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1.
Selective males and ardent females in pipefishes 总被引:6,自引:0,他引:6
Summary In the pipefishes Syngnathus typhle and Nerophis ophidion, males have been shown to limit female reproductive rate, and females to compete for access to males. Hence, these species fit the criteria for sex-role reversal. Males brood the eggs and provide the offspring with nutrients, oxygen and an osmoregulated environment. Moreover, in S. typhle both sexes prefer a larger mate when given a choice. Sexual selection theory predicts that males should be more choosy than females, and that was experimentally demonstrated in this study. We predicted that S. typhle males should be less eager to copulate than S. typhle females with an unattractive (i.e. small) mate. We measured eagerness as the time from the start of the experiment until copulation occurred. Males with unattractive partners took significantly longer to copulate than females with unattractive partners. Moreover, females invariably initiated the courtship dance, and resumed it quicker after copulation than did the males, again suggesting reproductive hesitation in males. Neither male nor female size per se was correlated with time until copulation. In N. ophidion, where we have previously shown that males prefer larger to smaller females, we found that females did not select males with regard to size. Our results are consistent both with earlier findings (males limit female reproduction and females compete for males) and with operational sex ratios in nature: in seven annual field samples in June, the numbers of S. typhle females with ripe eggs always significantly exceeded numbers of receptive males. Hence, the potential cost of being choosy in terms of lost matings is much higher in females than in males. In conclusion, S. typhle females were somewhat choosy, but less so than males, whereas N. ophidion females were not choosy at all.
Correspondence to: A. Berglund 相似文献
2.
Male limitation of female reproductive success in a pipefish: effects of body-size differences 总被引:2,自引:0,他引:2
Summary In the pipefish Syngnathus typhle, a species with exclusive male parental care, males limit female reproductive success because of their limited brood pouch space and long pregnancy. Sexual size dimorphism is absent in these 1-year-old animals but increases with age so that older females are larger than similarly aged males. Because fecundity is related to size in both sexes and increases more rapidly with body size in females than in males, the difference in growth increases female fecundity more, relative to male fecundity, as the fish get older. We therefore predicted that male limitation of female reproductive success is even more severe when all age classes are considered. To measure a female's maximum reproductive rate, she was provided with three males. Small 1-year-old females produced as many eggs, or produced eggs at the same rate, as a male of similar size could care for. Small females filled on average 1.06 males within the time span of one male pregnancy and actually produced on average 10 eggs fewer than needed to fill a similarly sized male. Large 2-year-old females, in contrast, produced on average a surplus of 149 eggs and filled 2.7 similarly sized males within the course of one pregnancy. The difference between females of the two size classes was highly significant. Males prefer to mate with larger females if given a choice. In nature sex ratios are equal, and males limit female reproductive success in the whole population. Therefore, small females are more severely constrained by mate availability than are larger females because males choose to mate with larger females.
Offprint requests to: A Berglund 相似文献
3.
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
4.
Sex ratios,mating behavior and sexual size dimorphism of the northern water snake,Nerodia sipedon 总被引:4,自引:0,他引:4
Patrick J. Weatherhead Frances E. Barry Gregory P. Brown Mark R. L. Forbes 《Behavioral ecology and sociobiology》1995,36(5):301-311
Competition among males to mate is generally associated with male-biased size dimorphism. In this study we examine mating behavior in the northern water snake (Nerodia sipedon), a species in which males are much smaller than females despite substantial competition among males to mate. Competition among males was a consequence of a male-biased operational sex ratio due to slightly higher female mortality from a birth sex ratio of 1 : 1, and, in 1 year, more synchronous and longer mating activity by males. Approximately one-third of both males and females appeared not to mate in a given year. Larger males were generally more likely to attempt mating, but size did not explain the variance in the number of aggregations in which individual males participated. Within aggregations, males that were successful at achieving intromission were larger than unsuccessful males in 1 of 2 years. Variation in condition (mass relative to length) and relative tail length were not generally useful predictors of either mating effort or success in males. Because large size was often advantageous to males, sexual size dimorphism appeared not to be a consequence of sexual selection favoring smaller males. Because sexual dimorphism was evident at birth, and both males and females matured sexually at about 4 years, sexual dimorphism was not simply a consequence of one sex growing at the maximum rate for longer. Female fecundity increased with size, and sex differences in size-fecundity relations may underly the pattern of sexual size dimorphism. However, because multiple mating by females is common, sperm competition is likely to be important in determining male reproductive success. Therefore, allocation of energy to sperm rather than growth may also prove to be an important influence on male growth rates and sexual size dimorphism. 相似文献
5.
