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1.
Mathias Kölliker 《Behavioral ecology and sociobiology》2007,61(9):1489-1497
The evolution of parental care and family group formation critically depends on offspring survival benefits and parental fecundity
costs of care under given ecological conditions. Investigations of the functional significance of care in insect species that
exhibit facultative parental care have been relatively rare but may be of particular interest for better understanding of
benefit and cost schedules at an early evolutionary stage. In this study, aspects of benefits and costs of care were addressed
in the sub-social European earwig (Forficula auricularia; Dermaptera: Forficulidae) by manipulating the presence of tending mothers and brood size in a fully crossed experimental
design. Larvae growing in broods tended by their mother or of reduced size showed a higher survival probability than larvae
growing in untended or large broods, as predicted if maternal care is beneficial and shaped by a trade-off between number
and quality of offspring. Analysis of patterns of food consumption and developmental time further suggested that the benefit
of maternal attendance is mediated by the maternal provisioning of food, while the quality–quantity trade-off seemed to be
driven by sibling rivalry. Further, tending mothers delayed the production of a second clutch, indicating a potential cost
of care in terms of lifetime fecundity. This study experimentally shows benefits and potential costs of maternal care and
family group formation in the European earwig. More detailed behavioural experiments will be required to fully understand
how behavioural interactions among family members mediate these reproductive outcomes. 相似文献
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3.
In order to remain stable, dispersed social groups have to solve two fundamental problems: the coordination of movement and cohesiveness within a group and the spacing between the groups. Here, we investigate mechanisms involved in intra-group coordination and inter-group spacing using the golden brown mouse lemur, Microcebus ravelobensis, as a model for a nocturnal, solitary foraging mammal with a dispersed social system. By means of radiotelemetry and bioacoustics we studied the olfactory and vocal behaviour during nocturnal dispersal and reunion of five sleeping groups.All groups used 3–17 sleeping sites exclusively, suggesting a sleeping site-related territoriality and competition for them. The occurrence of olfactory and vocal behaviour showed an asymmetrical temporal distribution. Whereas marking behaviour was observed exclusively during dispersal, a particular call type, the trill, was used by all groups during reunions. Interestingly, these trills carried group-specific signatures.Our findings provide the first empirical evidence for nocturnal primates in a natural environment that olfactory signals represent an important mechanism to regulate the distribution of different groups in space, whereas acoustic signals control intra-group cohesion and coordination. 相似文献
4.
Steven L. Lima Patrick A. Zollner Peter A. Bednekoff 《Behavioral ecology and sociobiology》1999,46(2):110-116
In socially feeding birds and mammals, as group size increases, individuals devote less time to scanning their environment
and more time to feeding. This vigilance “group size effect” has long been attributed to the anti-predatory benefits of group
living, but many investigators have suggested that this effect may be driven by scramble competition for limited food. We
addressed this issue of causation by focusing on the way in which the scan durations of free-living dark-eyed juncos (Junco hyemalis) decrease with group size. We were particularly interested in vigilance scanning concomitant with the handling of food items,
since a decrease in food handling times (i.e. scan durations) with increasing group size could theoretically be driven by
scramble competition for limited food resources. However, we showed that food-handling scan durations decrease with group
size in an environment with an effectively unlimited food supply. Furthermore, this food-handling effect was qualitatively
similar to that observed in the duration of standard vigilance scans (scanning exclusive of food ingestion), and both responded
to changes in the risk of predation (proximity of a refuge) as one might expect based upon anti-predator considerations. The
group size effects in both food-handling and standard scan durations may reflect a lesser need for personal information about
risk as group size increases. Scramble competition may influence vigilance in some circumstances, but demonstrating an effect
of competition beyond that of predation may prove challenging.
Received: 22 September 1998 / Received in revised form: 1 February 1999 / Accepted: 14 February 1999 相似文献
5.
Knowing how far away animals can detect food has important consequences for understanding their foraging and social behaviors.
As part of a broader set of field experiments on primate foraging behavior, we set out artificial feeding platforms (90 × 90 cm
or 50 × 50 cm) throughout the home range of one group of 22 brown capuchin monkeys, at sites where they had not seen such
platforms previously. Whenever the group approached such a new platform to within 100 m, we recorded the group's direction
and speed of approach, and the identity and distance from the platform of the group member that detected the platform or came
closest to it without detecting it. We used logistic regression on these data to examine the effects of group movement speed,
platform size and height, and focal individual age and sex on the probability of detecting the platform as a function of distance.
Likelihood of detecting a platform decreased significantly at greater distances – the probability of detecting a platform
reached 0.5 at 41 m from the group's center and 25.5 m from the nearest group member. These results show that detectability
of platforms by the entire group (9 adults, 13 juveniles) was less than twice that for single group members. Detectability
at a given distance decreased severely as the group moved faster; at their fastest speed, individuals had to approach a platform
to within less than 10 m to find it. The large platforms were significantly more likely to be detected than the small ones,
suggesting that increased use of larger food patches by wild primates may not necessarily reflect foraging preferences.
Received: 20 May 1996 / Accepted after revision: 5 April 1997 相似文献
6.
Carl D. Soulsbury Philip J. Baker Graziella Iossa Stephen Harris 《Behavioral ecology and sociobiology》2008,62(8):1289-1298
The costs of dispersal are an important factor promoting natal philopatry, thereby encouraging the formation of social groups.
