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1.
Christer Wiklund Adrian Vallin Magne Friberg Sven Jakobsson 《Behavioral ecology and sociobiology》2008,62(3):379-389
Insects that hibernate as adults have a life span of almost a whole year. Hence, they must have extraordinary adaptations
for adult survival. In this paper, we study winter survival in two butterflies that hibernate as adults and have multimodal
anti-predator defences—the peacock, Inachis io, which has intimidating eyespots that are effective against bird predation, and the small tortoiseshell, Aglais urticae, which does not have an effective secondary defence against birds. We assessed predation on wild butterflies hibernating
in the attic of an unheated house, as well as survival of individually marked butterflies placed by hand on different sites
in the attic. Our objectives were to assess (1) the number of butterflies that were killed during hibernation, (2) whether
survival differed between butterfly species, and (3) how predation was related to hibernation site and the identity of the
predator. There was a strong pulse of predation during the first 2 weeks of hibernation: 58% of A. urticae and 53% of I. io were killed during this period. Thereafter, predation decreased and butterfly survival equalled 98% during the final 16 weeks
of hibernation. There was no difference in survival between the two butterfly species, but predation was site-specific and
more pronounced under light conditions in locations accessible to a climbing rodent, such as the common yellow-necked mouse,
Apodemus flavicollis. We contend that small rodents are likely important predators on overwintering butterflies, both because rodents are active
throughout winter when butterflies are torpid and because they occur at similar sites. 相似文献
2.
Tsuyoshi Takeuchi 《Behavioral ecology and sociobiology》2011,65(8):1559-1566
Male butterflies compete over mating territories via aerial interactions. It has often been suggested that flight performance,
and thus flight-related traits, would play an important role in butterflies’ contest resolution; however, most studies have
not demonstrated a clear relationship between these traits and territory ownership in butterflies. Males of the satyrine butterfly
Lethe diana compete over territories via linear chases, a behavior that is uncommon among butterflies: rather, contests of most butterfly
species consist of circling flights. In the present study, some morphological and physiological traits of L. diana were compared between territory owners and intruders to search for traits correlated with resource holding power (RHP). Territory
owners had higher flight-muscle ratio (FMR) and were heavier than intruders, indicating that flight performance plays a key
role in their contest resolution. Contest duration was not affected by the owners’ FMR or body mass, and thus I obtained no
evidence supporting the hypothesis that contestants assess their relative RHP before making a decision to retreat. I speculate
that the fact that these traits had an effect on territorial status in L. diana was a result of the characteristics of the contest behavior of this butterfly. During their contests, males L. diana fly faster in their linear flights than males of most other butterflies, which engage in slower circling flights. Therefore,
males of L. diana probably need higher flight performance capabilities in order to win their contests. 相似文献
3.
Adrian Vallin Sven Jakobsson Johan Lind Christer Wiklund 《Behavioral ecology and sociobiology》2006,59(3):455-459
Butterflies that hibernate exhibit particularly efficient defence against predation. A first line of defence is crypsis, and
most hibernating butterflies are leaf mimics. When discovered, some species have a second line of defence; the peacock, I. io, when attacked by a predator flicks its wings open exposing large eyespots and performs an intimidating threat display. Here
we test the hypothesis that butterflies relying solely on leaf mimicking and butterflies with an intimidating wing pattern,
when attacked, exhibit different behavioural suites—because leaf mimicking is best implemented by immobility, whereas intimidating
coloration is best implemented by intimidating behaviour. In laboratory experiments blue tits, Parus caeruleus, were allowed 40 min to attack single individuals of three species of butterfly: one relying solely on crypsis, the comma,
Polygonia c-album; one relying on intimidating wing pattern in addition to crypsis, the peacock; and one intermediate species, the small tortoiseshell
Aglais urticae. The results are in accordance with expectations and demonstrate that: (1) birds take longer to discover the leaf mimicking
species, the comma, than the tortoiseshell and the peacock; (2) the comma remained motionless throughout experimental trials
but small tortoiseshells and peacocks flicked their wings when attacked; (3) the most intimidating butterfly, the peacock,
started flicking its wings at a greater distance from the attacking bird than the small tortoiseshell; and (4) the intimidating
pattern and behaviour of peacocks was effective—when discovered, all peacocks survived interactions with blue tits, whereas
only 22% of commas and 8% of small tortoiseshells survived. 相似文献
4.