Lingbing Wu Huaping Zhang Ting He Zeliang Liu Yu Peng 《Behavioral ecology and sociobiology》2013,67(2):205-212
Sexual cannibalism is hypothesized to have evolved as a way to obtain a high-quality meal, as an extreme mate choice or as a consequence of female aggressive spillover. Here, we examined underlying factors likely to influence sexual cannibalism in the wolf spider Pardosa pseudoannulata (Bösenberg & Strand, 1906) from China, including mating status, female egg-laid status, female hunger level, female adult age and mate size dimorphism. The results showed that about 10 % of P. pseudoannulata virgin females cannibalized the approaching males before mating and that 28 % of P. pseudoannulata virgin females immediately cannibalized the males after mating. No incidents of sexual cannibalism during copulation were observed. Before mating, previously mated females and starved females tended to engage in significantly higher rates of attacks compared to virgin and well-fed females. Females that had laid egg sacs tended to engage in a significantly higher rate of attacks and sexual cannibalism than virgin females before mating. Regardless of pre- or post-mating, there was a strong positive relationship between mate size dimorphism and the occurrence of sexual cannibalism. We also tested the effects of sexual cannibalism on the fecundity of cannibalistic females and the survival of their offspring. Our results indicated that sexual cannibalism affected positively the offspring survival of cannibalistic females, but not fecundity. Our findings support the hypothesis that sexual cannibalism has evolved as an adaptive component of female foraging strategy and that it benefits offspring survival as a result of paternal investment. 相似文献
6.
Chad C. Smith 《Behavioral ecology and sociobiology》2014,68(3):415-424
Genetic analyses of parentage provide crucial information about the prevalence of polyandry and the potential for sexual selection to operate in wild populations. In the swordtail Xiphophorus nigrensis, large males are thought to have a competitive advantage due to their superiority in male–male contests and attractiveness to females, who are presumed to mate multiply. I examined the distribution of paternity within broods, the relationship between male body size and paternity and the effect of sire number on fecundity from females collected in the field. Sixty-one percent of females produced offspring from two to four males, with 70% of the offspring typically sired by one of the males represented in the brood. Male body size did not affect paternity share or whether females were multiply mated, as predicted if precopulatory sexual selection has a strong effect on the outcome of postcopulatory sexual selection. Female fecundity increased with the number of sires; however, this relationship was not observed when the smallest broods, where multiple mating is more difficult to detect, were excluded from the analysis. The high levels of multiple paternity and reproductive skew suggest that postcopulatory sexual selection has important evolutionary consequences in X. nigrensis. Traits important in precopulatory sexual selection, such as male body size, however, are more likely to affect sexual selection by increasing the number of mates obtained rather than paternity share within broods. 相似文献
7.
Male seahorses (genus Hippocampus) provide all post-fertilization parental care, yet despite high levels of paternal investment, these species have long been
thought to have conventional sex roles, with female mate choice and male–male competition. Recent studies of the pot-bellied
seahorse (Hippocampus abdominalis) have shown that sex-role reversal occurs in high-density female-biased populations, indicating that male mating preferences
may lead to sexual selection on females in this species. Egg size, egg number, and offspring size all correlate positively
with female body size in Hippocampus, and by choosing large mating partners, male seahorses may increase their reproductive success. While male brood size is
also positively correlated with body size, small H. abdominalis males can carry exceptionally large broods, suggesting that the fecundity benefits of female preference for large partners
may be limited. We investigated the importance of body size in reproductive decisions of H. abdominalis, presenting focal individuals of both sexes with potential mating partners of different sizes. Mating preferences were quantified
in terms of time spent courting each potential partner. Male seahorses were highly active throughout the mate-choice trials
and showed a clear behavioral preference for large partners, while females showed significantly lower levels of activity and
equivocal mating preferences. The strong male preferences for large females demonstrated here suggest that sexual selection
may act strongly on female body size in wild populations of H. abdominalis, consistent with predictions on the importance of female body size for reproductive output in this species.
