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1.
Socially dominant males often signal their status to rival males and/or females. We tested the hypotheses that Lacerta monticola femoral gland secretions and copulatory plugs convey chemical information about male identity and dominance status. We estimated male dominance status by staging male–male agonistic encounters in a neutral arena. We then conducted two experiments to compare male tongue-flick behavior toward chemical stimuli consisting of cotton swabs bearing (1) deionized water (control), the lizard’s own femoral secretions, and the femoral secretions of another male and (2) phosphate-buffered saline solution (control), the lizard’s own plug products, and the plug products of another male. Results indicate that males discriminated their own femoral secretions and plugs from those of other males. They also discriminated morphological attributes of other males that were associated with dominance status based on chemical cues arising from femoral secretions and discriminated the dominance status of other males based on chemical cues arising from the plugs. Femoral secretions that convey information about male identity and dominance status may be hypothesized to function in the establishment of L. monticola dominance hierarchies through scent-marking of territories. We suggest that copulatory plugs and femoral secretions may allow males to scent-mark the female body and postulate that this behavior may influence male and female reproductive decisions under selective pressures of sperm competition. 相似文献
2.
Copulatory plugs do not assure high first male fertilisation success: sperm displacement in a lizard
Pedro L. Moreira Vera L. Nunes José Martín Octávio S. Paulo 《Behavioral ecology and sociobiology》2007,62(2):281-288
Sperm competition selects for opposing male defensive and offensive reproductive traits, and its outcome may be determined
by the effectiveness to which one trait has evolved to out-compete the other. We tested the effectiveness of a first male
plug physical interference with a second male insemination (defence) vs the effectiveness of plug and associated sperm displacement
by a second male (offence) on the outcome of sperm competition in Iberian rock lizards. We conducted a double mating experiment
where we compared the proportion of eggs per clutch fertilised by the same second males (against the same first males) when
they copulated with females 30 min (first male plug adhered firmly inside the female cloaca) and 4 h (first male plug loosely
adhered or shed from the female cloaca) after first males. We found that second males fertilised the majority of the eggs
per clutch in the 30-min treatment, whereas fertilisations were equally shared between the two males in the 4-h treatment.
These results show that plugs have little defensive effectiveness, and thus, do not assure high first male fertilisation success.
Instead, sperm displacement appears to be associated with plug displacement. That is, because sperm embedded in first male
plugs, and displaced from competition for fertilisations by second males, is expected to increase in number with decreasing
time allowed for female sperm transport, second males thus enjoy higher fertilisation success. This study shows that offensive
plug displacement out-competes plug defensive role in Iberian rock lizards. Moreover, it reveals sperm displacement as a novel
sperm competition mechanism in reptiles. 相似文献
3.
Female preference for dominant males is widespread and it is generally assumed that success in male-male competition reflects high quality. However, male dominance is not always attractive to females. Alternatively, relatively symmetric individuals may experience fitness advantages, but it remains to be determined whether males with more symmetrical secondary sexual traits experience advantages in both intra- and intersexual selection. We analysed the factors that determine dominance status in males of the lizard Lacerta monticola, and their relationship to female mate preference, estimated by the attractiveness of males' scents to females. Sexually dimorphic traits of this lizard (head size and femoral pores) appear to be advanced by different selection pressures. Males with relatively higher heads, which give them advantage in intrasexual contests, were more dominant. However, head size was unimportant to females, which preferred to be in areas marked by relatively heavier males, but also by males more symmetric in their counts of left and right femoral pores. Chemicals arising from the femoral pores and other glands might honestly indicate quality (i.e. related to the symmetry levels) of a male to females and may result from intersexual selection. Females may use this information because the only benefit of mate choice to female lizards may be genetic quality. Chemical signals may be more reliable and have a greater importance in sexual selection processes of lizards than has previously been considered. 相似文献
4.
