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1.
Use of signature whistles during separations and reunions by wild bottlenose dolphin mothers and infants 总被引:1,自引:0,他引:1
We examine the contexts and patterns of signature whistle production by wild bottlenose dolphin mother-infant pairs (Tursiops spp.) to gain insight into the functional significance of whistles. Results are based on focal observations and simultaneous recordings of underwater vocalizations. Whistles occur primarily when mother-infant pairs are separated, and the probability of whistles increases with distance of separation. The timing of whistles during separations varies, but whistles tend to be produced in repetitive series and are generally concentrated toward the later stages of the separation, i.e., during the process of reunion. Although we focused on infants, mothers do not appear to whistle during separations as frequently as infants. Infant whistles may function to facilitate reunions by conveying information to the mother concerning the infant's motivation to reunite and/or its location. Infant whistles could induce a cooperative response from the mother including approach, slowing to allow the infant to catch up or whistling. Highly individualized signature whistles may be particularly useful in a fission-fusion society in which individuals (mothers and infants as well as adults) join and leave temporary parties in a fluid manner, yet maintain consistent, long-term associations with particular individuals.
Correspondence to: R.A. Smolker 相似文献
2.
Summary We examined the hypothesis that among free-ranging rhesus monkeys (Macaca mulatta), maternal care patterns during estrus influence chances of conception independently of variation in the timing of the postpartum resumption of mating. We observed 24 multiparous mothers and their infants before and during the 1990 mating season. When mothers resumed mating, they abruptly sought less contact with their infants. Infants responded by increasing the rates with which they emitted distress calls and attempted to make nipple contact. High levels of maternal rejection and low levels of maternal nipple contact initiation during the mother's first estrus were associated with low suckling frequencies and high chances of conception. Although demanding infants had some success in gaining access to the nipples of reluctant mothers during estrus, mothers' chances of conception were unrelated to measures of infant demand or distress calling. Individual differences in maternal behavior regulating access to the nipple during estrus were unrelated to those shown previously. During estrus, mothers appeared to regulate nipple contact according to their infant's age and perhaps other factors related to its vulnerability.
Correspondence to: C.M. Berman 相似文献
3.
Nga Nguyen Russell C. Van Horn Susan C. Alberts Jeanne Altmann 《Behavioral ecology and sociobiology》2009,63(9):1331-1344
Close associations between adult males and lactating females and their dependent infants are not commonly described in non-monogamous
mammals. However, such associations [sometimes called “friendships” (Smuts 1985)] are regularly observed in several primate species in which females mate with multiple males during the fertile period.
The absence of mating exclusivity among “friends” suggests that males should invest little in infant care, raising questions
about the adaptive significance of friendship bonds. Using data from genetic paternity analyses, patterns of behavior, and
long-term demographic and reproductive records, we evaluated the extent to which friendships in four multi-male, multi-female
yellow baboon (Papio cynocephalus) groups in Amboseli, Kenya represent joint parental care of offspring or male mating effort. We found evidence that mothers
and infants benefited directly from friendships; friendships provided mother–infant dyads protection from harassment from
other adult and immature females. In addition, nearly half of all male friends were the genetic fathers of offspring and had
been observed mating with mothers during the days of most likely conception for those offspring. In contrast, nearly all friends
who were not fathers were also not observed to consort with the mother during the days of most likely conception, suggesting
that friendships between mothers and non-fathers did not result from paternity confusion. Finally, we found no evidence that
prior friendship increased a male’s chances of mating with a female in future reproductive cycles. Our results suggest that,
for many male–female pairs at Amboseli, friendships represented a form of biparental care of offspring. Males in the remaining
friendship dyads may be trading protection of infants in exchange for some resources or services not yet identified. Our study
is the first to find evidence that female primates gain social benefits from their early associations with adult males.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Birth sex ratios in toque macaques and other mammals: integrating the effects of maternal condition and competition 总被引:2,自引:0,他引:2
Wolfgang P. J. Dittus 《Behavioral ecology and sociobiology》1998,44(3):149-160
Mammalian life histories suggest that maternal body condition and social dominance (a measure of resource-holding potential)
influence the physical and social development of offspring, and thereby their reproductive success. Predictably, a mother
should produce that sex of offspring which contributes most to her fitness (as measured by the number of her grandchildren)
and that she is best able to raise within the constraints imposed by her condition, social rank, and environment. Such combined
effects were investigated by monitoring variations in body condition (weight) and behavior of female toque macaques, Macaca sinica of Sri Lanka, in a changing forest environment over 18 years. Maternal rank, by itself, had no influence on offspring sex,
but did affect maternal body condition. The combined effects of rank and condition indicated the following: mothers in robust
condition bore more sons, whereas those in moderate condition bore more daughters, but both effects were expressed most strongly
among mothers of high rank. Where the consequences of low rank were felt most acutely, as shown by poor condition, mothers
underproduced daughters. Environmental quality directly influenced rank and condition interactions, and thus sex ratios. These
relationships, and data from other mammals suggest an empirically and theoretically consistent pattern of sex allocation in
mammals. New predictions integrate effects, proposed by Trivers and Willard, that are rooted in male mate competition, which
is universal among polygynous mammals, with those of local resource competition (and/or female reproductive competition),
which are not universal and differ in intensity between the socioecologies and local environments of different species.
