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81.
Raphael Ligeiro Wander Ferreira Robert M. Hughes Marcos Callisto 《Environmental monitoring and assessment》2013,185(5):4077-4085
Subsampling has been widely applied in the laboratory to process freshwater macroinvertebrate samples. Currently, many governmental agencies and research groups apply the fixed-count approach, targeting a number of individuals per sample, and at the same time keeping track of the number of quadrats (fraction of the sample) processed. However, fixed-area methods are still in use. The objective of this paper was to evaluate the reliability of macroinvertebrate taxonomic richness estimates developed from processing a standard number of subsampling quadrats (i.e., fixed-area approaches). We used a dataset from 18 tropical stream sites experiencing three different levels of human disturbance (most-, intermediate-, and least-disturbed). With 12 quadrats processed (half the sample), the collection curves started to stabilize, and for more than half of the sites studied, it was possible to sample at least 80 % of the total taxonomic richness of the sample. However, we observed that the minimum number of quadrats to achieve 80 % of taxonomic richness was strongly negatively correlated with the number of individuals collected in each site: the fewer the individuals in a sample, the greater the processed proportion of that sample needed to represent it properly. Thus our results indicate that for any given areal subsampling effort (any fixed fraction of the sample), samples with different numbers of individuals will be represented differently in terms of the proportion of the total number of taxa of the whole samples, those with greater numbers being overestimated and those with fewer numbers being underestimated. Therefore, we do not recommend the use of fixed-area subsampling methods alone if the main purpose is to measure and analyze taxonomic richness; instead, we encourage researchers to use fixed-count approaches for this purpose. 相似文献
82.
Melissa Hughes Stephen Nowicki William A. Searcy Susan Peters 《Behavioral ecology and sociobiology》1998,42(6):437-446
One hypothesis for the function of song repertoires is that males learn multiple song types so that they may share songs
with neighbors, allowing them to match during territorial interactions. In at least one song sparrow population, in Washington,
territorial males share a high proportion of song types with their neighbors and use these shared songs in matching. We recorded
song sparrows in Pennsylvania and quantified sharing of whole songs and song segments. We found that song sharing is an order
of magnitude less common in the Pennsylvania population. We found sharing of song segments to be significantly more common
than the sharing of whole songs in three of the five fields we examined, while we found no significant differences between
whole and partial song sharing in the remaining two fields. Finally, we found no evidence that sharing is greater between
birds in the same field compared to birds in different fields. Taken with the data from Washington song sparrows, these results
provide evidence for intraspecific geographic variation in the organization of song repertoires, and suggest that song sharing
has not been a strong selective force in the evolution of song repertoires in song sparrows as a species. Furthermore, Washington
and Pennsylvania song sparrows differ in how they learn song, in that Washington birds copy whole songs, while Pennsylvania
birds appear to copy and recombine song segments, as has been found in laboratory studies of song learning. Thus both song
learning and the function of song repertoires differ between populations of song sparrows. Such intraspecific geographic variation
offers a unique opportunity to explore the ecological and historical factors which have influenced the evolution of song.
Received: 30 June 1997 / Accepted after revision: 8 March 1998 相似文献
83.
William H. Stickel Lucille F. Stickel Russell A. Dyrland Donald L. Hughes 《Environmental monitoring and assessment》1984,4(2):113-118
Formalin preservation, freezing, spoiling followed by freezing, and phenoxyethanol were compared in terms of concentrations of DDT, DDD, DDE, endrin, and heptachlor epoxide measured in brain, liver and carcass of birds fed dietary dosages of pesticides and in spiked egg homogenate. Phenoxyethanol proved to be an unsatisfactory preservative; the amount of extractable lipid was excessive, and measurements of concentrations in replicates were erratic. Concentrations of residues in formalin-preserved and frozen samples did not differ significantly in any tissue. Percentage lipid in brains and eggs, however, were significantly lower in formalin-preserved samples. Samples of muscle and liver that had been spoiled before freezing yielded less DDD, and muscle samples yielded more DDT than formalin-preserved samples. We conclude that formalin preservation is a satisfactory method for preservation of field samples and that the warming and spoiling of samples that may occur unavoidably in the field will not result in misleading analytical results. 相似文献
84.
Multiple mating by females with different males (polyandry) is difficult to explain in many taxa because it carries significant
costs to females, yet benefits are often hard to identify. Polyandry is a derived trait in social insects, the evolutionary
origins of which remain unclear. One of several leading hypotheses for its evolution is that it improves division of labour
by increasing intra-colonial genetic diversity. Division of labour is a key player in the ecological success of social insects,
and in many successful species of ants is based on morphologically distinct castes of workers, each with their own task specialisations.
