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1.
Change in host rejection behavior mediated by the predatory behavior of its brood parasite 总被引:3,自引:0,他引:3
Soler Juan Jose; Sorci Gabriele; Soler Manuel; Moller Anders Pape 《Behavioral ecology》1999,10(3):275-280
Passerine hosts of parasitic cuckoos usually vary in their abilityto
discriminate and reject cuckoo eggs. Costs of discriminationand rejection
errors have been invoked to explain the maintenanceof this within-population
variability. Recently, enforcementof acceptance by parasites has been
identified as a rejectioncost in the magpie (Pica pica) and its
brood parasite, the greatspotted cuckoo (Clamator glandarius).
Previous experimentalwork has shown that rejecter magpies suffer from
increased nestpredation by the great spotted cuckoo. Cuckoo predatory
behavioris supposed to confer a selective advantage to the parasitebecause
magpies experiencing a reproductive failure may providea second opportunity
for the cuckoo to parasitize a replacementclutch. This hypothesis implicitly
assumes that magpies modulatetheir propensity to reject parasite eggs as a
function of previousexperience. We tested this hypothesis in a magpie
populationbreeding in study plots varying in parasitism rate. Magpie pairs
thatwere experimentally parasitized and had their nests depredated,after
their rejection behavior had been assessed, changed theirbehavior from
rejection to acceptance. The change in host behaviorwas prominent in study
plots with high levels of parasitism,but not in plots with rare or no cuckoo
parasitism. We discussthree possible explanations for these differences,
concludingthat in study plots with a high density of cuckoos, the probability
fora rejecter magpie nest of being revisited and depredated bya cuckoo is
high, particularly for replacement clutches, and,therefore, the cost for
magpies of rejecting a cuckoo egg ina replacement clutch is increased.
Moreover, in areas with highlevels of host defense (low parasitism rate), the
probabilityof parasitism and predation of rejecter-magpie nests by thecuckoo
is reduced in both first and replacement clutches. Therefore,rejecter magpies
in such areas should not change their rejectionbehavior in replacement
clutches. 相似文献
2.
Martín-Gálvez D Soler JJ Martínez JG Krupa AP Richard M Soler M Møller AP Burke T 《Journal of evolutionary biology》2006,19(2):543-550
Avian brood parasites reduce the reproductive output of their hosts and thereby select for defence mechanisms such as ejection of parasitic eggs. Such defence mechanisms simultaneously select for counter-defences in brood parasites, causing a coevolutionary arms race. Although coevolutionary models assume that defences and counter-defences are genetically influenced, this has never been demonstrated for brood parasites. Here, we give strong evidence for genetic differences between ejector and nonejectors, which could allow the study of such host defence at the genetic level, as well as studies of maintenance of genetic variation in defences. Briefly, we found that magpies, that are the main host of the great spotted cuckoo in Europe, have alleles of one microsatellite locus (Ase64) that segregate between accepters and rejecters of experimental parasitic eggs. Furthermore, differences in ejection rate among host populations exploited by the brood parasite covaried significantly with the genetic distance for this locus. 相似文献
3.
We analysed the spatial and temporal pattern of egg laying in great spotted cuckoo females using microsatellite typing to
determine parentage of the eggs and nestlings found in host (magpie) nests. The results showed that there were no exclusive
laying territories in the study area. Cases of multiparasitism could be due to single females laying two or more eggs in a
nest, or to several females using the same nest. In the latter case multiparasitism was due to a shortage of available host
nests. We argue that the need for very large laying areas and the likely small cost of sharing parental care for chicks make
the costs of defending territories higher than the benefits, which has constrained the evolution of territoriality in this
species.
Received: 16 March 1998 / Accepted: 15 June 1998 相似文献
4.