Hannah M. ter Hofstede John M. Ratcliffe James H. Fullard 《Behavioral ecology and sociobiology》2008,63(2):217-226
Many nocturnal katydids (Orthoptera: Tettigoniidae) produce intense calling songs, and some bat species use these songs to
detect and locate prey. One Nearctic katydid species, Neoconocephalus ensiger, ceases or pauses singing in response to bat echolocation calls. We tested the hypothesis that song cessation is an effective
defence against gleaning bats (i.e., bats that take prey from surfaces). We observed Myotis septentrionalis, a sympatric bat species that uses prey-generated sounds when gleaning, attack and feed on singing N. ensiger in an outdoor flight room. These bats demonstrated a preference for the calling song of N. ensiger over a novel cricket calling song when they were broadcast from a speaker in the flight room. Bats attacked speakers broadcasting
N. ensiger calling song as long as the song was continuous and aborted their attack if the sound stopped as they approached, regardless
of whether a katydid was present as a physical target on the speaker. Echolocation calls were recorded during attacks and
no significant differences were found between continuous and interrupted song approaches for four call parameters, suggesting
that M. septentrionalis may not use echolocation to locate silent prey. Therefore, song cessation by katydids in response to ultrasound is an effective
defence against gleaning bats. 相似文献
5.
Adrian Vallin Sven Jakobsson Christer Wiklund 《Behavioral ecology and sociobiology》2007,61(9):1419-1424
Large eyespots on the wings of butterflies and moths have been ascribed generally intimidating qualities by creating a frightening
image of a bird or mammal much larger than the insect bearing the eyespots. However, evidence for this anti-predator adaptation
has been largely anecdotal and only recently were peacock butterflies, Inachis io, shown to effectively thwart attacks from blue tits, Parus caeruleus. Here, we test whether large eyespots on lepidopterans are generally effective in preventing attacks from small passerines
and whether the size of insect or bird can influence the outcome of interactions. We staged experiments between the larger
eyed hawkmoths, Smerinthus ocellatus, and the smaller peacock butterflies, I. io, and the larger great tits, Parus major, and the smaller blue tits, P. caeruleus. Survival differed substantially between the insect species with 21 of 24 peacock butterflies, but only 6 of 27 eyed hawkmoths,
surviving attacks from the birds. Thus, surprisingly, the smaller prey survived to a higher extent, suggesting that factors
other than insect size may be important. However, great tits were less easily intimidated by the insects’ eyespots and deimatic
behaviour and consumed 16 of 26, but the blue tits only 8 of 25, of the butterflies and hawkmoths. Our results demonstrate
that eyespots per se do not guarantee survival and that these two insects bearing equally large eyespots are not equally well
protected against predation. 相似文献
6.
Hatchery rearing of the scallop Argopecten purpuratus has resulted in successive generations of scallops not exposed to predators that are less sensitive to and escape more slowly
from predators than wild scallops. The present study examined whether conditioning hatchery-reared A. purpuratus to its natural predator, the sea star Meyenaster gelatinosus, improved its escape responses. Both juvenile and adult A. purpuratus from Tongoy Bay, Chile, were exposed for 7 days to different conditions: (1) continuous predator odor, (2) predator contact
for 30 min three times a day, (3) a combination of the two previous conditions, and (4) no exposure to the predator (control).
After conditioning, we evaluated scallop’s escape responses: reaction time, total clap number, duration of the clapping response,
clapping rate, and the time scallops spent closed when exhausted. Conditioning with contact and odor plus contact (i.e., high
predation risk) resulted in 25 and 50% shorter reaction times of juveniles and adults, respectively. Further, these stimuli
caused juveniles to increase the number of claps and clapping rate. For adults, the time spent closed after exhaustion decreased
by 50 and 63% after conditioning with contact and odor plus contact, respectively. Therefore, it is shown for the first time
that exposure of scallops to increasing predator stimuli enhances escape responses, evidence of threat-sensitive predator
avoidance. 相似文献
7.
Among the diverse patterns of energy allocation to the offspring of gastropods, the presence of egg capsules to protect embryos
is common. Females of the edible snail Zidona
dufresnei attach egg capsules to hard substrates in shallow Argentine Patagonian waters (40°45′S, 64°56′W) during spring-summer. Embryonic
development takes about 30 days at 22°C. In this study, three likely capsule predator species and the marks left by each on
egg capsule walls were identified in laboratory experiments in February 2010. Abundances of predators and egg capsules with
evidence of predation were assessed in the field in the summers of 2010 and 2011. Under laboratory conditions (N = 10 replicates per treatment and control), the predation rate by the chiton Chaetopleura
isabellei was the highest (up to 90%), followed by the gastropod Tegula
patagonica and the crab Neohelice
granulata (~20% each). Nearly 60% of 41 capsules found in the field showed signs of predation. According to the marks identified in
the laboratory, C. isabellei was responsible for 79% of this predation, and T. patagonica for the rest. Predation appears to be important during the encapsulated early life and could be an agent for selecting for
resistant capsule walls and a relatively shorter development time. 相似文献
8.
