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1.
Diego Rubolini Paolo Galeotti Gabriele Ferrari Michele Spairani Franco Bernini Mauro Fasola 《Behavioral ecology and sociobiology》2006,60(2):212-219
Sperm competition is a well-recognised agent in the evolution of sperm and ejaculate structure, as well as variation in female quality. Models of the evolution of ejaculate expenditure predict that male body condition, female fecundity and the risk and intensity of sperm competition may be the ultimate factors shaping optimal ejaculate size. We investigated sperm allocation in Austropotamobius italicus, a freshwater crayfish exhibiting a coercive mating system and external fertilisation, in relation to male and female traits and copulation behaviour under laboratory conditions. We found that mating males were sensitive to female size and produced larger ejaculates when mating with larger females, which were more fecund in terms of number of eggs produced. We found no evidence for female egg production being sperm-limited, as the number of eggs was not dependent on male sperm expenditure. Copulation duration and number of ejaculations reliably predicted the amount of sperm transferred, and both these behavioural measures positively covaried with female body size. These results indicate that male freshwater crayfish can modulate their sperm expenditure in accordance with cues that indicate female fecundity. In addition, a novel finding that emerged from this study is the decrease in sperm expenditure with male body size, which may either suggest that large, old male crayfish are better able than small males to economise sperm at a given mating to perform multiple matings during a reproductive season, or that they experience senescence of their reproductive performance. 相似文献
2.
Sperm allocation in an uncertain world 总被引:3,自引:0,他引:3
Models of optimal sperm allocation are constructed using stochastic dynamic programming techniques, yielding predictions
about sperm allocation when males mate sequentially, breeding time is finite, sperm stores are limited and females vary in
quality. The models suggest that uncertainty of future reproductive opportunities should favour withholding of sperm, so that
males tend to allocate less (for a given level of stored sperm) earlier in the breeding season. This effect is more pronounced
the greater the variance in female quality. We also show that while allocation will be influenced by mate value, it is not
necessarily optimal to allocate preferentially to high-quality females, since the benefits of a higher-quality mate may be
offset by increased risk of rejection of sperm or higher sperm competition. The relationship between mate quality and level
of allocation will depend strongly on the amount of remaining stored sperm, with males whose supplies are depleted being more
likely to favour lower-quality partners.
Received: 12 September 1997 / Accepted after revision: 28 June 1998 相似文献
3.
Paolo Galeotti Fabio Pupin Diego Rubolini Roberto Sacchi Pietro A. Nardi Mauro Fasola 《Behavioral ecology and sociobiology》2007,61(5):711-718
Sperm competition models predict that males should adjust their sperm expenditure according to the risk and/or intensity of
sperm competition. In this paper, we analysed copulatory behaviour of both sexes and sperm expenditure in relation to female
mating status (virgin or mated) in the freshwater crayfish Austropotamobius italicus, a species where males have been reported to feed on and remove sperm laid by other males. The same females were allowed
to be inseminated sequentially by two males, and we compared the sexual behaviours of partners between the first (virgin females)
and the second mating (mated females). We found that female resistance did not differ between the first and the second mating,
nor males refused or took more time to mount a mated female. However, when mating with a mated female, males reached an effective
copulation position significantly later. This occurred because second-mating males removed, by eating, all or most spermatophores
previously deposited by first males. As removal was often incomplete, this resulted in a larger amount of sperm being deposited
on female ventral parts after the second mating, although second males did not allocate more sperm to mated females than first
males did. Thus, the peculiar mode of sperm competition, where males remove previously deposited sperm, and the consequent
predictable strong last male prevalence in paternity likely led to the observed lack of adjustment of sperm expenditure to
female mating status in this species. 相似文献
4.
Patterns of courtship behavior and ejaculate characteristics in male red-winged blackbirds 总被引:1,自引:0,他引:1
David F. Westneat Lisa A. McGraw Jennifer M. Fraterrigo Tim R. Birkhead F. Fletcher 《Behavioral ecology and sociobiology》1998,43(3):161-171
Sperm competition in birds is likely to have important effects on the behavior and physiology of reproduction in both sexes.