JUAN J. SOLER JESUS M. AVILES MANUEL SOLER ANDERS P. MØLLER 《Biological journal of the Linnean Society. Linnean Society of London》2003,79(4):551-563
Brood parasitism in birds is one of the best examples of coevolutionary interactions in vertebrates. Coevolution between hosts and parasites is assumed to occur because the parasite imposes strong selection pressures on its hosts, reducing their fitness and thereby favouring counter-adaptations (e.g. egg rejection) which, in turn, select for parasite resistance (e.g. egg mimicry). Great spotted cuckoos ( Clamator glandarius ) are usually considered a brood parasite with eggs almost perfectly mimicking those of their host, the magpie ( Pica pica ). However, Cl. glandarius also exploits South African hosts with very different eggs, both in colour and size, while the Cl. glandarius eggs are similar to those laid in nests of European hosts. Here, we used spectrophotometric techniques for the first time to quantify mimicry of parasitic eggs for eight different host species. We found: (1) non-significant differences in appearance of Cl. glandarius eggs laid in nests of different host species, although eggs laid in South Africa and Europe differed significantly; (2) contrary to the general assumption that Cl. glandarius eggs better mimic those of the main host in Europe ( P. pica ), Cl. glandarius eggs more closely resembled those of the azure-winged magpie ( Cyanopica cyana ), a potential host in which there is no evidence of recent parasitism; (3) the appearance of Cl. glandarius eggs was not significantly related to the appearance of host eggs. We discuss three possible reasons why Cl. glandarius eggs resemble eggs of some of their hosts. We suggest that colouration of Cl. glandarius eggs is an apomorphic trait, and that variation between eggs laid in South African and European host nests is due to genetic isolation among these populations and not due to variation in colouration of host eggs. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 551–563. 相似文献
5.
Juan Jos Soler Juan Gabriel Martinez Manuel Soler Anders Pape Mller 《Evolution; international journal of organic evolution》1999,53(3):947-956
Host responses toward brood parasitism have been shown to differ among populations depending on the duration of sympatry between host and parasite, although populations not currently parasitized show rejection behavior against parasitic eggs. The persistence of rejection behavior in unparasitized host populations and rapid increases of rejection rate in parasitized ones have sometimes been explained as the result of gene flow of rejecter genes from sympatry to allopatry (rejecter-gene flow hypothesis). We present data on the rejection behavior of magpies (Pica pica) the main European host of the great spotted cuckoo (Clamator glandarius), in 15 populations (nine sympatric six allopatric) across their distribution range in Europe. Rejection rates of mimetic and nonmimetic model eggs were significantly higher in sympatric than in allopatric magpie populations, although differences in rejection rate of both mimetic and nonmimetic model eggs between magpie populations were significantly correlated even after controlling tor phylogenetic effects, with differences between sympatric and allopatric magpie populations being larger for mimetic than for nonmimetic model eggs. Differences in rejection of mimetic model eggs were related to both genetic and geographic distances between populations, but differences in rejection rate of nonmimetic model eggs were unrelated to these distances. However, when comparing only sympatric populations, differences in rejection rate of both mimetic and nonmimetic model eggs were related to geographic distances. A multiple autocorrelation analysis revealed that differences among populations in rejection rates of mimetic model eggs had a strong geographic component whereas the main component of rejection rate of nonmimetic model eggs was genetic rather than geographic. These results support the rejecter-gene flow hypothesis. We discuss differences in rejection rates of mimetic and nonmimetic model eggs that suggest the egg-recognition ability of the host is genetically based, but is affected by a learning process for fine tuning of recognition. 相似文献
6.
Manuel Soler Liesbeth De Neve Tomás Pérez‐Contreras Luis A. Rubio 《Biological journal of the Linnean Society. Linnean Society of London》2014,111(2):280-289
Altricial nestlings are under strong selection pressures to optimize digestive efficiency because this is one of the main factors affecting nestling growth and survival. Bird species vary in their ability to assimilate different nutrients and current theory predicts that nestlings should also be able to adjust their nutritional physiology to feeding frequency. Variation in parental provisioning to nestlings would select for flexibility in nestling digestive physiology, which would allow maximization of nutrient assimilation. In the present study, by making use of a brood parasite–host study system in which great spotted cuckoo nestlings (Clamator glandarius) are reared by magpie (Pica pica) host foster parents when sharing the nest with host nestlings, we tested several predictions of the adaptive digestive efficiency paradigm. A hand‐feeding experiment was employed in which we fed both great spotted cuckoo and magpie nestlings with exactly the same diet simulating one food abundance period and one food deprivation period. The results obtained show that cuckoo nestlings ingested more food, gained significantly more weight during the abundance period, and assimilated a higher proportion of the ingested food than magpie nestlings. These results demonstrate for the first time that cuckoo nestlings enjoy digestive adaptations that favour a rapid processing of the ingested food, thereby maximizing their intake rate but without decreasing digestive efficiency. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 280–289. 相似文献
7.