M. Gristina M. Sinopoli F. Fiorentino G. Garofalo F. Badalamenti 《Marine Biology》2011,158(6):1331-1337
The skill of recognizing and reacting to predators is often based on a learned component. Few studies have examined the role
of learning in spiny lobster anti-predator behavior. We investigated whether European spiny lobster (Palinurus elephas) shelter selection is influenced by olfactory stimuli released by one of the most common lobster predators, the common octopus
(Octopus vulgaris), and whether the behavioral response to octopus chemical stimuli is innate or influenced by experience. In experimental
arenas, we conditioned wild-caught lobsters with three levels of predation threat: no threat, with no predator–prey interaction;
medium threat, with odor and visual predator cues only; high threat, active predation risk. We subsequently tested the shelter
choice of the conditioned lobster under different experimental conditions: (1) shelter plus seawater; (2) shelter plus seawater
plus chemical octopus cue. Our results showed significant differences in mean shelter occupancy with conditioning level. We
conclude that P. elephas individuals use chemosensory systems in predator-avoidance mechanisms. Moreover, lobsters subject to a training period of
high-level predation threat were able to learn the octopus chemical stimuli and treat its odor as a cue related to predation
risk. The findings relative to the spiny lobster learning abilities could be an important tool for future management of lobster
populations, e.g., by re-introduction of reared juveniles, which have not yet experienced predation. 相似文献
9.
Bivalves demonstrate various morphological and behavioural adaptations to reduce the risk of being attacked by predators.
This paper examines how the presence of the crab Carcinus maenas (L.), a natural predator of the cockle Cerastoderma edule (L.), affects its burrowing depth and clearance or feeding rate. Cockles were placed in experimental tanks and treated with
three levels of predatory disturbance: (1) unfed crab loose inside the tank, (2) unfed crab inside a cage suspended in the
water column and (3) no crab present. Cockles’ burrowing depth was measured in two sediment types: mud and sand. Cockles burrowed
more deeply in treatments with no crabs. Burrowing depth in sand was significantly greater than in mud. Two factors may contribute
to the reduction in burial depth of C. edule in the presence of C. maenas: the change in the vertical orientation of the cockle and the ‘cough response’. No significant difference was found in the
cockles’ clearance rate among the different levels of predator threat. 相似文献
10.
It is unclear whether stingless bees in the genus Melipona (Hymenoptera, Apidae, Meliponini) can reliably encode the distance to a food source through recruitment sounds produced inside the nest, in part because the sound features correlated with distance also vary with food quality. We therefore trained marked foragers of two species, Melipona mandacaia and M. bicolor, to feeders at different distances and to different sucrose concentrations at the same distance. In both species, foragers successfully recruited to a rich 2.5-m food source and produced pulsed recruitment sounds in which pulse duration was significantly and positively correlated with distance to the rich food source. When returning from poorer food sources (0.6–1.5 m), foragers of both species decreased sound production, producing shorter sound pulses and longer sound interpulses than they did for 2.5 m food located at the same distance. Thus the temporal structure of M. mandacaia and M. bicolor recruitment sounds varies with distance and food quality. However, nestmates were not recruited by performances for poorer food sources (0.6–1.5 m), whose sucrose concentration was sufficiently low to affect recruitment sounds. Surprisingly, the interphase (the time between behavioral phases that communicate location) also increases with decreasing food quality in the closely related honeybees (Apis), suggesting a potential homology in the effect of food quality on the recruitment systems of Apis and Melipona. We explore the evolutionary implications of these similarities.Communicated by M. Giurfa 相似文献
11.