For males, such competition should select for large sperm reserves and behavioral adjustment of copulation when reserves are
low. We investigated both these possibilities in free-living red-winged blackbirds (Agelaius phoeniceus), a highly polygynous species with apparently strong sperm competition. We found that the recent copulatory behavior of males
did not affect the propensity to copulate with a model female. Ejaculates collected from individual males at 1-h intervals
showed no evidence of sperm depletion, yet repeated ejaculates collected less than 10 min apart did. Male ejaculate size was
significantly larger if it was the first one of the day (i.e., after an overnight rest). The average ejaculate size was 12.5
(±12.5 SD) million sperm. Males captured during the breeding season had an average of 111.7 (±52.8) million sperm stored in
their seminal glomera. Because males average a peak copulation rate of six per female per day, in one day a male might utilize
all the sperm in his seminal glomera if more than two females on his territory are fertilizable. We hypothesize that polygyny
and sperm competition in this species have combined to select for rapid replenishment of the seminal glomera throughout the
day, in contrast to other species that have been studied. Testis size and sperm reserves of male red-winged blackbirds are
intermediate between monogamous species and species with intense sperm competition. Several possible explanations for this
are discussed.
Received: 21 October 1997 / Accepted after revision: 15 February 1998 相似文献
5.
Luke Holman 《Behavioral ecology and sociobiology》2009,63(11):1679-1688
The causes and consequences of variation in sperm quality, survival and ageing are active areas of research in ecology and
evolution. In order to address these topics, many recent studies have measured sperm viability using fluorescent staining.
Although sperm viability staining has produced a number of interesting results, it has some potential pitfalls that have rarely
been discussed. In the present paper, I review the major findings of ecology and evolution studies employing sperm viability
staining and outline the method’s principle limitations. The key problem is that the viability assay may itself kill sperm,
which is likely to confound many common experimental designs in addition to producing artificially low estimates of sperm
viability. I further suggest that sperm number should be routinely measured in sperm viability studies, as it may be an important
but overlooked source of spurious results. I provide methodological advice on sperm viability staining aimed at minimising
artefacts and producing robust conclusions, and discuss possible avenues for future research.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
G. W. Uetz William J. McClintock Douglas Miller Elizabeth I. Smith Kristina K. Cook 《Behavioral ecology and sociobiology》1996,38(4):253-257
Males of the brush-legged wolf spider Schizocosa ocreata (Hentz) have conspicuously decorated forelegs used in courtship and agonistic displays. Approximately one in five juvenile
males has a missing or regenerating foreleg, and regeneration of a leg lost during development usually results in the absence
of a decorative tuft on that leg. The subsequent asymmetry in this male secondary character significantly decreases success
in both courtship of females and male-male agonistic interactions. Experimental removal of tufts from one leg of previously
successful symmetric males produces similar results. As a test for concomitant behavioral effects, female spiders were shown
video images of a courting male with symmetric tufts and the same video image altered to have asymmetric tufts. Female receptivity
to the asymmetric video image was lower. In contrast to fluctuating asymmetry resulting from developmental instability, leg
tuft asymmetry in S. ocreata most likely arises from a single event during ontogeny – possibly leg loss from an aggressive or predator encounter – and
may serve as a quality indicator in female mate choice.
Received: 27 July 1995/ Accepted after revision: 19 November 1995 相似文献
7.
In insects, the last male to mate with a female often gains access to a disproportionate number of subsequent fertilizations.
This study examined last-male sperm precedence patterns in doubly and triply mated Tribolium castaneum females. Sperm storage processes were investigated by measuring the quantity of sperm stored within the female spermatheca
following single, double, and triple matings. Both doubly mated and triply mated females exhibited high last-male sperm precedence
for progeny produced during the first 48 h following the last mating, with females in both groups exhibiting parallel declines
in sperm precedence 1 and 2 weeks later. The number of sperm stored by females increased by 33% between singly mated and doubly
mated females, indicating that the spermatheca is filled to only two-thirds capacity following insemination by the first male.