Cloacal protuberances (CP) in male birds result from spermatic engorgement of storage tubules around the cloaca during the breeding season. We examined seasonal changes in the volume and orientation of the CP in the New Zealand stitchbird Notiomystis cincta. The male stitchbird has one of the largest recorded CPs for any species (max = 1,570 mm3), with CP volume increasing by almost 400% between the non-breeding and breeding seasons. While sperm competition has been positively correlated with the magnitude of CP storage in other species, no evidence previously existed for the CP improving copulation efficiency. By measuring the relative orientation of the CP throughout the year, we show that not only does the CP increase in size as males become sexually active, it also changes its orientation by approximately 60°. This results in it shifting from facing posteriorly to becoming almost perpendicular to the abdomen. This cloacal erection improves the apposition of the male and female cloacal openings during face-to-face forced copulation in this species. This provides the first reported evidence supporting the copulation efficiency hypothesis of the avian CP. While the magnitude of seasonal changes in female cloacal volume was similar to males, female cloacal orientation remained virtually unchanged across seasons. This difference between the sexes is likely to reflect differing selection pressures for optimizing sperm transfer. In females, a posterior-facing cloaca is ideal for both waste evacuation and sperm reception, whereas, for the male, a posterior-facing cloaca is well suited for waste evacuation, but possibly hinders sperm delivery. Changes in male cloacal orientation from the non-breeding to the breeding season are a likely reflection of conflict in this dual function. Evidence of changes in CP orientation in another passerine species suggests this phenomenon is widespread and also important for understanding related fields such as sperm competition, forced copulation and constraints on the evolution of the avian intromittent organ. 相似文献
5.
Roles of male residence and relative size in the social behavior of Iberian rock lizards, Lacerta monticola 总被引:2,自引:0,他引:2
Many studies on contest competition used residency asymmetry as a discrete variable. However, the probability of winning an
interaction may change as a continuous function of the value of the location where the encounter occurs. We performed a field
study to examine the importance of location within a home range and relative body size to the outcomes of agonistic interactions
between male lizards, Lacerta monticola. The distances to activity centers (the most used locations based on a density function of sightings) and relative size play
important roles in agonistic interactions and had interacting effects in natural conditions. On the other hand, previous studies
with lizards suggested that inferior competitors are able to avoid agonistic interactions in the field. Thus, we staged encounters
in the laboratory to examine the behavioral responses of smaller individuals. The responses of each focal smaller male were
measured in its own home cage (resident), in the cage of a larger male (intruder) and in a cage in which no male was previously
present (control). The predominant behavioral tactics of smaller males were avoidance when they are the intruders and displaying
when they are the residents. Submissive displays by smaller males may help reduce the costs of agonistic encounters. 相似文献
6.
Gauri R. Pradhan Antje Engelhardt Carel P. van Schaik Dario Maestripieri 《Behavioral ecology and sociobiology》2006,59(3):333-343
Female copulation calls are mating-associated vocalizations that occur in some species of Old World monkeys and apes. We argue
that copulation calls have two immediate functions: to encourage mating attempts by other males and to increase mate guarding
by the consort male. We hypothesize that female copulation calls have evolved under the selective pressures of risk of infanticide
and sperm competition. When male mate guarding is effective, copulation calls allow females to concentrate paternity in dominant
males and benefit from their protection against the risk of infanticide. When mate guarding is ineffective, copulation calls
may bring genetic benefits to females through facilitation of sperm competition. We present a quantitative model in which
interspecific variation in females' promiscuity predicts their tendency to use copulation calls in conjunction with mating.
The model predicts that in species with little female promiscuity, copulation calls should be rare and exhibited only in association
with mating with dominant males. In species in which females are highly promiscuous, copulation calls should be frequent and
unrelated to male dominance rank. The limited data available to test the model support its main predictions as well as the
predicted relation between copulation calls and male dominance rank.
相似文献
Dario MaestripieriEmail: |
7.
Joris M. Koene Kora Montagne-Wajer Andries Ter Maat 《Behavioral ecology and sociobiology》2006,60(3):332-338
Simultaneous hermaphrodites have the opportunity to control the allocation of resources to the male and female function depending on the circumstances. Such flexibility also provides the possibility to influence sex allocation in the mating partner. To investigate this idea, we measured egg production (female investment) and sperm production as well as prostate gland size (both are part of male investment) under different mating regimes in the great pond snail Lymnaea stagnalis. We find no evidence for the prediction from sex allocation theory that sperm production increases with mating frequency. However, we do find that animals with more mating opporunities develop smaller prostate glands, in which seminal fluid is produced. Moreover, repeated mating increases egg production, thus shifting allocation towards the female function, and probably decreases growth. So, our data hint at a three-way trade-off between part of the male function (prostate gland), female function, and growth. Interestingly, sex allocation seems to be shifted in the opposite direction from the one predicted by theory. We discuss how this feminization is suggestive of a direct manipulation by the sperm donor, probably to stimulate immediate sperm use. 相似文献
8.
