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1.
Frank Marlowe 《Behavioral ecology and sociobiology》1999,46(1):57-64
Paternal care figures prominently in many scenarios of human evolution. Recently, however, such scenarios have been challenged
on two scores. First, the level of male contribution may be insignificant. Second, male care may be provided as a form of
mating effort, rather than parenting effort. In theory, since men can enhance their Darwinian fitness both by providing care
to their own offspring if this raises offspring fitness and by pursuing additional mates if this leads to additional offspring,
men should respond to payoffs from both mating and parenting effort. If men respond to payoffs from parenting effort, paternity
ought to make a difference. And if men respond to payoffs from mating effort, mating opportunities ought to make a difference.
I analyzed the impact of these two factors on variation in male care among the Hadza, a foraging society in Tanzania. Two
predictions were tested: (1) biological children will receive more care than stepchildren, and (2) men will provide less care
to their biological children as their mating opportunities increase. Both predictions were supported. These results suggest
men provide care, in part, as parenting effort, and that they trade off parenting effort for mating effort when they have
greater mating opportunities.
Received: 21 January 1998 / Received in revised form: 24 January 1999 / Accepted: 1 February 1999 相似文献
2.
Alternative male mating tactics in a cichlid, Pelvicachromis pulcher: a comparison of reproductive effort and success 总被引:2,自引:0,他引:2
Pelvicachromis pulcher is a small African cichlid which breeds in holes. Males may either reproduce monogamously (pair males), polygynously (harem
males), or be tolerated as helpers in a harem territory (satellite males). These helpers share in defence of the territory
against conspecifics, heterospecific competitors and predators. There are two male colour morphs that are fixed for life and
are apparently genetically determined. These differ in their potential mating strategy. Red morph males may become harem owners,
while yellow morph males may become satellite males, and males of both morphs may alternatively pair up monogamously. We compared
the reproductive effort and success of these three male reproductive strategies. Effort was measured as attack rates, time
expenditure and the risk of being injured or killed when attacking competitors or predators of three sympatric fish species.
Reproductive success was measured by observing how many eggs were fertilized by each male when this was possible, and by using
genetic markers. The number of fry surviving to independence of parental care was used as a criterion of success. The reproductive
success of harem males was 3.3 times higher than that of pair males and 7 times higher than that of the average satellite
male. Dominant satellite males, however, were as successful as monogamous pair males, using the measure of fertilized eggs.
To our knowledge, this has not been found previously in any fish species. Both harem and pair males had lower parental defence
costs per sired offspring, however, than males using the alternative satellite tactic. Defence effort was significantly related
to the risk of injury.
Received: 17 January 1996 / Accepted after revision: 9 June 1997 相似文献
3.
Ø. Holand R. B. Weladji K. H. Røed H. Gjøstein J. Kumpula J.-M. Gaillard M. E. Smith M. Nieminen 《Behavioral ecology and sociobiology》2006,59(5):682-688
The manipulation of the sex ratio and age structure in many managed ungulate populations calls for a better understanding
of their potential consequences on females’ condition and behavior during rut. During 1996–2002, we manipulated the male age
structure and male percentage (nine treatments during 7 years) within an experimental herd of semidomestic reindeer (Rangifer tarandus) and investigated their influence on both the body mass change and the behavior of females during rut. On average, the females
lost body mass (−0.95±SE 0.18 kg) during rut, which we contend to reflect somatic costs. The females’ losses increased as
the percentage of male decreased, but this was certainly ascribed to one treatment with high male percentage (27.7%) as compared
to the others (ranging from 3.9 to 12.2%). Female losses were highest for treatments including both young and adult males
as compared to only adult or only young males, and higher for treatments including only young compared to only adult males.
This is supported by (1) the higher female harassment frequency when females are exposed to only young or a mixture of young
and adult males as compared to only adults, (2) the higher female harassment frequency by young males as compared to adults
in the mixed treatments, and (3) the reduced females’ feeding activity in treatments including both young and adult males.
We conclude that the male age structure during rut will influence the females’ behavior and mass change and may have implications
for females’ life history and for population dynamics. 相似文献
4.