Based on the proportion of stored sperm from first and second matings, we tested predictions about sperm precedence values
based on models of random sperm mixing. High initial last-male sperm precedence strongly supports stratification of last-male
sperm. By 1–2 weeks after double matings, sperm precedence declined to levels indistinguishable from values expected under
random mixing. These results provide insight into mechanisms of sperm storage and utilization in this species.
Received: 20 August 1997 / Accepted after revision: 24 May 1998 相似文献
8.
Merja Otronen 《Behavioral ecology and sociobiology》1998,42(3):185-191
The significance of male asymmetry in postcopulatory sexual selection was studied in the fly Dryomyza anilis by examining whether male asymmetry is related to fertilization success. The traits measured were wing length, tibia length
and the length of small and large claspers. The male claspers are situated at the tip of the abdomen, functional pair of claspers
consists of a large and a small clasper on the same side of the body. These claspers are used to tap the female abdomen after
sperm transfer, which has been shown to increase fertilization success for the mating male. Fertilization success was negatively
related to the fluctuating asymmetry of wing length, suggesting either female preference for more symmetrical males or a relationship
between male asymmetry and intrasexual selection which was reflected in mating performance. Fertilization success was also
related to the length of small claspers, decreasing with increasing length of the claspers. In addition, males with asymmetrical
small claspers enjoyed higher fertilization success than symmetrical ones. This study shows that fluctuating asymmetry in
wing length is an important fitness trait in postcopulatory sexual selection. Since male tapping affects sperm distribution
in the female's sperm storage organs, the higher fertilization success of males with asymmetrical small claspers could have
a functional relationship with the asymmetrical position of female sperm storage organs.
Received: 6 March 1997 / Accepted after revision: 8 November 1997 相似文献
9.
Gauri R. Pradhan Antje Engelhardt Carel P. van Schaik Dario Maestripieri 《Behavioral ecology and sociobiology》2006,59(3):333-343
Female copulation calls are mating-associated vocalizations that occur in some species of Old World monkeys and apes. We argue
that copulation calls have two immediate functions: to encourage mating attempts by other males and to increase mate guarding
by the consort male. We hypothesize that female copulation calls have evolved under the selective pressures of risk of infanticide
and sperm competition. When male mate guarding is effective, copulation calls allow females to concentrate paternity in dominant
males and benefit from their protection against the risk of infanticide. When mate guarding is ineffective, copulation calls
may bring genetic benefits to females through facilitation of sperm competition. We present a quantitative model in which
interspecific variation in females' promiscuity predicts their tendency to use copulation calls in conjunction with mating.
The model predicts that in species with little female promiscuity, copulation calls should be rare and exhibited only in association
with mating with dominant males. In species in which females are highly promiscuous, copulation calls should be frequent and
unrelated to male dominance rank. The limited data available to test the model support its main predictions as well as the
predicted relation between copulation calls and male dominance rank.
相似文献
Dario MaestripieriEmail: |
10.
Ben C. Sheldon Pete Davidson Gabriella Lindgren 《Behavioral ecology and sociobiology》1999,46(3):141-148
There is increasing evidence that sexual selection may be intense even in socially monogamous birds, resulting from both mate choice and sperm competition. We studied these two modes of sexual selection experimentally by removing paired male collared flycatchers, Ficedula albicollis, from their mates for 2 days and investigating the factors that influenced the likelihood of a replacement male appearing and how the removals influenced paternity. Replacement males (usually neighbouring males) appeared at 81% (n = 37) of nests where males were removed. The likelihood of this appearance was unaffected by the probable reproductive value of the female's clutch to the replacing male. A replacement was, however, less likely when the original male had a large forehead patch, a trait previously shown to be subject to sexual selection in this population. Experimental removal of males increased the level of sperm competition: 74% of experimental broods were multiply sired, compared to 29% of unmanipulated broods in a previous study. Only two factors predicted how paternity was shared between males: removed males fathered more young if removed closer to laying, and if they had larger forehead patches. The former result is consistent with last-male sperm precedence determining paternity, whereas the latter adds to other evidence that forehead patch size is the target of female preference in this species. Our results suggest that females exert some control over male replacement, and also that they may influence the fertilisation success of males by behavioural means. Received: 15 July 1998 / Received in revised form: 16 March 1999 / Accepted: 28 March 1999 相似文献
11.