Received: 30 May 1998 / Accepted after revision: 29 August 1998 相似文献
5.
Effects of environmental parameters on the oxygen consumption of four marine invertebrates: a comparative factorial study 总被引:1,自引:0,他引:1
The oxygen consumption curves of two decapod crustaceans (Palaemon serratus, Penaeus monodon) and two prosobranch molluscs (Trunculariopsis trunculus, Nassarius mutabilis) have been detected in the entire pO2 interval from 0 to 160 mmHg, under different conditions of temperature and salinity. From the experimental curves, physiological
parameters such as the initial oxygen consumption velocity, the Q
10 values and the oxygen independence indices have been measured. The latter parameters have been obtained using normalised
plots which allow their better evaluation. The effects of temperature, salinity and oxygen partial pressure on the oxygen-consumption
features have been studied using a factorial experimental plan which allows measurement of the effects of each experimental
variable as well as the effects of synergistic interactions between different variables.
Received: 27 March 2000 / Accepted: 13 November 2000 相似文献
6.
The evolution of non-maternal caretaking among anthropoid primates: do helpers help? 总被引:5,自引:0,他引:5
Non-maternal infant care among nonhuman primates has frequently been investigated from the perspective of the caretaker.
Here we examine whether allocaretaking behavior provides direct reproductive benefits to mothers. Comparative analyses that
control for the effects of allometry and phylogeny reveal that allocaretaking behavior correlates with relatively fast infant
growth and reproduction, but is not associated with the production of large infants. These results are consistent with those
from studies of other taxa; primate helpers appear to increase the reproductive success of female breeders. In addition, our
findings contrast with those derived from traditional allometric analyses and underscore the importance of controlling for
the potentially confounding effects of phylogeny in comparative analyses.
Received: 28 May 1996 / Accepted after revision: 16 November 1996 相似文献
7.
Temperature is known to have a strong influence on cephalopod growth during the early exponential growth phase. Most captive
growth studies have used constant temperature regimes and assumed that populations are composed of identically sized individuals
at hatching, overlooking the effects of seasonal temperature variation and individual hatchling size heterogeneity. This study
investigated the relative roles of initial hatchling size and simulated natural seasonal temperature regimes on the growth
of 64 captive Octopus pallidus over a 4-month period. Initial weights were recorded, and daily food consumption and fortnightly growth monitored. Two temperature
treatments were applied replicating local seasonal water temperatures: spring/summer (14–18°C) and summer/autumn (18–14°C).
Overall octopuses in the spring/summer treatment grew at a rate of 1.42% bwd−1 (% body weight per day) compared to 1.72% bwd−1 in the summer/autumn treatment. Initial size influenced growth rate in the summer/autumn treatment with smaller octopuses
(<0.25 g) growing faster at 1.82% bwd−1 compared to larger octopuses at 1.68% bwd−1. This was opposite to individuals in the spring/summer treatment where smaller octopuses grew slower at 1.29% bwd−1 compared to larger octopuses at 1.60% bwd−1. Initial size influenced subsequent growth, however, this was dependent on feeding rate and appears to be secondary to the
effects of temperature. 相似文献
8.