MAGDALENA RUIZ-RODRÍGUEZ FRANÇOISE S. LUCAS PHILIPP HEEB JUAN J. SOLER 《Biological journal of the Linnean Society. Linnean Society of London》2009,96(2):406-414
The intestinal microbiota determines the effectiveness of digestion in vertebrates, and is influenced by the external environment (mainly the diet), gut characteristics, and phylogeny. Avian brood-parasitic nestlings of the sub-family Cuculinae develop in nests of phylogenetically distant passerines and can be fed with the host diet. If the shaping of bacterial communities is dominated by phylogenetic constraints, and therefore the microbiota of parasitic nestlings differs from that of host nestlings, the energy and micronutrients that parasites and hosts obtain from a similar amount of food would be different. In this case, the bacterial communities of parasitic and host nestlings would have important consequences with respect to brood parasite development. By experimentally creating mixed broods of magpies ( Pica pica ) and great spotted cuckoos ( Clamator glandarius ), we investigated their cloacal microbiota using ribosomal intergenic spacer analysis. We found significant differences in bacterial assemblages of the parasitic and host nestlings, although none of the phylotypes were specific in either great spotted cuckoos or magpies. Cuckoos presented more complex communities, which could help the brood parasitic life style and allow the digestion of food provided by different potential hosts. Moreover, the intestinal morphology is different between the two species due to phylogenetic differences in the two taxa, which would influence the dissimilar bacterial assemblages. The detected differences in microbiota of great spotted cuckoo and magpie nestlings, which might occur in other brood parasite–host systems, may imply a lower digestion efficiency in parasites. Thus, the higher level requirements of cuckoo nestlings may be explained, at least in part, by cuckoos having a suboptimal bacterial community for processing the host diet. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 406–414. 相似文献
8.
M. Soler J. J. Soler J. G. Martinez A. P. Mller 《Evolution; international journal of organic evolution》1995,49(4):770-775
Why should the hosts of brood parasites accept and raise parasitic offspring that differ dramatically in appearance from their own? There are two solutions to this evolutionary enigma. (1) Hosts may not yet have evolved the capability to discriminate against the parasite, or (2) parasite-host systems have reached an evolutionary equilibrium. Avian brood parasites may either gain renesting opportunities or force their hosts to raise parasitic offspring by destroying or preying upon host eggs or nestlings following host ejection of parasite offspring. These hypotheses may explain why hosts do not remove parasite offspring because only then will hosts avoid clutch destruction by the cuckoo. Here we show experimentally that if the egg of the parasitic great spotted cuckoo Clamator glandarius is removed from nests of its magpie Pica pica host, nests suffer significantly higher predation rates than control nests in which parasite eggs have not been removed. Using plasticine model eggs resembling those of magpies and observations of parasites, we also confirm that great spotted cuckoos that have laid an ejected egg are indeed responsible for destruction of magpie nests with experimentally ejected parasite eggs. Cuckoos benefit from destroying host offspring because they thereby induce some magpies to renest and subsequently accept a cuckoo egg. 相似文献
9.
Antagonistic antiparasite defenses: nest defense and egg rejection in the magpie host of the great spotted cuckoo 总被引:2,自引:2,他引:0
Soler Juan Jose; Soler Manuel; Perez-Contreras Tomas; Aragon Santiago; Moller Anders Pape 《Behavioral ecology》1999,10(6):707-713
Brood parasites dramatically reduce the reproductive successof their
hosts, which therefore have developed defenses againstbrood parasites. The
first line of defense is protecting thenest against adult parasites. When the
parasite has successfullyparasitized a host nest, some hosts are able to
recognize andreject the eggs of the brood parasite, which constitutes the
secondline of defense. Both defense tactics are costly and would be
counteractedby brood parasites. While a failure in nest defense implies
successfulparasitism and therefore great reduction of reproductive successof
hosts, a host that recognizes parasitic eggs has the opportunityto reduce the
effect of parasitism by removing the parasiticegg. We hypothesized that, when
nest defense is counteractedby the brood parasite, hosts that recognize
cuckoo eggs shoulddefend their nests at a lower level than nonrecognizers
becausethe former also recognize adult cuckoos. Magpie (Pica pica)
hoststhat rejected model eggs of the brood parasitic great spottedcuckoo
(Clamator glandarius) showed lower levels of nest defensewhen
exposed to a great spotted cuckoo than when exposed toa nest predator (a
carrion crow Corvus corone). Moreover, magpiesrejecting cuckoo eggs
showed lower levels of nest defense againstgreat spotted cuckoos than
nonrecognizer magpies, whereas differencesin levels of defense disappeared
when exposed to a carrion crow.These results suggest that hosts specialize in
antiparasitedefense and that different kinds of defense are antagonistically
expressed.We suggest that nest-defense mechanisms are ancestral, whereasegg
recognition and rejection is a subsequent stage in the coevolutionaryprocess.