An erratum to this article can be found at 相似文献
8.
Summary Over five hundred adult longhorn milkweed beetles, Tetraopes tetraophthalmus, were individually marked and their copulatory success followed for one month in a pasture of Asclepias syriaca in northern Indiana, USA. Migration of beetles from the field site was greatest from areas of low population density. Dispersal was significantly greater for males experiencing low copulatory success; a similar but nonsignificant trend was observed for females. Large males, which displayed greater site tenacity than small males, copulated more frequently than small males because of their ability to displace small males from females. Both large and small males demonstrated a preference for large females in laboratory tests. Male preference in combination with aggressive displacement of small males results in size-assortative mating which was much stronger under conditions of high population density. It contributes to variance in male reproductive success since female size is known to be correlated with fecundity and offspring viability. Variance in copulatory success is similar for males and females, suggesting that both sexes experience similar intensities of sexual selection with respect to this component of reproductive success. Futhermore, comparison of this with other studies suggests that the intensity of sexual selection among males is positively correlated with the variance in body size which appears to be under both stabilizing and directional sexual selection in males but not in females. 相似文献
9.
Optimal parental investment usually differs depending on the sex of the offspring. However, parents in most organisms cannot
discriminate the sex of their young until those young are energetically independent. In a species with physical male–male
competition, males are often larger and usually develop sexual ornaments, so male offspring are often more costly to produce.
However, Onthophagus dung beetles (Coleoptera; Scarabaeidae) are highly dimorphic in secondary sexual characters, but sexually monomorphic in
body size, despite strong male–male competition for mates. We demonstrate that because parents provide all resources required
by their offspring before adulthood, O.
atripennis exhibits no sexual size dimorphism irrespective of sexual selection pressure favoring sexual dimorphism. By constructing
a graphic model with three fitness curves (for sons, daughters, and expected fitness return for parents), we demonstrate that
natural selection favors parents that provide both sons and daughters with the optimal amount of investment for sons, which
is far greater than that for daughters. This is because the cost of producing small sons, that are unable to compete for mates,
is far greater than the cost of producing daughters that are larger than necessary. This theoretical prediction can explain
sexual dimorphism without sexual size dimorphism, widely observed in species with crucial parental care such as dung beetles
and leaf-rolling beetles, and may provide an insight into the enigmatic relationship between sexual size dimorphism and sexual
dimorphism. 相似文献
10.
Jennifer D. Cooper Peter M. Waser Eric C. Hellgren Timothy M. Gabor J. A. DeWoody 《Behavioral ecology and sociobiology》2011,65(4):775-785
Sexual dimorphism is common in polygynous species, and there is clear evidence that both intra-sexual competition and female
preferences can drive the evolution of large body size in males. In contrast, sexual monomorphism is often argued to reflect
a relaxation of male mate competition or an intensification of resource competition among females. Alternatively, it might
imply opportunities for females to circumvent or counteract male mate competition in a polygynandrous mating system. We test
the prediction that sexual monorphism is associated with polygynandry in the collared peccary (Pecari tajacu, Tayassuidae), a social ungulate closely related to the old-world suids. The genetic mating system in the Tayassuidae is
unknown, but its sexual monomorphism presents a striking contrast to the strong size dimorphism found in most Suidae, so that
a departure from the polygynous system common in Suidae would be noteworthy. We characterized genetic relationships among
adults within herds in three geographically distinct populations, assigned parents to 75 offspring, and tested for skew in
individual reproductive success. Parentage assignment data indicated that multiple males sire offspring within a herd, and
in the population for which genetic data were most complete, 19% of parentage assignments were potentially sired by extra-herd
males. Some litters have multiple sires, and neither males nor females monopolized reproduction, even in small herds. This
result supports our prediction and suggests that sexual monomorphism may either select for or be an evolutionary consequence
of a promiscuous mating system. 相似文献
11.
