共查询到20条相似文献,搜索用时 31 毫秒
1.
In mammalian polygynous mating systems, male reproductive effort consists mainly of male–male competition and courting of
females, which entail substantial somatic costs. Males are thus expected to adjust their reproductive effort according to
their age and condition. In this study, we examined how activity budgets of male mountain goats (Oreamnos americanus), a polygynous ungulate, varied with age in a marked population over two periods: (1) summers 1995–2006 and (2) ruts 2004–2006.
We then assessed if the proportions of time spent in male–male competition and courtship behaviors were influenced by age-specific
body mass and social rank during the rut. Males spent most of their time foraging and resting during summer, and rested more
and foraged less with increasing age. During the rut, pronounced shifts in activity budgets occurred as juveniles (1–2 years)
increased time spent foraging, whereas adults (≥3 years) increased standing and time spent in social interactions at the expense
of foraging. At old age, reproductive effort either stabilized or decreased slightly, providing weak support for the ‘mating
strategy–effort’ hypothesis, predicting that courtship behaviors should peak in prime-aged males. Age-specific body mass did
not affect time spent in male–male competition, but was positively related with time spent in courtship behaviors, providing
support for the ‘individual quality’ hypothesis, predicting that males with more resources at the start of the rut should
spend more time in mating-related activities. Age-specific social rank did not affect reproductive effort. Surviving to prime
age while increasing mass each year should thus allow male ungulates to gain greater ability to court estrus females. 相似文献
2.
Information about foraging speeds is particularly valuable when the impact of a predator species upon a community of prey has to be defined, as in the case of great cormorants. We measured the swim speed of 12 (six males and six females) free-ranging great cormorants Phalacrocorax carbo, foraging off the Greenland coast during the summer of 2003, using miniaturized data-loggers. Although mean body mass of males was 27% greater than that of females, and mean swim speed of males were 29–57% higher than that of females during foraging phases (but not descent phases) of dives, these differences in speeds were not significant due to high variances. Birds descended to the mean maximum depth of 4.7 m at an average speed of 1.6±0.5 m s−1, a speed similar to that measured in captive cormorants in previous studies. Although bursts of up to 4 m s−1 were recorded, speed usually decreased during the deepest (foraging) phase of dives, being on average 0.8±0.6 m s−1. Speeds measured here should be taken with caution, because the large propeller loggers used to measure speed directly decreased descent speeds by up to 0.5 m s−1 when compared to smaller depth-only loggers. Cormorants in Greenland seem to combine two searching strategies, one requiring low speed to scan the water column or benthos, and one requiring high speed to pursue prey. These two strategies depend on the two main habitats of their prey: pelagic or demersal. 相似文献
3.
F. Bentivegna F. Valentino P. Falco E. Zambianchi S. Hochscheid 《Marine Biology》2007,151(5):1605-1614
Previous studies have shown that loggerhead sea turtles (Caretta caretta), monitored by satellite telemetry, complete long-distance migration between the western and eastern Mediterranean basins
following a seasonal pattern. This study investigated if these migration routes may be influenced by surface currents by superimposing
the tracks of three loggerhead turtles (curved carapace length >55 cm), migrating from the western to the eastern Mediterranean
basin, on Lagrangian data of current developed into pseudo-eulerian speed fields. The average travel speed of the turtles
was 1.6 km h−1 and did not depend on the current speed or direction. We observed a connection between surface currents and the turtles’
migration routes, although not a conclusive one. These observations show that neritic stage loggerhead turtles conduct migration
in two distinct alternate phases: the first characterized by high and constant speed of travel both when swimming with or
against currents and the second typified by low travel speeds and a good concurrence between the trailed routes and the course
of the currents. These two phases corresponded to two types of movements, one where the turtle migrates actively to reach
a specific destination (either neritic foraging, wintering or nesting ground) and the other, where the turtle drifts with
the mesoscale current and forages pelagically. It seemed thus, that the influence of currents on a turtle’s movements depends
on the turtle’s momentary behaviour and location of residence. 相似文献
4.