However, host recognition ability will not be expressedwhen brood parasites
break this second line of defense. 相似文献
10.
Arms races between brood parasites and their hosts provide model systems for studying the evolutionary repercussions of species interactions. However, how naive hosts identify brood parasites as enemies remains poorly understood, despite its ecological and evolutionary significance. Here, we investigate whether young, cuckoo-naive superb fairy-wrens, Malurus cyaneus, can learn to recognize cuckoos as a threat through social transmission of information. Naive individuals were initially unresponsive to a cuckoo specimen, but after observing conspecifics mob a cuckoo, they made more whining and mobbing alarm calls, and spent more time physically mobbing the cuckoo. This is the first direct evidence that naive hosts can learn to identify brood parasites as enemies via social learning. 相似文献
11.
12.
Temporal patterns of host availability, brown-headed cowbird brood parasitism, and parasite egg mass 总被引:2,自引:0,他引:2
Bill M. Strausberger 《Oecologia》1998,116(1-2):267-274
I studied relationships between temporal patterns of host availability, brood parasitism, and egg mass for the parasitic
brown-headed cowbird (Molothrus ater). At a study site consisting largely of edge habitat in north-eastern Illinois, I found 834 bird nests from 27 species. A
total of 407 cowbird eggs and nestlings were found in these nests over three laying seasons. Nearly all (n= 379; 93%) were found in the nests of seven host species. For these species and all taken together, weekly nest availability
generally decreased whereas parasitism frequency generally increased throughout the cowbird laying season, but the proportions
of nests parasitized and the mean number of cowbird eggs in them did not. Additionally, no correlation was found between the
proportions of nests parasitized and nest availability. Cowbird egg mass generally increased throughout the laying season,
indicating that foraging conditions improved and that, early in the laying season, egg mass and quality may be less important
than quantity. Consistently high weekly levels of parasitism indicate that cowbird reproduction was less limited by resources
needed for egg production and more by the availability of suitable host nests. Fluctuating weekly host availabilities suggest
that previously established, constant rates of cowbird egg laying would produce an excess of eggs during periods of low host
availability. Further, the low frequency of parasitism (1%) of nests in stages too advanced for successful parasitism, and
of abandoned nests, is consistent with the hypothesis that cowbirds' consistently high rate of egg production helps assure
an egg is available when an appropriate nest is found. Frequently, nests were parasitized multiple times, raising the possibility
that cowbirds were interfering with their own reproduction. A diverse host community increases the possibility that a decline
of any one host species is unlikely to affect cowbird reproduction significantly.
Received 11 July 1997 / Accepted: 31 March 1998 相似文献
13.
MICHAEL G. ANDERSON HOWARD A. ROSS DIANNE H. BRUNTON MARK E. HAUBER 《Biological journal of the Linnean Society. Linnean Society of London》2009,98(1):208-216
Studies of avian brood parasite systems have typically investigated the mimicry of host eggs by specialist parasites. Yet, several examples of similarity between host and parasite chick appearance or begging calls suggest that the escalation of host–parasite arms races may also lead to visual or vocal mimicry at the nestling stage. Despite this, there have been no large-scale comparative studies of begging calls to test whether the similarity of host and parasite is greater than predicted by chance or phylogenetic distance within a geographically distinct species assemblage. Using a survey of the begging calls of all native forest passerines in New Zealand, we show that the begging call of the host-specialist shining cuckoo ( Chrysococcyx lucidus ) is most similar to that of its grey warbler ( Gerygone igata ) host compared to any of the other species, and that this is unlikely to have occurred by chance. Randomization tests revealed that the incorporation of the shining cuckoo's begging calls into our species-set consistently reduced the phylogenetic signal within cluster trees based on begging call similarity. By contrast, the removal of the grey warbler calls did not reduce the phylogenetic signal in the begging call similarity trees. These two results support a scenario in which coevolution of begging calls has not taken place: the begging call of the host retains its phylogenetic signal, whereas that of the parasite has changed to match that of its host. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 208–216. 相似文献
14.