Joris M. Koene Tina Pförtner Nico K. Michiels 《Behavioral ecology and sociobiology》2005,59(2):243-249
Sexual conflict between mating partners can give rise to strategies that are advantageous for one sex but harmful to the opposite sex. Usually, sperm donors develop (offensive) traits to enhance their chances in sperm competition, while sperm recipients evolve (defensive) traits that allow them to stay in control of who fathers their offspring. Here, we demonstrate that these processes are also at work in simultaneous hermaphrodites. The hermaphroditic earthworm Lumbricus terrestris uses 40 to 44 copulatory setae to pierce into its partner's skin, causing damage and injecting a substance from its setal glands. Experimental injection of the gland substance indicates that a refractory period may be induced. More importantly, removal of the copulatory setae shows that they influence the partner's sperm uptake. When the setae are present, more sperm are taken up and sperm are distributed more equally over the four spermathecae. We interpret this as a strategy that stacks the odds for the donor's sperm in fertilizing cocoons. 相似文献
9.
Bart Kempenaers G. R. Verheyen André A. Dhondt 《Behavioral ecology and sociobiology》1995,36(1):33-42
This study investigates the importance of mate guarding for males and females in the facultatively polygynous blue tit Parus caeruleus. We present observational data in combination with a paternity analysis using DNA fingerprinting to show that (1) male blue tits guard their mate, since they stay closer to their mate, initiate fewer flights and follow their mate more often during the female's presumed fertile period; (2) polygynous males do not suffer more from lost paternity despite lower mate guarding; (3) in monogamous pairs there is either no relation or a positive relation (depending upon the variable measured) between measures of mate guarding intensity and the proportion of extra-pair young in the nest; and (4) monogamous males that are more often followed by their fertile female suffered less from lost paternity. We conclude that, despite mate guarding, paternity seems to be largely under female control and unattractive males guarding their mate are making the best of a bad situation. Experimental evidence is provided showing that when males were temporarily removed from their territory, their mate suffered from increased harassment from neighbouring males that intruded in the territory and tried to copulate with the female. Almost all of these copulation attempts were unsuccessful because females refused to copulate. We conclude that mate guarding may be beneficial for females because harassment by neigbouring males is prevented. 相似文献
10.
Ben C. Sheldon Pete Davidson Gabriella Lindgren 《Behavioral ecology and sociobiology》1999,46(3):141-148
There is increasing evidence that sexual selection may be intense even in socially monogamous birds, resulting from both mate choice and sperm competition. We studied these two modes of sexual selection experimentally by removing paired male collared flycatchers, Ficedula albicollis, from their mates for 2 days and investigating the factors that influenced the likelihood of a replacement male appearing and how the removals influenced paternity. Replacement males (usually neighbouring males) appeared at 81% (n = 37) of nests where males were removed. The likelihood of this appearance was unaffected by the probable reproductive value of the female's clutch to the replacing male. A replacement was, however, less likely when the original male had a large forehead patch, a trait previously shown to be subject to sexual selection in this population. Experimental removal of males increased the level of sperm competition: 74% of experimental broods were multiply sired, compared to 29% of unmanipulated broods in a previous study. Only two factors predicted how paternity was shared between males: removed males fathered more young if removed closer to laying, and if they had larger forehead patches. The former result is consistent with last-male sperm precedence determining paternity, whereas the latter adds to other evidence that forehead patch size is the target of female preference in this species. Our results suggest that females exert some control over male replacement, and also that they may influence the fertilisation success of males by behavioural means. Received: 15 July 1998 / Received in revised form: 16 March 1999 / Accepted: 28 March 1999 相似文献
11.