Antonia Köhler Philipp Hildenbrand Elke Schleucher Rüdiger Riesch Lenin Arias-Rodriguez Bruno Streit Martin Plath 《Behavioral ecology and sociobiology》2011,65(8):1513-1523
Sexual harassment by males has the potential to affect almost any aspect of female behavior and life history. Using Atlantic
mollies (Poecilia mexicana) as a model—a species in which males do not court but almost constantly try to forcefully mate with females—we asked whether
and how male harassment influences (a) females’ time budgets and (b) feeding rates (e.g., through frequent flight from male
approaches), and (c) whether metabolic rates are increased as a response to stress. Field observations in a natural P. mexicana population revealed that males (average feeding rate 15%) spent far less time feeding than females (60%), and clearly traded
off frequent pursuit of females with foraging. Most importantly, females’ feeding times were dramatically reduced when being
pursued by a harassing male. Also in standardized lab experiments, females spent significantly less time feeding when accompanied
by a male as compared to being in the presence of another female. This effect was also observed when partner fish (male or
female) were presented only visually, but could not interact physically with the focal female. It seems, therefore, that females
increase vigilance when a harassing male is around, which keeps them from feeding even before males actually approach them.
Based on the latter result, we asked whether a stress-induced increase in metabolic rates would be discernible. We measured
oxygen consumption and gill ventilation frequencies (opercular rates) of females in different social contexts (alone, with
another female, or a male). The predicted, strong body mass dependency of both physiological parameters was uncovered, but
no evidence for an effect of social context was detected. We argue that male harassment represents such a constant (but non-lethal)
stressor for poeciliid females that their metabolic stress responses have adapted to this through habituation. 相似文献
5.
According to indicator models of sexual selection, mates may obtain indirect, i.e. genetic, benefits from choosing partners indicating high overall genetic quality by honest signals. In the scorpionfly Panorpa vulgaris, both sexes show mating preferences on the basis of the condition of the potential partners. Females prefer males that produce nuptial gifts (i.e. salivary secretions) during copulation, while males invest more nuptial gifts in females of high nutritional status. Both characters, males' ability to produce nuptial gifts and high nutritional status of females, are known to be reliable indicators of foraging ability. Thus, besides possible direct benefits, both sexes might also obtain indirect benefits in terms of “good foraging genes” by their choice and thereby increase the fitness of their offspring. A prerequisite for this possibility is the heritability of the respective trait. In the present study, we estimated the repeatability and the heritability of foraging ability. Our results indicate (1) a significant repeatability of individual foraging efficiencies in males and females and (2) a heritable component of this trait by a significant parent–offspring regression. These findings suggest that genetic benefits in terms of increased offspring foraging ability might contribute to selection for mating preferences in both sexes. 相似文献
6.
S. Boinski 《Behavioral ecology and sociobiology》1988,23(3):177-186
Summary The effects of sex and seasonal changes in food abundance on foraging behavior was studied in squirrel monkeys (Saimiri oerstedi) in Costa Rica over an eleven-month period. Females searched for and ate food at significantly greater frequencies than did males throughout the study. The frequency of the specific foraging techniques used occasionally differed significantly within seasons, but not across the study period. Few differences were found in the foraging behaviors of nonreproductive sexually mature females compared to females that were pregnant or lactating. The major exception was that during the month following parturition reproductive females foraged for flowers and fruits more frequently than did non-reproductive females. The reduction of time spent by males in foraging activities gives them more time for other activities, especially anti-predator vigilance. Foraging techniques and the proportions of different food types in the diet changed seasonally. Foraging for arthropods was most frequent in the season when arthropod abundance was lowest, resulting in the amount of time spent eating arthropods to vary less across the seasons. Fruits and flowers were not eaten in a direct relationship to availability, but were used more than expected relative to availability when arthropod abundance was reduced. Individuals were more dispersed when foraging compared to other activities. Overall, there was little evidence of any direct foraging benefits for a squirrel monkey from being social. 相似文献
7.