Maija K. Marsh Michael R. Hutchings Steven R. McLeod Piran C. L. White 《Behavioral ecology and sociobiology》2011,65(2):183-195
It is becoming increasingly evident that the social behaviour of many group-living species is more complex than previously
assumed and that free mixing of individuals, even within social groups, is rare. This has important implications for ecological
processes, such as disease transmission, which are dependent on interactions between individuals. European wild rabbits (Oryctolagus cuniculus) have been considered traditionally as highly sociable animals that mix freely within groups but interact less frequently
between groups. We deployed proximity logging devices to quantify the intra- and inter-group contact behaviour of free-living
wild rabbits in two populations in a temperate region of Australia. Altogether, 126 rabbits were fitted with proximity loggers
at least once during the study. Radio-tracking was carried out alongside proximity data collection to determine the space
use of rabbit social groups within the study sites. On average, a rabbit made only 1.54 ± 0.23 (SE) (median = 0.54) contacts
per day with each other rabbit carrying a proximity logger in its social group, and the mean daily contact duration was 202 ± 38 s/day
(SE) (median = 29 s). Despite the high degree of home range overlap between the neighbouring social groups, inter-group contacts
were highly infrequent and brief. Our results demonstrated considerable spatial and temporal heterogeneities in the contact
behaviour between individual rabbits, both between populations and between and within social groups in the same population.
Such variations in the social organisation of rabbits are likely to create complex patterns of disease transmission through
direct contact and may contribute towards observed heterogeneities in the effects of disease on wild rabbit populations. 相似文献
9.
Wolfgang Völkl 《Behavioral ecology and sociobiology》2001,49(2-3):135-144
Pauesia picta, P. pinicollis and P. silvestris (Hymenoptera: Aphidiidae) are common parasitoids of the conifer aphid Cinara pinea, which is regularly attended by red wood ants (Formica spp.). In this study, I tested whether females of these parasitoid species learned during interactions with honeydew-collecting Formica polyctena workers that caution is not necessary if searching behaviour is adapted, and whether parasitoids benefit from being able
to learn. When searching on Scots pines, naive females of P. picta and P. pinicollis generally retreated to a pine needle when making contact with a honeydew-collecting ant, did not approach ants from the side
or from the front and kept a ”safe distance” from ants when sitting on needles. After some non- aggressive ant encounters,
experienced female parasitoids changed their behaviour: they reduced their searching speed, approached ants from the side
and even from the front, retreated less often in response to an approaching ant and reduced the ”safe distance”. These experienced
females had a significantly higher rate of oviposition than naive females or females foraging for an unattended host. Thus,
the ability of the parasitoid to learn during interactions with an antagonist led to a prolonged retention time and a higher
oviposition rate. By contrast, there was no evidence of learning in P. silvestris. Females of this species showed no behavioural change in response to ant encounters, and there was no difference in the foraging
success of naive and experienced female parasitoids.
Received: 7 December 1999 / Revised: 23 September 2000 / Accepted: 10 March 2000 相似文献
10.
