be obtained. Here we present a technique for analysing the variance in P 2 when a given mechanism of P 2 is assumed. We apply this technique to P 2 data collected from Plodia interpunctella (Lepidoptera, Pyralidae), assuming a ‘fair raffle’ mechanism of sperm competition. We compare observed distributions of P 2 with theoretical distributions generated assuming random mixing of two ejaculates drawn randomly from a population of known mean and variance in sperm numbers. Ejaculates of known size were obtained by counting the number of sperm ejaculated by males mating for the first (large ejaculate) or second (small ejaculate) time. Females either received two small or one small and one large ejaculate, and the distribution of P 2 (estimated using the sterile male technique) was compared with our theoretical predictions. The observed variance in P 2 was greater than our model prediction, thus we conclude that sperm from P. interpunctella do not mix randomly before fertilization.

Variation in sperm precedence during mating in male flies,Dryomyza anilis

To understand how individual differences in fertilization success arises in the flyDryomyza anilisvariation in sperm precedence between and within males was studied. InD.anilisa mating consists of a copulation followed by tapping sequences during which the male taps the external genitalia of the female. These tapping sequences increase last male sperm precedence. Each male in the experiment was repeatedly mated with a set of females. In the first treatment, mating was interrupted after the male had an intromission. In the second treatment, the male was allowed to perform five tapping sequences after an intromission. In the third treatment, the male was allowed to perform an unlimited number of tapping sequences after an intromission until interrupted by female resistance. There were large differences between males in all three treatments as shown by the 95% confidence limits of the mean fertilization success. Repeatabilities of mating time and the number of tapping movements per tapping sequence were high indicating clear differences between males in these components of mating behaviour. Within individual males, the more tappings per sequence, the higher the fertilization success. In matings with an unlimited number of tapping sequences, fertilization success depended on female resistance. Within-male variation in fertilization success was higher in matings with an unlimited number of tapping sequences than in matings interrupted after a copulation. Several components of male mating behaviour thus contribute to the variation in sperm precedence inD.anilisFemale behaviour, in particular, resistance of tapping movements, can also increase variation in sperm precedence.

FEMALE CONTROL OF SPERM TRANSFER AND INTRASPECIFIC VARIATION IN SPERM PRECEDENCE: ANTECEDENTS TO THE EVOLUTION OF A COURTSHIP FOOD GIFT.

Manipulation of ejaculates is believed to be an important avenue of female choice throughout the animal kingdom, but evidence of its importance to sexual selection remains scarce. In crickets, such manipulation is manifest in the premature removal of the externally attached spermatophore, which may afford females an important means of postcopulatory mate choice. We tested the hypothesis that premature spermatophore removal contributes significantly to intraspecific variation in sperm precedence by (1) experimentally manipulating spermatophore attachment durations of competing male Gryllodes sigillatus and (2) employing protein electrophoresis to determine the paternity of doubly mated females. The relative spermatophore attachment durations of competing males had a significant influence on male paternity, but the pattern of sperm precedence deviated significantly from the predictions of an ideal lottery. Instead, paternity data and morphological evidence accorded best with a model of partial sperm displacement derived here. Our model is similar to a displacement model of Parker et al. in that sperm of the second male mixes instantaneously with that of the first throughout the displacement process, but the novel feature of our model is that the number of sperm displaced is only a fraction of the number of sperm transferred by the second male. Regardless of the underlying mechanism, female G. sigillatus can clearly alter the paternity of their offspring through their spermatophore-removal behavior, and employ such cryptic choice in favoring larger males and those providing larger courtship food gifts. We discuss how female control of sperm transfer and intraspecific variation in sperm precedence may be important precursors to the evolution of gift giving in insects.

Female Control of Sperm Transfer and Intraspecific Variation in Sperm Precedence: Antecedents to the Evolution of a Courtship Food Gift

Female Control of Sperm Transfer and Intraspecific Variation in Sperm Precedence: Antecedents to the Evolution of a Courtship Food Gift

Extreme variability in sperm precedence in the fungus beetle, Bolitotherus cornutus (Coleoptera Tenebrionidae)

Most previous studies of sperm precedence have reported only average values for species. Intraspecific variation in sperm precedence, however, is necessary for the evolution of adaptations that alter sperm precedence patterns. To examine intraspecific variation in sperm precedence, virgin female fungus beetles were mated to two different males in succession, and all females, males, and offspring were genotyped at eight allozyme loci. The proportion of offspring fathered by the second male varied from zero to one. Future studies should not only measure intraspecific variability in sperm precedence, but should attempt to determine causes of this variability.

