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21.
In many species, the ability to evade predators is known to be periodically impaired by increased weight loads due to feeding
and reproduction. Not only may extra weight reduce escape speed, but feeding and mating can also make the prey more noticeable
to visually hunting predators. A number of butterfly species mate for hours, and if a mating couple is disturbed, one of the
butterflies is responsible for flying, whereas its partner remains still. This study investigated the ability of male Pieris napi butterflies to fly while mating, with the prediction that mate carrying impairs flight ability compared to single flying
males and that males with relatively high flight muscle ratios (FMR; male thorax mass/male + female body mass) will have better
flight performance in copula. Our results clearly show that whereas single males always take off at steep angles and fly upwards,
couples invariably have a negative take-off angle and rarely gain height. Moreover, landing height of the couples is positively
associated with higher FMR. Hence, male flight ability when in copula is positively associated with a high relative thorax
mass. Butterfly pairs may thus be at greater risk of predation as a consequence of their impaired flight ability, especially
couples with critically low FMRs (<16%). 相似文献
22.
Mate availability can vary widely in nature depending upon population density and sex ratio and can affect the ability of
individuals to be selective in mate choice. We tested the effects of prior encounters with the opposite sex (i.e., exposure
to the opposite sex either with or without mating) on subsequent mating behavior in two experiments that manipulated mate
availability for both males and females in the wolf spider, Hogna helluo. The probability of mating in the experimental trial depended upon whether the prior encounter involved mating or not, and
males and females responded in opposite directions. Exposure without mating resulted in a higher subsequent frequency of mating
for females and a lower subsequent frequency of mating for males, while prior mating experience resulted in a lower frequency
of female remating and a higher frequency of male remating. Prior exposure without mating did not affect female aggression.
However, mated females engaged in precopulatory cannibalism more frequently than virgins. Mated males escaped postcopulatory
cannibalism more frequently than virgins. Our results show that males respond to exposure without mating in the expected manner.
However, prior mating (1 week earlier) had unexpected effects on males, which may be due to mated males being of higher quality.
There were little or no effects of the size of the prior exposure individual or mate on subsequent mating behaviors. Further
research is needed to determine why different species use different degrees of prior information in mate choice. 相似文献
23.
Lauryn Benedict 《Behavioral ecology and sociobiology》2008,62(6):983-988
Previous studies suggest that extrapair young are very rare or absent in socially monogamous avian species that produce vocal
duets. These results are generally consistent with functional hypotheses suggesting that duets may signal commitment between
partners, or aid males as a paternity guard to ensure genetic as well as social monogamy. Additionally, species that exhibit
social monogamy with the same partner across multiple breeding seasons tend to exhibit low levels of extrapair paternity,
so duetting species that mate for life may be particularly likely to exhibit genetic monogamy. This study examined the social
and genetic mating systems of California towhees (Pipilo crissalis), a duetting species thought to have life-long pair bonds. Observation of a color-banded population confirmed that California
towhees exhibit long-term social monogamy. Known social families were genotyped at four microsatellite loci with high allelic
diversity. Unexpectedly, paternity exclusion indicated that at least 13 of 31 (42%) nests contained extrapair young. All chicks
exhibited maternal alleles, but 21 of 81 (26%) young were not the offspring of social fathers. Thus, in contrast to previous
work, this study documents high frequencies of extrapair young among socially monogamous duetting birds with long-term pair
bonds. 相似文献
24.
Geir Rudolfsen Rudolf Müller Davnah Urbach Claus Wedekind 《Behavioral ecology and sociobiology》2008,62(4):561-567
The mating behavior and reproductive strategies of Alpine whitefish like Coregonus zugensis (Nüsslin) are poorly understood, probably because they spawn in deep water where direct observations are difficult. In this
study, we interpret life-history and sperm quality traits of fish that we caught from their spawning place. We found that
males invest heavily into gonadal tissue (up to 5.6% of their body weight), which is, in comparison to other fish, consistent
with external fertilization, distinct pairing and moderate to high communal spawning, or no pairing and low to moderate communal
spawning. Sperm competition theory and recent experimental studies on other salmonids predict that males optimize ejaculate
characteristics in relation to the costs of sperm and the level of competition they have to expect: dominant males are predicted
to invest less into ejaculate quality and to have slower spermatozoa than subdominant males. We found that spermatozoa of
older males are slower than those of younger males. Moreover, older males have larger breeding tubercles, a secondary sexual
trait that has, in some previous studies, been found to be linked to good condition and to good genetic quality. Our results
suggest that C. zugensis has age-linked reproductive strategies, that multimale spawning is common, i.e., that sperm competition plays a significant
role, and that older males are on average dominant over younger males at the spawning place. 相似文献
25.
Five hypotheses have been proposed to explain polygyny in the red-winged blackbird (Agelaius phoeniceus). We categorized the hypotheses into three groups based on female preference for unmated versus monogamously mated males:
(1) the “polygyny threshold” model, “sexy son” hypothesis and the “asynchronous settlement” model, which assume that females
prefer unmated males to mated males on breeding situations of homogeneous quality; (2) the “neutral mate choice” hypothesis,
which assumes that females have no preference; and (3) the “cooperative female choice” model, which assumes that females prefer
monogamously mated males to unmated males. We tested the direction of female preference in two field experiments. In both
experiments, newly settling females were given a choice of two adjacent territories, one defended by an unmated male and the
other by a monogamously mated male. Male mating status was randomized with respect to the variation in territory quality and
male quality. Early in the breeding season, significantly more females settled with the unmated males than with the mated
males. Although more females settled with the unmated males than with the mated males late in the breeding season, the difference
was no longer significant. Female settlement late in the season appeared to be related to the tenure of the resident females:
the new females avoided territories where the resident females were in early stages of their nesting, but settled on territories
where the resident females were in late stages. The pattern of female settlement shows that females prefer unmated males to
mated males. The preference is consistent with the polygyny threshold model, sexy son hypothesis and the asynchronous settlement
model, and inconsistent with the neutral mate choice hypothesis and the cooperative female choice model. For this reason,
the latter two hypotheses are unlikely to explain the occurrence of polygyny in our population of red-winged blackbirds.
Received: 1 December 1994 / Accepted after revision: 28 October 1995 相似文献
26.
Past reproductive success affects future habitat selection 总被引:4,自引:0,他引:4
Paul V. Switzer 《Behavioral ecology and sociobiology》1997,40(5):307-312
Correlational studies have shown that an individual's past reproductive success often increases its breeding site fidelity
(i.e., the tendency to return to a previously occupied location), suggesting that individuals use their reproductive experience
to assess habitat quality. However, the causality of the relationship between reproductive success and site fidelity is still
uncertain. In a field experiment, the effect of mating success on site fidelity was isolated from potential confounding variables
in a territorial dragonfly, the eastern amberwing (Perithemis tenera). The experiment controlled for site quality, intrinsic characteristics of males, previous territorial experience at the
site, arrival order, and territorial evictions. Males that were prevented from mating were much more likely to change sites
the following day than control males that were allowed to mate. This result was not affected by age, the amount of time a
male spent on the site, or mortality. These results imply that individuals use their own reproductive success to assess the
quality of the habitat. The benefit to an individual of using its reproductive success to determine habitat quality is discussed
relative to other sources of information.
Received: 31 May 1996 / Accepted: 31 January 1997 相似文献
27.
Maria I. Sandell 《Behavioral ecology and sociobiology》2007,62(2):255-262
In the European starling, Sturnus vulgaris, optimal mating systems differ between males and females. Males gain from polygyny, whereas monogamy increases female fitness.
The cost of polygyny to females lead to intense female–female competition, and it has previously been shown that the intensity
of female aggression during the pre-breeding period can predict the realised mating system. The physiological regulation of
such female aggression in starlings is not yet known. This study examines the role of testosterone in mediating aggressive
behaviours involved in intra-specific reproductive competition in female starlings. Testosterone levels were experimentally
elevated with testosterone implants in females during the pre-laying period. To simulate a situation in which an additional
female tried to mate with the focal female’s mate, a caged female was presented close to a nest-site to which the male could
attract a secondary female. Testosterone was significantly related to several behaviours involved in female–female interactions.
Females with testosterone implants spent significantly more time close to the caged female and produced more song bouts than
control females. In contrast, male behaviour was unrelated to the experimental status of the mate. Females mated to males
that attracted a secondary female were less aggressive towards the caged female than those that remained monogamously mated.