J. H. M. Kouwenberg H. I. Browman J. A. Runge J. J. Cullen R. F. Davis J.-F. St-Pierre 《Marine Biology》1999,134(2):285-293
The copepod Calanus finmarchicus Gunnerus is a key component of the planktonic food web in the Gulf of St. Lawrence, Canada. In this region, productivity-determining
biophysical interactions occur in the upper 0 to 30 m of the water column. The eggs and nauplii of C. finmarchicus are found in this layer. Measurements of the diffuse attenuation coefficients for solar ultraviolet-B radiation (280 to 320 nm,
UV-B) at various locations in this region indicated maximum 10% depths (the depth to which 10% of the surface energy penetrates)
of 3 to 4 m at a wavelength of 310 nm. This represents a significant percentage of the summer mixed-layer water column: organisms
residing in this layer are exposed to UV-B radiation. Laboratory experiments using a Xenon-arc-lamp based solar simulator
revealed that C. finmarchicus embryos exposed to UV-B exhibited high wavelength-dependent mortality. The strongest effects occurred under exposures to
wavelengths below 312 nm. A significant percentage of nauplii hatched from eggs exposed to these wavelengths exhibited malformations
indicative of errors in pattern formation during embryogenesis. At the shorter wavelengths (<305 nm), UV-B-induced mortality
was strongly dependent on cumulative exposure. The biological weighting function (BWF) derived for UV-B-induced mortality
in C. finmarchicus eggs is similar to that reported for naked DNA. This suggests that the UV-B-induced mortality effect on C. finmarchicus embryos is a direct result of DNA damage. There was no evidence of a detrimental effect of ultraviolet-A radiation (320 to
400 nm). Calculations based upon the BWF indicate that, under current noon surface irradiance, 50% of C. finmarchicus eggs located at or very near (within 10 cm) the ocean surface will be dead after 2.5 h of exposure. Under solar spectral
irradiance simulating a 20% decrease in ozone layer thickness, this time drops to 2.2 h. These are first-order estimates based
upon irradiance taken at a time of day during which the values would be maximal. Nonetheless, they illustrate the relative
changes in UV-B effects that will result from ozone layer depletions expected over the coming decades. It is also important
to point out that variability in cloud cover, water quality, and vertical distribution and displacement within the mixed layer,
can all have a greater effect on the flux of UV-B radiation to which C. finmarchicus eggs are exposed than will ozone layer depletion at these latitudes.
Received: 2 March 1998 / Accepted: 18 December 1998 相似文献
11.
It has been argued that female mammals should terminate expensive forms of infant care earlier as habitat quality declines.
More recently it has been shown that among a variety of mammalian species, early termination of care is also associated with
highly favourable conditions. In this paper we present data on maternal investment decisions among baboons (Papio cynocephalus ursinus) inhabiting the Drakensberg Mountains of South Africa, and compare these with data from East African baboon studies. Mothers
in the mountain habitat face a set of environmental conditions where the problem of resource allocation to offspring is expected
to be particularly acute. We begin by using the model of Altmann (1980) of maternal time budgets to demonstrate that mountain
baboon mothers experience greater perturbations to their activity budgets while suckling than do mothers in other populations.
They also provide consistently greater levels of care to their infants and do so in the absence of any form of overt conflict
over access to the nipple. Although this investment results in a relative lengthening of the interbirth interval (IBI), it
is accompanied by relatively higher infant survival. We argue that factors that influence the maternal strategy adopted by
mountain baboons include slow infant growth rates and a lack of predation in the habitat which influences probability of offspring
survival beyond the immediate postnatal period. We suggest that both “care-dependent” sources of mortality (e.g. female reproductive
condition, the amount of milk transferred to offspring) as well as “care independent” sources of mortality (e.g. predation,
infectious disease) should be considered in studies of parental investment.
Received: 26 May 1997 / Accepted after revision: 9 August 1997 相似文献
12.
Craig B. Stanford 《Behavioral ecology and sociobiology》1992,30(1):29-34
Summary Data from a 15-month field study of the capped langur monkey, Presbytis pileata, in Bangladesh indicate that allomothering behavior is restricted to particular female-infant dyads. Primary allomothers were all parous adult females; nulliparous females rarely allo-mothered, Newborn infants were transferred from the mother to other females within a short time of birth, as reported for some other colobine species, but over the first 3 months of life each neonate's contact with nonmothers was largely restricted to a single allomother in each of five study groups. Capped langur mothers with newborn infants spent more time feeding when the infant was being allomothered than when it was in the mother's care. The model of allomothering as a selfish behavior by nulliparous or pregnant females used to enhance maternal skills at the expense of mothers is not supported by this study. Rather, allomothering may have adaptive significance as altruistic behavior among group females, in that it enables lactating females to increase feeding time. Capped langur allomothering is best interpreted as a low-cost behavior that can benefit recipients that may or may not be related.
Offprint requests to the present address 相似文献
13.
The influence of genetic relatedness on the individual performance (e.g. growth, development) of animals is often tied to
agonistic or cooperative behaviors among conspecifics, and studies of the effects of kinship have produced mixed results.