Sperm competition or sperm selection: no evidence for female influence over paternity in yellow dung flies Scatophaga stercoraria 总被引:2,自引:0,他引:2
L. W. Simmons P. Stockley R. L. Jackson G. A. Parker 《Behavioral ecology and sociobiology》1996,38(3):199-206
Recent studies of non-random paternity have suggested that sperm selection by females may influence male fertilization success.
Here we argue that the problems originally encountered in partitioning variation in non-random mating between male competition
and female choice are even more pertinent to interpreting patterns of non-random paternity because of intense sperm competition
between males. We describe an experiment with the yellow dung fly, Scatophaga stercoraria, designed to partition variance in the proportion of offspring sired by the second male, P
2, between males and females, and to control for sperm competition. Large males were shown to have a higher P
2 than small males but P
2 was independent of the size of the female’s first mate. This result might suggest an absolute female preference for large
males via sperm selection. However, large males have a higher constant rate of sperm transfer and displacement. After controlling
for this effect of sperm competition, large males did not achieve higher paternity than small males. We argue that a knowledge
of the mechanism of sperm competition is essential so that male effects can be controlled before conclusions are made regarding
the influence of sperm selection by females in generating non-random paternity.
Received: 4 April 1995 / Accepted after revision: 17 October 1995 相似文献
12.
Sperm transfer and storage in relation to sperm competition in Callosobruchus maculatus 总被引:2,自引:0,他引:2
Paul Eady 《Behavioral ecology and sociobiology》1994,35(2):123-129
This paper examines the underlying mechanisms of sperm competition in the beetle Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). Recently developed mathematical models of sperm competition are combined with an empirical investigation of the processes of sperm transfer and storage. During a single insemination virgin males transfer approximately 46000 sperm, 85% more sperm than females can effectively store in their spermathecae. Many of these sperm remain in the bursa copulatrix where they are apparently rapidly degraded and can therefore play no role in fertilization. The spermatheca (primary site of sperm storage) is filled by a single insemination and sperm are lost from this organ at a constant rate. This rate of sperm loss from the spermatheca is insufficient for sperm mixing (without displacement) or sperm stratification to account for the degree of last male sperm precedence measured as P
2; the proportion of offspring fathered by the second male to mate reported for this species (P
2 = 0.83, when two inseminations are separated by 24 h). Models of sperm displacement correctly predict high levels of sperm precedence although the precision of these predictions is limited because the proportion of sperm entering the spermatheca cannot be accurately determined. The results suggested that last male sperm precedence in C. maculatus the result of sperm displacement, although the exact mechanism of displacement (sperm-for-sperm or fluid displacement) remains unknown. Possible constraints imposed by female genital anatomy on sperm displacement are discussed. 相似文献
13.
Bart Kempenaers G. R. Verheyen André A. Dhondt 《Behavioral ecology and sociobiology》1995,36(1):33-42
This study investigates the importance of mate guarding for males and females in the facultatively polygynous blue tit Parus caeruleus. We present observational data in combination with a paternity analysis using DNA fingerprinting to show that (1) male blue tits guard their mate, since they stay closer to their mate, initiate fewer flights and follow their mate more often during the female's presumed fertile period; (2) polygynous males do not suffer more from lost paternity despite lower mate guarding; (3) in monogamous pairs there is either no relation or a positive relation (depending upon the variable measured) between measures of mate guarding intensity and the proportion of extra-pair young in the nest; and (4) monogamous males that are more often followed by their fertile female suffered less from lost paternity. We conclude that, despite mate guarding, paternity seems to be largely under female control and unattractive males guarding their mate are making the best of a bad situation. Experimental evidence is provided showing that when males were temporarily removed from their territory, their mate suffered from increased harassment from neighbouring males that intruded in the territory and tried to copulate with the female. Almost all of these copulation attempts were unsuccessful because females refused to copulate. We conclude that mate guarding may be beneficial for females because harassment by neigbouring males is prevented. 相似文献
14.