C. Cordero 《Behavioral ecology and sociobiology》2000,48(6):458-462
The differential costs of mating paid by males and females influence the nature and strength of sexual selection. In butterflies,
males invest a relatively large amount of time and resources in each mating, but male survival costs of mating have not been
demonstrated. I present the results of experiments designed to measure the effect of different aspects of mating on male longevity
in the polygynous butterfly Callophrys xami. In experiment 1, I compared the longevity of pairs of males that produced similar amounts of spermatophore, but that mated
at different rates, a different numbers of times, and that produced spermatophores at different rates, and found that the
longevity of ”low-mating-rate” males was not different from that of ”high-mating-rate” males. In experiment 2, the longevity
of virgin males was not significantly different from that of multiply mated males. In experiment 3, I used resource-limited
males resulting from experimental food limitation of last-instar larvae; resource-limited virgin males lived significantly
more days than resource-limited multiply mated males. Since ecological costs of mating (e.g., disease transmission, predation
risk) were excluded in the experiment, diminished male longevity was a product of physiological costs of sexual interactions.
These results suggest that the cost of ejaculate production is an important cause of longevity reduction when there are resource
limitations; however, the role of other possible physiological costs of mating in longevity reduction is still unknown.
Received: 21 March 2000 / Accepted: 26 August 2000 相似文献
5.
Kit Magellan Lars B. Pettersson Anne E. Magurran 《Behavioral ecology and sociobiology》2005,58(4):366-374
Although many studies have examined the effects of male size on attractiveness and mating behaviour, few have taken genetic background into consideration. Phenotypic manipulation permits the experimental adjustment of morphological traits while keeping genetic background constant. Here, male guppies, Poecilia reticulata, an ideal model for this type of manipulation, were raised at different temperatures to produce sibling pairs that differed in size. These were then used to investigate male mating behaviour and male attractiveness, assessed through female mate choice, in relation to this size dimorphism. Further, male–male competition, which is intrinsic to male mating behaviour, is also likely to be affected by their size. Through the use of repeated measures analyses we demonstrate that females significantly prefer larger males and male size and competition significantly affect several aspects of male mating behaviour. Larger siblings perform more sneaky mating attempts and spend more time chasing females. The frequencies of both these behaviours increase with competition. While display frequency is unaffected by male size and competition, display duration and the amount of time spent attending females are reduced in the presence of competitors. This study highlights the use of phenotypic manipulation as a valuable tool for investigating behavioural interactions and confirms that both male size and competition are significant factors in the guppy mating system. 相似文献
6.
Rocky Mountain bighorn rams use three distinct tactics in competition for mates. Two tactics (tending and blocking) feature
defense and cooperative mating over a relatively prolonged consort period (up to 3 days). In the coursing tactic, subordinate
rams fight dominants for temporary copulatory access (lasting seconds) to defended ewes. By combining population-wide genetic
(microsatellite) exclusion of paternity, behavioral data and a model of bighorn reproductive competition, we estimated that
coursing rams fathered 44% of 142 lambs assigned paternity in two natural populations. In one population, the probability
of successful defense against coursing was lowest among rams that had many female consorts and held highest dominance rank.
Even so, per capita annual male reproductive success was positively associated with social rank in both herds when measured
in terms of fall conceptions. The proportion of coursing versus defending ram matings in each population (0.36 and 0.39) was
similar to the corresponding fraction of lambs (0.43 and 0.47) fathered by coursing rams, suggesting that sperm competition
approximated a fair lottery. Male traits important in gaining social status and obtaining cooperative consorts with ewes were
different and potentially in conflict with those needed to defend against (and practise) coursing. Although the concussive
weapons (horns) of rams are less dangerous than, for example, the piercing weapons of other bovids, injury from falls and
horn blows during coursing brawls may cause death, handicap future mating competition or increase the risk of predation. Coursing
is a rare example of an unconventional alternative mating tactic that is high-gain and high-risk.
Received: 17 April 1996 / Accepted after revision: 15 March 1997 相似文献
7.
Jay D. Evans 《Behavioral ecology and sociobiology》1996,39(4):275-284
In many polygynous ant species, established colonies adopt new queens secondarily. Conflicts over queen adoption might arise
between queens and workers of established colonies and the newly mated females seeking adoption into nests. Colony members
are predicted to base adoption decisions on their relatednesses to other participants, on competition between queens for colony
resources, and on the effects that adopted queens have on colony survivorship and productivity. To provide a better understanding
of queen-adoption dynamics in a facultatively polygynous ant, colonies of Myrmica tahoensis were observed in the field for 4 consecutive years and analyzed genetically using highly polymorphic microsatellite DNA markers.