To explore genetic relatedness independent of these behaviors, we investigated the effects of kinship on the growth of the
kelp perch Brachyistius frenatus, a live-bearing, planktivorous marine reef fish that is capable of only limited dispersal. Although juveniles occur in aggregations
and compete for food resources, they do not exhibit overt aggressive or cooperative behavioral interactions. We hypothesized
that under competition and in the absence of these behaviors, sibling and non-sibling groups of juvenile B. frenatus raised at the same densities in the field would not differ in average growth, but that siblings would exhibit lower variation
in growth, simply due to genetic similarities in inherent growth rates. Pregnant, female kelp perch were collected and placed
in cages until parturition was complete. Groups of young, recently born from the same mother or from different mothers, were
then raised in the field for 9 wk. Our results revealed that average growth rates were similar between sibling and non-sibling
treatments. While variation in growth increased initially in non-siblings, siblings showed little such variation. This divergence,
however, was not consistent over the duration of the experiment, and variation in the growth of siblings ultimately converged
with that of non-siblings. Effects of genetic relatedness would be most likely to manifest themselves early after birth, before
environmental factors exert their influence, and this may explain the initial separation but eventual convergence in variation
in growth between sibling and non-sibling treatments. For B. frenatus and other organisms that will encounter relatives and compete for resources without overt behavioral interactions, the degree
of kinship may play a minor role in the demography of local populations.
Received: 26 January 1998 / Accepted: 30 September 1998 相似文献
14.
Hatchery rearing of the scallop Argopecten purpuratus has resulted in successive generations of scallops not exposed to predators that are less sensitive to and escape more slowly
from predators than wild scallops. The present study examined whether conditioning hatchery-reared A. purpuratus to its natural predator, the sea star Meyenaster gelatinosus, improved its escape responses. Both juvenile and adult A. purpuratus from Tongoy Bay, Chile, were exposed for 7 days to different conditions: (1) continuous predator odor, (2) predator contact
for 30 min three times a day, (3) a combination of the two previous conditions, and (4) no exposure to the predator (control).
After conditioning, we evaluated scallop’s escape responses: reaction time, total clap number, duration of the clapping response,
clapping rate, and the time scallops spent closed when exhausted. Conditioning with contact and odor plus contact (i.e., high
predation risk) resulted in 25 and 50% shorter reaction times of juveniles and adults, respectively. Further, these stimuli
caused juveniles to increase the number of claps and clapping rate. For adults, the time spent closed after exhaustion decreased
by 50 and 63% after conditioning with contact and odor plus contact, respectively. Therefore, it is shown for the first time
that exposure of scallops to increasing predator stimuli enhances escape responses, evidence of threat-sensitive predator
avoidance. 相似文献
15.
Lisa A. Simoncelli Christine J. Delevan Omar Ali S. Al-Naimi Maryam Bamshad 《Behavioral ecology and sociobiology》2010,64(5):865-873
Most monogamous male mammals display parental care, but the mechanism by which they become motivated to care for infants remains
unknown. We used prairie voles (Microtus ochrogaster) as a model of biparental species to test the hypothesis that physical contact with a female enhances male parental responsiveness
before the birth of offspring. We tested four groups of males: mated with physical contact with their mate, mated with only
distal cues from their mate, mated with no cues, and unmated with distal cues from a female. The subjects were placed in an
oversized cage divided into two compartments by a perforated barrier. At mid-gestation, the bedding and females were removed,
and the males’ responses toward two infants were videotaped. Although most males behaved parentally, mated males exposed to
their mate’s tactile or distal cues approached the young faster and were more likely to care for both infants than unmated
males which received female distal cues. Males who had physical contact with their mate showed “kyphosis” (a crouching position
over infants) and contacted infants more frequently than mated males which received no cues from their mate or unmated males
which received female distal cues. Furthermore, the frequency of non-social behaviors was lowest in mated males that had physical
contact with their mate. The data suggest that exposure to female distal cues after mating is sufficient to increase male
parental attentiveness, but female somatosensory cues affect the male's tendency to remain in physical contact with infants. 相似文献
16.
