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1.
Body size has often been related to reproductive success in bees and wasps. The objective of this 3-year study was to analyze
the relationship between nesting female body size, provisioning rate and longevity and their effect on several traits related
to parental investment and reproductive success in the solitary bee Osmia cornuta. Body size was not correlated to longevity, and it was only correlated to provisioning rate in the third year (with poor
weather conditions during nesting). Variation in fecundity, offspring size and offspring mortality was not well explained
by nesting female body size in any of the 3 years. However, in the third year, small females biased their investment toward
males, the sex requiring smaller pollen–nectar provisions. Large females were more successful usurpers of other females' nests,
but fecundity of usurpers was no higher than fecundity of nonusurpers. Large females were more likely to establish at the
release site, probably in relation to size-dependent vigor at emergence. A review of the literature on parental investment
in solitary aculeate Hymenoptera showed a stronger relationship between body size and reproductive success in wasps than in
bees. In O. cornuta, fecundity was strongly related to longevity and provisioning rate in all 3 years. Offspring size was associated with provisioning
rate in 1 year, when females with higher provisioning rates tended to produce larger sons and daughters. Both longevity and
provisioning rate appeared to be strongly conditioned by stochastic events. 相似文献
2.
Male-biased size dimorphism is usually expected to evolve in taxa with intense male–male competition for mates, and it is
hence associated with high variances in male mating success. Most species of pycnogonid sea spiders exhibit female-biased
size dimorphism, and are notable among arthropods for having exclusive male parental care of embryos. Relatively little, however,
is known about their natural history, breeding ecology, and mating systems. Here we first show that Ammothella biunguiculata, a small intertidal sea spider, exhibits male-biased size dimorphism. Moreover, we combine genetic parentage analysis with
quantitative measures of sexual selection to show that male body size does not appear to be under directional selection. Simulations
of random mating revealed that mate acquisition in this species is largely driven by chance factors, although actual paternity
success is likely non-randomly distributed. Finally, the opportunity for sexual selection (I
s), an indirect metric for the potential strength of sexual selection, in A. biunguiculata males was less than half of that estimated in a sea spider with female-biased size dimorphism, suggesting the direction of
size dimorphism may not be a reliable predictor of the intensity of sexual selection in this group. We highlight the suitability
of pycnogonids as model systems for addressing questions relating parental investment and sexual selection, as well as the
current lack of basic information on their natural history and breeding ecology. 相似文献
3.
Smith Adam R. Wcislo William T. O'Donnell Sean 《Behavioral ecology and sociobiology》2003,54(1):14-21
Assured fitness returns models for the evolution of sociality emphasize the selective value of ensuring that offspring receive adequate parental care to reach maturity. If a member of a social group dies, it can accrue returns on investment in offspring through the efforts of surviving social partners. We provide evidence that in the mass-provisioning, facultatively social sweat bee Megalopta genalis, adult presence in the nest throughout brood development provides protection from ant predation. Nests with adults present were well protected, and brood in nests with adults removed suffered higher predation. Females in observation nests showed effective defensive behavior against experimentally introduced ants, and bees in natural nests repulsed naturally occurring ant raids. Megalopta nest architecture and behavior are such that the brood of several cooperating females can be defended with little additional cost relative to solitary nesting. The benefits of cooperative defense may favor group living in mass provisioning bees. Our observations and experiments suggest that parental care throughout brood development can be adaptive in mass provisioning species, supporting the predictions of assured fitness returns models. 相似文献
4.
Linda A. Whittingham 《Behavioral ecology and sociobiology》1989,25(1):73-80
Summary The effect of brood size and female nesting status on male parental behavior was investigated in red-winged blackbirds Agelaius phoeniceus using brood size manipulation experiments. Male redwings allocated parental effort on the basis of brood size and nestling age. Males began assisting females only at nests with at least three offspring older than three days. Female nesting status had no singificant influence on male parental care. When females were unable to meet a brood's demand for food, males assisted females with nestling feeding. Females did not reduce the amount of food delivered to nestlings when males assisted. The amount of food brought to nestlings by the male was additional to the amount of food provided by the female. Male assistance increased fledgling success. When female provisioning was sufficient to meet a brood's demand for food males did not assist. The value of male parental care varied inversely with the ability of the female to meet nestling food demands. The ability of unassisted females to provide sufficient food and to raise a brood of nestlings successfully appeared to be influenced by resource abundance. 相似文献
5.