In species where males use alternative reproductive tactics and male phenotypes are confronted with different risks of sperm
competition, theory predicts that between-male-type differences in sperm expenditure may evolve. In the frog Crinia georgiana big males can monopolize females, whereas small males often engage in polyandrous matings. Consequently, big males may experience
a lower risk of sperm competition than do small males. We tested if the predictions from theoretical models can be applied
to the mating system of C. georgiana. Our results showed that small males do not have larger testes relative to their body size compared to their larger counterparts
and that the efficiency with which sperm number, size, motility, and longevity are produced by the testes does not differ
between small and large males in the predicted way. These results are not in alignment with predictions from a loaded raffle
model of sperm competition on sperm expenditure in males with alternative phenotypes. The plasticity in mating tactics used
by C. georgiana males and a high intraseasonal variation in male densities may have prevented the evolution of enhanced sperm performance
in smaller males. A fair raffle in the sperm competition game played by C. georgiana males could also explain the observed patterns in sperm traits. Future investigations determining the parameters responsible
for the deviation from theoretical predictions in this system will test the degree to which current theoretical models can
indeed be applied to species with plastic reproductive tactics. 相似文献
15.
Stefan Lüpold George M. Linz Tim R. Birkhead 《Behavioral ecology and sociobiology》2009,63(6):899-909
Post-copulatory sexual selection (PCSS) is thought to be one of the evolutionary forces responsible for the rapid and divergent
evolution of sperm design. However, whereas in some taxa particular sperm traits are positively associated with PCSS, in other
taxa, these relationships are negative, and the causes of these different patterns across taxa are poorly understood. In a
comparative study using New World blackbirds (Icteridae), we tested whether sperm design was influenced by the level of PCSS
and found significant positive associations with the level of PCSS for all sperm components but head length. Additionally,
whereas the absolute length of sperm components increased, their variation declined with the intensity of PCSS, indicating
stabilising selection around an optimal sperm design. Given the diversity of, and strong selection on, sperm design, it seems
likely that sperm phenotype may influence sperm velocity within species. However, in contrast to other recent studies of passerine
birds, but consistent with several other studies, we found no significant link between sperm design and velocity, using four
different species that vary both in sperm design and PCSS. Potential reasons for this discrepancy between studies are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
Sperm competition and the level of polyandry in a bushcricket with large nuptial gifts 总被引:4,自引:0,他引:4
Variation in paternity due to sperm competition or post-copulatory female choice has a major influence on animal mating system evolution and on the levels of genetic variability in natural populations. However, there are relatively few studies comparing the outcome of sperm-competition experiments in the laboratory with natural variation in polyandry among families from the field. In the bushcricket Ephippiger ephippiger, females mate multiply, and the males provide them with a large, nutritious, and probably expensive, donation at mating. We examined paternity in a series of laboratory matings, where females mated with two males, and amongst a series of families collected from a natural population. In the laboratory, paternity was highly bimodally distributed: 24% of families had offspring fathered by the first male to mate, 68% by the second male (in only 8% was paternity shared). In the field, paternity was more mixed: only 27% of families had a single father, 14% had more than two fathers, whilst 59% had two fathers. While unsuccessful matings may contribute to the highly biased paternity in the laboratory, they cannot fully explain the high incidence of complete P2 families. Nonrandom sperm utilisation is therefore likely. Greater sperm mixing in the field probably results from females mating with more males, but the distribution of paternity also reflects an active process of nonrandom sperm utilisation. Confidence of paternity due to last male advantage may be relatively high in this species, and therefore may have facilitated the evolution of the large spermatophore in E. ephippiger.Communicated by D. Gwynne 相似文献
17.