Haemolymph constituent levels and ammonia efflux rates of Nephrops norvegicus during emersion 总被引:2,自引:0,他引:2
Nephropsnorvegicus (L.) were subjected to 8 h of emersion, either between layers of seawater-soaked hessian with periodical (20 min) flushes
of seawater (high humidity, HH) or to unprotected emersion (low humidity, LH). Blood ammonia levels rose during emersion in
both groups but reached higher levels under LH conditions. Ammonia efflux rates after re-immersion were higher than those
of control prawns, and amounts of ammonia excreted at such times were considerably higher than those calculated to have accumulated
in the blood during emersion. Possible explanations for such differences are discussed. C
aO2 and C
vO2 decreased rapidly to ca. 10% normoxia values within 2 h of HH and LH emersion and remained low throughout the remaining emersion
time. Emersion-induced tissue hypoxia increased blood concentrations of glucose and lactate. Lactate accumulation was higher
during LH emersion, compared with HH emersion. Blood pH dropped ca. 0.40 units but increased again after 2 h of re-immersion.
Acidosis was probably related more to respiratory difficulties (CO2 accumulation) than to lactate accumulation, as blood lactate values remained high after 2 h of re-immersion. The ability
of N. norvegicus to cope with emersion appears to be little influenced by high humidity conditions.
Received: 26 June 1996 / Accepted: 5 August 1996 相似文献
17.
Summary Infant-carrying, the most costly form of primate parental care other than lactation, was investigated in savannah baboons of Amboseli, Kenya. Measurements of physical growth, counts and length of paces, and simultaneous records of carrying and locomotion were used to evaluate the time, distance, and energetic expenditure of infant-carrying. Finally, we modeled the energetics of independent infant locomotion and considered ontogenetic patterns in the alternative energetic costs of carrying versus independent infant locomotion under assumptions of complete nutritional dependency. The youngest infants were carried by their mothers during all travel and foraging, for a total of 8–10 km/day. By 8 months of age, both carrying time and distance were almost zero. However, daily carrying distance, unlike carrying time, did not decline in the first few months, because older infants were carried disproportionately during rapid travel and, consequently, for greater travel distances per unit carrying time. Females of low dominance rank carried their infants the most; the highest ranking mothers not only carried their infants least but biased their carrying against sons. Although carrying a growing infant is an increasingly costly behavior, during the period of nutritional dependence energetic costs to the mother are appreciably greater if an infant travels independently instead of being carried by its mother. Yet infants increased locomotor independence at a younger age than predicted by a simple model of maternal energetic efficiency. Trade-offs in energetic economy may enhance a mother's future reproduction at the expense of her present infant, may enhance survival of the present infant by promoting early acquisition of developmentally essential skills, or may suggest the importance of additional factors that influence the mother's and infant's behavior.
Offprint requests to: J. Altmann 相似文献
18.
To assess the effects of both temperature and food ration on gonad growth and oogenesis of the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller), individuals collected December 1996 (winter experiment) and June 1997 (summer experiment) were maintained
for 3 months in one of four experimental treatments: (1) 3 °C and fed ad libitum (high ration), (2) 3 °C and fed one-seventh of the maximum ration (low ration), and (3) 12 °C and fed the high ration; (4) 12 °C and fed
the low ration. All individuals were fed an artificial diet and exposed to only 1 h of light every day. At the end of both
experiments, mean gonad indices of sea urchins fed the high ration had increased significantly (11–24% and 6–19% in the winter
and summer experiments, respectively), while the gonad indices of individuals fed the low ration did not change. At the high
ration (both experiments), the increase in gonad index of sea urchins occurred primarily as the result of a significant increase
in the mass of nutritive phagocytes, as revealed by histological analyses. Primary oocytes were significantly larger in individuals
held at 3 °C than at 12 °C throughout the winter experiment, regardless of food ration; during the summer experiment, primary
oocytes were significantly larger in individuals receiving the high ration, regardless of the temperature at which they were
held. These results suggest that: (1) food availability is the most important factor regulating energy storage and the relative
size of gonads throughout the year, (2) temperature affects the rate of growth and maturation of primary oocytes during the
later stages of oogenesis, and (3) once gametogenesis has been initiated, mature ova will be produced, even under conditions
of low food availability. Conditions of high food availability in summer and low temperature in winter would thus favor reproductive
output in sea urchin populations.