Determinants of paternity success in the spider Pholcus phalangioides (Pholcidae: Araneae): the role of male and female mating behaviour 总被引:1,自引:0,他引:1
In double mating experiments, we examined whether and to what extent various male and female behavioural traits influence
the course of mating and fertilization success in the cellar spider. In males, we focussed on pre-copulatory behaviour and
on the rhythmic twisting movements that the male performs with his pedipalps during copulation. In females, we investigated
remating decisions and the effect of female termination of copulation. Second males fertilized a high proportion of the eggs
(P
2: median 89%) despite much shorter second matings, with high variation in relative paternity success. The number of pedipalp
movements (PPMs) of either male was a better predictor of paternity than copulation duration. Our results suggest that in
second matings, PPMs help to remove sperm from previous males, whereas in first matings a high number of PPMs enhances fertilization
success, either due to numerical sperm competition or cryptic female choice. Furthermore, we found a negative male age effect
on paternity in second matings, implying that age-related deterioration of spermatozoa may promote variation in fertilization
success. Female receptivity decreased significantly in second matings; only 70% of the females remated. Females that accepted
a second copulation were found to terminate these much earlier and with higher probability than first matings. This suggests
that the intensity of conflict between the sexes is higher in second matings. Increased intensity of sexual conflict may be
responsible for stronger selection on male traits, as pre-copulatory behaviour and age only affected male copulatory performance
and paternity in second matings.
Electronic Publication 相似文献
12.
Luke Holman 《Behavioral ecology and sociobiology》2009,63(11):1679-1688
The causes and consequences of variation in sperm quality, survival and ageing are active areas of research in ecology and
evolution. In order to address these topics, many recent studies have measured sperm viability using fluorescent staining.
Although sperm viability staining has produced a number of interesting results, it has some potential pitfalls that have rarely
been discussed. In the present paper, I review the major findings of ecology and evolution studies employing sperm viability
staining and outline the method’s principle limitations. The key problem is that the viability assay may itself kill sperm,
which is likely to confound many common experimental designs in addition to producing artificially low estimates of sperm
viability. I further suggest that sperm number should be routinely measured in sperm viability studies, as it may be an important
but overlooked source of spurious results. I provide methodological advice on sperm viability staining aimed at minimising
artefacts and producing robust conclusions, and discuss possible avenues for future research.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
13.
Costs and benefits associated with matings and the effects of mating frequency on fitness commonly differ between the sexes. As a result, outcrossing simultaneous hermaphrodites may prefer to copulate in the more rewarding sex role, generating conflicts over sperm donation and sperm receipt between mates. Because recent sex role preference models remain controversial, we contrast here some of their assumptions and predictions in the sea slug Chelidonura sandrana. For this hermaphrodite with sperm storage and internal fertilisation, risk-averse models assume that fitness pay-offs are constantly higher in the female than in the male function in any single mating. Moreover, excluding mutual partner assessment, these models predict male mating behaviour to be independent of receiver traits. The competing gender ratio hypothesis assumes that relative fitness pay-offs, and thus the preferred mating roles, vary and may reverse between matings and predicts that ejaculation strategies co-vary with receiver quality. We found that field mating rates of C. sandrana substantially exceeded what is required to maintain female fertility and fecundity, indicating large variation in direct female benefits between matings. We further demonstrate that male copulation duration adaptively increased with partner body size (i.e. fecundity) but decreased with recent partner promiscuity. These findings are compatible with the gender ratio hypothesis but contradict risk-averse models. 相似文献
14.
Patterns of courtship behavior and ejaculate characteristics in male red-winged blackbirds 总被引:1,自引:0,他引:1
David F. Westneat Lisa A. McGraw Jennifer M. Fraterrigo Tim R. Birkhead F. Fletcher 《Behavioral ecology and sociobiology》1998,43(3):161-171
Sperm competition in birds is likely to have important effects on the behavior and physiology of reproduction in both sexes.
For males, such competition should select for large sperm reserves and behavioral adjustment of copulation when reserves are
low. We investigated both these possibilities in free-living red-winged blackbirds (Agelaius phoeniceus), a highly polygynous species with apparently strong sperm competition. We found that the recent copulatory behavior of males
did not affect the propensity to copulate with a model female. Ejaculates collected from individual males at 1-h intervals
showed no evidence of sperm depletion, yet repeated ejaculates collected less than 10 min apart did. Male ejaculate size was
significantly larger if it was the first one of the day (i.e., after an overnight rest). The average ejaculate size was 12.5
(±12.5 SD) million sperm. Males captured during the breeding season had an average of 111.7 (±52.8) million sperm stored in
their seminal glomera. Because males average a peak copulation rate of six per female per day, in one day a male might utilize
all the sperm in his seminal glomera if more than two females on his territory are fertilizable. We hypothesize that polygyny
and sperm competition in this species have combined to select for rapid replenishment of the seminal glomera throughout the
day, in contrast to other species that have been studied. Testis size and sperm reserves of male red-winged blackbirds are
intermediate between monogamous species and species with intense sperm competition. Several possible explanations for this
are discussed.