The red fox, Vulpes vulpes, exhibits a highly flexible social system and one that is thought to represent a possible stage in the evolution of more
complex patterns of group-living. Although the potential benefits accruing to philopatric offspring have previously been studied
in this species, the potential costs of dispersal have received less attention. We contrasted survival rates, nutritional
status, injuries and reproductive output of dispersing and non-dispersing male and female foxes in an urban population to
assess the relative costs of dispersal versus natal philopatry. Mortality rates were not significantly higher for dispersing
foxes, either in the short- or long-term. There was no evidence of increased nutritional stress in dispersing individuals.
Dispersing individuals did, however, exhibit greater levels of wounding, although this did not appear to affect survival.
Dispersing females were more likely to miss a breeding opportunity early in their reproductive lifespan. In contrast, both
dispersing and non-dispersing males were unlikely to breed in their first year. We conclude that the major fitness component
in females affected by dispersing is age at first reproduction. 相似文献
7.
Social aphid species provide ideal systems to study the ecological influences upon the evolution of sociality because they consist of discrete colonies which are entirely clonal and therefore devoid of any genetic conflict over altruistic behaviour. Although selfishness can be discounted as an obstacle preventing the evolution of altruistic defenders, the vast majority of aphid species are not social. To examine the key life-history and ecological characteristics that interact to facilitate social evolution, we designed a matrix population model based on the natural history of one of the unique aphid species with soldiers, Pemphigus spyrothecae. In addressing the life-history factors, our special interest was to examine the optimal trade-off faced by colonies that can increase their defence investment by producing defenders at birth and/or increasing the duration of the defensive stage. The level and period of exposure to predation and a declining colony birth rate were key factors that selected for social defence. The model demonstrated that, in species which have soldiers that can facultatively develop to make a direct contribution to colony fitness, temporal extension of the soldier stage is a key mechanism of increasing defence investment. This extension is particularly favoured when predation is high and the lifetime of a colony is long. An increase in production of defenders at birth was favoured when mortality due to predation was strongly biased towards defenders. The model suggests that, in species which have the defensive flexibility of choosing whether soldiers remain as such, there is little requirement for flexibility in the morph allocations made at birth. All these predictions were found to be fully compatible with the available empirical data. 相似文献
8.
Michael P. Lombardo 《Behavioral ecology and sociobiology》2008,62(4):479-497
A central question in behavioral ecology has been why animals live in groups. Previous theories about the evolution of sociality
focused on the potential benefits of decreased risk of predation, increased foraging or feeding efficiency, and mutual aid
in defending resources and/or rearing offspring. This paper argues that access to mutualistic endosymbiotic microbes is an
underappreciated benefit of group living and sets out to reinvigorate Troyer’s hypothesis that the need to obtain cellulolytic
microbes from conspecifics influenced the evolution of social behavior in herbivores and to extend it to nonherbivores. This
extension is necessary because the benefits of endosymbionts are not limited to nutrition; endosymbionts also help protect
their hosts from pathogens. When hosts must obtain endosymbionts from conspecifics, they are forced to interact. Thus, complex
forms of sociality may be more likely to evolve when hosts must repeatedly obtain endosymbionts from conspecifics than when
endosymbionts can be obtained either directly from the environment, are vertically transmitted, or when repeated inoculations
are not necessary. Observations from a variety of taxa are consistent with the ideas that individuals benefit from group living
by gaining access to endosymbionts and the complexity of social behavior is associated with the mode of acquisition of endosymbionts.
Ways to test this theory include (a) experiments designed to examine the effects of endosymbionts on host fitness and how
endosymbionts are obtained and (b) using phylogenetic analyses to examine endosymbiont–host coevolution with the goal of determining
the relationship between the mode of endosymbiont acquisition and host sociality. 相似文献
9.
The evolution of genome size has been discussed in relation to the evolution of various biological traits. In the present study, the genome sizes of 22 dictyopteran species were estimated by Feulgen image analysis densitometry and 6-diamidino-2-phenylindole (DAPI)-based flow cytometry. The haploid genome sizes (C-values) of termites (Isoptera) ranged from 0.58 to 1.90 pg, and those of Cryptocercus wood roaches (Cryptocercidae) were 1.16 to 1.32 pg. Compared to known values of other cockroaches (Blattaria) and mantids (Mantodea), these values are low. A relatively small genome size appears to be a (syn)apomorphy of Isoptera + Cryptocercus, together with their sociality. In some phylogenetic groups, genome size evolution is thought to be influenced by selective pressure on a particular trait, such as cell size or rate of development. The present results raise the possibility that genome size is influenced by selective pressures on traits associated with the evolution of sociality. 相似文献
10.
Prior residency as a key determinant of social dominance in the willow tit (Parus montanus) 总被引:1,自引:0,他引:1
Kari Koivula Kimmo Lahti Markku Orell Seppo Rytkönen 《Behavioral ecology and sociobiology》1993,33(4):283-287
Summary We studied how age, body size and prior residency affected social dominance in the willow tit (Parus montanus) groups. The contribution of each variable was experimentally tested in unisexual two-bird trials, in which the birds were matched for all variables except the one studied. Large birds were dominant over smaller ones (Fig. 1). The effect of body size was more prominent in males than in females. Age had no influence on dominance. Residents became dominant more often than newcomers (Fig. 2). Adulthood or larger body size did not override the advantage of prior residency (Fig. 2). Therefore, the proximate reason for the age-dependent dominance seen in natural willow tit flocks is most likely the prior residency advantage of the adults. Factors connected with fighting ability (body size and age) seem to be less important than the time of establishment of rank, which may reflect the importance of resource value differences between residents and newcomers in this context. The advantage of residency might make it advantageous to be a member of a flock even as a subordinate, rather than being solitary. 相似文献