Individuals of species that change sex from male to female may gain a “size advantage” from that sex change; that is, as males
become larger, they become female, thus increasing their fecundity with their size. However, males could also gain an early
and different reproductive size advantage by choosing large females as mates. While male preference for large females has
been observed in many dioecious species, we know little about male size preference in sex-changing species. In choice experiments,
we examined whether males of two congeneric species of marine sex-changing snails, Crepidula fornicata and C. convexa, chose large females over small ones as partners. We also used choice tests to see whether males of C. fornicata, a species whose members form long-term, multi-animal stacks, would choose two females in a stack over a single female. Surprisingly,
males of neither species showed a preference for large females, in spite of the documented fecundity advantage associated
with large female-size. Males of C. fornicata chose slightly, but not significantly, more single females than stacks, suggesting that neither number nor size drives mate
choice in these animals. Key factors that may influence this lack of size preference include long association time, the likelihood
of sperm competition, and the cost of extended mate search; it may also be that sex-change itself, the very factor that creates
female-biased sexual size dimorphism in these species, prevents size preference, as males may gain sufficient reproductive
advantage from eventually becoming large females themselves to offset any benefit of choosing large females. 相似文献
12.
Denson Kelly McLain 《Behavioral ecology and sociobiology》1992,30(5):347-356
Summary Population density affects the dynamics of mate acquisition and the opportunity for sexual selection in natural populations of the seed bug, Neacoryphus bicrucis Say (Hemiptera : Lygaeidae). The opportunity for sexual selection and the intensity of directional sexual selection on body length increased as the population density declined within a season for a population in a small, disjunct patch of host plant, Senecio anonymus. In a larger, dispersed population, both measures of selection were greater in host plant patches of low rather than high adult density when the population was sampled at peak density. Under conditions of higher density, males were more likely to share plants, larger males were less likely to monopolize patches of host plant to which females were attracted for mating, and smaller males were more likely to mate in the presence of large males. Thus, resource defense polygyny collapsed under high density, obviating the advantage of size in territory control, and resulted in scramble competition among males for mates. The population exhibited significant additive genetic variation for body length. This suggests that natural selection acting on other components of fitness favors smaller size or that the direction of sexual selection on size fluctuates between generations in response to the between-year variation in population density. Thus, strong sexual selection appears to impose a significant genetic load. 相似文献
13.
The genetic mating system of a sex-role-reversed pipefish (Syngnathus typhle): a molecular inquiry 总被引:4,自引:0,他引:4
Adam G. Jones Gunilla Rosenqvist Anders Berglund John C. Avise 《Behavioral ecology and sociobiology》1999,46(5):357-365
In the pipefish Syngnathus typhle as in other species of Syngnathidae, developing embryos are reared on the male's ventral surface. Although much laboratory
research has been directed toward understanding sexual selection in this sex-role-reversed species, few studies have addressed
the mating behavior of S. typhle in the wild, and none has capitalized upon the power of molecular genetic assays. Here we present the first direct assessment
of the genetic mating system of S. typhle in nature. Novel microsatellite loci were cloned and characterized from this species, and employed to assay entire broods
from 30 pregnant, field-captured males. Genetic analysis of 1340 embryos revealed that 1–6 females (mean = 3.1) contributed
to each brooded clutch, the highest rate of multiple maternity yet documented in any pipefish. Evidence of multiple mating
by females was also detected. Thus, this population of S. typhle displays a polygynandrous mating system, a finding consistent with previous field and laboratory observations. Our results,
considered together with similar studies of other syngnathid species, provide preliminary support for the hypothesis that
the genetic mating system is related to the evolution of sexual dimorphism in the fish family Syngnathidae.
Received: 19 January 1999 / Received in revised form: 15 April 1999 / Accepted: 9 May 1999 相似文献
14.