Detecting ancient codispersals and host shifts by double dating of host and parasite phylogenies: Application in proctophyllodid feather mites associated with passerine birds 下载免费PDF全文
Pavel B. Klimov Sergey V. Mironov Barry M. OConnor 《Evolution; international journal of organic evolution》2017,71(10):2381-2397
Inferring cophylogeographic events requires matching the timing of these events on both host and symbiont (e.g., parasites) phylogenies because divergences of hosts and their symbionts may not temporally coincide, and host switches may occur. We investigate a large radiation of birds (Passeriformes) and their permanent symbionts, the proctophyllodid feather mites (117 species from 116 bird species; six genes, 11,468 nt aligned) using two time‐calibration strategies for mites: fossils only and host phylogeography only. Out of 10 putative cophylogeographic events 4 agree in timing for both symbiont and host events being synchronous co‐origins or codispersals; three were based on host shifts, but agree in timing being very close to the origin of modern hosts; two disagree; and one large basal mite split was seemingly independent from host phylogeography. Among these events was an ancient (21–25.3 Mya), synchronous codispersal from the Old World leading to the origin and diversifications of New World emberizoid passerids and their mites, the thraupis + quadratus species groups of Proctophyllodes. Our framework offers a more robust detection of host and symbiont cophylogeographic events (as compared to host‐symbiont reconciliation analysis and using host phylogeography for time‐calibration) and provides independent data for testing alternative hypotheses on timing of host diversification and dispersal. 相似文献
15.
Paternity-parasitism trade-offs: a model and test of host-parasite cooperation in an avian conspecific brood parasite 总被引:1,自引:0,他引:1
Lyon BE Hochachka WM Eadie JM 《Evolution; international journal of organic evolution》2002,56(6):1253-1266
Efforts to evaluate the evolutionary and ecological dynamics of conspecific brood parasitism in birds and other animals have focused on the fitness costs of parasitism to hosts and fitness benefits to parasites. However, it has been speculated recently that, in species with biparental care, host males might cooperate with parasitic females by allowing access to the host nest in exchange for copulations. We develop a cost-benefit model to explore the conditions under which such host-parasite cooperation might occur. When the brood parasite does not have a nest of her own, the only benefit to the host male is siring some of the parasitic eggs (quasi-parasitism). Cooperation with the parasite is favored when the ratio of host male paternity of his own eggs relative to his paternity of parasitic eggs exceeds the cost of parasitism. When the brood parasite has a nest of her own, a host male can gain additional, potentially more important benefits by siring the high-value, low-cost eggs laid by the parasite in her own nest. Under these conditions, host males should be even more likely to accept parasitic eggs in return for copulations with the parasitic female. We tested these predictions for American coots (Fulica americana), a species with a high frequency of conspecific brood parasitism. Multilocus DNA profiling indicated that host males did not sire any of the parasitic eggs laid in host nests, nor did they sire eggs laid by the parasite in her own nest. We used field estimates of the model parameters from a four-year study of coots to predict the minimum levels of paternity required for the costs of parasitism to be offset by the benefits of mating with brood parasites. Observed levels of paternity were significantly lower than those predicted under a variety of assumptions, and we reject the hypothesis that host males cooperated with parasitic females. Our model clarifies the specific costs and benefits that influence host-parasite cooperation and, more generally, yields precise predictions about expected levels of host male paternity. These predictions will enable a more rigorous assessment of field studies designed to test adaptive hypotheses of host-parasite cooperation. 相似文献
16.
In many bird species, parents usually feed the first nestling that starts to beg before its nest‐mates. The pressure to avoid missed feeds could trigger nestlings to perform in erroneous begging in absence of parents, which has the same costs as begging in the presence of parents but without any reward. So, nestlings should try to minimize both erroneous begging and missed feeds simultaneously. The threshold to start begging is predicted to be lower for hungry nestlings and for nestlings that are unrelated to their nest‐mates, because they suffer lower inclusive fitness costs when depriving nest‐mates of food. In line with this idea, we found that brood parasitic great spotted cuckoo nestlings responded sooner than their magpie nest‐mates when an adult arrived to the nest. Under laboratory conditions, nestlings of both species rarely incurred in erroneous begging when food was abundant, but under conditions of restricted food, magpie nestlings increased erroneous begging while cuckoo nestlings did not. Highly conspicuous begging in cuckoos results in an increased predation risk, which could have resulted in stronger selection pressures on cuckoos to avoid erroneous begging, probably resulting in better developed perceptual abilities, allowing cuckoos to perform better than their host nest‐mates. 相似文献
17.