Multiple paternity and individual variation in sperm precedence in the simultaneously hermaphroditic land snail Arianta arbustorum

Intraspecific variation in the proportion of offspring sired by the second mate with a female (P2) is an aspect of sperm competition that has received little attention. I examined the effects of delay between copulations (range 9–380 days) and size of sperm donor on sperm precedence in double-mated individuals of the simultaneously hermaphroditic land snail Arianta arbustorum. Using shell colour as a genetic marker, paternity was analysed in 132 broods produced by 35 snails that had mated with two partners of different genotype. Sperm precedence (P2) was influenced by the time between the two matings when the mating delay exceeded 70 days (one reproductive season). P2 averaged 0.34 in the first brood of snails that mated twice within 70 days indicating first mate sperm precedence. In contrast, P2 averaged 0.76 in broods of snails that remated in the following season, indicating a decreased viability of sperm from the first mate. The size of sperm-donating individuals had no effect on the fertilization success of their sperm in the first brood produced after the second copulation. Analysis of long-term sperm utilization in 23 snails that laid three to nine egg batches over 2 years revealed striking differences among individuals. Five snails (21.7%) exhibited first-mate sperm precedence throughout, eight snails (34.8%) showed second-mate sperm precedence throughout, whereas ten snails (43.5%) exhibited sperm mixing in successive batches. It is suggested that the individual variation in sperm precedence in A. arbustorum may partly be due to differences in the amount of sperm transferred. Paternity analysis in 34 batches laid by 19 wild-caught individuals of A. arbustorum indicated that at least 12 snails (63.2%) used sperm from two or more mates for the fertilization of their eggs. This suggests a high incidence of multiple paternity in broods of A. arbustorum under field conditions.

Multiple paternity and individual variation in sperm precedence in the simultaneously hermaphroditic land snail Arianta arbustorum

Multiple paternity and individual variation in sperm precedence in the simultaneously hermaphroditic land snail Arianta arbustorum

Intraspecific variation in sperm precedence in the bruchid beetle Callosobruchus maculatus

Abstract. By examining potential sources of intraspecific variation in sperm precedence, the underlying mechanisms of sperm competition in Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) were investigated. The extent of sperm precedence was not related to either copulatory behaviour or body size (male and female). The extent of sperm precedence increased during the egg‐laying period, suggesting that the stratification of sperm within the spermatheca is not the mechanism of sperm precedence. Direct removal of sperm from the female's reproductive tract was not observed. Four other mechanisms (not mutually exclusive) are proposed to account for last‐male sperm precedence in this species.

Sources of Intraspecific Variation in Sperm Precedence in Red Flour Beetles

Sperm precedence, or differential fertilization success among mating males, is likely to be important in mediating male reproductive success in many species. Numerous studies have provided measures of sperm precedence for diverse taxonomic groups, but previous discussions have focused on species-specific mean P2 values. In this study, which systematically examined sources of variation in sperm precedence in Tribolium castaneum, consistent differences among male pairs represent a significant percentage (17.8%) of the total variation in sperm precedence. These results in T. castaneum and a reexamination of published studies reveal a high degree of intraspecific variation in sperm precedence, suggesting that mean values are insufficient to adequately characterize sperm-precedence patterns. Such individual variation in sperm precedence may profoundly influence differential reproductive success among males.

Mechanisms of sperm competition in birds: mathematical models

We built models of sperm competition and compared their predictions with observations from domestic chickens in an attempt to elucidate the mechanism of sperm competition. The models suggest that (1) observed levels of precedence of sperm are not merely a passive consequence of the greater mortality of sperm from earlier inseminations; (2) displacement of existing sperm from sperm storage tubules by incoming sperm explains observed levels of sperm precedence and disappearance from the reproductive tract, even in the absence of recognition of sperm from different inseminations; (3) stratification of sperm within the sperm storage tubules fails as an explanation of observed patterns of sperm precedence and disappearance because long-term levels of sperm precedence as high as those observed can only be predicted in combination with rates of disappearance of sperm much lower than those observed in chickens. The predictions of sperm precedence levels following multiple inseminations also suggest that displacement rather than stratification is the most likely mechanism of sperm competition in chickens. We discuss the consequences of male or female control of sperm competition, non-uniform distribution of sperm between sperm storage tubules, and variation in sperm precedence with time after the last insemination, and suggest ways in which the models may be used in future to aid in the elucidation of mechanisms of sperm competition.