We studied movement and site fidelity of males and females of the territorial frog Allobates femoralis (Aromobatidae) in a population in the Nature Reserve “Les Nouragues” in French Guiana, South America. Observations during
3 months in 2006 ascertained intra-seasonal site fidelity for males and females. Males actively defend large multi-purpose
territories whereas females retreat to small resting sites from where they commute to neighbouring males for courtship and
mating. Female short-term movement corroborates the previous assumption of a polygynous or promiscuous resource-defence mating
system. Year-to-year recaptures from 2005 until 2008 revealed distinct patterns of inter-annual movement for males and regional
site fidelity for females. Males abandon their territories and have to re-negotiate them when reproduction starts again at
the end of the dry season. Females are not subject to intra- or inter-sexual territorial competition and as a result move
significantly less between reproductive seasons than males. Male long-term movement reflects spatial structure and prevailing
social interactions and is a reliable indicator for tadpole deposition sites. The combined effects of intra- and inter-seasonal
movement promote the diversity of mates for both sexes. 相似文献
8.
Christian Ramp Wilhelm Hagen Per Palsbøll Martine Bérubé Richard Sears 《Behavioral ecology and sociobiology》2010,64(10):1563-1576
Analyses of social structures in baleen whales are rare, and so far, they are thought to consist of mostly short and unstable
associations. We investigated the association patterns of individual humpback whales from a summer feeding aggregation in
the Gulf of St. Lawrence from 1997 to 2005. Photo-identified animals were sexed using genetic methods and were grouped into
five categories: juvenile males/females, mature males and lactating/non-lactating females. We calculated half-weight association
indices within and between the groups and found that 45% of the observation showed single animals and another 45% small groups
(two to three) consisting mainly of mature animals besides lactating females. Using permutation tests, we found evidence for
long-term associations between mature males and non-lactating females as well as among non-lactating females. Standardised
lagged association rates revealed that these male–female groups disassociated quickly over about 2 weeks, whereas associations
increased again towards the beginning of the breeding season. Non-lactating females of similar age engaged in multi-seasonal
stable pairs for up to six consecutive feeding seasons; no mature male–female association was observed in consecutive years.
The females with the most stable and long-term associations also had the highest reproductive output. While the risk of predation
could not explain these long-term bonds, feeding cooperation seemed the most plausible explanation for group forming behaviour
during the summer months. 相似文献
9.
Hydrodynamic forces are an important determinant of subtidal community structure, particularly when they limit the distribution
and foraging ability of mobile consumers. We examined the effect of wave action on the rate of movement and destructive grazing
of a kelp bed by the green sea urchin (Strongylocentrotus droebachiensis) under field conditions. We measured density and rate of advance at fixed intervals along ∼100 m of a grazing front over
1 year, and quantified individual movement rates in the barrens 5–10 m behind the urchin front using a time-lapse videography.
Seasonal variation in the mean rate of advance of the front (range: 0–4 m month−1) was explained by changes in urchin density at the front (120–360 individuals m−2), which in turn varied inversely with significant wave height (0.5–2 m). Water temperature (0.8–17.6°C) had no effect on
the rate of advance or on urchin density (aggregation) at the front, except when temperature exceeded 17°C. Movement of individual
urchins also was affected by wave action: we observed a significant decrease in speed and displacement of urchins with increasing
significant wave height. Wave action had no effect on the proportion of urchins moving or the degree of linearity of their
movements. We propose that the decrease in urchin density at the front associated with increased wave action, results from
de-aggregation, which reduces the risk of dislodgement, combined with a reduction in urchin movement in barrens, which supplies
new urchins to the front. 相似文献
10.