Giuseppe Boncoraglio Roberta Martinelli Nicola Saino 《Behavioral ecology and sociobiology》2008,62(5):729-738
In diverse taxa, offspring solicit parental care using complex displays, which may evolve as reliable signals of condition
or as mechanisms to manipulate parental investment. Differential sex allocation may therefore result from adaptive parental
decisions or sex-related variation in competitive ability or because of sex-related asymmetries in kin selection. Under normal
food provisioning, female barn swallow (Hirundo rustica) nestlings begged more loudly but did not receive more food than male nestlings. After food deprivation, begging call loudness
of males but not females increased. Begging loudness positively predicted the number of feedings received by the nestlings,
and males gained more mass than females after food deprivation. Male nestlings are more severely affected by chronic food
reduction and may therefore accrue a larger benefit compared to females by increasing their food intake under short-term conditions
of food scarcity. These results suggest that either females do not increase begging intensity to favour male broodmates which
are more vulnerable to prolonged food stress, or that males prevail in scramble competition despite being similar in size
to females. 相似文献
6.
Host location and exploitation by the cleptoparasitic wasp Argochrysis armilla: the role of learning (Hymenoptera: Chrysididae) 总被引:3,自引:0,他引:3
Jay A. Rosenheim 《Behavioral ecology and sociobiology》1987,21(6):401-406
Summary The nesting behaviors of many solitary ground-nesting wasps incorporate temporal barriers against would-be cleptoparasites. Nests being excavated are conspicuous but relatively invulnerable to parasites, while nests being provisioned, often several hours to days later, are inconspicuous but highly vulnerable, Argochrysis armilla, a cleptoparasite of solitary ground-nesting wasps, Ammophila spp., bridges the temporal gap between nest excavation and provisioning by (i) visually locating digging hosts, (ii) learning the locations of associated nests, (iii) maintaining surveillance on a series of nests during the hosts' absence, and (iv) ovipositing in nests when the host returns with provisions. Patterns of surveillance and parasitism of Ammophila dysmica nests were generated by the number of cleptoparasites discovering and learning the nest's location during excavation. These results support recent suggestions that learning may play an important role in shaping foraging strategies of insect parasites. 相似文献
7.
Parental investment, adult sex ratios, and sexual selection in a socially monogamous seabird 总被引:7,自引:0,他引:7
Although most birds are monogamous, theory predicts that greater female parental investment and female-biased adult sex ratios
will lower the polygyny threshold. This should result in polygynous mating, unless obligate biparental care or the spatial
and temporal distribution of fertilizable females constrains a male’s ability to take advantage of a lowered polygyny threshold.
Here we present data on the extent of male sexually dimorphic plumage, adult sex ratios and breeding season synchrony in three
populations of a socially monogamous seabird, the brown booby Sula leucogaster. For one of these populations, San Pedro Mártir Island, we also present data on differences in male and female parental investment,
mortality and probability of pairing. The extent of plumage dimorphism varied among populations. Sex ratios were female biased in all populations. On San Pedro
Mártir Island, parental investment was female biased, females failed more often than males to find a mate, but there was no
polygyny. We suggest that on San Pedro Mártir: (1) a period of obligate biparental care coupled with a relatively synchronous
breeding season constrained the ability of males to take advantage of a high environmental polygamy potential and (2) the
resulting socially monogamous mating system, in combination with the female-biased adult sex ratio, caused females to be limited
by the availability of males despite their greater parental investment.
Received: 18 November 1999 / Accepted: 24 January 2000 相似文献
8.
Fisher's theory of sex allocation predicts that, in a panmictic population, parental investment will be equally distributed between male and female progeny. Most studies on parental investment in nesting solitary bees and wasps use offspring or provision weight as estimators of parental investment and do not corroborate Fisher's theory. The measurement of parental investment may be confounded by several factors. First, the use of offspring or provision size does not account for seasonal variation in foraging costs associated with aging of nesting females. Second, provision or offspring size do not reflect parental investment associated with nest construction. In this two-year study we measured parental investment in a solitary bee. We calculated sex allocation using both provision weight and foraging time as parental investment estimators. Investment in pollen-nectar provisions decreased, while investment in mud structures (nest construction) increased, as the nesting period progressed. Overall investment in provisions per nest was ∼25 times higher than investment in mud. Pollen-nectar foraging trips became longer as the season progressed, but mud trip duration did not vary. Due to weather differences between years, more offspring per female were produced in the first year, but progeny sex ratio and mean offspring size of both sexes were similar between years. Mortality did not differ between sexes. As predicted by Fisher's theory, production cost ratios did not differ from 1 in either year, irrespective of the currency used to estimate parental investment (provision weight or foraging time). Our results strongly support Fisher's theory. 相似文献
9.
The morphology and behavior of dimorphic males in Perdita portalis (Hymenoptera : Andrenidae) 总被引:4,自引:0,他引:4
Bryan N. Danforth 《Behavioral ecology and sociobiology》1991,29(4):235-247
Summary In Perdita portalis, a ground nesting, communal bee, males are clearly dimorphic. The two male morphs are easily distinguished based on head size and shape into (1) a flight-capable, small-headed (SH) morph that resembles the males of other closely related species and (2) a flightless, large-headed (LH) morph that possesses numerous derived traits, such as reduced compound eyes, enlarged facial foveae and fully atrophied indirect flight muscles. The SH morph occurs exclusively on flowers while the LH morph is found only in nests with females. While on flowers, SH males are aggressive, fighting with conspecific males and heterospecific male and female bees, and they mate frequently with foraging females. Using artificial observation nests placed in the field, I observed the behavior of females and LH males within their subterranean nests. LH males are aggressive fighters; males attacked each other with mandibles agape, and male-male fights always ended in the death of one male. LH males are highly attentive to the reproductive behavior of females; they spend increasing amounts of time near open cells during cell provisioning, and mating only takes place immediately prior to oviposition when females are forming the accumulated pollen and nectar into a ball. Based on larvae reared to adulthood in the laboratory, the two male morphs occur in equal proportions. The behavior of males in closely related species, especially P. texana, and the origin and maintenance of male dimorphism are discussed. 相似文献
10.
Stone provisioning is a nest-maintenance activity accomplished by pygoscelid penguins after reliefs during the incubation/brooding period. The functional significance of this behaviour has been mainly explained as a parental strategy preventing nest flooding under detrimental weather conditions. In addition, and in the light of recent studies, this behaviour could also fit into the sexual selection process. In this study, we tested the first idea, that is, whether stone provisioning is a nest-maintenance behaviour to increase egg/nestling survival by lowering the risk of nest flooding, and can thus be considered a form of parental care. Additionally, we investigated if the effort invested by parents in nest maintenance is constrained by physiologically limiting resources. The effort of stone collection and the perceived risk of nest flooding were experimentally manipulated during the incubation and early brooding phases in a chinstrap penguin, Pygoscelis antarctica, colony. Three groups of nests were established. After weighing, control nests were left unmanipulated. In a second group of nests (reduced group), only one-half of the initial weight of stones was returned to the nests. In a third group of nests (snow-added group), we both reduced nest weight by a half and added snow outside the nest bowl over 6 consecutive days. Ten days after manipulation, the difference in nest weight between initial and final conditions was significantly related to treatment: penguins increased stone provisioning in the reduced group (44% of half-reduced nests), but drastically more in the reduced and snow-added group (123% of half-reduced nests), while the weight of control nests was unchanged compared to premanipulation conditions. The intensity of stone provisioning was affected by nest date, peaking about hatching time and shortly after, and declining with advancing chick age. These results suggest that stone provisioning is a mechanism that has evolved to prevent egg or chick mortality by nest flooding. The haematocrit, but not leukocyte numbers as expressed by the buffy coat layer, varied with the experimental conditions. Penguins investing more time in nest maintenance had a lower haematocrit, suggesting a physiological trade-off probably mediated by competition between the time devoted to nest maintenance versus foraging activities. The amount of stones collected and the haematocrit were positively related to the number of neighbour nests, so those individuals surrounded by more nests seemed to obtain benefits in the availability of nest material and energy savings. This study indicates that stone-provisioning behaviour is a nest-maintenance activity evolved to improve thermal nest characteristics potentially increasing offspring survival, and competing in time and energy with other reproductive activities. Stone provisioning in penguins should therefore be regarded as a form of parental care and an important part of individual reproductive effort in species breeding in harsh environments. Furthermore, nest size and nest-maintenance effort should be considered reproductive traits indicative of parental quality and thus could also be involved in the post-mating sexual selection process. 相似文献
11.