Received: 21 October 1997 / Accepted after revision: 15 February 1998 相似文献
15.
Diego Rubolini Paolo Galeotti Gabriele Ferrari Michele Spairani Franco Bernini Mauro Fasola 《Behavioral ecology and sociobiology》2006,60(2):212-219
Sperm competition is a well-recognised agent in the evolution of sperm and ejaculate structure, as well as variation in female quality. Models of the evolution of ejaculate expenditure predict that male body condition, female fecundity and the risk and intensity of sperm competition may be the ultimate factors shaping optimal ejaculate size. We investigated sperm allocation in Austropotamobius italicus, a freshwater crayfish exhibiting a coercive mating system and external fertilisation, in relation to male and female traits and copulation behaviour under laboratory conditions. We found that mating males were sensitive to female size and produced larger ejaculates when mating with larger females, which were more fecund in terms of number of eggs produced. We found no evidence for female egg production being sperm-limited, as the number of eggs was not dependent on male sperm expenditure. Copulation duration and number of ejaculations reliably predicted the amount of sperm transferred, and both these behavioural measures positively covaried with female body size. These results indicate that male freshwater crayfish can modulate their sperm expenditure in accordance with cues that indicate female fecundity. In addition, a novel finding that emerged from this study is the decrease in sperm expenditure with male body size, which may either suggest that large, old male crayfish are better able than small males to economise sperm at a given mating to perform multiple matings during a reproductive season, or that they experience senescence of their reproductive performance. 相似文献
16.
Stefan Lüpold George M. Linz Tim R. Birkhead 《Behavioral ecology and sociobiology》2009,63(6):899-909
Post-copulatory sexual selection (PCSS) is thought to be one of the evolutionary forces responsible for the rapid and divergent
evolution of sperm design. However, whereas in some taxa particular sperm traits are positively associated with PCSS, in other
taxa, these relationships are negative, and the causes of these different patterns across taxa are poorly understood. In a
comparative study using New World blackbirds (Icteridae), we tested whether sperm design was influenced by the level of PCSS
and found significant positive associations with the level of PCSS for all sperm components but head length. Additionally,
whereas the absolute length of sperm components increased, their variation declined with the intensity of PCSS, indicating
stabilising selection around an optimal sperm design. Given the diversity of, and strong selection on, sperm design, it seems
likely that sperm phenotype may influence sperm velocity within species. However, in contrast to other recent studies of passerine
birds, but consistent with several other studies, we found no significant link between sperm design and velocity, using four
different species that vary both in sperm design and PCSS. Potential reasons for this discrepancy between studies are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Sperm competition can be a powerful selective force in the evolution of reproductive strategies and mating systems. In studies on sperm competition, patterns of sperm use are typically reported as the mean species value of P
2, determined as the proportion of offspring sired by the second male to copulate with a doubly mated female. However, the within-species variance in P
2 has mostly been ignored, although taking this variance into account may be crucial for understanding the underlying mechanisms of sperm competition. Paternity analysis among the offspring of doubly mated females of Panorpa germanica (Mecoptera, Panorpidae) revealed a relationship between relative copulation durations of both males and the proportion of offspring each male will sire. This correlation between proportional copulation durations and paternity suggests mixing of sperm from different males inside the female’s spermatheca. Yet, sperm mixing appears to be incomplete, as paternity was overall slightly shifted towards the second male on average fathering a higher proportion of the offspring than its relative copulation duration would predict in case of complete sperm mixing. For individual males, however, the outcome of sperm competition is rather unpredictable as the intraspecific variance in P
2 was found to be very high, irrespective of copulation durations. Possible causes of the observed variance in P
2 and the partial last male sperm precedence are discussed. 相似文献
18.