The effect of exogenous testosterone in this study indicates that androgens may mediate social behaviours in female starlings
during the breeding season. 相似文献
28.
Rocky Mountain bighorn rams use three distinct tactics in competition for mates. Two tactics (tending and blocking) feature
defense and cooperative mating over a relatively prolonged consort period (up to 3 days). In the coursing tactic, subordinate
rams fight dominants for temporary copulatory access (lasting seconds) to defended ewes. By combining population-wide genetic
(microsatellite) exclusion of paternity, behavioral data and a model of bighorn reproductive competition, we estimated that
coursing rams fathered 44% of 142 lambs assigned paternity in two natural populations. In one population, the probability
of successful defense against coursing was lowest among rams that had many female consorts and held highest dominance rank.
Even so, per capita annual male reproductive success was positively associated with social rank in both herds when measured
in terms of fall conceptions. The proportion of coursing versus defending ram matings in each population (0.36 and 0.39) was
similar to the corresponding fraction of lambs (0.43 and 0.47) fathered by coursing rams, suggesting that sperm competition
approximated a fair lottery. Male traits important in gaining social status and obtaining cooperative consorts with ewes were
different and potentially in conflict with those needed to defend against (and practise) coursing. Although the concussive
weapons (horns) of rams are less dangerous than, for example, the piercing weapons of other bovids, injury from falls and
horn blows during coursing brawls may cause death, handicap future mating competition or increase the risk of predation. Coursing
is a rare example of an unconventional alternative mating tactic that is high-gain and high-risk.
Received: 17 April 1996 / Accepted after revision: 15 March 1997 相似文献
29.
Pair and extra-pair mating success relative to male quality in red-winged blackbirds 总被引:9,自引:0,他引:9
We tested whether the reproductive success of male red-winged blackbirds (Agelaius phoeniceus) varied with male secondary sexual traits or with haematozoa prevalence, and whether these patterns were consistent with females preferring genetically superior males. We also determined whether the traits that correlated with male success on their own territories were also correlated with male success at siring young on other males territories. Our analysis included data from a 6-year study involving 617 nestlings for which paternity was determined by DNA profiling. Larger males sired more young on their territories, principally because they obtained larger harems. The success of larger males at acquiring more mates did not appear to be a consequence of larger males holding larger or better-quality territories. Older and longer-lived males sired more young by extra-pair fertilizations. Larger males sired the most offspring overall (on territory + off territory). Variation in epaulet size and color, responses to male and female models, nest defence and parasitism was not correlated with male success either on or off their territories or overall. Male success in a given year was significantly correlated with success the previous year, as expected if females were selecting genetically superior males. The male that was by far the most successful individual in this study was highly consistent from year to year. Because male body size is positively correlated with survival in this population (although not within the sample of males included in this study), female preference for larger males may have reflected a general preference for males with superior Survival ability. We propose that the direct advantage realized by older males in extra-pair matings might indicate that experience is important, such that experienced males are better at creating or exploiting the opportunities for extra-pair mating. This hypothesis is consistent with a pairwise analysis of cuckoldry that showed that cuckolders were most often older than the males they cuckolded. 相似文献
30.
The reproductive behavior of male gray seals (Halichoerus grypus) breeding on land-fast ice at Amet Island, Nova Scotia, was studied. Data on energy expenditure (rate of mass loss over time) were collected. The average time budget of males at Amet Island was comparable to that of land-breeding males. The behavior of males showed seasonal changes, with a decrease in the proportion of time spent in the water and an increase in agonistic behavior during the peak mating period. The estimated amount of body mass lost over the season ranged between 25.6 and 77.1 kg, and the estimated percent of initial body mass lost ranged between 7.7 and 26.5% (n=10). The maximum number of observed copulations for an individual male was nine. Only 15 out of 42 males observed during 1992 and 1993 were seen copulating. The number of observed copulations per male was strongly correlated with success in remaining close to, or attending, females (r=0.91, P<0.001, n=42). The mean duration of attendance was 4.5 ± 5.54 days (n=42). Large size was not an important factor in determining attendance success, but reproductive effort (the estimated proportion of body mass lost over the season) and success in agonistic interactions with other males were both correlated with male success. 相似文献