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481.
Francis C. Neat Peter J. Wright Alain F. Zuur Iain M. Gibb Fiona M. Gibb David Tulett David A. Righton Robert J. Turner 《Marine Biology》2006,148(3):643-654
Atlantic cod stocks are subdivided into geographically and biologically discrete populations; some being locally resident,
others migratory. The reasons for the variation in migration pattern and the consequences it may have for population structuring
is poorly understood. We studied a group of cod from the coastal waters of the Shetland Isles in the northern North Sea. During
the spawning season, electronic tags that record depth and temperature over time were implanted into 133 individuals and the
fish released within a few kilometres of where they were captured. Thirty-nine cod have been recaptured up to 608 days later,
throughout the year and, in all but two cases, within 15 km of their release site. Geolocation methods based on temperature
and bathymetry also suggested that the cod had a limited home range, remaining resident year-round in coastal waters. The
cod were deeper during the winter and moved to shallower water in late spring and summer. They showed diel, fortnightly and
monthly cycles in depth movement that varied much within and between individuals over the season. Residency and the individual
variability in vertical movement may reflect a combination of locally complex depth strata, variable seabed substrate and
the wide range of seasonally available prey resources. 相似文献
482.
483.
In situ measurements comparing vertical SO42− profiles in vegetated and non-vegetated sediments showed that SO42− concentrations in vegetated sediments increased significantly at the beginning of the growing season and then gradually decreased during the rest of the growing season. Throughout the growing season, SO42− concentrations remained higher in the vegetated sediments than in the sediments without plants. The higher SO42− concentrations in the vegetated sediments indicate that oxygen release from roots and evapotranspiration-induced advection by plants play an important role in the dynamics of sulfur species in sediments. Since the total pool of solid-phase sulfide is relatively large compared to the mass of SO42− in the sediments, the gradual decrease of SO42− concentrations may result from limitation of the solid-phase sulfide that is in direct contact with or very close to the roots and rhizomes. This would mean that the main pool of solid-phase sulfide and associated trace metals are not affected by the oxygen release from roots, and the associated trace metals will not become bioavailable during the growing season. 相似文献
484.
The high frequency of extra-pair paternity in tree swallows is not an artifact of nestboxes 总被引:6,自引:0,他引:6
C. A. Barber Raleigh J. Robertson Peter T. Boag 《Behavioral ecology and sociobiology》1996,38(6):425-430
A common criticism of nestbox studies is one of creating artificial nesting conditions and breeding behavior different from
what would be seen under natural conditions. We assessed the frequency of extra-pair paternity (percentage of broods with
at least one extra-pair young) in 25 families of tree swallows (Tachycineta bicolor) nesting in natural cavities and compared it to that in a nestbox population. We found that 84% of females nesting in natural
cavities obtained fertilizations from extra-pair males. These extra-pair males fathered 69% of all nestlings. Studies of tree
swallows breeding in nestboxes have shown that 50–87% of broods contained extra-pair young, with extra-pair males fathering
38–53% of all the young. In broods with extra-pair paternity, natural cavities contained a significantly greater proportion
of extra-pair young than did nestboxes. Despite differences in nesting habitat and female age structure, the frequency of
extra-pair paternity did not differ significantly between the natural-cavity and nestbox populations. Therefore, the presence
of extra-pair paternity in tree swallows is not an artifact of nestboxes or of artificial nesting conditions.
Received: 2 May 1995/Accepted after revision: 14 January 1996 相似文献
485.
Peter D. Dijkstra Renske Hekman Rüdiger W. Schulz Ton G. G. Groothuis 《Behavioral ecology and sociobiology》2007,61(4):599-609
The nature of the costs maintaining honesty of sexual signalling in inter- and intrasexual interactions remains a contentious
issue. For carotenoid-based colour ornaments, it has been hypothesized that the honesty of the signal is enforced when carotenoid
allocation to colour expression is traded off against carotenoid availability for immunocompetence. In addition, honesty is
enforced if androgens required for colour expression are immunosuppressive. We tested whether there is a trade-off between
colour expression and immunocompetence in a lek-breeding haplochromine cichlid fish, Pundamilia nyererei, from Lake Victoria with a carotenoid-based nuptial dress. First, we showed that expression of red nuptial colouration and
social rank in a group were positively correlated. We then successfully manipulated the level of colour advertisement by socially
stimulating individually housed males with a rival male: Stimulated males developed larger areas of red nuptial colouration
and had higher levels of circulating 11-ketotestosterone (11-KT) than non-stimulated males. We subsequently tested the humoral
immune response to a novel antigen (sheep red blood cells). There was no overall significant effect of social stimulation
on antibody production, but in the stimulated males, the degree of red colouration and the antibody response were negatively
correlated. This significant interaction between colour and treatment thus shows that the negative correlation between colouration
and antibody production is dependent on the (manipulated) social environment. This study provides correlational and experimental
evidence for a trade-off between expression of a sexual trait and one component of immune function in fish. We found no evidence
for a direct effect of 11-KT on antibody production, and we discuss alternative mechanisms that could mediate the trade-off. 相似文献
486.
Body mass is a consistent individual trait that characterises the state of adult birds and mammals and is positively related
with long-term reproductive success. However, whether and to what extent body mass changes over lifetime in long-lived birds
is poorly studied. In this paper, we investigate how individual body mass varies with age. Furthermore, we try to separate
possible effects of age and experience on body mass. This study was conducted in a Common Tern colony on the German Wadden
Sea coast. Transponders allowed registration of individuals throughout the breeding season and consecutive years with an antenna
system combined with electronic balances for recording individual body-mass changes within and between years. Individual body
masses of males and females were measured during three stages of the breeding season: at arrival, during incubation and chick
rearing when mass was lowest in both sexes. Individual-based longitudinal analyses clearly showed that body mass during arrival,
incubation and chick rearing increased up to an age of 5 or 6 years. First-time breeders had lower body mass than experienced
breeders. Experience had stronger effects on incubation mass than age. Recruiting age also affected body-mass development
of breeders: Three-year-old recruits showed a stronger increase in mass with experience than 4-year-old recruits. We assume
that increasing experience enables birds to cope better with the physiological challenge of reproduction. To explain the general
phenomenon of higher body mass in older birds, our results support the constraint hypothesis rather than either the selection
or restraint hypothesis. 相似文献
487.
Summary We investigated multiple paternity in acorn woodpeckers (Melanerpes formicivorus) from central New Mexico by starch-gel electrophoresis. Seven of thirty-one presumptive genetic loci were polymorphic. Multiple paternity was revealed in one of three multi-male groups sampled on the basis of offspring and adult electrophoretic phendtypes, and was suggested in the two other groups. This study provides the first documentation of multiple paternity for any avian cooperative breeder. 相似文献
488.
Predation and hunger are threats for most organisms, and appropriate behavioural responses to both factors should be shaped by natural selection. In combination, however, the behavioural demands of predation avoidance and effective foraging often cannot be satisfied at the same time and lead to a conflict within organisms. We examined the behavioural responses of two closely-related species of tadpoles, Rana lessonae and R. esculenta, to simulated predation by fish and hunger. Tadpoles, hatched and reared in the laboratory, were tested in a three-way factorial (predation risk × hunger × species) experiment with four predation levels and four hunger levels. Both species decreased their swimming activity with increasing predation risk. Predation risk did not influence the amount of activity time invested in feeding but caused the tadpoles to spend less time in patches with food. Refuges were not used to avoid predation. R. esculenta was more sensitive to predation risk than R. lessonae. Hunger increased both the activity of tadpoles and the amount of activity time invested in feeding, thus indicating an increased energy intake. No interactions were observed between predation risk and hunger. These results show that tadpoles possess genetically-based behavioural mechanisms that allow them to respond in a graded manner to predation and hunger. However, they did not balance the two conflicting demands of predation avoidance and effective foraging; the two mechanisms appeared to act independently.
Correspondence to: R.D. Semlitsch 相似文献
489.
Sexual selection and cuckoldry in a monogamous songbird: implications for sexual selection theory 总被引:11,自引:0,他引:11
Geoffrey E. Hill Robert Montgomerie Christina Roeder Peter Boag 《Behavioral ecology and sociobiology》1994,35(3):193-199
Sexual selection is generally assumed to be weaker in monogamous than in polygynous animals. Recently, though, extra-pair fertilizations have been hailed as an important force in generating variance in reproductive success among males in socially monogamous species, thereby increasing the intensity of sexual selection. To see if extra-pair copulations contribute to variance in male reproductive success in the house finch (Carpodacus mexicanus), we used DNA fingerprinting to determine the paternity of chicks from 35 nests. This species is a socially monogamous passerine in which plumage brightness serves as a sexually selected indicator of male quality. Out of 119, nestlings 10 (8.3%) were fathered by a male other than the attending male, but cuckoldry occurred randomly with respect to the plumage colouration, size, or age of the attending male. Thus extra-pair fertilizations do not generate variance in male reproductive success with respect to plumage colour. On the other hand, a strongly male-biased sex ratio and asynchronous breeding by females may generate substantial variance in male reproductive success and could explain the evolution of ornamental colouration. 相似文献
490.
Peter M. Waser 《Behavioral ecology and sociobiology》1984,15(3):197-202
Summary Spatial associations between members of different animal species may arise through mutual behavioral attraction, through attraction to common resources or locations, or by chance. I outline a means of calculating the expected duration of associations based on the null hypothesis that members of different species move independently and randomly. Observed association durations can be compared to these expectations to identify those cases of association (or avoidance) that have biologically interesting causes. The method is applicable to any species in which the presence of a second species can be recorded during focal samples of an individual or a cohesive social group. The data required are readily collected in the field; I illustrate the use of the technique with data from several East African forest primates. 相似文献