Maud C. O. Ferrari François Messier Douglas P. Chivers 《Behavioral ecology and sociobiology》2008,62(7):1079-1083
A prerequisite for prey to show adaptive behavioural responses to predators is that the prey has the ability to recognise
predators as threats. While predator recognition can be innate in many situations, learning is often essential. For many aquatic
species, one common way to learn about predators is through the pairing of a novel predator odour with alarm cues released
from injured conspecifics. One study with fish demonstrated that this mode of learning not only allows the prey to recognise
the predatory cues as a threat, but also mediates the level of threat associated with the predator cues (i.e. threat-sensitive
learning). When the prey is exposed to the novel predator with a high concentration of alarm cues, they subsequently show
a high intensity of antipredator response to the predator cues alone. When exposed to the predator with a low concentration
of alarm cues, they subsequently show a low-intensity response to the predator cues. Here, we investigated whether larval
mosquitoes Culex restuans have the ability to learn to recognise salamanders as a threat through a single pairing of alarm cues and salamander odour
and also whether they would learn to respond to salamander cues in a threat-sensitive manner. We conditioned individual mosquitoes
with water or a low, medium or high concentration of crushed conspecific cues (alarm cues) paired with salamander odour. Mosquitoes
exposed to salamander odour paired with alarm cues and subsequently exposed to salamander odour alone responded to the salamander
as a threat. Moreover, the intensity of antipredator response displayed during the conditioning phase matched the response
intensity during the testing phase. This is the first demonstration of threat-sensitive learning in an aquatic invertebrate. 相似文献
12.
Esther Clarke Ulrich H. Reichard Klaus Zuberbühler 《Behavioral ecology and sociobiology》2012,66(1):85-96
Predation on gibbons is rarely observed in the wild. However, the gibbons' moderate body size and relatively small social
groups suggest high vulnerability to predation. To assess the role of predation and to study their anti-predator behaviour,
we presented visual predator models to nine groups of wild white-handed gibbons at Khao Yai National Park, Thailand. We measured
subjects' immediate and delayed responses to four potential predators: tiger, clouded leopard, crested serpent eagle and reticulated
python. Subjects reliably approached all four predators. In response to tigers and leopards, they additionally produced predator-specific
songs and defecated copiously. In terms of delayed responses, distance between mated adults decreased, but only after exposure
to the tiger model. In response to eagles and pythons, gibbons consistently vocalised, but this did not always include predator
singing, and we found no long-term effects in overall activity or strata use. However, during 6 of 26 predator encounters,
the gibbons produced songs with a structure that was intermediate between a duet song and a predator song more than 20 min
after the predator encounter, indicating a long-term effect on their vocal behaviour. This study demonstrates that gibbons
discriminate between different potential predators and respond to them with adaptive anti-predator behaviour, which include
predator-specific vocal responses. We conclude that gibbons are not immune to predation and that terrestrial predators elicit
consistent immediate and delayed anti-predation responses. 相似文献
13.
Vincent Ouisse Pascal Riera Aline Migné Cédric Leroux Dominique Davoult 《Marine Biology》2012,159(1):165-175
The food web of two intertidal seagrass (Zostera marina and Zostera noltii) beds that may be influenced by the seasonal variation in food source abundance was studied in winter and in summer with
δ13C and δ15N analysis. In spite of high relative variation of abundance of main primary producers at the two sites, the food web did
not vary between winter and summer. The δ13C range of primary producers was wide. Zostera leaves, the most 13C-enriched source, were not consumed directly by grazers. Deposit and filter feeders have a similar δ13C and could use a mix of suspended and sedimented organic particulate matter, largely composed of detritus from macroalgae
to seagrass. This trophic pathway allows the local incorporation of the high biomass produced by seagrasses. The wide δ15N range of predators was linked either to a large variety from omnivore to carnivore predators or to the also wide ranges
of δ15N of primary consumers. 相似文献
14.
The apparently maladaptive tendency of fish to approach and inspect potential predators has been explained in terms of useful information gathering or as a signal to the predator that it has been seen. We examined this behaviour in 16 populations of wild-caught stickleback (Gasterosteus aculeatus) from ponds with and without predatory perch (Perca fluviatilis). Three large and three small individuals per population were each exposed to three model predators differing in realism. A final cooperative treatment entailed pairing subjects with a second individual from the same population, but of the alternative size class, during predator presentation. As might be expected, predator inspection behaviour was much greater in the predator-sympatric populations, and only these fish increased their level of inspection as the models became incrementally more realistic. This suggests that reductions occur in the level of costly inspection behaviour in populations without predators. Subject body size had no effect on inspection effort, which suggests a limited role for experience (we assumed larger fish to be older than smaller fish), at least over the relative age differences utilized. However, small predator-sympatric fish were the only subjects to increase inspection significantly when in a cooperative context, perhaps reflecting the inherent value of a relatively larger partner in this context. These results confirm that levels of predator inspection are both population- and situation-dependent, suggesting a trade-off in the potential costs and benefits of this behaviour.Communicated by C. St. Mary 相似文献
15.