Polyandry in the Grouse Locust, Paratettix texanus Hancock, with Notes on Inheritance of Acquired Characters and Telegony

Previous articleNext article No AccessPolyandry in the Grouse Locust, Paratettix texanus Hancock, with Notes on Inheritance of Acquired Characters and TelegonyRobert K. NaboursRobert K. Nabours Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 61, Number 677Nov. - Dec., 1927 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/280174 Views: 5Total views on this site Citations: 16Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Mark A Elgar, Therésa M Jones, Kathryn B McNamara Promiscuous words, Frontiers in Zoology 10, no.11 (Jan 2013): 66.https://doi.org/10.1186/1742-9994-10-66E. L. LARSON, G. L. HUME, J. A. ANDRÉS, R. G. HARRISON Post-mating prezygotic barriers to gene exchange between hybridizing field crickets, Journal of Evolutionary Biology 25, no.11 (Nov 2011): 174–186.https://doi.org/10.1111/j.1420-9101.2011.02415.xKlaus Reinhardt Variation in sperm precedence in Chorthippus grasshoppers (Caelifera: Gomphocerinae), Physiological Entomology 25, no.44 (Jul 2008): 324–329.https://doi.org/10.1111/j.1365-3032.2000.00200.xKlaus Reinhardt , Physiological Entomology 25, no.44 ( 2000): 324.https://doi.org/10.1046/j.1365-3032.2000.00200.xL.W. Simmons, M.T. Siva-Jothy Sperm Competition in Insects: Mechanisms and the Potential for Selection, (Jan 1998): 341–434.https://doi.org/10.1016/B978-012100543-6/50035-0 Sara M. Lewis , and Steven N. Austad Sources of Intraspecific Variation in Sperm Precedence in Red Flour Beetles, The American Naturalist 135, no.33 (Oct 2015): 351–359.https://doi.org/10.1086/285050MARK RIDLEY The incidence of sperm displacement in insects: four conjectures, one corroboration, Biological Journal of the Linnean Society 38, no.44 (Jan 2008): 349–367.https://doi.org/10.1111/j.1095-8312.1989.tb01582.xTOMOHIRO ONO, MICHAEL T. SIVA-JOTHY, AKI KATO Removal and subsequent ingestion of rivals' semen during copulation in a tree cricket, Physiological Entomology 14, no.22 (Jun 1989): 195–202.https://doi.org/10.1111/j.1365-3032.1989.tb00952.xWolfgang Wickler, Uta Seibt Reproductive Behaviour in Zonocerus elegans (Orthoptera: Pyrgomorphidae) with Special Reference to Nuptial Gift Guarding, Zeitschrift für Tierpsychologie 69, no.33 (Apr 2010): 203–223.https://doi.org/10.1111/j.1439-0310.1985.tb00147.xDARRYL T. GWYNNE Male Mating Effort, Confidence of Paternity, and Insect Sperm Competition, (Jan 1984): 117–149.https://doi.org/10.1016/B978-0-12-652570-0.50011-7 William F. Walker Sperm Utilization Strategies in Nonsocial Insects, The American Naturalist 115, no.66 (Oct 2015): 780–799.https://doi.org/10.1086/283600E. BOORMAN, G. A. PARKER Sperm (ejaculate) competition in Drosophila melanogaster, and the reproductive value of females to males in relation to female age and mating status, Ecological Entomology 1, no.33 (Aug 1976): 145–155.https://doi.org/10.1111/j.1365-2311.1976.tb01217.xG. A. PARKER SPERM COMPETITION AND ITS EVOLUTIONARY CONSEQUENCES IN THE INSECTS, Biological Reviews 45, no.44 (Nov 1970): 525–567.https://doi.org/10.1111/j.1469-185X.1970.tb01176.xG.A. Parker Sperm competition and its evolutionary effect on copula duration in the fly Scatophaga stercoraria, Journal of Insect Physiology 16, no.77 (Jul 1970): 1301–1328.https://doi.org/10.1016/0022-1910(70)90131-9 B. P. Kaufman , and M. Demerec Utilization of Sperm by the Female Drosophila Melanogaster, The American Naturalist 76, no.766766 (Sep 2015): 445–469.https://doi.org/10.1086/281068Robert K. Nabours The Genetics of the Tettigidae (Grouse Locusts), (Jan 1929): 27–100.https://doi.org/10.1007/978-94-011-9487-7_1