Richard A. Phillips Rona A. R. McGill Deborah A. Dawson Stuart Bearhop 《Marine Biology》2011,158(10):2199-2208
Considerable attention has focused on inter- and intraspecific variation in trophic niches of marine predators. Although this
has revealed evidence for sexual segregation in distribution in some species, few studies have been able to address sex-related
dietary specialisation. Stable isotope analysis of blood cells collected from albatrosses and petrels at South Georgia during
chick-rearing indicated a difference in δ13C, suggesting that females fed to the north of males, only in two species with male-biased sexual size dimorphism; in no species
did sexes differ in trophic level (δ15N). Based on a wider review, significant differences between sexes in isotope signatures were much more common in seabirds
during the pre-laying or breeding than the nonbreeding period, presumably reflecting greater between-sex partitioning of resources
when foraging ranges are more constrained and competition is greater. Sex differences, or their absence, were usually consistent
across successive stages during the pre-laying and breeding periods, but not necessarily year-round nor between populations.
Significant differences in isotope signatures between males and females were extremely rare in monomorphic species, suggesting
a link between sexual size dimorphism and segregation in diet or distribution. Among the Southern Ocean albatrosses, sex differences
in δ13C suggested the underlying mechanism was related to habitat specialisation, whereas in other size-dimorphic taxa (both male-
and female-biased), sex differences were more common in δ15N than δ13C and therefore more consistent with size-mediated competitive exclusion or dietary specialisation. 相似文献
12.
Facultative joint colony founding by social insects provides opportunities to analyze the roles of genetic and ecological
factors in the evolution of cooperation. Although cooperative nesting is observed in range of social insect taxa, the most
detailed studies of this behavior have been conducted with Hymenoptera (ants, bees, and wasps). Here, we show that foundress
associations in the haplodiploid social thrips Dunatothrips aneurae (Insecta: Thysanoptera) are most often comprised of close relatives (sisters), though groups with unrelated foundresses are
also found. Associations among relatives appear to be facilitated by limited female dispersal, which results in viscous population
structure. In addition, we found that per capita productivity declined with increasing group size, sex ratios were female-biased,
and some female offspring apparently remained in their natal domicile for some time following eclosion. D. aneurae thus exhibits a suite of similarities with eusocial Hymenoptera, providing evidence for the convergent evolution of associated
social and life-history traits in Hymenoptera and Thysanoptera. 相似文献
13.
Elisabet Forsgren Anna Karlsson Charlotta Kvarnemo 《Behavioral ecology and sociobiology》1996,39(2):91-96
In some fish species with paternal care, females prefer to spawn with males whose nests already contain eggs. Several hypotheses
have been put forward to explain this behaviour, such as reduced risk of predation or cannibalism (the dilution effect), increased
parental investment, and mate copying. This experimental study focuses on female mate choice in the sand goby, Pomatoschistus minutus. Females were found to choose males with eggs in their nests. In addition, hatching success increased with clutch size, mainly
because males with larger clutches showed less filial cannibalism. Increased egg survival in large clutches may thus be explained
by a combination of the dilution effect and higher parental investment. In another experiment, females did not seem to copy
the observed mate choice of other females. In conclusion, female preference for males with eggs in their nests is adaptive,
and can be explained by direct benefits, as more surviving offspring are produced.
Received: 23 December 1995/Accepted after revision: 11 May 1996 相似文献
14.