The extreme rarity of newly founded colonies suggests that most newly mated queens that succeed do so by entering established
nests. Queens are closely related on average (rˉ = 0.58), although a sizable minority of queen pairs (29%) are not close relatives. An experiment involving transfers of queens
among nests showed that queens are often accepted by workers to which they are completely unrelated. Average queen numbers
estimated from nest excavations (harmonic mean = 1.4) are broadly similar to effective queen numbers inferred from the genetic
relatedness of colony members, suggesting that reproductive skew is low in this species. Queens appear to have reproductive
lifespans of only 1 or 2 years. As a result, queens transmit a substantial fraction of their genes posthumously (through the
reproduction of related nestmates), in comparison to direct and indirect reproduction while they are alive. Thus queens and
other colony members should often accept new queens when doing so will increase colony survivorship, in some cases even when
the adopted queens are not close relatives.
Received: 20 February 1996/Accepted after revision: 25 May 1996 相似文献
8.
Hybridization is a widespread phenomenon in many vertebrate groups. Prezygotic isolating mechanisms, probably caused by selection against hybrids with reduced fitness, reduce the likelihood of such events. Although hybrid-reduced fitness relatively to parental species is common, hybridization can also be beneficial, and hybrids sometimes outperform the pure species type. In this study, we examined two potential processes, Hubbs’s principle and male–male competition, which could enhance hybridization in the waterfrog complex and thus explain the proportion of heterospecific pairs collected in a natural pond. Firstly, by collecting 791 frogs in the field to study pair and chorus composition, we showed that in a mixed Rana lessonae–Rana esculenta population, the scarcity of hybrid R. esculenta males did not account for the proportion of heterospecific pairs: indeed, when examining pairing composition in six different choruses, we found that hybrid males were always under-represented and that R. esculenta females were found paired with R. lessonae males. Secondly, we investigated experimentally whether or nor male–male competition mechanism could explain pair formation in waterfrogs. Our mating speed experiment highlights mechanisms that could explain heterospecific pairs in a context of promiscuous mating where scramble competition was intense. To measure the rapidity with which a male grasps a female, we placed males in a grid cage with a female, and the dynamics of pair formation was monitored. R. esculenta males showed a lower pairing success than R. lessonae males as a smaller proportion of them amplexed females, and more time was needed for them to get amplexed. Thus, a less adaptative mechanism than female mate choice may also explain the mating pattern observed in waterfrog species. 相似文献
9.
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
10.
Experimental evidence of a testosterone-induced shift from paternal to mating behaviour in a facultatively polygynous songbird 总被引:5,自引:2,他引:3
Previous studies have suggested that testosterone (T) profiles of male birds reflect a trade-off between mate attraction behaviours
(requiring high T levels) and parental care activities (requiring low T levels). In this study, we experimentally elevated
T levels of monogamous males in the facultatively polygynous European starling (Sturnus vulgaris), and compared mate attraction and paternal behaviour of T-treated males with those of controls (C-males). T-males significantly
reduced their participation in incubation and fed nestlings significantly less often than C-males. Females paired to T-treated
males did not compensate for their mate’s lower paternal effort. The observed reduction in a male’s investment in incubating
the eggs was accompanied by an increased investment in typical female-attracting behaviours: T-males spent a significantly
higher proportion of their time singing to attract additional females. They also occupied more additional nestboxes than C-males,
although the differences just failed to be significant, and carried significantly more green nesting materials into an additional
nestbox (a behaviour previously shown to serve a courtship function). T-males also behaved significantly more aggressively
than C-males. During the nestling period, the frequency of mate-attracting behaviours by T-treated and control males no longer
differed significantly. Despite the reduced paternal effort by T-males and the lack of compensation behaviour by females,
hatching and breeding success did not differ significantly between T- and C-pairs.
Received: 7 February 2000 / Revised: 10 August 2000 / Accepted: 3 September 2000 相似文献
11.