Male mosquitofish are very persistent in their sexual activity and harass any female they encounter. Gravid females pay a
large tribute to this intense male sexual activity in terms of reduced foraging efficiency. Previous observations have demonstrated
that gravid females, when chased by a male, dilute male harassment by moving closer to other females to form shoals. They
also approach other males to promote male competition, and when males differ in size, they preferentially target large males,
whose harassment is less intense. In this study, we tested whether the modulation of females’ social preferences in response
to male harassment is innate or learned. We tested social preference in three groups of females that differed in experience
of sexual harassment and in the factors affecting it. Females of the first group were reared without any sexual experience,
and pregnancy was induced through artificial insemination. The second group was composed of naive females kept singly with
a male; these females experienced sexual harassment but were prevented from experiencing the effects of male–male competition
and shoaling on the amount of male sexual harassment. In the third group (controls), females were reared in multi-male, multi-female
groups and could experience the modulating effects of social interactions on sexual harassment. When exposed to a harassing
male, females of the three groups immediately reduced their distance from another female, approached a group of males or moved
toward the larger of two available males. Moreover, the results for these three groups of females were similar to those obtained
in wild-caught females that were tested in the same three tests in a previous study (Dadda et al. An. Behav., 70:463–471, 2005). This suggests that the strategies adopted by females in response to male sexual harassment do not need to be learned through
specific experience of the social contexts. 相似文献
11.
Carola Borries Kristin Launhardt Cornelia Epplen Jörg T. Epplen Paul Winkler 《Behavioral ecology and sociobiology》1999,46(5):350-356
Hypotheses about the evolution of gregariousness and social organisation in primates are based on ecological explanations
as well as on social factors such as conspecific threat (especially infanticide by males). The social explanation fits well
with the conditions found in strepsirrhine primates and furthermore explains why infanticide in anthropoid primates living
in one-male groups mainly occurs when the resident male (protector) is replaced. However, whether it likewise fits to the
conditions in multimale groups will depend on the role of resident males as infant protectors, which has rarely been examined.
We investigated long-term data of wild Hanuman langurs (Presbytis entellus) inhabiting a forest near the village of Ramnagar (southern Nepal). Twenty-two eye-witnessed attacks on infants by males
were analysed in connection with male residency, paternity (DNA analyses) and sexual behaviour. Adult males played a major
role in infant defence (65%). Only the genetic father or males who had been residents when the infant was conceived were observed
to protect infants. Males who immigrated after a female had conceived may later attack her infant and were never observed
to defend it. lt seems that the males took only copulations with potentially fertile females but not with pregnant females
as clues for paternity. In the light of these results it seems likely that the risk of infanticide is an important determinant
in female-male associations even in anthropoid primate multimale groups.
Received: 22 December 1998 / Received in revised form: 30 April 1999 / Accepted: 1 May 1999 相似文献
12.
Sarie Van Belle Alejandro Estrada Paul A. Garber 《Behavioral ecology and sociobiology》2013,67(1):31-41
Maintaining social cohesion through coordinating traveling time and direction is a primary benefit of group living in mammals. During a 15-month study, we investigated socioecological factors underlying leadership of collective group movements in three multimale–multifemale groups of black howler monkeys (Alouatta pigra) at Palenque National Park (PNP), Mexico. A total of 691 independent group movements across a variety of contexts were collected. Leadership of group movements was partially shared, with adult females initiating and leading group movements significantly more often than did adult males and juveniles, an outcome that has been observed among a diverse set of group living taxa. Adult females did not lead their group more often to feeding sites nor did they lead group movements more frequently when pregnant or lactating compared to when cycling, providing little evidence that energetic demands were the primary drivers underlying female leadership in this primate species. Instead, only one adult female in each social group was identified as a habitual leader of their group. These ‘leader’ females had the highest centrality eigenvectors among the adult group members in their group, suggesting an embedded leadership with the spatially widest connected adult group member emerging as recurrent leader of collective group movements. 相似文献
13.