Matteo Pizzolon Maria B. Rasotto Carlotta Mazzoldi 《Behavioral ecology and sociobiology》2008,62(4):521-528
Female ornamentation may be directly sexually selected, by male choice or female competition, or occurs as the result of a
genetic correlation, arising from sexual selection on males. However, increasing evidence supports the former hypothesis,
suggesting that males actively choose their partner preferring traits indicative of female quality. In the lagoon goby, Knipowitschia panizzae, a polygynous species whose males perform parental care to eggs, body length and the size of a sex-specific yellow patch
on the belly are known to be reliable indicators of female fecundity. In this paper, we tested, using dummies, the male’s
mating preferences for female body and yellow belly patch sizes. The two experimental trials in which a single female trait
was variable showed that males prefer a larger belly patch and a larger body size, indicating that both these characters are
selected by male mate choice. However, when faced with dummies exhibiting an inverse combination of body and belly patch sizes
(experiment 3), males significantly preferred the smaller ones with larger yellow belly patches. A calculation of dummy theoretical
fecundity reveals that in the first two experiments, males would have received an immediate benefit from their choice in terms
of egg number, whereas in the third one, males chose partners that would have provided them with fewer eggs. The male lagoon
goby preference for females with larger belly patches, regardless of their size, suggests that this trait, in addition to
indicating fecundity, conveys information about other aspects of female and/or egg quality. 相似文献
15.
Anders Berglund Gunilla Rosenqvist Sarah Robinson-Wolrath 《Behavioral ecology and sociobiology》2006,60(2):281-287
In a sex role reversed pipefish, Syngnathus typhle, we found that basic life history allocations were directly influenced by sexual selection. We investigated time allocation to foraging and mating, respectively, in a choice experiment, giving males and females, of small or large body size, a choice between food and a potential partner. We found that males were more interested in foraging than mating, i.e., were more frequently observed in front of the food than in front of the partner, whereas females were more interested in the potential partner. This reflects sexual selection operating differently on the two sexes, as males and females are relatively similar in other life history traits, such as growth, mortality, age of maturity, dispersal, and parental expenditure. Moreover, large individuals allocated more time to mating activities, small to feeding. Individuals more interested in mating compared to food were subsequently more critical when given a choice between a large (high-quality) and a small (low-quality) partner, whereas individuals more interested in food were not selective. These findings are consistent with our predictions: sex-role reversed males can be relatively sure of achieving one or more matings, and should allocate more time to feeding and, hence, to parental investment, growth and/or future reproduction. Females, on the other hand, have more uncertain mating prospects and should allocate time to imminent reproductive activities, thereby foregoing other life history traits such as growth and future egg production. By this, they also sacrifice future fecundity and attractiveness. 相似文献
16.
A. J. Moore 《Behavioral ecology and sociobiology》1994,35(4):235-241
The adaptive nature of female mate choice remains one of the most contentious issues in the study of sexual selection. Here, I provide evidence that mate choice by females of the ovoviviparous cockroach Nauphoeta cinerea influences the rate at which offspring develop and provides both direct and indirect benefits to the female. Males that are more attractive to females produce offspring with shorter development times than less preferred males. Development time is heritable and apparently unconstrained by antagonistic pleiotropy. Male attractiveness and rate of offspring development are genetically correlated. Offspring gain an indirect benefit from their mother's mate choice because, on average, individuals that hatch faster reach sexual maturity more quickly. Females that discriminate among males gain a direct benefit because N. cinerea is ovoviviparous and the time between clutches is decreased by producing offspring with shorter development. In addition to providing evidence for beneficial consequences of mate choice, this study highlights how genetic data provide insights into the process of sexual selection not gained in a purely phenotypic study.Communicated by P. Pamilo 相似文献
17.
Sexual selection is often characterized by polygynous breeding systems, size dimorphism, and skewed operational sex ratios.
Koalas are sexually dimorphic in multiple domains, yet are absent from the literature on sexual selection and the structure
of their mating system is unclear. We provide the first documentation of the strength of sexual selection in koalas by using
microsatellite markers to identify sires. We combine the genetic data with morphological data in order to assess the role
of body size in regulating reproductive output. During our 4-year study, 37% of males were identified as possible sires. Males
were significantly larger than females, with sires heavier than non-sires. Male body mass correlated with annual reproductive
output, with Crow’s Index of Opportunity for Selection revealing that variation in male reproductive success was threefold
higher than that of females. Since it appears that male koalas rarely engage in physical confrontations over access to females,
size dimorphism could be based upon non-agonistic competition and/or female mate choice. We propose that size dimorphism in
koalas evolved as a consequence of endurance rivalry promoting vocal sexual advertisements that attract females. We suggest
that female choice is a key mediator of male reproductive output. 相似文献
18.
