摘要:

An operational sex ratio is defined as the ratio of males to females ready to mate. Temperature has been shown to affect patterns of mating competition over the breeding season, as ambient water temperature differentially influences the potential reproductive rates of male and female sand gobies,Pomatoschistus minutus(Pallas), creating an unbiased operational sex ratio in colder water, and a male biased operational sex ratio in warmer water. Here, the direct effect of water temperature on frequencies of inter- and intrasexual interactions was studied in a short (24 hr) time perspective in aquaria with an unbiased adult sex ratio. Males were found to interact significantly more with other males, and also tended to interact more with females, in a warm (16 °C) water treatment, as compared with a cold (8 °C) treatment, even though there was no general increase in total number of interactions in the warm water treatment. Female-initiated interactions were not significantly affected by temperature. An altered operational sex ratio is unlikely to account for the observed difference in male-male interactions between treatments, for two reasons: (1) the operational sex ratio, which was estimated after the last behavioural recording in each replicate, was slightly, but equally, male biased in both treatments; (2) the operational sex ratio of each replicate was not correlated with the number of male-male interactions recorded from that replicate. Instead, these results suggest that temperature may influence the intensity of male mating competition directly, and I propose that individual fish use water temperature as a proximate cue for estimating and forecasting operational sex ratios.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522860

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The prairie vole, Microtus ochrogaster forms communal groups by retention of philopatric offspring and the addition of unrelated individuals at malefemale and single female breeding units. Populations undergo high amplitude fluctuations in density with frequent low density bottle necks of 10-15 generations. We review the mating system and social behavior of the prairie vole with respect to potential for formation of genetically unique trait groups within the population as predicted by group selection theory. Hormonal-behavioral interactions reduce the opportunity for inbreeding within communal groups. Demographic traits, combined with dispersal and settlement behavior of those offspring that do disperse from the natal nest are such that breeding units would rarely include related animals. We predict that genetically distinct trait groups do not form in prairie vole populations, including during periods of low density bottlenecks.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522861

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

It has been hypothesized that females could use promiscuity to prevent male infanticide: a female will mate with several males as a way to confuse paternity of her offspring, so the males will tolerate these infants that might be their own. If so, and all other things being equal, a female should prefer an infanticidal over a noninfanticidal male as a mating partner. To test this prediction, I examined the social preferences of female meadow voles (Microtus pennsylvanicus) and house mice (Mus musculus) toward infanticidal and noninfanticidal conspecific males. In each trial, a female was allowed to visit two compartments containing either an infanticidal or a noninfanticidal male. Females of both species visited both kinds of males with the same frequency. Similarly, females of both species spent a similar amount of time inspecting the compartments of the infanticidal and the noninfanticidal male. The frequencies of other female behaviors such as self-grooming, scent marking, or aggression, were also similar. These results provide no support for the hypothesis that female promiscuity is a female strategy to prevent male infanticide in house mice or meadow voles.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522862

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Four species of nocturnal trans-saharan passerine migrants (Ficedula hypoleuca, Phylloscopus trochilus, Phoenicurus phoenicurus, Sylvia borin) were tested in Emlen funnels to assess the relative importance of the setting sun and stars in determining the nocturnal course. The experiments took place during spring migration at a Mediterranean stop-over site (Sardinia, Italy). The birds were caught during the day in mist-nets and kept in opaque plastic cages preventing them seeing outside, until the time of the experiment, on the same night; each bird was tested only once. Two experimental groups were exposed to the sunset, the first including the sight of the sun disc, the other after the sun had set. A third group was kept in the closed cages until the time of the test. A fourth group was directly tested in the funnels at sunset time, after the sun disc had set. The first three groups were tested in the funnels later, in complete darkness. Exposure and tests occurred under the same sky conditions, either clear or overcast. Under a clear sky, 10 out of 16 distributions are oriented in the expected migratory direction, or have a tendency towards it, irrespective of their exposure to the setting sun. This shows that the cues present at sunset are not necessary for the orientation of these birds, whose ability to orient correctly in the absence of any celestial cues is also confirmed by the results of the tests performed in overcast conditions with no previous exposure to visual cues. Unexpectedly, exposure to the setting sun with an overcast sky, followed by a test in the same overcast conditions lead to disorientation, suggesting that exposure to visual cues makes the birds look, at least at first, for other similar cues before turning to non-visual compass information.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522863

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This study reports on the aggressive behavior of the gall-forming aphidSmynthurodes betaeWest. Videotaped behavior and experiments demonstrated that first instar offspring of the fundatrix protect their galling sites against conspecific competitors (the larger individuals win), as well as against first instar competitors of the sympatric galling aphidForda riccobonii(Steph.). In mature galls, adult aphids also protect their gall and their offspring from conspecific invaders and natural enemies. The fighting behavior of the adult aphid is unique: the aphid seizes the intruder while lying on its back, enabling use of all six legs and the mouthparts. This is the first documentation of aggressive defensive behavior by adult aphids. Although the aggressive behavior of the adult aphid protects the gall and offspring, no distinct parental care behavior was observed. The territoriality and aggression are highly adaptive because of the limited number of galling sites. Under natural conditions, removal of the adult aphids from the galls resulted in significantly increased invasion by conspecific intruders. The results indicate that the role of interspecific competition and natural enemies in shaping adult behavior is rather limited. The open galls and the unique life-cycle ofS. betaeencourage and prolongintraspecific competition and facilitate confrontations between adults and invading nymphs. The ability of the adult owner of the gall to prevent invasions of nymphs has promoted the evolution of maternal defense in this aphid. This study supports the hypothesis that galls, as high value resources that combine food and shelter, are often associated with defensive and social behavior.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522864

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The amount of oral secretion, which mostly consists of proteinaceous materials, used for the construction and maintenance of nests by foundresses ofPolistes chinensiswas analysed in 95 field nests (1994–1996). The amounts always exceeded 50% of mean percent secretion to total the dry nest weights, and it was greater in nests built at sites exposed to direct rainfall than in those at sheltered sites. Further, exposed nests built in 1995 (a rainy year) were much smaller than those of 1994 and 1996, and the amount of secretion in that year was much greater than in the other years. The nitrogen content of adult workers, immatures, those left inside cells and the oral secretion in nests of 1996 showed that 10–20% of total protein resources brought in during the founding phase may be devoted to producing the secretion. The results suggest that the foundresses may regulate the amounts of oral secretion used for such purposes in response to environmental conditions.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522865

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Different experiments of simulated predators (flights of a raptor model, playbacks of raptor whistles and of alarms by conspecifics) were carried out on groups of captive Grey partridges (Perdix perdix) from game-farm stock, either intensively- or parent-reared. Both flights and alarms elicited high levels of antipredator behaviour. Freezing and vigilance occurred significantly more in parentthan in intensively-reared coveys. Upright vigilant posture was performed significantly more by males than by females. Good sentinels, i.e. the more vigilant males, formed a stable pair bond earlier than the other males. Advanced reproductive timing might compensate for the increased risk of predation from a sustained vigilance.

ISSN:0394-9370    

DOI:10.1080/08927014.1998.9522866

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor