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1.
Assuming that a male’s genetic characteristics affect those of his offspring, extra-pair copulation has been hypothesized
to increase heterozygosity of the progeny—the “genetic compatibility” hypothesis—and the genetic diversity within litters—the
“genetic diversity” hypothesis. We tested these two hypotheses in the alpine marmot (Marmota marmota), a socially monogamous mammal showing a high rate of extra-pair paternity (EPP). In a first step, we tested the assumption
that a male’s genetic characteristics (heterozygosity and genetic similarity to the female) affect those of his offspring.
Genetic similarity between parents influenced offspring heterozygosity, offspring genetic similarity to their mother, and
litter genetic diversity. The father’s heterozygosity also influenced litter genetic diversity but did not affect offspring
heterozygosity. Hence, heterozygosity seems not to be heritable in the alpine marmot. In a second step, we compared genetic
characteristics of extra-pair young (EPY) and within-pair young (WPY). EPY were less genetically similar to their mother but
not more heterozygous than WPY. EPY siblings were also less genetically similar than their WPY half siblings. Finally, the
presence of EPY promoted genetic diversity within the litter. Thus, our data support both the “genetic compatibility” and
the “genetic diversity” hypotheses. We discuss further investigations needed to determine the primary causes of EPP in this
species. 相似文献
2.
Jason Munshi-South 《Behavioral ecology and sociobiology》2007,62(2):201-212
Monogamy is rare in mammals (<5% spp.) but occurs in greater frequency among primates (15%) and their close relatives, the
treeshrews (100%; Order: Scandentia). Two genetic studies of parentage in monogamous primates revealed high rates of extra-pair
paternity (EPP), but to date parentage has not been studied in a treeshrew species. I analyzed the genetic parentage of 22
offspring from two populations of large treeshrews in Sabah, Malaysia (NE Borneo), using seven autosomal microsatellite loci
and one mitochondrial DNA marker. Half of these offspring were sired by males that were not the presumed partner of the mother
(50% EPP), and three litters exhibited evidence of multiple paternity. However, comparative analysis indicated that the high
rate of EPP in Tupaia tana is not associated with intense sperm competition. Relative testis size of treeshrews was similar to testis size in 22 primate
species with uni-male mating systems but smaller than 44 primates with multi-male mating systems. After factoring out the
effects of body size and phylogeny, I also found that the evolution of multi-male mating systems was significantly associated
with the evolution of larger testis size. Male–female pairs of T. tana occupy joint territories but forage and sleep alone (“dispersed pair-living”), and I argue that this form of behavioral monogamy
renders mate guarding ineffective. The adaptive advantages of behavioral monogamy likely differ from the advantages driving
EPP in large treeshrews. However, small testis size suggests that behavioral monogamy is not masking a dispersed multi-male
mating system in this species. 相似文献
3.
Extra-pair copulations in a lek: the secondary mating system of monogamous razorbills 总被引:1,自引:0,他引:1
Richard H. Wagner 《Behavioral ecology and sociobiology》1992,31(1):63-71
Summary I studied the mating strategies of razorbills Alca torda, a monogamous colonial seabird, during 1987–1989 in Wales, U.K. The outstanding feature of the study population's mating system was the performance of most copulations in mating arenas outside the colony. Females visited the arenas and sometimes accepted extra-pair copulations (EPCs), and males aggressively competed for EPCs. During the fertilizable period of most females, the arenas resembled leks because they contained no resources except mates, and males contributed only sperm to extra-pair females. Typical of leks, the operational sex ratio was strongly male-biased, and male mating success was highly skewed. To examine the potential for sexual selection to operate in this system, I correlated male EPC success with variables that could be associated with male-male competition and/or female choice. The frequencies of three behaviors (interference of copulation attempts, fights won against other males, and EPC attempts), accounted for 62% of the variance in EPC success and were strongly intercorrelated, with interference explaining most of the variance in a multivariate test. EPC success was not correlated with body size, age, paired status or either of two estimates of the time spent in the arena. The hypothesis that male EPC success was determined by active female choice was tested by examining the relative success (EPCs per attempt) of males. Relative success was not correlated with any of the three behaviors associated with absolute success, or with age, body size or attendance, suggesting that male-male competition, mainly in the form of copulation interference, is the principal correlate of EPC success. These findings in a monogamous species illustrate that EPC is a secondary mating system of razorbills in which sexual selection operates. The existence of this system outside the colony raises the possibility that lekking for EPCs may also occur within the nesting territories of other monogamous, colonial species but is hidden by competition for nests and breeding partners. 相似文献
4.
Extra-pair paternity and the opportunity for sexual selection in a socially monogamous bird (Dendroica petechia) 总被引:7,自引:0,他引:7
Stephen M. Yezerinac Patrick J. Weatherhead Peter T. Boag 《Behavioral ecology and sociobiology》1995,37(3):179-188
We used multi-locus DNA fingerprinting to characterise the genetic mating system of the socially monogamous yellow warbler (Dendroica petechia). Over 2 years there were no instances of brood parasitism, but 59% of families (n = 90) contained extrapair sired young and 37% of offspring (n = 355) were of extra-pair paternity. Most hypotheses for extra-pair mating in monogamous species assume a paternity benefit to extra-pair sires, and focus on the benefit(s) to females. However, the assumption of male benefit has been little tested. Among yellow warblers, known extra-pair sires were just as likely to be cuckolded as any male in the population, and there was at least one reciprocal exchange of extra-pair paternity. Nevertheless, among known extra-pair sires, the paternity gains from extra-pair paternity were, on average, greater than the losses in their own families. These results show there is a paternity benefit to certain males. However, the benefit is not absolute but relative and therefore more difficult to measure. The results also suggest that patterns of extra-pair fertilisation are not determined by female choice alone. Most confirmed extra-pair mates were territorial neighbours, but some resided as far as three territories apart, and greater spatial separation was implied in other cases. Thus, the opportunity for extra-pair mating is great. We estimate that as a result of extra-pair fertilisations, variance in male mating success is increased somewhere between 3-fold and 15-fold over that which would result from within-pair reproduction alone. These findings affirm the potential importance of extra-pair reproduction for sexual selection in monogamous species and they support earlier suggestions that extra-territorial forays by male yellow warblers are for the purpose of extra-pair mating. 相似文献
5.
A. Cohas N. G. Yoccoz A. Da Silva B. Goossens D. Allainé 《Behavioral ecology and sociobiology》2006,59(5):597-605
Extra-pair paternity (EPP) can be influenced by both social setting and female mate choice. If evidence suggests that females
try to obtain extra-pair copulations (EPCs) in order to gain genetic benefits when mated to a homozygous and/or to a related
male, females may not be able to choose freely among extra-pair mates (EPMs) as the social mate may constrain female access
to EPMs. In this study, we investigated, first, how EPP depended on social setting and specifically on the number of subordinate
males in the family group in a highly social and monogamous mammal, the alpine marmot. Second, we investigated how EPP depended
on female mate choice for genetic benefits measured as male mate-heterozygosity and within-pair relatedness. Our results reveal,
first, that EPP depended on the social setting, increasing with the number of subordinate males. Second, EPPs were related
to relatedness between mates. Third, EPMs were found to be more heterozygous than within-pair males. Thus, social setting
may constrain female choice by limiting opportunities for EPC. However, after accounting for social confounding factors, female
choice for genetic benefits may be a mechanism driving EPP in monogamous species. 相似文献
6.
Social monogamy and extra-pair fertilization in an Australian lizard, Tiliqua rugosa 总被引:3,自引:0,他引:3
C. Michael Bull Steven J. B. Cooper Ben C. Baghurst 《Behavioral ecology and sociobiology》1998,44(1):63-72
This study investigates social monogamy in the Australian sleepy lizard, Tiliqua rugosa. At a 70-ha site near Mount Mary, South Australia, we radio tracked 55 adult female and 39 adult male lizards during their
spring activity periods. Each lizard was observed in 1–5 years. Females were observed with a single male partner on an average
of 10.8 days per year, although in 17.3% of cases, females were observed on 2 or fewer days with a male. The most intense
pairing period each year was 15 September–15 November when females were with male partners on an average of 36% of observation
days. Partnerships lasted an average of 43.3 days each year. After mating in early November, the pairs separated. Observations
of females pairing with other males were rare. Most males (82%) were also consistently monogamous, although 7 were observed
pairing with 2 females within one season. To investigate paternity, we allowed 21 gravid females to give birth to 42 offspring
in the laboratory. We determined genotypes at five polymorphic microsatellite DNA loci for the females, their male partners
and their offspring. Four litters (19%) and 6 of the offspring from those litters (14.3%) showed evidence of extra-pair fertilization
(EPF). Although the sample sizes are small, females of polygynous males were more likely to experience EPF.
Received: 22 February 1998 / Accepted after revision: 23 May 1998 相似文献
7.
Emma L. Taylor Dominique Blache David Groth John D. Wetherall Graeme B. Martin 《Behavioral ecology and sociobiology》2000,47(5):359-364
Parentage in emus (Dromaius novaehollandiae) was examined by microsatellite analysis using four independent loci. Of 106 chicks sampled in one breeding season from 18
nests, 54 (51%) were not fathered by the nesting male, 12 (11%) were not from the observed mate of the sitting male, and 9
(8%) represented intra-specific brood parasitism, having no alleles in common with either nest parent. Some males (11%) fathered
all chicks in their nests, but the majority showed high levels of cuckoldry. Those males commencing incubation earliest in
the season tended to have the highest levels of paternity in their own nests. These results reveal a high frequency of extra-pair
fertilisations and resultant cuckoldry in a predominantly socially monogamous bird and support recent reports which have described
the emu mating system as a complexity of polyandrous, promiscuous and monogamous behaviour. Parentage assignment of chicks
resulting from extra-pair fertilisations revealed an evenly scattered pattern of paternity that did not show any particular
male dominance in reproductive success. These results lead to a reassessment of behavioural observations of emus, the consequences
of parentage distribution, and theories about mating systems and sexual selection. The frequency of extra-pair copulations
and intra-specific brood parasitism suggests patterns of descent that differ greatly from those implied by social monogamy.
Received: 27 November 1999 / Received in revised form: 8 January 2000 / Accepted: 8 February 2000 相似文献
8.
Extra-pair paternity is common in socially monogamous passerines; however, despite considerable research attention, consistent
differences in fitness between within-pair offspring (WPO) and extra-pair offspring (EPO) have not been demonstrated. Recent
evidence indicates that differences between maternal half-siblings may depend on environmental conditions, but it is unclear
whether the influence of paternal genetic contribution should be most apparent under comparatively poor or favourable conditions.
We compared phenotypic characteristics of WPO and EPO in 30 mixed-paternity broods of the tree swallow (Tachycineta bicolor) in relation to experimentally increased nest temperature (n = 13 heated nests; 17 control nests) and natural abundance of haematophagous parasites (Protocalliphora spp.). This allowed us to test the hypothesis that genetic benefits of extra-pair mating are environment dependent. EPO grew
their ninth primary feathers faster than WPO regardless of nest temperature or parasite load and had significantly longer
ninth primary feathers at fledging when parasite abundance was low, and when they were positioned early in the hatching sequence
relative to WPO. In contrast, WPO under similar conditions did not differ from EPO in any phenotypic trait measured. These
results indicate that the fitness benefits of extra-pair mating are likely to be context dependent, and that genetic effects
on some phenotypic traits may be more apparent when conditions are relatively favourable. 相似文献
9.
Condition-dependent control of paternity by female purple martins: implications for coloniality 总被引:9,自引:0,他引:9
Proposed causal links between extra-pair copulation (EPC) and colony formation in socially monogamous birds hinge on the
question of which sex controls fertilizations. We examined in colonial purple martins Progne subis (1) whether EPCs were forced or accepted by females, and (2) the degree to which apparently receptive females were able to
obtain EPCs against their mates’ paternity defenses. Paternity analyses of multilocus DNA fingerprinting confirmed previous
findings of a marked relationship between age class and extra-pair fertilizations (EPFs), with young males losing paternity
of 43% (n = 53) of their putative offspring compared to 4% (n = 85) by old males. All assignable extra-pair offspring were sired by old males, with one male obtaining most EPFs each year.
Contrary to the hypothesis that EPCs are forced, EPF frequency within age class did not increase with seasonal increases in
the number of males per fertile female. Whereas the male control hypothesis predicted that the male age class that mate-guarded
more would be cuckolded less, the reverse was true: young males guarded significantly more intensely. The male age class difference
in cuckoldry could not be explained by the possibility that young and inexperienced females (which are usually paired to young
males) were more vulnerable to forced copulation because EPFs were unrelated to female age. These findings suggest that females
(1) pair with old males and avoid EPCs, or (2) pursue a mixed mating strategy of pairing with young males and accepting EPCs
from old males. The receptivity to EPCs by females paired to young males put them in conflict with their mates. Two factors
determined the paternity achieved by young males: (1) the relative size of the male to the female, with young males achieving
much higher paternity when they were larger than their mates, and (2) the intensity of mate-guarding. Both variables together
explained 77% of the variance in paternity and are each aspects of male-female conflict. Given female receptivity to EPCs,
mate-guarding can be viewed as male interference with female mating strategies. We conclude that EPCs are rarely or never
forced, but the opportunity for females paired to young males to obtain EPCs is relative to the ability of their mates to
prevent them from encountering other males. Evidence of mixed mating strategies by females, combined with other features of
the martin mating system, is consistent with the female-driven “hidden lek hypothesis” of colony formation which predicts
that males are drawn to colonies when females seek extra-pair copulations.
Received: 23 March 1995/Accepted after revision: 14 January 1996 相似文献
10.
Multiple paternity and offspring quality in tree swallows 总被引:1,自引:0,他引:1
Peter O. Dunn Jan T. Lifjeld Linda A. Whittingham 《Behavioral ecology and sociobiology》2009,63(6):911-922
There is mounting evidence in a variety of taxa that females increase offspring quality by mating with multiple males, often
resulting in multiple paternity. In birds, however, few studies have explicitly examined the benefits of mating with several
different males; instead, the focus has been on whether or not extra-pair mating occurs, and its adaptive significance remains
controversial. We examined the hypothesis that offspring quality, particularly immune response (phytohaemagglutinin assay)
and growth, increases with the number of sires in broods of socially monogamous tree swallows (Tachycineta bicolor). We found one of the highest known levels of multiple paternity in birds (84% of nests with two or more extra-pair young
had at least two extra-pair sires). Among nests with extra-pair young, the number and diversity of sires continued to increase
linearly with the number of extra-pair young, so there was no evidence that some males monopolized paternity at high levels
of extra-pair fertilization. Indeed, the number of sires was actually greater than expected in large broods, suggesting that
some females might be seeking more mates. We found no effect of the number of sires on nestling immune response or growth.
In mixed paternity broods, the immune response of extra-pair young did not differ from that of their within-pair half-siblings.
However, among all broods, nestlings had a stronger immune response in nests with at least one extra-pair nestling than in
nests with all within-pair nestlings. These results are not consistent with a good genes benefit of extra-pair mating, but
they do suggest that there are environmental effects associated with extra-pair mating that increase nestling immune response.
These environmental effects could produce indirect genetic effects on sexual selection if they are heritable. The extraordinarily
high number of sires in this species highlights a relatively unexplored source of sexual selection in birds. 相似文献
11.
Historically, most mammals have been classified as polygynous; although recent molecular evidence suggests that many mammals
may be polygynandrous, particularly the ground-dwelling sciurids. We genotyped 351 round-tailed ground squirrels (Xerospermophilus tereticaudus) using seven microsatellite loci to determine paternity in 31 litters from 2004 to 2007. Polygyny was evident in all years
except in 2007, when the population size was reduced. Multiple paternity occurred in the majority of litters (55%) with 2.5 ± 0.26
sires/litter (n = 31). Forty-nine percent of resident males (n = 114) sired offspring, and of males that sired offspring (n = 56) 27% sired young in multiple litters in a single breeding season. Litter size was positively correlated with the number
of sires. Through an indirect analysis of paternity, we found 21 litters (68%) with an average relatedness of 0.5 or less.
Males had a greater opportunity for sexual selection (I
s = 1.60) than females (I
s = 0.40); Bateman’s gradient was also greater in males (1.07 ± 0.04, n = 56) than females (0.82 ± 0.08, n = 31). The mating system in round-tailed ground squirrels defined through genetic analyses and Bateman’s gradients is polygynandrous
compared to the previously suggested polygynous mating system as established by behavioral observations and fits within the
predictions of the ground squirrel sociality models. Upon evaluating the predictions of the sociality models among sciurid
species, we found a negative relationship between the level of sociality with litter size and the average percentage of multiple
paternity within a litter. Thus, recent genetic information and reclassification of mating systems support the predictions
of the ground-dwelling squirrel sociality models. 相似文献
12.
Ioana Chiver Bridget J. M. Stutchbury Eugene S. Morton 《Behavioral ecology and sociobiology》2008,62(12):1981-1990
Extra-pair fertilizations are common in many socially monogamous species, and paternity studies have indicated that females
may use male vocal performance and plumage ornaments as cues to assess male quality. Female off-territory forays may represent
a key component of female choice and male extra-pair mating success, and female foray behaviour is expected to be strongly
influenced by indictors of male quality. In this study, we examined how male song and ornamentation affect how often females
left their territories, which males they visited and extra-pair paternity in a socially monogamous passerine, the hooded warbler
(Wilsonia citrina). We radiotracked 17 females during the fertile period and quantified male vocal performance (song output and rate) and plumage
characteristics (size of the black melanin hood and colour of the black hood, yellow cheeks and breast areas). We obtained
blood samples and determined paternity at 35 nests including those of 14 females that we radiotracked. Eleven (65%) of the
17 females forayed off-territory, whilst fertile and female foray rate was positively correlated with the number of extra-pair
young in the nest. Females that left their territories more frequently were paired with males that sang at a low rate. In
addition, extra-pair mates had higher song rates than the social mates they cuckolded (5.3 songs/min vs. 4.4 songs/min). Female
off-territory forays or extra-pair paternity were not significantly related to male plumage characteristics. Our results indicate
that a high song rate influences both the foray behaviour of a male’s social mate and the likelihood that he will sire extra-pair
offspring with neighbouring females. 相似文献
13.
Davina L. Hill Jan Lindström Ruedi G. Nager 《Behavioral ecology and sociobiology》2011,65(11):2049-2059
Whether parental effort can be negotiated between partners over ecological time and adjusted across different contexts is
not well understood. We manipulated male extra-pair copulation (EPC) opportunity in captive zebra finches, Taeniopygia guttata, to test whether males adjust incubation effort to the mating context and to examine how females respond to their partner’s
effort. Birds without previous breeding experience were paired randomly and bred with the same partner twice. In the first
breeding attempt, half the males received EPC opportunities with ‘extra-pair females’ during incubation, while the other half
did not. Males that received EPC opportunities in the first breeding attempt did not in the second breeding attempt and vice
versa. We recorded incubation effort on days when EPC opportunities were not presented. In their first breeding attempt, males
with EPC opportunities incubated less than those without. Females compensated fully for the deficit in male care so that a
pair’s combined incubation effort was unchanged. In the second attempt, when a male’s opportunity for EPCs was switched, individuals
showed the same level of incubation effort that they had previously, irrespective of the current availability of extra-pair
females. This suggests that division of effort was negotiated in the first breeding attempt and maintained without significant
adjustments in the second attempt. The effects of male EPC opportunity in the first breeding attempt on subsequent incubation
effort suggests that individual parental decisions can be shaped by previous experience and this may partly explain conflicting
results in studies where individuals’ histories were not known. 相似文献
14.