Paolo Galeotti Fabio Pupin Diego Rubolini Roberto Sacchi Pietro A. Nardi Mauro Fasola 《Behavioral ecology and sociobiology》2007,61(5):711-718
Sperm competition models predict that males should adjust their sperm expenditure according to the risk and/or intensity of
sperm competition. In this paper, we analysed copulatory behaviour of both sexes and sperm expenditure in relation to female
mating status (virgin or mated) in the freshwater crayfish Austropotamobius italicus, a species where males have been reported to feed on and remove sperm laid by other males. The same females were allowed
to be inseminated sequentially by two males, and we compared the sexual behaviours of partners between the first (virgin females)
and the second mating (mated females). We found that female resistance did not differ between the first and the second mating,
nor males refused or took more time to mount a mated female. However, when mating with a mated female, males reached an effective
copulation position significantly later. This occurred because second-mating males removed, by eating, all or most spermatophores
previously deposited by first males. As removal was often incomplete, this resulted in a larger amount of sperm being deposited
on female ventral parts after the second mating, although second males did not allocate more sperm to mated females than first
males did. Thus, the peculiar mode of sperm competition, where males remove previously deposited sperm, and the consequent
predictable strong last male prevalence in paternity likely led to the observed lack of adjustment of sperm expenditure to
female mating status in this species. 相似文献
19.
Paolo Galeotti Diego Rubolini Fabio Pupin Roberto Sacchi Mauro Fasola 《Behavioral ecology and sociobiology》2008,62(11):1739-1745
Asymmetry in traits of sexual relevance may impair copulation behaviour and sexual performance of males, ultimately resulting
in a fitness cost. Freshwater crayfish males use chelae, a sexually selected trait, to secure and position the female prior
to and during mating. Thus, a relatively large chelae asymmetry, resulting from accidental loss and regeneration of one cheliped
after autotomy, could have great consequences for male sexual behaviour. We studied copulatory behaviour and sperm expenditure
of males paired to a mated female in Austropotamobius italicus, a freshwater crayfish species where both male and female mate multiply and where last-mating males are able to actively
remove previously deposited sperm. We aimed at assessing whether male sperm removal and expenditure varied according to sperm
allocated by first-mating males, and according to copulation behaviour and phenotypic traits (carapace length, chelae length
and relative chelae asymmetry) of second-mating males. Second-mating males did not adjust their ejaculate size in relation
to first-mating male ejaculate, nor to the first-mating male’s sperm removed. Moreover, the amount of sperm removed by second-mating
males increased with increasing first-mating males ejaculate size, and first-mating male sperm remaining after removal did
not correlate with the original first-mating male ejaculate size. Interestingly, the amount of sperm removed by second-mating
males decreased with increasing relative chelae asymmetry, while increasing with male body size. However, second-mating (but
not first-mating) asymmetric-clawed males produced larger ejaculates than symmetric-clawed ones. Importantly, the proportion
of second-mating male sperm remaining after the two matings did not vary with relative chelae asymmetry nor with body size
of second-mating males. Thus, small, asymmetric-clawed crayfish males appear to adopt sperm allocation tactics that allow
them to fully compensate for their inferior sperm removal ability. 相似文献
20.
Because time spent in refuge may be costly if prey lose opportunities to forage, fight, or mate, prey allow predators to approach closer before beginning to flee when opportunity costs are high. Because the same opportunity costs may apply to refuge use as to escape, prey should make similar trade-offs between risk of emerging and cost of remaining in refuge. In the Iberian rock lizard, Lacerta monticola, we studied the effects of sex, reproductive season, speed of predator approach, and potential loss of mating opportunities on time spent in refuge following simulated predatory attacks. Lizards of both sexes adjusted refuge use to the level of risk by spending more time in refuge when approached rapidly than slowly. Females remained in refuge for equal times in the mating and postreproductive seasons, but males emerged sooner during the mating season, suggesting adjustment to a cost of lost opportunity to search for mates during the mating season. When a tethered female was nearby, males emerged from refuge earlier than if no female was present, indicating a trade-off between risk and mating opportunity. Approach speed affected emergence time when females were absent, but not when a female was present. Approach speed did not affect the probability that, after emerging, a male would return to court the female. For males that courted females intensely (bit them) before entering refuge, approach speed did not affect latency to emerge, but males that courted less intensely emerged sooner if approached slowly than rapidly. These findings show that males adjust the length of time spent in refuge to both risk of predation and reproductive cost of refuge use.Communicated by A. Mathis 相似文献