Andreas Vermeulen Sierk Engels Klaus Peter Sauer 《Behavioral ecology and sociobiology》2008,63(1):77-83
Variation in traits closely related to fitness is expected to be low. This is because these traits are under directional selection
and the best genotype should prevail. However, there have been a number of studies demonstrating the existence of considerable
variance in sexually selected traits, which is generally known as the lek paradox. Accordingly, earlier studies found substantial
variation in sperm transfer rates in Panorpa vulgaris. Aiming at finding the mechanism that maintains this variation, we analyzed the condition dependence and the narrow sense
heritability of sperm transfer rates. Food deprivation in the larval/adult phase caused a decrease in the males’ capability
of saliva secretion resulting in shorter copulations and a reduced number of transferred sperm. There was a positive correlation
between mean sperm transfer rates and mean body mass. Additionally, intermale variation in sperm transfer rates decreased
with increasing food availability. Hence, we suggest that sperm transfer rates in P. vulgaris are influenced by adult feeding history. Heritability analyses of sperm transfer rates did not provide significant results,
which is consistent with the general hypothesis that additive genetic variance in traits closely related to fitness is small.
Since a trait’s potential to respond to selection is proportional to the amount of contained additive genetic variance, the
ascertained small heritability provides a satisfying explanation for the maintenance of substantial variation in sperm transfer
rates. 相似文献
18.
Charlyn Partridge Ingrid Ahnesjö Charlotta Kvarnemo Kenyon B. Mobley Anders Berglund Adam G. Jones 《Behavioral ecology and sociobiology》2009,63(3):345-354
The last several decades of research in behavioral ecology have resulted in a deeper appreciation of post-mating processes
and sexual conflict in sexual selection. One of the most controversial aspects of sexual selection is cryptic mate choice.
Here, we take advantage of male pregnancy in a sex-role-reversed pipefish (Syngnathus typhle) to quantify cryptic choice based on perceived parasite load and other sources of variance in female fitness. Studies have
shown that S. typhle males preferentially mate with females with lower parasite loads and that a male’s perception of female parasite load can
be altered by tattooing females. We manipulated the apparent parasite load of females in controlled mating experiments to
test the hypothesis that post-copulatory sexual selection is dependent on a male’s perception of female parasite load in pipefish.
Our results provided no evidence for cryptic male choice based on perceived female parasite load. However, we found evidence
that eggs from larger females were more likely to result in viable offspring than eggs from smaller females and that the first
female to mate with a male transferred more eggs per copulation on average. Overall, our results show that potential for post-copulatory
sexual selection does exist in pipefish, but the male’s perception of female parasite load does not play a major role in this
process. 相似文献
19.
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.
Received: 28 July 1998 / Received in revised form: 15 March 1999 / Accepted: 28 March 1999 相似文献
20.
Copulatory plug displacement and prolonged copulation in the Iberian rock lizard (Lacerta monticola)
Male Iberian rock lizards (Lacerta monticola) produce copulatory plugs that adhere firmly inside the female cloaca and occlude both oviducts. These plugs do not prevent rival male insemination, as they neither reduce female attractiveness or receptivity to rival males nor do they function as chastity belts. Prior to copulation, males bite various regions of the female body, including the cloacal region. A previous plug in the female cloaca is expelled only after rival male intromission. We hypothesized that: (1) such male pre-copulatory behaviours function to loosen plug adherence to the female cloaca, thereby facilitating intromission, and that (2) the hemipenis plays a role in displacing a previous plug prior to the delivery of a new plug. Neither of these hypotheses was supported. Instead, our results indicate that rival males can intromit the hemipenis past a previous plug in the female cloaca and deliver their own plug underneath it. Consequently, previous plugs are pushed away from the oviductal openings and even dislodged from the female cloaca. Copulation duration was determined both by the time used by males to deliver a plug and by the fact that males prolonged copulation beyond plug delivery. There seemed to be sexual conflict over prolonged copulation, which was resolved by the male/female head-length ratio. The adaptive value of Iberian rock lizard copulatory plugs and prolonged copulation in Iberian rock lizards is discussed in the context of sperm competition.Communicated by S. Downes 相似文献