Received: 1 March 2000 / Accepted: 4 October 2000 相似文献
19.
Ammonium concentrations of ∼1 M are commonly cited as being the threshold for inhibition of NO3
− uptake, but the applicability of this threshold to phytoplankton from different taxonomic classes has rarely been examined.
Additionally, little is known about the influence of environmental variables (e.g. growth temperature) on the interaction
between ambient NH4
+ and NO3
− uptake. Four species of estuarine phytoplankton, two diatom [Chaetoceros sp., and Thalassiosira weissflogii (Grunow) Fryxell et Hasle] and two dinoflagellate [Prorocentrum minimum (Pavillard) Schiller, and Gyrodinium uncatenum Hulburt], were grown on NO3
− at several different temperatures (4, 10, 15, or 20 °C), and the impact of NH4
+ additions on NO3
− uptake/assimilation (non-TCA-extracted) and assimilation (TCA-extracted) was assessed. For all species at all temperatures,
NO3
− uptake/assimilation and assimilation rates decreased in a roughly exponential manner with increasing NH4
+ concentrations but were not completely inhibited even at elevated NH4
+ concentrations of 200 μM. Estimated half-inhibition concentrations (K
i) were significantly greater in the diatom species (mean ± SE; 2.70 ± 0.67 μM) than in the dinoflagellate species (1.26 ± 0.55 μM). Half-inhibition constants were positively related to temperature-limited relative growth rate although not significantly.
The observed inhibition of NO3
− uptake and assimilation, as a percentage of NO3
− uptake in the absence of NH4
+, averaged about 80% and ranged from 49 to 100%. For all species, a significant (P < 0.001) positive correlation was found between percent inhibition of NO3
− assimilation and temperature-limited relative growth rate. Two experiments on Chesapeake Bay phytoplankton during an April
1998 diatom bloom showed that in short-term (∼1 h) temperature manipulation experiments, percent inhibition of NO3
− uptake/assimilation was also positively related (P = 0.05) to experimental temperature. The observed relationships between temperature-limited relative growth rate and percent
inhibition of NO3
− assimilation rates for the species tested suggest that at the enzyme level, the inhibitory mechanism of NO3
− assimilation is similar among species, but at the whole cell level may be regulated by species-specific differences in the
accumulation of internal metabolites. These findings add not only to our understanding of species-specific variability and
the role of growth temperature, but also provide additional data with which to evaluate current models of NH4
+ and NO3
− interactions.
Received: 31 August 1998 / Accepted: 7 December 1998 相似文献
20.
B. A. Kerrigan 《Marine Biology》1997,127(3):395-402
The effects of food availability, female size, and social interactions on the quality of Pomacentrus amboinensis larvae at hatching were examined using two field-based experiments. In Experiment 1, food availability and female size significantly
influenced size, eye diameter and levels of yolk reserves of larvae at hatching. Small females (47 to 52 mm standard length,
SL) whose diets were not supplemented, produced the longest larvae (3.0 ± 0.01 mm total length, TL) with the least yolk reserves
(50.1 ± 1.04 μm2). Irrespective of female size, those that received additional food produced larvae with the largest yolk-sacs (large females:
87.60 ± 1.53 μm2; small females: 80.14 ± 1.24 μm2). In Experiment 2, interactions with conspecifics had a greater affect on the somatic development of larvae at hatching than
food availability. Increased social interactions resulted in larvae that were ⋍3% longer, with 2% greater head depth, than
larvae from females that spawned in isolation on the experimental reefs. Fed females produced larvae with ⋍20% more yolk than
larvae from females whose diets were not supplemented. All three factors (food availability, female size, and intensity of
social interactions) tested within these experiments vary spatially and temporally among reefs. There is the potential, therefore,
for larvae at the onset of the planktonic stage to vary in quality, level of development, and probability of survival.
Received: 12 August 1996 / Accepted: 26 August 1996 相似文献