Most studies suggest that during times of nutritional stress, an animal faced with two foraging choices should follow a risk-prone
strategy, choosing the option with highest payoff variance. This “scarcity/risk” hypothesis was developed to account for the
foraging patterns of small animals with high metabolic rates susceptible to the threat of starvation. In this paper, we propose
that animals should also be risk-prone when their diet quality is particularly high, far exceeding that which is needed to
survive. Under these circumstances, the costs of experiencing a low or negative payoff can easily be recouped. We suggest
that large-bodied omnivores are most likely to adopt this “abundance/risk” strategy. We investigate this question among wild
chimpanzees (Pan troglodytes) that choose between a risk-averse strategy of feeding on plant material and a risk-prone strategy of hunting red colobus
monkeys. Using 14 years of data on the Kanyawara chimpanzees of Kibale National Park, Uganda, we find strong evidence that
chimpanzees follow the “abundance/risk” strategy. Both hunting rate (hunts/100 observation hours) and the probability of hunting
upon encountering red colobus monkeys were positively correlated with seasonal consumption of ripe drupe fruits, a class of
preferred food associated with elevated reproductive performance by females. Critically, these results remained statistically
significant after controlling for the potentially confounding effects of male chimpanzee party size and the presence of sexually
receptive females. These findings suggest that the relationship between risk-sensitive foraging and diet quality depends upon
the daily probability of starvation, the number of alternative foraging strategies, and the degree to which diet quality satisfies
an animal’s nutritional requirements. 相似文献
14.
Facultative traits that have evolved under sexual selection, such as the acoustic ornaments present in the advertisement signals
of male túngara frogs (Physalaemus pustulosus), offer a unique opportunity to examine selection for trait exaggeration with a focus on individual differences amongst signalers.
By contrast, many studies of mate choice use experimental designs that obscure the inter-individual variation amongst signalers
available for selection to act on—through the use of “typical” or average signals from the population. Here, we use dichotomous
female phonotaxis choice tests to determine how the value of male call embellishment varies across 20 individual males frogs
recorded from the wild—a sample which captures the acoustic diversity present in the population. We tested 20 females for
each male call pair (i.e., 400 females). The results show widespread preference amongst females for ornamented calls (“whine–chucks”)
over simple calls (“whines”), yet also demonstrate substantial variation in the relative benefits for individual male frogs—some
males enjoy appreciable benefits by using ornaments while others (30% of males in this study) do not. We also show that the
relative amplitude of the chuck to the whine correlates positively with the value of call elaborations across these 20 males.
Finally, by manipulating the relative amplitude of whines and chucks using both natural and synthetic calls, we demonstrate
directly that this single call parameter is key to determining the relative value of call elaborations across males. 相似文献
15.
S. E. Lewis 《Behavioral ecology and sociobiology》1996,39(5):335-344
Despite potential costs of changing roost or densites, many animals frequently move between roosts or dens. Pallid bats (Antrozous pallidus) change diurnal roost sites frequently and also reportedly have a variety of cooperative social behaviors, many of which
are associated with the care of developing offspring. Roost switching is likely to increase the costs of maintaining the group
stability expected with social cooperation. Pallid bats roosting in rock crevices in central Oregon were studied with radiotelemetry
to (1) examine characteristics of day roosts, (2) determine what ecological factors were correlated with low roost fidelity,
and (3) examine the temporal stability of roosting groups of pregnant and lactating bats. Pallid bats changed roosts an average
of once every 1.4 days throughout the summer. The bats exhibited seasonal shifts in roost use, occupying roosts behind thin
slabs of rock in cool weather and roosts in deep rock crevices in warm weather. Roost switching was not correlated with daily
variations in weather conditions or with structural characteristics of the diurnal roosts, although switching may have allowed
bats to maintain familiarity with several roosts that vary in microclimate. Roost switching was positively correlated with
ectoparasite load. High ectoparasite levels were correlated with lower body weights in lactating females (Fig. 3), suggesting
that parasites may be costly to the bats. Roost switching may be a strategy to decrease ectoparasite loads by interrupting
the reproductive cycles of those parasites that spend at least part of their life cycle on the walls of the roost. Both pregnant
and lactating pallid bats frequently changed their diurnal roost location, but lactating bats tended to travel shorter distances
between consecutive roosts. Lactating bats were more likely to continue to associate with particular roostmates despite changes
in the location of the diurnal roost (Fig. 4) and were less likely to roost alone. Although the stability of groups of lactating
bats was not absolute, evidence supported the prediction that such groups are more cohesive than are those of pregnant bats.
Received: 20 June 1995/Accepted after revision: 13 July 1996 相似文献
16.