Although mysids play important roles in marine food chains, studies on their production are scarce, especially for warm-water
species. We investigated life history and production of Orientomysis robusta in a shallow warm-temperate habitat of the Sea of Japan. Its spawning and recruitment occurred throughout the year; 19 overlapping
cohorts were recognizable over an annual cycle. The summer cohorts recruited in July–September exhibited rapid growth, early
maturity, small brood size, and small body size. A converse set of life history traits characterized the autumn–winter cohorts
recruited in October–March. The spring cohorts recruited in April–June had intermediate characteristics of both cohorts. Life
spans were 19–33, 21–48, and 69–138 days for summer, spring, and autumn–winter cohorts, respectively, and mortality rates
were high for spring and summer cohorts, especially during June–August but were low for autumn–winter cohorts. Production
calculated from the summation of growth increments was 488.8 mg DW m−2 year−1 with an annual P/B ratio of 21.26. The short life span seems to be responsible for such an extremely high P/B ratio. A method not requiring recognition and tracking cohorts gave similar values (534.0 mg DW m−2 year−1 and 20.49). The close agreement in production values between the two methods indicates our estimates are valid. 相似文献
16.
Susanna Andersson 《Chemoecology》2003,13(1):1-11
Summary. For butterflies to be efficient foragers, they need to
be able to recognize rewarding flowers. Flower signals such as colours
and scents assist this recognition process. For plant species to attract
and keep butterflies as pollinators, species-specific floral signals are
crucial. The aim of this study is to investigate foraging responses to
floral scents in three temperate butterfly species, Inachis io L.
(Nymphalidae), Aglais urticae L. (Nymphalidae), and
Gonepteryx rhamni L. (Pieridae), in behavioural choice
bioassays. The butterflies were allowed to choose bet-ween flower models
varying in scent and colour (mauve or green). Flowers or vegetative
parts from the plants Centaurea scabiosa L. (Asteraceae),
Cirsium arvense (L.) (Asteraceae), Knautia arvensis (L.)
(Dipsacaceae), Buddleja davidii Franchet (Loganicaeae), Origanum vulgareL. (Lamiaceae), Achillea millefolium L. (Asteraceae), and
Philadelphus coronarius L. (Hydrangiaceae) were used as scent
sources. All visits to the models — those that included probing and
those that did not — were counted, as was the duration of these
behaviours. Both flower-naive and flower-experienced (conditioned to
sugar-water rewards, the colour mauve, and specific floral scents)
butterflies were tested for their preference for floral versus
vegetative scents, and to floral scent versus colour. The butterflies
were also tested for their ability to switch floral scent preferences in
response to rewards. Flower-naive butterflies demonstrated a preference
for the floral scent of the butterfly-favourable plants C.
arvense and K. arvensis over the floral scent of the non-favourable
plants Achillea millefolium (Asteraceae), and Philadelphus
coronarius cv. (Hydrangiaceae). Most of the butterflies that were
conditioned to floral scents of either C. arvense, K. arvensis,
or B. davidii readily switched theirfloral scent preferences to
the one most recently associated with reward, thus demonstrating that
floral scent constancy is a result from learning. These findings suggest
that these butterflies use floral scent as an important cue signal to
initially identify and subsequently recognize and distinguish among
rewarding plants.
Received 2 September 2001; accepted 9 September 2002. 相似文献
17.
Recruitment of capelin in the Barents Sea fail when juvenile herring and cod are abundant and the potential for feeding competition
of wild sympatric capelin and herring larvae and small cod juveniles were investigated. The frequency of gut evacuation after
capture of capelin larvae were also studied in mesocosms. Small capelin larvae (<35 mm length) fed on small prey including
phytoplankton, invertebrate eggs and nauplii, bivalves, other invertebrate larvae and small copepods. Calanus copepodites were only observed in large capelin larvae (>26 mm length). Calanus copepodites were the major food sources for contemporary herring larvae (25–35 mm length) and Calanus and euphausiids were the major prey for small juvenile herring (37–60 mm length) and cod (18–40 mm length). Capelin larvae
reared in mesocosms evacuated the guts shortly after capture. Capelin larvae had a smaller mouth and fed on smaller prey than
herring and cod of the same length. This implies that the small capelin larvae, in contrast to sympatric small herring and
cod, are not tightly linked to the food chain involving Calanus and euphausiids. Thus, exploitative competition between capelin larvae and planktivorous fish that rely on Calanus and euphausiids in the Barents Sea may be relaxed. 相似文献
18.
