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631.
Abstract Festuca rubra L. plants are pseudometallophytes colonizing abandoned Pb/Zn mine areas, successfully employed in phytostabilization. To study the contribution of low-molecular weight organic acids to metal tolerance, F. rubra plants were grown for three months in hydroponics with Cd (1.8, 18 and 36 µmol?L?1), Pb (50, 250 and 500?µmol?L?1) and Zn (0.3, 3 and 6?mmol?L?1), separately, and in ternary combination (18?µmol?L?1 Cd + 250?µmol?L?1 Pb + 0.3?mmol?L?1 Zn). The roots retained most of the metals but their distribution from shoot to root was altered when the plants were treated with the ternary combination. The main organic acids in roots were citrate and malate. At the lowest concentrations, the metals caused small reductions in biomass, had no effects on photosynthetic pigments nor on malondialdehyde, but led to increases in root organic acids. At higher concentrations, phytotoxic responses were observed, associated with a decline of citrate and malate in the roots. 相似文献
632.
Carel?P.?van?SchaikEmail author Sagar?A.?Pandit Erin?R.?Vogel 《Behavioral ecology and sociobiology》2004,57(2):101-109
Perhaps the most common form of cooperation among primates is the formation of coalitions. Competition among males within a group concerns a constant quantity of the limiting resource (fertilizations). Contest competition over fertilizations is known to produce payoffs that are distributed according to the priority-of-access model, and hence show an exponential decline in payoff with rank. We develop a model for rank-changing, within-group coalitions among primate males. For these coalitions to occur, they must be both profitable (i.e. improve fitness) for all coalition members and feasible (i.e. be able to beat the targets). We assume that the value of the coalition is the sum of the payoffs of the partners in their original ranks. We distinguish three basic coalition configurations, depending on the dominance ranks of the coalition partners relative to their target. We predict five basic coalition types. First, all-up, rank-changing coalitions targeting individuals ranking above all coalition partners; these are expected to involve coalition partners ranking just below their target, concern top rank, and be small, just two or three animals. Second, bridging, rank-changing coalitions, where higher-rankers support lower-rankers to rise to a rank below themselves; these are expected to be most common where a high-ranking male in a despotic system can support a low-ranking relative. Third, bridging non-rank-changing coalitions; these are expected to be common whenever high-ranking males have low-ranking close relatives. Fourth, non-rank-changing coalitions by high-rankers against lower-ranking targets; these are expected to serve to counteract or prevent the first type. Fifth, non-rank-changing, leveling coalitions, in which all partners rank below their target and which flatten the payoff distribution; these are expected to be large and mainly involve lower-ranking males. Bridging, rank-changing coalitions are expected in situations where contest is strong, all-up rank-changing coalitions where contest is intermediate, and leveling coalitions where contest is weak. We review the empirical patterns found among primates. The strong predictions of the model are confirmed by observational data on male-male coalitions in primates.
相似文献
Carel P. van SchaikEmail: |
633.
Marieke C. Verweij Ivan Nagelkerken Suzanne L. J. Wartenbergh Ido R. Pen Gerard van der Velde 《Marine Biology》2006,149(6):1291-1299
Caribbean seagrass beds are important feeding habitats for so-called nocturnally active zoobenthivorous fish, but the extent to which these fishes use mangroves and seagrass beds as feeding habitats during daytime remains unclear. We hypothesised three feeding strategies: (1) fishes feed opportunistically in mangroves or seagrass beds throughout the day and feed predominantly in seagrass beds during night-time; (2) fishes start feeding in mangroves or seagrass beds during daytime just prior to nocturnal feeding in seagrass beds; (3) after nocturnal feeding in seagrass beds, fishes complete feeding in mangroves or seagrass beds during the morning. We studied the effect of habitat type, fish size, social mode and time of day on resting and feeding behaviour of large juvenile (5–10 cm) and sub-adult (10–15 cm) Haemulon flavolineatum in mangroves and seagrass beds during daytime. Sub-adults occurred in mangroves only, spent most time on resting, and showed rare opportunistic feeding events (concordant with strategy 1), regardless of their social mode (solitary or schooling). In contrast, large juveniles were present in both habitat types and solitary fishes mainly foraged, while schooling fishes mainly rested. Exceptions were small juveniles (±5 cm) in seagrass beds which foraged intensively while schooling. Large juveniles showed more feeding activity in seagrass beds than in mangroves. In both habitat types, they showed benthic feeding, whereas pelagic feeding was observed almost exclusively in the seagrass beds. In both habitat types, their feeding activity was highest during 8:00–10:30 hours (concordant with strategy 3), and for seagrass fishes, it was also high during 17:30–18:30 hours (concordant with strategy 2). The study shows that both mangroves and seagrass beds provide daytime feeding habitats for some life-stages of H. flavolineatum, which is generally considered a nocturnal feeder. 相似文献
634.