Males often use elaborate courtship displays to attract females for mating. Much attention, in this regard, has been focused
on trying to understand the causes and consequences of signal variation among males. Far less, by contrast, is known about
within-individual variation in signal expression and, in particular, the extent to which males may be able to strategically
adjust their signalling output to try to maximise their reproductive returns. Here, we experimentally investigated male courtship
effort in a fish, the Australian desert goby, Chlamydogobius eremius. When offered a simultaneous choice between a large and a small female, male gobies spent significantly more time associating
with, and courting, the former, probably because larger females are also more fecund. Male signalling patterns were also investigated
under a sequential choice scenario, with females presented one at a time. When first offered a female, male courtship was
not affected by female size. However, males adjusted their courtship effort towards a second female depending on the size
of the female encountered previously. In particular, males that were first offered a large female significantly reduced their
courtship effort when presented with a subsequent, smaller, female. Our findings suggest that males may be able to respond
adaptively to differences in female quality, and strategically adjust their signalling effort accordingly. 相似文献
12.
O. Anne E. Rasa 《Behavioral ecology and sociobiology》1998,43(2):105-113
Parastizopus armaticeps is a nocturnal subsocial detritivorous desert tenebrionid that produces very few offspring per brood. The two environmental
factors that constrain reproduction, rapid sand desiccation rate and food scarcity, are countered by biparental effort. Males
dig and extend breeding burrows, maintaining their moisture level; females forage on the surface at night for high-quality
detritus, the larval food. This was shown to be a scarce and unpredictable resource for which there is high competition. When
food was supplemented in a field experiment, offspring number and survivorship doubled and burrow failure due to desiccation
dropped from approximately half, the typical failure rate for unsupplemented burrows, to zero. Food supplementation did not,
however, increase larval foodstore size and there was no difference in the size of the offspring produced. Supplemented females
reallocated their time, foraging less and digging more with the male. This change in maternal behaviour patterns resulted
in deeper burrows which remained moist longer, thus extending the larval production period. Female foraging efficiency, particularly
food retrieval speed, determined how much time females could allocate to digging, consequently increasing the reproductive
success of the pair. Burrow depth and sand moisture level at the burrow base were the major correlates of reproductive success,
but the scarcity and unpredictability of high-quality food on the surface and the competition for this resource influenced
the number of offspring indirectly through their effect on female behaviour.
Received: 29 November 1996 / Accepted after revision: 7 December 1997 相似文献
13.
There is genetic variation in the female mating rate in the green-veined white butterfly (Pieris napi), and females benefit from male ejaculates that contain both sperm and accessory gland substances. Although polyandry corresponds to higher lifetime fecundity than monandry, some females abstain from remating irrespective of the number of available mates. Explaining genetic variation in mating rates requires that monandrous females perform better than polyandrous ones under some conditions. We experimentally explored the reproductive performance of females either with a low or high intrinsic mating rate by allowing them to mate, feed, and lay eggs freely in a laboratory. Individual females followed different life histories: during the early days of reproduction, females with a low mating rate produced more eggs than females with a high mating rate. Hence, refraining from the benefits of multiple mating may be beneficial, if the time for reproduction is limited, or other female traits associated with polyandry are traded off against longevity. Given the day length of 10 h, a model shows that even if polyandrous females enjoy higher lifetime reproductive success, changeable and unpredictable weather will favor monandry if each period of suitable weather lasts, on average, less than 5 days. Thus, a combination of life history cost and unpredictability of fitness may explain the maintenance of monandry in the wild. Our results are also consistent with the observation that frequency of monandry increases with latitude. 相似文献
14.
J. Antonio Baeza 《Behavioral ecology and sociobiology》2007,61(3):365-370
Sex allocation theory predicts phenotypic adjustments by individuals in their investments into the male and female reproductive function in response to environmental conditions. I tested for phenotypically plastic shifts in sex allocation in a protandric simultaneous hermaphrodite, in which individuals mature and reproduce as males first, and later in life, as simultaneous hermaphrodites. I predicted that initially maturing males should adjust the timing of maturation as hermaphrodites according to male mating opportunities mediated by population size of hermaphrodites. In a first experiment, males maintained with only one hermaphrodite reduced the time they spent as males in comparison to males maintained with no conspecifics, presumably because total reproductive output is maximized by two individuals being simultaneous hermaphrodites when the mating system is a pair. Conversely, males maintained in groups with two or more hermaphrodites increased the time they spent as males in comparison to single males. This delay in maturation was not an effect of resource depletion with increasing shrimp density because the growth rate of males did not differ among most of the experimental treatments. One hypothesis to explain this social mediation of sex allocation is that the smaller males are more successful in mating as males than are the larger hermaphrodites: it will pay reproductively for males to delay maturation as hermaphrodites in large but not in small groups. In agreement with this notion, a second experiment demonstrated that smaller males were four times more successful than were larger hermaphrodites in inseminating shrimps reproducing as females. The informative cue that males may use to perceive different group sizes deserves further attention. 相似文献
15.