Verena Dietrich-Bischoff Tim Schmoll Wolfgang Winkel Sven Krackow Thomas Lubjuhn 《Behavioral ecology and sociobiology》2006,60(4):563-571
Females of many socially monogamous bird species commonly engage in extra-pair copulations. Assuming that extra-pair males are more attractive than the females’ social partners and that attractiveness has a heritable component, sex allocation theory predicts facultative overproduction of sons among extra-pair offspring (EPO) as sons benefit more than daughters from inheriting their father’s attractiveness traits. Here, we present a large-scale, three-year study on sex ratio variation in a passerine bird, the coal tit (Parus ater). Molecular sexing in combination with paternity analysis revealed no evidence for a male-bias in EPO sex ratios compared to their within-pair maternal half-siblings. Our main conclusion, therefore, is that facultative sex allocation to EPO is absent in the coal tit, in accordance with findings in several other species. Either there is no net selection for a deviation from random sex ratio variation (e.g. because extra-pair mating may serve goals different from striving for ‘attractiveness genes’) or evolutionary constraints preclude the evolution of precise maternal sex ratio adjustment. It is interesting to note that, however, we found broods without EPO as well as broods without mortality to be relatively female-biased compared to broods with EPO and mortality, respectively. We were unable to identify any environmental or parental variable to co-vary with brood sex ratios. There was no significant repeatability of sex ratios in consecutive broods of individual females that would hint at some idiosyncratic maternal sex ratio adjustment. Further research is needed to resolve the biological significance of the correlation between brood sex ratios and extra-pair paternity and mortality incidence, respectively. 相似文献
15.
It is generally accepted that if a female can improve her offspring’s genetics via extra-pair copulations (EPC), it is by
copulating with extra-pair males whose phenotypes are more superior or whose genes are more compatible to hers than those
of her bonded male. Here, we present a model that puts together uncertainties about the male genetic quality, a postcopulatory
sperm bias in favor of the better or the more compatible genes, and costs that females pay by being choosy about extra-pair
male quality. The model’s conclusions challenge traditional views of good genes explanations of EPC. When phenotypes give
incomplete information about genotypes, a female choosing a phenotypically superior extra-pair male, may nevertheless find
herself trading good genes of a bonded male for poor genes of an extra-pair male. Such “unfortunate sperm replacements” can
limit the female involvement in EPC even when EPC are otherwise cost-free. The model also shows that even a female bonded
to a phenotypically superior male may benefit by EPC, provided that sperm competition is biased toward sperm with more fit
or more compatible genes. Furthermore, if choosiness is sufficiently costly, a female may even do best by copulating with
a random extra-pair male. 相似文献
16.
It is still unclear why females in many bird species pursue extra-pair copulations. Current hypotheses focus mainly on indirect benefits such as obtaining particular good genes for their offspring or maximizing genetic compatibility between themselves and the father of their offspring. Supporting the latter, a recent study of shorebirds suggests that extra-pair matings may function to avoid the negative effects of genetic similarity between mates. Here, we further investigate genetic parentage in the Kentish plover, Charadrius alexandrinus, a shorebird with a highly variable social mating system. DNA fingerprinting revealed that most pairs were genetically monogamous: 7.9% of the broods (7/89) contained extra-pair young, comprising 3.9% of all chicks (9/229). These cases represented, however, three alternative reproductive behaviors: extra-pair paternity, quasi-parasitism (extra-pair maternity) and intraspecific brood parasitism. This is the first study showing the occurrence of all three behaviors in one shorebird species. We also found that extra-pair fertilizations (extra-pair paternity and quasi-parasitism) were more frequent later in the breeding season. There was no consistent relationship between genetic similarity of mates and laying date; the pattern, as well as the degree of genetic similarity, differed among breeding sites within the study population.Communicated by M. Webster 相似文献
17.