Summary. Infochemicals are known to play a key role in mediating predator-prey interactions, both in aquatic and terrestrial communities. However, state-dependent variation may exist in how effectively individuals can use this information, depending on genotype, life stage and experience. For our study, we used the predator-prey model system fish-waterflea Daphnia magna Straus (Cladocera, Daphniidae). Adult Daphnia use fish-derived infochemicals, so-called kairomones, as indicators of predation risk, and exhibit a spectrum of morphological, behavioural and life-history responses to the presence of fish kairomones. Here, we investigate whether diapausing eggs, an embryonic resting stage in the life cycle of D. magna, also use fish kairomones and tune their hatching to the risk of fish predation, as reported for diapausing stages of dinoflagellates. In two laboratory experiments, we studied hatching proportion and time until hatching of D. magna diapausing eggs in the absence and presence of fish kairomones. D. magna families differed significantly in their response to the presence of fish kairomones; some families reduced hatching proportion, whereas others increased it. Our results imply genotype-dependent differences in the hatching reactions to fish kairomones as observed for other traits in adult Daphnia. 相似文献
635.
The evolution of female social relationships in nonhuman primates 总被引:38,自引:14,他引:38
Elisabeth H. M. Sterck David P. Watts Carel P. van Schaik 《Behavioral ecology and sociobiology》1997,41(5):291-309
Considerable interspecific variation in female social relationships occurs in gregarious primates, particularly with regard
to agonism and cooperation between females and to the quality of female relationships with males. This variation exists alongside
variation in female philopatry and dispersal. Socioecological theories have tried to explain variation in female-female social
relationships from an evolutionary perspective focused on ecological factors, notably predation and food distribution. According
to the current “ecological model”, predation risk forces females of most diurnal primate species to live in groups; the strength
of the contest component of competition for resources within and between groups then largely determines social relationships
between females. Social relationships among gregarious females are here characterized as Dispersal-Egalitarian, Resident-Nepotistic,
Resident-Nepotistic-Tolerant, or Resident-Egalitarian. This ecological model has successfully explained differences in the
occurrence of formal submission signals, decided dominance relationships, coalitions and female philopatry. Group size and
female rank generally affect female reproduction success as the model predicts, and studies of closely related species in
different ecological circumstances underscore the importance of the model. Some cases, however, can only be explained when
we extend the model to incorporate the effects of infanticide risk and habitat saturation. We review evidence in support of
the ecological model and test the power of alternative models that invoke between-group competition, forced female philopatry,
demographic female recruitment, male interventions into female aggression, and male harassment. Not one of these models can
replace the ecological model, which already encompasses the between-group competition. Currently the best model, which explains
several phenomena that the ecological model does not, is a “socioecological model” based on the combined importance of ecological
factors, habitat saturation and infanticide avoidance. We note some points of similarity and divergence with other mammalian
taxa; these remain to be explored in detail.
Received: 30 September 1996 / Accepted after revision: 20 July 1997 相似文献
636.
The effects of solar and artificial ultraviolet radiation on the motility and graviorientation of three strains of the dinoflagellate Prorocentrum were studied. P. micans isolated from the Baltic Sea shows a pronounced negative gravitaxis which switches to a positive one even after short exposure times to either solar or artificial UV irradiation. In constrast P. minimum strains isolated from the Kattegat and the Atlantic coast off Portugal showed only a weak upward orientation. In all three strains the linear swimming velocity decreases after short exposure times and, in addition, the percentage of motile cells in the populations drastically decreases. Removing the ultraviolet component of solar radiation with a cut-off filter prolongs the tolerated exposure times. 相似文献
637.
Jepma Catrinus J. van der Gaast Wytze 《Mitigation and Adaptation Strategies for Global Change》2004,9(2):97-102
Mitigation and Adaptation Strategies for Global Change - 相似文献
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