Female and male reproductive interests often differ. In species in which matings are accompanied by a transfer of resources
valuable for both participants, such as nuptial prey gifts, conflicts may readily occur. Scorpionflies may use alternative
mating tactics. One is to offer a prey item (dead arthropod) to females in exchange for mating. This prey gift tactic includes
a conflict because a male must decide on whether to offer the gift rather than to fight the female and consume the gift. The
outcome may depend on the nutritional status of both males and females. Males may be more willing to give if they themselves
are satiated and the condition of the females may influence the payoff from the males’ investment. Similarly, females may
be more willing to accept food gifts if they are in poor nutritional condition. In this study of the scorpionfly Panorpa cognata, I experimentally manipulated the feeding history of both males and females. I observed the outcome of the direct interactions
that followed when males that were holding prey were approached by females. I found that well-fed males offered the food gift
sooner than males in poor nutritional condition that fed extensively on the food item before offering. Female condition had
no significant influence on whether prey items were offered by males or accepted by females. I also found that well-fed males
rarely searched for prey to pursue the prey gift tactic in courtship. Thus, the prey tactic does not seem to be the males’
first option. 相似文献
16.
Adjustment of parental effort to manipulated foraging ability in a pelagic seabird,the thin-billed prion Pachyptila belcheri 总被引:6,自引:0,他引:6
Henri Weimerskirch Olivier Chastel Luc Ackermann 《Behavioral ecology and sociobiology》1995,36(1):11-16
An experiment was designed to examine in a long-lived seabird, the thin-billed prion (Pachyptila belcheri), how adults adjust their food provisioning strategy when their foraging abilities are reduced and when the chick's needs are increased. To reduce the foraging abilities of adults we impaired their flying ability by removing some flight feathers (handicapped), and to increase the food needs of the chick one parent was retained (single). Birds made either short foraging trips lasting 1–3 days, or long trips lasting 5–9 days. Control birds alternated long and short trips whereas single birds or handicapped birds made several successive short trips and thereafter a long trip. In each treatment, food loads tended to be heavier after long trips than after short trips, and single birds tended to bring heavier loads than control or handicapped birds. Birds in the three treatments lost similar amounts of mass after short trips and gained similar amounts of mass after long trips. However, the mass of handicapped birds declined through the experiment, while that of control and single birds remained stable. Although the proportion of chicks that died during the experiment was similar among the three treatments, the chicks fledged by a single bird were lighter than those in control nests. The results of the experiment suggest that thin-billed prions adjust their breeding effort differently to decreased flying ability or increased food demand by the chick. Single birds increase foraging effort without allowing their condition to deteriorate. Conversely, handicapped birds are unable to maintain their body condition while sustaining the chick at the same rate as control birds. It is suggested that in this long-lived seabird, adults probably adjust their breeding effort so that they do not incur the risk of an increased mortality, this risk being monitored by the body condition. 相似文献
17.
Geir Rudolfsen Rudolf Müller Davnah Urbach Claus Wedekind 《Behavioral ecology and sociobiology》2008,62(4):561-567
The mating behavior and reproductive strategies of Alpine whitefish like Coregonus zugensis (Nüsslin) are poorly understood, probably because they spawn in deep water where direct observations are difficult. In this
study, we interpret life-history and sperm quality traits of fish that we caught from their spawning place. We found that
males invest heavily into gonadal tissue (up to 5.6% of their body weight), which is, in comparison to other fish, consistent
with external fertilization, distinct pairing and moderate to high communal spawning, or no pairing and low to moderate communal
spawning. Sperm competition theory and recent experimental studies on other salmonids predict that males optimize ejaculate
characteristics in relation to the costs of sperm and the level of competition they have to expect: dominant males are predicted
to invest less into ejaculate quality and to have slower spermatozoa than subdominant males. We found that spermatozoa of
older males are slower than those of younger males. Moreover, older males have larger breeding tubercles, a secondary sexual
trait that has, in some previous studies, been found to be linked to good condition and to good genetic quality. Our results
suggest that C. zugensis has age-linked reproductive strategies, that multimale spawning is common, i.e., that sperm competition plays a significant
role, and that older males are on average dominant over younger males at the spawning place. 相似文献
18.