Most studies of social polygyny in birds have examined male provisioning on the basis of the number of feeding visits. This
may be misleading if males compensate for infrequent visits by bringing larger prey at each visit. We investigated nestling
provisioning in the socially polygynous great reed warbler, Acrocephalus arundinaceus, in south Central Sweden in 1996–1997. We collected data on rate of feeding visits, prey size and the amount of biomass delivered
by males and females. Males had lower rates of feeding visits and provided smaller prey to nestlings in secondary than in
monogamous and primary nests. Secondary females had higher rates of feeding visits and brought larger prey than monogamous
and primary females. These results confirm that secondary females face a potential cost of polygyny through a lower rate of
male feeding, and that this cost was reinforced by the significantly lower male provisioning rate (biomass h–1) at secondary nests. Secondary females compensated for the lack of male assistance by increasing their rate of feeding and
bringing larger prey. As a result, offspring in nests of secondary females received as much food as did those in nests of
primary females. Prey load size increased with the parent’s proportion of feeding visits, suggesting that parents use different
feeding strategies depending on their amount of responsibility for nestling provisioning. We suggest that parents which take
the main responsibility for nestling feeding have to forage further away from the nest, and based on optimal-foraging theory,
they should then on average bring larger prey to their nest.
Received: 4 April 1999 / Received in revised form: 12 October 1999 / Accepted: 23 October 1999 相似文献
15.
Francesco Ferretti Alessia Costa Marcello Corazza Venusta Pietrocini Gloria Cesaretti Sandro Lovari 《Behavioral ecology and sociobiology》2014,68(8):1335-1344
Availability of food resources and individual characteristics can influence foraging behaviour, which can differ between males and females, leading to different patterns of food/habitat selection. In dimorphic species, females are usually more selective in food choice, show greater bite rates and spend more time foraging than males. We evaluated sexual differences in foraging behaviour in Apennine chamois Rupicapra pyrenaica ornata, during the warm season, before the rut. Both sexes selected nutritious vegetation patches and spent a comparable amount of time feeding. However, males had a significantly greater feeding intensity (bite rate) and a lower search effort for feeding (step rate), as well as they spent more time lying down than females. Females selected foraging sites closer to refuge areas than males. In chamois, sexual size dimorphism is seasonal, being negligible in winter–spring, but increasing to 30–40 % in autumn. Our results suggest that males enhance their energy and mass gain by increasing their food intake rate during the warm season, to face the costs of the mating season (November). Conversely, females seem to prioritize a fine-scale selection of vegetation and the protection of offspring. A great food intake rate of males in the warm season could have developed as a behavioural adaptation leading herbivores to the evolutionary transition from year-round monomorphism to permanent dimorphism, through seasonal dimorphism. 相似文献
16.
Cynthia A. Ursino María C. De Mársico Mariela Sued Andrés Farall Juan C. Reboreda 《Behavioral ecology and sociobiology》2011,65(12):2279-2286
Obligate avian brood parasites lay their eggs in nests of other species (hosts), which raise parasitic young. Parasitic nestlings
are likely to influence host’s parental behaviours as they typically beg for food more vigorously than young host for a given
hunger level. However, few studies have tested this idea, with conflicting results. These prior studies were largely limited
to biparental hosts, but little is known about the effect of brood parasitism on parental behaviours in hosts that breed cooperatively.
We followed a multimodel approach to examine the effect of brood parasitism on nest provisioning and helper recruitment in
the baywing (Agelaioides badius), a cooperative breeder parasitised by screaming (Molothrus rufoaxillaris) and shiny (Molothrus bonariensis) cowbirds. Multimodel inference results indicated that feeding visits increased with nestling age, cooperative group size
and number of cowbird nestlings in the brood. Brood size had little influence on feeding visits, which further suggests that
baywings adjusted their provisioning effort in response to cowbird parasitism. In addition, nests parasitised artificially
with shiny cowbird eggs or hatchlings recruited more helpers than unmanipulated nests having only host or screaming cowbird
young. Our results provide novel evidence that brood parasitism and cooperative breeding interact in determining the levels
of nest provisioning. 相似文献
17.