Understanding the rules and factors that drive the foraging behavior of large herbivores is important to describe their interaction with the landscape at various spatial scales. Some unresolved questions refer to landscape-behavioral interactions that result in oriented or random search in seasonally changing landscapes. Remotely sensed position data indicate that herbivores select local patches of heterogeneous landscapes depending on a complex host of dynamically varying animal and environmental conditions. Since foraging paths consist in successions of relatively short steps, increasing the frequency at which position information is acquired would contribute to entangle the mechanisms resulting in herbivores’ foraging paths. We addressed the question whether herbivores would obtain information at a patch scale that would modify their distribution at a landscape scale based on directed movement or navigation ability. We considered a set of 100,000 high-frequency (1 min intervals) position data of several free-ranging sheep (Ovis aries) at a seasonal-varying range (Patagonian Monte, Argentina) and observed their movements at landscape and at single vegetation patch scales. At a landscape scale, we inspected the spatial co-variation of seasonally varying forage offer and ewes’ movement speeds. At a patch scale, we developed a phase-state (P-S) model of movement cycles based on the occurrence of behavioral phases along foraging paths, and fitted it to the observed daily time series of ewes’ movement speeds. Ewes were preferentially distributed in areas with high forage offer during periods of low forage availability and the reverse occurred during the season of high forage availability. Parameters of the model of activity cycles amenable to control by ewes (duration of speed phases, time elapsed between speed cycles) did not covariate with forage offer, but varied significantly among ewes. The shape (kurtosis) parameter of the model of movement cycles, one which is unlikely under ewes’ control, co-varied significantly with spatial forage offer but did not differ among ewes. We conclude that ewes allocated foraging time along a series of similar movement efforts irrespective of forage availability at small patches. Average forage scarcity at multi-patch level increases the ratio of searching to feeding time. This results in apparent selective time allocation to richer forage areas but does not imply evidence for oriented movement at a landscape scale. We advance a behavioral-based definition of forage patches and discuss its implications in developing foraging theory and models. The P-S model applied to high-frequency position data of large herbivores substantially improves the interpretation of the factors controlling their time allocation in space with respect to previous models of herbivore spatial behavior by discriminating among behavioral-based and environmentally induced components of their movements. 相似文献
17.
Infanticide by males is common in mammalian species such as primates in which lactation lasts much longer than gestation.
It frequently occurs in one-male groups following male takeovers and is likely a male reproductive strategy. Reported female
countertactics include abrupt weaning of infants, dispersal, or paternity confusion. Here, we estimated costs of female countertactics
in terms of weaning ages and interbirth intervals. We observed a population of white-headed leaf monkeys (Trachypithecus leucocephalus) in Nongguan Nature Reserve, China (1995–2006) mainly composed of one-male groups. Takeovers (N = 11) coincided with the peak conception period. Detailed data are presented for five takeovers (34 females, 29 infants,
and 47 group-years) leading to six infant disappearances (42.9% of infant mortality). All presumed infanticides were in accordance
with the sexual selection hypothesis. Following a takeover, females without infants or with old infants stayed with the new
males, incurring no or low costs (via abrupt weaning). Females with young infants dispersing with the old males also experienced
low costs. High costs (due to infant loss) were incurred by pregnant females and those with young infants who stayed with
the new males indicating that paternity was not confused. Costs in terms of long interbirth intervals were also high for females
leaving with the old males to later join the new males, despite infant survival. Female countertactics reflected female philopatry
mediated by infant age. Presumably due to the seasonal timing of takeovers, most countertactics seemed successful given that
32.3% of females apparently incurred no costs and 41.2% incurred only low costs. 相似文献
18.
Kevin C. Weng Andre M. Boustany Peter Pyle Scot D. Anderson Adam Brown Barbara A. Block 《Marine Biology》2007,152(4):877-894
Satellite telemetry studies of 20 adult and sub-adult white sharks (360–530 cm estimated total length (TL)) in the eastern
North Pacific during 1999–2005 revealed long distance seasonal migrations from the coast of California to an offshore focal
area 2,500 km west of the Baja Peninsula, as well as the Hawaii Islands. Three tags were recovered allowing detailed behavioral
analyses, including one shark’s migration cycle from the coast to the offshore focal area and back. While near pinniped rookeries
in autumn and winter, sharks avoided the surface and used water to 50 m depth, consistent with a silhouette-based hunting
strategy. Offshore migrations were initiated during November–March and followed periods of decreasing pinniped abundance.