We tested great reed warbler (Acrocephalus arundinaceus) discrimination against two common cuckoo (Cuculus canorus) female color morphs (gray and rufous) in two areas with different parasitism rates and proportions of the two morphs. Hosts recognized the two cuckoo morphs from a control, the feral pigeon (Columba livia), at Apaj, Hungary (where brood parasitism was heavy), whereas no significant differences among the models were recorded at Lužice, Czech Republic (where the parasitism rate was moderate). At Apaj, the hosts discriminated the rufous morph (which is slightly predominant there) better than the gray morph from the control. Between-site comparison (after controlling for background aggression) revealed that great reed warblers were more aggressive towards the rufous morph at Apaj than at Lužice, whereas their responses to the gray morph did not differ, corresponding with much higher between-site difference in the relative abundance of the rufous morph. Our results suggest that both local parasitism pressure and relative abundance of two female color morphs of a brood parasite may significantly influence host nest defenses. 相似文献
18.
Understanding host-parasite coevolution requires multigenerational studies in which changes in both parasite infectivity and host susceptibility are monitored. We conducted a coevolution experiment that examined six generations of interaction between a freshwater snail (Potamopyrgus antipodarum) and one of its common parasites (the sterilizing trematode, Microphallus sp.). In one treatment (recycled), the parasite was reintroduced into the same population of host snails. In the second treatment (lagged), the host snails received parasites from the recycled treatment, but the addition of these parasites did not begin until the second generation. Hence any parasite-mediated genetic changes of the host in the lagged treatment were expected to be one generation behind those in the recycled treatment. The lagged treatment thus allowed us to test for time lags in parasite adaptation, as predicted by the Red Queen model of host-parasite coevolution. Finally, in the third treatment (control), parasites were not added. The results showed that parasites from the recycled treatment were significantly more infective to snails from the lagged treatment than from the recycled treatment. In addition, the hosts from the recycled treatment diverged from the control hosts with regard to their susceptibility to parasites collected from the field. Taken together, the results are consistent with time lagged, frequency-dependent selection and rapid coevolution between hosts and parasites. 相似文献
19.
Colony structure of a slavemaking ant. II. Frequency of slave raids and impact on the host population 总被引:1,自引:0,他引:1
The parasite pressure exerted by the slavemaker ant Protomognathus americanus on its host species Leptothorax longispinosus was analyzed demographically and genetically. The origin of slaves found in colonies of the obligate slavemaker was examined with nuclear and mitochondrial DNA markers to make inferences about the frequency and severity of slave raids. Relatedness of enslaved L. longispinosus workers in the same nest was very low, and our data suggest that, on average, each slavemaker nest raids six host colonies per season. Therefore, the influence of slavemaker species on their hosts is much stronger than simple numerical ratios suggest. We also found that slave relatedness was higher in small than in large slavemaker nests; thus, larger nests wield a much stronger influence on the host. We estimated that in the study population, on average, a host nest has a 50% chance of being attacked by a slavemaker colony per year. Free-living Leptothorax colonies in the vicinity of slavemaker nests did not represent the source of slaves working in P. americanus colonies, which suggests that raided nests either do not survive or migrate after being raided. Colony composition and intranest relatedness of free-living L. longispinosus colonies differed markedly between areas with slavemakers and those that are parasite-free. In the presence of slavemakers, host colonies were less likely to be polygynous and had fewer workers and a higher relatedness among worker brood. Host nests with slavemaker neighbors allocated more resources into sexuals, possibly caused by these shifts in nest demography. Finally, enslaved Leptothorax workers in P. americanus nests appeared to be less efficient than their counterparts in free-living colonies. Thus, slavemakers exert a much stronger impact on their hosts than had previously been suspected and represent an unique system to study parasite-host coevolution. 相似文献
20.
Nicola Ferrari Isabella M. Cattadori Javier Nespereira Annapaola Rizzoli Peter J. Hudson 《Ecology letters》2004,7(2):88-94
We investigated the role of host sex in parasite transmission and questioned: ‘Is host sex important in influencing the dynamics of infection in free living animal populations?’ We experimentally reduced the helminth community of either males or females in a yellow‐necked mice (Apodemus flavicollis) population using an anthelmintic, in replicated trapping areas, and subsequently monitored the prevalence and intensity of macroparasites in the untreated sex. We focussed on the dominant parasite Heligmosomoides polygyrus and found that reducing parasites in males caused a consistent reduction of parasitic intensity in females, estimated through faecal egg counts, but the removal of parasites in females had no significant influence on the parasites in males. This finding suggests that males are responsible for driving the parasite infection in the host population and females may play a relatively trivial role. The possible mechanisms promoting such patterns are discussed. 相似文献