Female choice and male–male aggression are two modes of sexual selection that can lead to elaboration of male morphological
and behavioral traits. In lek-mating species, male mating success is often strongly skewed, and it is puzzling why variation
in male traits is still observed given directional female choice. If male traits correlated with reproductive success are
honest signals of male quality, there may be survival costs associated with the expression of those traits. In this study,
we examined whether morphological, behavioral, and territorial traits are correlated with male mating success and survival
in the lek-mating greater prairie-chicken (Tympanuchus cupido). We introduce a novel application of multinomial discrete choice models for analysis of female mate choice behavior. We
found that behavioral and territorial attributes showed 6.5 times more variability among males than morphological traits.
Both display and aggressive behaviors were strong predictors of male mating success, suggesting that both female choice and
male–male aggression were important in determining mating success among male greater prairie-chickens. Moreover, annual survival
of male prairie-chickens was independent of mating success and male traits. Females appear to be choosing males based on behavioral
traits where large variation exists between males (coefficient of variation >30%). Behavioral traits were the most important
factor in determining mating success of male prairie-chickens, but the mechanism underlying this relationship is unknown.
In the future, experimental manipulations of male hormones or parasite loads could bridge the proximate mechanisms and ultimate
consequences of factors mediating male mating success in lek-mating grouse. 相似文献
19.
Defensive and parental care behaviour of convict cichlids that differed in past effort was compared. Before testing, some fish were bred three times while others were not bred. Age was held constant; all individuals in this study were approximately 20 months old (±2 months) at test time. Furthermore, half of the pairs in this study had their broods experimentally reduced by 50%. Results indicated that past effort across breeding attempts affects investment in the current brood. Experienced pairs were more aggressive toward a model predator than inexperienced parents. However, no major differences were observed in depreciable care (i.e. fanning). Contrary to previous studies, brood size had minor effects on parental care. This discrepancy could be due to the age of the parents; individuals in this study were significantly older than fish tested in previous studies. The results support parental investment theory and suggest that past effort is not only important within breeding episodes but also within an animal's lifetime. 相似文献
20.
L. Hughes B. Siew-Woon Chang D. Wagner N. E. Pierce 《Behavioral ecology and sociobiology》2000,47(3):119-128
The mating system of the Australian lycaenid butterfly, Jalmenus evagoras, is highly unusual compared to most other Lepidoptera. Characteristics of this system, which has been termed an ’explosive
mating strategy,’ include the formation of an intensely competitive mating aggregation of males, a highly male biased operational
sex ratio, a lack of discrimination and mate choice by both sexes, a high variance in male mating success, and female monogamy.
In this study, we tested the hypothesis that multiple mating by males imposes physiological costs resulting in smaller spermatophores,
and that this results in a fitness cost to females. We found that male J. evagoras transferred only 2.2% of their eclosion weight during their first mating, consistent with the hypothesis that males of monandrous
species produce a relatively small investment. The wet weight of the ejaculate declined by an average of 27% at the second
mating and the dry weight by 29%, and an intermating interval of 5–9 days was needed for the ejaculate to return to the size
at the first mating, regardless of male size or age. Wet ejaculate mass increased proportionally with male size, though dry
mass was proportionally larger in smaller males. Ejaculate mass tended to increase with male age at both first and second
matings. Female characteristics, in general, did not affect ejaculate mass, although the wet weight of the ejaculate was positively
associated with female weight at the second mating. Copulation duration increased from 2.4 h to approximately 3 h at the second
mating, and to over 4 h at the third and fourth matings. Fecundity was positively correlated with female size but not with
mating history, copulation duration, or any other characteristics measured for either males or females. Female longevity declined
significantly as the number of times the male partner had previously mated increased. We conclude that despite the small male
investment in ejaculate, the costs of multiple mating may nonetheless be significant, as indicated by the reduction in ejaculate
mass, an increase in copulation duration, and reduction in female lifespan with increasing mating number.
Received: 22 January 1999 / Received in revised form: 28 July 1999 / Accepted: 18 September 1999 相似文献