Migrations were highly directed, taking 23 ± 5 days to reach the offshore focal area along similar paths among sharks and
years, defining a migration corridor. Sharks exhibited a broad depth distribution (0–644 m) in the offshore focal area, and
remained there for up to 167 days during spring and summer, though primary productivity and fishery data suggest that forage
resources are scarcer there than in other regions of the eastern North Pacific. Archival data from one shark revealed intensive
oscillatory movements while in the offshore focal area, a behavior that may be related to foraging or mating. Sharks traveling
to Hawaii remained near the islands up to 122 days, potentially feeding on pelagic fishes and marine mammals that concentrate
around the islands.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Nga Nguyen Russell C. Van Horn Susan C. Alberts Jeanne Altmann 《Behavioral ecology and sociobiology》2009,63(9):1331-1344
Close associations between adult males and lactating females and their dependent infants are not commonly described in non-monogamous
mammals. However, such associations [sometimes called “friendships” (Smuts 1985)] are regularly observed in several primate species in which females mate with multiple males during the fertile period.
The absence of mating exclusivity among “friends” suggests that males should invest little in infant care, raising questions
about the adaptive significance of friendship bonds. Using data from genetic paternity analyses, patterns of behavior, and
long-term demographic and reproductive records, we evaluated the extent to which friendships in four multi-male, multi-female
yellow baboon (Papio cynocephalus) groups in Amboseli, Kenya represent joint parental care of offspring or male mating effort. We found evidence that mothers
and infants benefited directly from friendships; friendships provided mother–infant dyads protection from harassment from
other adult and immature females. In addition, nearly half of all male friends were the genetic fathers of offspring and had
been observed mating with mothers during the days of most likely conception for those offspring. In contrast, nearly all friends
who were not fathers were also not observed to consort with the mother during the days of most likely conception, suggesting
that friendships between mothers and non-fathers did not result from paternity confusion. Finally, we found no evidence that
prior friendship increased a male’s chances of mating with a female in future reproductive cycles. Our results suggest that,
for many male–female pairs at Amboseli, friendships represented a form of biparental care of offspring. Males in the remaining
friendship dyads may be trading protection of infants in exchange for some resources or services not yet identified. Our study
is the first to find evidence that female primates gain social benefits from their early associations with adult males.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
Frank Rosell Gry Gundersen Jean-François Le Galliard 《Behavioral ecology and sociobiology》2008,62(10):1559-1568
Neighbour–stranger discrimination occurs when individuals respond with more aggression to strangers than to territorial neighbours—a
phenomenon termed the “dear enemy phenomenon” (DEP). We investigated the DEP with male and female root voles (Microtus oeconomus Pallas 1776) using field dyadic arena tests conducted in enclosures where we could test for the effects of familiarity (familiar
versus stranger), ownership (resident versus intruder status) and resource-holding potential (body mass) on territorial behaviours.
The results showed that males put more effort into territorial defence than females, and males could discriminate between
neighbours and strangers. In males, aggressiveness was influenced by a significant two-way interaction between treatment and
ownership. Male residents were more aggressive towards stranger intruders than towards neighbour intruders, while male intruders
were less aggressive towards stranger residents than towards neighbour residents. In females, neither treatment nor ownership
status had a significant effect on aggressiveness. Familiar males performed more social behaviours but less non-social behaviours
than stranger males. Furthermore, there was a clear dominance hierarchy between residents and intruders in stranger dyads,
with the male territory holders dominating the intruder in pairwise interactions. To our knowledge, these results demonstrate
for the first time DEP in a small mammal with a known pedigree and present the first evidence for “prior resident advantage”
in voles. We argue that both ownership status and familiarity status affect how much an individual invests in territory defence.
The benefits of neighbour–stranger discrimination for male root voles and the absence of neighbour–stranger discrimination
in female root voles are discussed. 相似文献