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191.
The relationship between various experimental concentrations of CO2 and calcification in Bossiella orbigniana (Decaisne) was studied by measuring Ca-45 incorporation into the crystalline matrix. Air containing CO2 at partial pressures (PCO
2) of 0.04 to 5.5% was bubbled through synthetic seawater in incubation vessels. The resultant pH values in the presence of plants ranged from 6.5 to 8.7. The maximum calcification rate appears to lie between 0.11 and 1.05% PCO
2. The data suggest that calcification is controlled by a biological process that may be sensitive to pH and/or to the relative bicarbonate concentration. The data also suggest that a severalfold increase in CO2 over the present atmospheric level might lead to increased calcification in this marine alga. 相似文献
192.
P. J. Smith 《Marine Biology》1979,53(4):305-310
Esterase and glucosephosphate isomerase loci were examined in different year classes of the snapper Chrysophrys auratus Forster from the Hauraki Gulf in New Zealand and compared with temperatures during the immediate post-spawning period, the time when snapper larvae suffer high mortality. Year classes spawned in warm years have a low frequency of the Est-42 allele and year classes from cold years a high frequency of Est-42. Gpi-12 frequencies showed no significant change between warm and cold years. Annual fluctuations in allele frequencies within stocks may account for the observed excess of esterase homozygotes in other marine teleosts. 相似文献
193.
Concentrations of 40 elements were determined in tissues and whole bodies of mussels (Bathymodiolus thermophilus) and/or whole bodies of limpets (Neomphalus fretterae) collected from the submarine thermal springs on the Galápagos Rift in 1977. Concentrations of Ag, As, Fe, Mn, Mo, Se, Sr, and Zn were comparable or elevated relative to those of intertidal mollusks, which have been utilized as indicators of anthropogenic trace-metal contamination. Both species contained concentrations of some elements (e.g. Ag, As, Fe, Mn, Mo, Se, Zn) which corresponded with the elevated levels of those elements discharged from hydrothermal vents. Many elements were most enriched in the gills and digestive glands of the mussels. Iron:manganese ratios of those tissues were similar to ratios of pelagic and transitional sediments, indicating that metal-rich suspended particulates had been absorbed onto mucous membranes. Comparisons with other benthopelagic organisms were precluded, since the present data represent essentially the only trace-element analyses of deep-sea macroinvertebrates. 相似文献
194.
Social parasitism has evolved at least ten times in the allodapine bees but studies that explore the parasite’s integration
and exploitation of host colonies are lacking. Using colony content and dissection data, we examine how Inquilina schwarzi affects the social organisation of its host Exoneura robusta. Our samples include three critical periods in the host life cycle: initial formation of dominance hierarchies in late autumn,
commencement of oviposition by host queens in late winter, and development of secondary reproductives in late spring. I. schwarzi preferentially parasitises larger host colonies in autumn, but during autumn and winter, the parasite appears to be socially
invisible, living in the nest without disrupting the normal functioning of these colonies. Inquilines begin egg laying much
later than their hosts, and by late spring, they have disrupted host reproductive hierarchies, leading to lower skew in ovarian
sizes of their host nestmates. Living invisibly within the host nest for the first 6 months and waiting until well after host
reproduction has begun before disrupting their social organisation appear to be unique among social insects. Such a change
in strategy may be facilitated by the different social systems found in allodapine bees, with the social parasites possibly
disrupting the reproductive hierarchies during spring to prevent or reduce the normal dispersal of some host females from
their natal nests. 相似文献
195.
P.J. Somerfield M. Atkins S.G. Bolam K.R. Clarke E. Garnacho H.L. Rees R. Smith R.M. Warwick 《Marine Biology》2006,148(6):1231-1240
Phylum-level meta-analysis was applied to 192 samples from a variety of dredgings disposal and relocation sites around the
coast of England and Wales. No consistent relationship was found between the disturbance status of macrobenthic communities
within disposal sites and the nature or amount of dredgings disposed. Differences between samples within and outside disposal
sites were generally smaller than differences between different sites and various patterns of impact were detected. It is
concluded that dredgings disposal has two contrasting impacts on benthic communities. One, associated with organic enrichment,
leads to communities dominated by annelids and nematodes. The other, associated with intense physical disturbance, favours
large motile or armoured forms, such as bivalve molluscs and crustaceans. These effects may act antagonistically, and in a
phylum-level meta-analysis may cancel each other out. None of the samples examined from offshore disposal sites was grossly
disturbed, in terms of the proportional contribution to production from different phyla, and overall most samples ranged from
moderately disturbed to undisturbed. The ecological impacts associated with the intertidal placement of material (beneficial
use schemes) were comparable to those observed for the conventional sea disposal sites. 相似文献
196.