The aim of this study was to investigate reproductive strategies and their consequences in gray mouse lemurs (Microcebus murinus), small solitary nocturnal primates endemic to Madagascar. Previous reports of sexual dimorphism in favor of males and females,
respectively, a high potential for sperm competition and pheromonal suppression of mating activity among captive males, led
us to investigate mechanisms of intrasexual competition in a wild population. Based on 3 years of mark-recapture data, we
demonstrate that sexual dimorphism in this species fluctuated annually as a result of independent changes in male and female
body mass. Male body mass increased significantly prior to the short annual mating season. Because their testes increased
by 100% in the same period and because their canines are not larger than those of females, we suggest that large male size
may be advantageous in searching for estrous females and in enabling them to sustain periods of short-term torpor. In contrast
to reports from captive colonies, we found no evidence for two morphologically distinct classes of males. Finally, we also
show that most adult males are active throughout the cool dry season that precedes the mating season, whereas most adult females
hibernate for several months. This is in contrast to other solitary hibernating mammals, where males typically emerge 1–2
weeks before females. Thus, this first extended field study of M.␣murinus clarified previous conflicting reports on sexual dimorphism and male reproductive strategies in this primitive primate by
showing that their apparent deviation from predictions of sexual selection theory is brought about by specific environmental
conditions which result in sex-specific life history tactics not previously described for mammals. A general conclusion is
that sexual selection can operate more strongly on males without resulting in sexual dimorphism because of independent selection
on the same traits in females.
Received: 6 July 1997 / Accepted after revision: 28 March 1998 相似文献
19.
Sjouke A. Kingma István Szentirmai Tamás Székely Veronika Bókony Maarten Bleeker András Liker Jan Komdeur 《Behavioral ecology and sociobiology》2008,62(8):1277-1288
Melanin-based ornaments are often involved in signaling aggression and dominance, and their role in sexual selection is increasingly
recognized. We investigated the functions of a melanin-based plumage ornament (facial ‘mask’) in male Eurasian penduline tits
Remiz pendulinus in the contexts of male–male aggression, mating success, and parental care. The penduline tit is a passerine bird with a
unique mating system in which both sexes may mate with several mates in a breeding season, and one (or both) parent deserts
the clutch. Our study revealed that mask size of males is more likely an honest signal used by females in their mate choice
decisions than a trait involved in male–male competition. First, mask size increased with both age and body condition, indicating
that the mask may signal male quality. Second, males with larger masks paired more quickly and had more mates over the breeding
season than males with smaller masks. Third, we found no evidence that male mask size signals male–male aggression or dominance
during competitive encounters. The increased mating success of large-masked males, however, did not translate into higher
reproductive success, as nestling survival decreased with mask size. Therefore, we conclude that there is either no directional
selection on male mask size or males with larger masks receive indirect, long-term benefits. 相似文献
20.
The occurrence of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) provides an exceptionally
fertile system in which to investigate issues related to the evolution of parental care. Here, we take advantage of this unique
reproductive system to study the influence of maternal body size on embryo survivorship in the brood pouches of pregnant males
of the broad-nosed pipefish, Syngnathus typhle. Males were mated with either two large females, two small females, a large then a small female, or a small then a large
female. Our results show that offspring survivorship depends on an interaction between female body size and the number of
eggs transferred by the female. Eggs of larger females deposited in large numbers are more likely to result in viable offspring
than eggs of smaller females laid in large numbers. However, when females deposited smaller numbers of eggs, the eggs from
smaller females were more likely to produce viable offspring compared to those from larger females. We found no evidence that
this result was based on mating order, the relative sizes of competing females, or egg characteristics such as dry weight
of eggs. Additionally, male body size did not significantly influence the survivorship of offspring during brooding. Our results
suggest that the factors underlying offspring survivorship in pipefish may be more complex than previously believed, with
multiple factors interacting to determine the fitness of individual offspring within the broods of pregnant males. 相似文献