Seasonal variation in animal signalling behaviour has been well documented and has contributed much to our understanding of
male signals. In contrast, we know little about seasonal variation in female signals or signals produced jointly by males
and females, such as the vocal duets of birds. Here, we examine how singing behaviour changes in relation to time of year
and breeding stage in rufous-and-white wrens (Thryothorus rufalbus), neotropical songbirds where both males and females sing and where breeding partners coordinate songs to produce vocal duets.
We recorded a colour-marked population of birds over an extended time period encompassing multiple breeding stages. Across
all time frames and breeding stages, males sang at higher rates than females and male solos were more common than duets or
female solos. Males and females showed divergent seasonal patterns of singing. Females sang more often early in the year,
during the pre-breeding season, and female song tapered off as the breeding season progressed. Duetting followed a parallel
pattern, which resulted from females showing less duet responsiveness to their partner’s songs later in the year. Male independent
song rate peaked at the onset of the rainy season – a time when females become fertile – and males showed the highest level
of duet responsiveness during this period. Our results suggest that early in the year, duets appear to be cooperative displays,
functioning in joint territory defence and/or the coordination of breeding activities. When females are fertile, however,
increased duet responsiveness by males is consistent with mate or paternity guarding. 相似文献
19.
Intensive study of arboreal forest-dwelling primates and their predators in Africa is increasingly revealing that crowned
eagles (Stephanoaetus coronatus) are major predators of primates. Gray-cheeked mangabeys (Lophocebus albigena) are overrepresented in the diets of crowned eagles in Kibale National Park, Uganda, and adult male mangabeys are represented
more than females. We focused on the behavior of adult male gray-cheeked mangabeys living in social groups in Kibale National
Park (1) to clarify the interactions between mangabeys and eagles that might put adult males at greater risk and (2) to better
understand individual variation in behavioral responses to predators. Adult male mangabeys in five groups responded to observer-confirmed
presence of crowned eagles 88 times over a 13-month period. While all males gave alarm calls, only the highest-ranking male
in each of four groups chased eagles. These males had elevated levels of fecal cortisol metabolites in the days immediately
after they engaged in active defense, suggesting that they perceived such behavior as risky. In the one group where male ranks
were unstable and there were no infants, no male was observed to chase eagles. We suggest that males pursue the dangerous
tactic of chasing eagles only when they are likely to have offspring in the group. Males in larger groups also spent less
time alarm calling to crowned eagles (from first to last call in a group), and our observations confirmed that the duration
of their alarm calls was related to eagle presence. Thus, eagles spent less time around larger mangabey groups. Alarm calling
by adult male mangabeys may signal to this ambush predator that it has been detected and should move on. 相似文献
20.
Ivo H. Machatschke Barbara E. Bauer Cornelia Schrauf John Dittami Bernard Wallner 《Behavioral ecology and sociobiology》2008,62(8):1341-1350
Polygynous mating systems can inflict considerable costs on males, often causing the emergence of alternative mating strategies
to ensure reproductive success. These strategies can lead to different morphs of color, size, or behavior. The present work
was done on guinea pigs, a polygynous rodent species. Some males can show a reduced readiness for conflict, perhaps employing
an alternative mating strategy. To test this hypothesis, a two-stage experiment was set up, with males (N = 16) and females (N = 16) initially living in isosexual groups. Visual and olfactory contact was possible through a wire mesh. Male agonistic
behavior was observed for 15 days, confirming the existence of less-conflict-involved (LCI, N = 7) and more-conflict-involved males (MCI, N = 9). Significant differences were found for a conditional parameter, body mass, and a morphometric one, testis width: LCI
consistently surpassed MCI. Hormonally, cortisol was comparable, while testosterone was distinctly higher in MCI. Next, males
and females were joined and observed for further 24 days. Males initially lost weight but reached original mass towards the
end of the experiment. Testis width patterns were similar. Again, LCI had higher body mass. Cortisol was comparable, but testosterone
release 3 days after merging was significantly higher in LCI. Behaviorally, LCI exhibited significantly less male–male aggression
and more socio-sexual behavior than MCI. The former were more successful, with 57% capable of accessing females, in contrast
to 11% of MCI. The existence of two distinct behavioral phenotypes in guinea pig males suggests that different reproductive
strategies may exist in this species. 相似文献