Many environmental sampling problems involve some specified regulatory or contractual limit (RL). Often the interest is in estimating the percentile of the underlying contaminant concentration distribution corresponding to RL. The focus of this paper is on obtaining a point estimate and a lower confidence limit for that percentile when all observations are nondetectable, with the ith observation known to be less than some detection limit DLI, where DLi RL. Since composite samples are being considered, it is not unreasonable to assume an underlying normal distribution. 相似文献
197.
Adam R. Smith William T. Wcislo Sean O’Donnell 《Behavioral ecology and sociobiology》2007,61(7):1111-1120
Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively
social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks
in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on
one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did
social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests
had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests.
After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions
of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures,
M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from
collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate
of solitary nest productivity. 相似文献
198.
Application of adaptive cluster sampling to low-density populations of freshwater mussels 总被引:5,自引:0,他引:5
David R. Smith Rita F. Villella David P. Lemarié 《Environmental and Ecological Statistics》2003,10(1):7-15
Freshwater mussels appear to be promising candidates for adaptive cluster sampling because they are benthic macroinvertebrates that cluster spatially and are frequently found at low densities. We applied adaptive cluster sampling to estimate density of freshwater mussels at 24 sites along the Cacapon River, WV, where a preliminary timed search indicated that mussels were present at low density. Adaptive cluster sampling increased yield of individual mussels and detection of uncommon species; however, it did not improve precision of density estimates. Because finding uncommon species, collecting individuals of those species, and estimating their densities are important conservation activities, additional research is warranted on application of adaptive cluster sampling to freshwater mussels. However, at this time we do not recommend routine application of adaptive cluster sampling to freshwater mussel populations. The ultimate, and currently unanswered, question is how to tell when adaptive cluster sampling should be used, i.e., when is a population sufficiently rare and clustered for adaptive cluster sampling to be efficient and practical? A cost-effective procedure needs to be developed to identify biological populations for which adaptive cluster sampling is appropriate. 相似文献
199.
Jennifer E. Smith Sandra K. Memenis Kay E. Holekamp 《Behavioral ecology and sociobiology》2007,61(5):753-765
When social partners vary in their relative value, individuals should theoretically initiate partnerships with conspecifics
of the highest value. Here, we tested this prediction in a wild population of spotted hyenas (Crocuta crocuta). Crocuta live in complex, fission–fusion societies structured by dominance hierarchies in which individuals vary greatly in their
value as social companions. Because patterns of association among Crocuta reflect social preferences, we calculated association indices (AIs) to examine how social rank influences intrasexual partner
choice among unrelated adults of both sexes. The highest-ranking individuals were generally most gregarious in both sexes.
Females associated most often with dominant and adjacent-ranking females. Females joined subgroups based on the presence of
particular conspecifics such that subordinates joined focal females at higher rates than did dominants. Dominants benefit
from associations with subordinates by enjoying priority of access to resources obtained and defended by multiple group members,
but the benefits of these associations to subordinates are unknown. To investigate this, we tested three hypotheses suggesting
how subordinates might benefit from rank-related partner choice among unrelated females. We found that subordinates who initiated
group formation benefited by gaining social and feeding tolerance from dominants. However, rates at which dominants provided
coalitionary support to subordinates did not vary with AIs. Overall, our data resemble those documenting patterns of association
among cercopithecine primates. We consider our results in light of optimal reproductive skew theory, Seyfarth’s rank attractiveness
model, and biological market theory. Our data are more consistent with the predictions of Seyfarth’s model and of biological
market theory than with those of skew theory. 相似文献
200.
There has now been an abundance of research conducted to explore genetic bases that underlie learning performance in the honey bee (Apis mellifera). This work has progressed to the point where studies now seek to relate genetic traits that underlie learning ability to learning in field-based foraging problems faced by workers. Accordingly, the focus of our research is to explore the correlation between laboratory-based performance using an established learning paradigm and field-based foraging behavior. To evaluate learning ability, selected lines were established by evaluating queens and drones in a proboscis extension reflex (PER) conditioning procedure to measure learning in a laboratory paradigm—latent inhibition (LI). Hybrid queens were then produced from our lines selected for high and low levels of LI and inseminated with semen from many drones chosen at random. The genetically diverse worker progeny were then evaluated for expression of LI and for preference of pollen and/or nectar during foraging. Foragers from several different queens, and which had resulted from fertilization by any of several different drone fathers, were collected as they returned from foraging flights and analyzed for pollen and nectar contents. They were subsequently evaluated for expression of LI. Our research revealed that pollen foragers exhibited stronger learning, both in the presence (excitatory conditioning) and absence (LI) of reinforcement. The heightened overall learning ability demonstrated by pollen foragers suggests that pollen foragers are in general more sensitive to a large number of environmental stimuli. This mechanism could contribute toward explanations of colony-level regulation of foraging patterns among workers.Communicated by R. Page 相似文献