Correlates of extra-pair fertilization success in hooded warblers 总被引:13,自引:0,他引:13
Bridget J. M. Stutchbury W. H. Piper D. L. Neudorf S. A. Tarof Judith M. Rhymer G. Fuller R. C. Fleischer 《Behavioral ecology and sociobiology》1997,40(2):119-126
We examined correlates of extra-pair fertilization (EPF) success in the hooded warbler (Wilsonia citrina), a species where females pursue extra-pair matings. The good genes hypothesis predicts that females choose extra-pair mates
with morphological or behavioral traits that reflect differences in male genetic quality. EPFs were common, as 35.3% (42/119)
of broods contained extra-pair young (EPY) and 26.7% (95/356) of nestlings were the result of EPFs. There was a strong skew
in male EPF success which increased the variance in annual male mating success 2–3 fold. However, male morphology did not
predict EPF success, as extra-pair males were not older or larger than the males they cuckolded. Likewise, there were no significant
correlations between the proportion of extra-pair young in a brood and male size or age. The good genes hypothesis predicts
that high-quality males will be consistently preferred as genetic mates, but the number of young sired by a male with his
social mate was not consistent from one year to the next. There was a significant negative correlation between female age
and proportion of EPY produced, which could result if older females obtain higher-quality social mates. We found no strong
evidence that females choose extra-pair mates for good genes, but females may use behavioral rather than morphological cues
to assess relative male quality.
Received: 31 May 1996 / Accepted after revision: 17 October 1996 相似文献
18.
Aneta Arct Szymon M. Drobniak Edyta Podmokła Lars Gustafson Mariusz Cichoń 《Behavioral ecology and sociobiology》2013,67(11):1809-1815
Extra-pair mating constitutes a relatively common reproductive strategy in many socially monogamous bird species. This strategy may considerably improve reproductive success of males, but female benefits from extra-pair matings still remain unclear and empirical evidence is scarce. This may be because genetic benefits of extra-pair mating are not always revealed. It is possible that they are shown only in unfavourable environmental conditions and hence problems arise with detecting differences between within- and extra-pair offspring whose performance is measured under favourable conditions. In order to test this prediction, we manipulated environmental conditions by altering brood sizes of blue tits and compared phenotypic characteristics of within- and extra-pair offspring in mixed-paternity broods. We found that extra-pair young exhibited a higher response to phytohemagglutinin in comparison to within-pair young, but this was only observed among nestlings from experimentally enlarged broods. These results indicate that genetic benefits may interact with the environment, and thus benefits of extra-pair mating are likely to become visible only when conditions are relatively unfavourable. 相似文献
19.
Do female black-capped chickadees prefer high-ranking males as extra-pair partners? 总被引:14,自引:0,他引:14
Ken Otter Laurene Ratcliffe Denise Michaud Peter T. Boag 《Behavioral ecology and sociobiology》1998,43(1):25-36
Previous studies have shown that some female black-capped chickadees (Poecile atricapillus) solicit copulations from males that rank higher in winter flocks than their social mates, and extra-pair paternity in nests
occurs commonly enough to be considered a potential female mating tactic. This study uses blood samples collected in 1992–1995
from 58 families of black-capped chickadees to test whether females with extra-pair offspring have chosen extra-pair sires
higher in social rank than their mates. Paternity was assessed with multilocus DNA fingerprinting in 1992–1994 nests and with
microsatellite and single-locus minisatellite DNA typing in 1995 nests. Seventeen of 58 nests (29.3%) contained young genetically
mismatched with their social father. In 11 of 15 cases where the identity of the extra-pair male was known, the extra-pair
male was dominant to the social father. Using data from 29 nests located in 1994 and 1995 for which we had the most data on
relative ranks of males, high-ranking males had greater realized reproductive success than low-ranking males as a result of
extra-pair fertilizations. There was no significant difference between the number of nests containing extra-pair young of
females mated to low-ranked versus high-ranked males. Two nests in 1995 contained young either genetically mismatched with
both social parents (intraspecific brood parasitism) or, in one nest, genetically mismatched with the social mother but not
the social father (quasi-parasitism). The implications of female strategies acquiring genetic benefits through extra-pair
copulations are discussed.
Received: 7 July 1997 / Accepted after revision: 14 March 1998 相似文献
20.
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