John Alcock 《Behavioral ecology and sociobiology》1996,39(3):181-188
I examine three alternative hypotheses on the male size dimorphism of Dawson’s burrowing bees (Amegilla dawsoni) in which there are large (major) and small (minor) males. One possibility is that minor males are simply the incidental
byproduct of environmental conditions that prevent females from provisioning brood cells optimally. This hypothesis is not
supported by the finding that males of intermediate size are consistently rare in populations sampled across years and in
different regions, nor can it easily account for the absence of a size dichotomy in females. A second possibility is that
minors represent a “best of a bad job” response of those females that are small or otherwise disadvantaged. However, presumptive
male siblings sometimes include both majors and minors, a result not predicted from this hypothesis. A third explanation is
that female brood provisioning strategy results in the production of minors and majors with equal fitness benefit to fitness
cost ratios. However, although it is true that minor males weigh on average about half what a major weighs, and so represent
approximately half the provisioning expense of a major, minor males on average appear to secure far fewer than half the number
of matings of majors. If the estimate of mating success of minors is accurate, the net gain to females from producing a minor
son is unlikely to equal that derived from a major son. Therefore the third hypothesis must also be tentatively rejected,
although with caution given the uncertainties in estimating the relative costs and benefits of producing major and minor sons.
Received: 12 January 1996/Accepted after revision: 27 April 1996 相似文献
18.
Wendt Müller Ellen Kalmbach Corine M. Eising Ton G. G. Groothuis Cor Dijkstra 《Behavioral ecology and sociobiology》2005,59(2):313-320
In sexually size dimorphic species, individuals of the larger sex often suffer from enhanced mortality during the nestling period. This has been attributed to higher nutritional requirements of the larger sex, which may render this sex more vulnerable to adverse food conditions. However, sex-biased mortality might not exclusively depend on the differences in food demand but also on other phenotypic differences, e.g., in competitiveness. Interference competition between the sexes and position in the laying sequence in particular may be essential components contributing to biased mortality.By creating synchronously-hatched unisex broods in the sexually size dimorphic black-headed gull, we specifically tested the effect of sex-specific food demand by excluding interference competition between the sexes as well as hatching asynchrony. To test the effect of egg quality, which varies with the position in the laying sequence, we composed each nest of chicks from eggs of all different positions in the laying sequence.All-male nests showed significantly enhanced mortality compared to all-female nests from the beginning of the development of the sexual size dimorphism onwards. This underlines the role of a higher food demand in biased mortality of the larger sex.In males but not females, asymptotic body mass and skeletal size were negatively associated with position in the laying sequence, while survival was not affected by position. As a consequence, sexual size dimorphism at the end of the nestling period was less pronounced compared to the natural situation. These data show that, although male growth is more sensitive to a decrease in egg quality, the higher mortality of last hatched chicks in natural nests is mainly due to hatching asynchrony and egg size but not egg content. 相似文献
19.
M. Pyron 《Behavioral ecology and sociobiology》2000,48(2):132-136
Most comparative analyses of relative testes mass find that testes are larger in species in which more sperm competition is
predicted (multiple males mate with individual females). I tested for differences in adjusted testes mass (for body mass)
by spawning mode and by sexual size dimorphism in a comparative analysis of 37 minnow species. No significant differences
were found for testes mass by spawning mode or sexual size dimorphism. These results imply a lack of response to selection
on testes size from sperm competition in minnow species. Possible explanations for the lack of the expected relationship between
testes mass and mating systems in minnows are presented.
Received: 8 November 1999 / Received in revised form: 27 January 2000 / Accepted: 13 February 2000 相似文献
20.
Summary The southern elephant seal is among the most sexually dimorphic and polygynous of all mammals: males may be more than 10 times the weight of reproducing females and only the largest 2–3% of males are likely to breed. Current optimization theories of sexual selection predict that evolution would favor greater parental investment in individual males than in females. Because southern elephant seals represent an extreme of polygyny and sexual dimorphism, they might be expected to show a dramatic difference in parental investment in male and female pups. However, in a study of parental investment in elephant seals at South Georgia, using several different methods, we found no such difference after parturition. Mother-pup pairs were immobilized and weighed early in lactation, recaptured near the end of lactation and reweighed. A further 30 pups were weighed an average of five times during lactation to establish the shape of the growth curve and to serve as partial controls for the previous set of animals. Initial post-partum weight in females ranged from 346 to 803 kg (=506, SD=111, n=26). Pup birth weight was related to mothers' post-partum weight in female pups but small females often gave birth to large male pups. Male pups were significantly heavier at birth than females. However, this size difference did not persist. Male and female pups were suckled for the same period, grew at the same rate and were not significantly different in weight at weaning. Mothers lost weight at the same rate regardless of their pup's sex. 相似文献