Atta leaf-cutting ants exhibit one of the most extreme and complicated forms of morphologically specialised worker castes and
have been reported to be polyandrous but with relatively low mating frequencies (~2.5 on average). Here, we show for the first
time that there is a significant genetic influence on worker size in Atta colombica leaf-cutting ants. We also provide the first estimate of the mating frequency of Atta cephalotes (four matings) and, by analysing much higher within-colony sample sizes, find that Atta are more polyandrous than previously thought (approximately six to seven matings). The results show that high polyandry and
a genetic influence on worker caste are present in both genera of leaf-cutting ants and add weight to the hypothesis that
division of labour is a potential driver of the evolution of polyandry in this clade of ants. 相似文献
85.
Size assessment via a visual signal in snapping shrimp 总被引:2,自引:0,他引:2
Melissa Hughes 《Behavioral ecology and sociobiology》1996,38(1):51-57
Snapping shrimp are highly aggressive decapod crustaceans, with large, asymmetric chelae. Body size determines the outcome
of both inter- and intrasexual interactions. Both the body and chela sizes of mated pairs are correlated, but the body size
correlation is significantly stronger. In competitive interactions between individuals of the same sex, larger individuals
usually win. Because the size of the major chela is a function of body size in both males and females, chela size could be
used to assess body size early in interactions, before engaging in more high risk behaviors. To determine whether the major
chela is used in size assessment, I presented shrimp with isolated chelae. Male snapping shrimp responded aggressively to
isolated chelae when they were fixed open in a display posture, and the degree of aggressive response depended on the relative
size of the chela. These data provide direct experimental evidence for the use of a visual signal in size assessment. Females,
in contrast, responded aggressively to both the open and closed chela, and their responses did not depend on relative size.
This sex difference in response may be due to differences in the value of certain resources, such as shelters, to males and
females: females may be more willing to respond aggressively regardless of the apparent size of their opponent, in order to
acquire more reliable information regarding size, motivation or fighting ability.
Received: 30 December 1994/Accepted after revision: 14 August 1995 相似文献
86.
Andrew O. Hughes Jon M. Olley Jacky C. Croke Ian T. Webster 《Journal of environmental radioactivity》2009,100(10):858-865
Fallout 137Cs has been widely used to determine floodplain sedimentation rates in temperate environments, particularly in the northern hemisphere. Its application in low fallout, tropical environments in the southern hemisphere has been limited. In this study we assess the utility of 137Cs for determining rates of floodplain sedimentation in a dry-tropical catchment in central Queensland, Australia. Floodplain and reference site cores were analysed in two centimetre increments, depth profiles were produced and total 137Cs inventories calculated from the detailed profile data. Information on the rates of 137Cs migration through local soils was obtained from the reference site soil cores. This data was used in an advection–diffusion model to account of 137Cs mobility in floodplain sediment cores. This allowed sedimentation rates to be determined without the first year of detection for 137Cs being known and without having to assume that 137Cs remains immobile following deposition. Caesium-137 depth profiles in this environment are demonstrated to be an effective way of determining floodplain sedimentation rates. The total 137Cs inventory approach was found to be less successful, with only one of the three sites analysed being in unequivocal agreement with the depth profile results. The input of sediment from catchment sources that have little, or no, 137Cs attached results in true depositional sites having total inventories that are not significantly different from those of undisturbed reference sites. 相似文献
87.
Increasing demands on freshwater and challenges in disposal of wastewaters encourage their use for irrigation. The study evaluated the effects of irrigation of signal grass (Urochloa decumbens) with sludgewater on leaching, uptake and retention of a range of elements in two contrasting soils in columns. The grass was grown on a sandy loam and a clay soil packed in plastic columns and irrigated for 119 days with either undiluted, diluted sludgewater or tap water. The sludgewater had a pH of 6.9 and high aluminum (Al), manganese (Mn), iron (Fe), and boron (B). Analyses were conducted on leachates, above-ground plant biomass (two harvests), and soils at the end of the experiment. Sludgewater treatments increased grass biomass yield and uptake of nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) in both soils with a greater nutrient uptake from the clay than the sandy loam. The application of sludgewater increased Mn and reduced P (sandy loam only) in the leachate with no effects on Al, Fe, or B. Uptake of Al, Fe, and B was increased by sludgewater application. Even when diluted, the sludgewater increased extractable Mn, particularly in the clay soil. The findings showed that irrigation of the soils with sludgewater increased Mn and B concentrations and uptake by signal grass, with no negative effects on biomass production. Leaching and accumulation in the soils of toxic elements were minimal in the short term. Sludgewater can therefore be used to grow signal grass in both soils although these effects need to be evaluated under field conditions. 相似文献
88.
Castro-Castellon Ana Teresa Hughes Jocelyne Mary Rose Read Daniel Steven Azimi Yaldah Chipps Michael James Hankins Nicholas Peter 《Environmental science and pollution research international》2021,28(22):27731-27741
Environmental Science and Pollution Research - A continuous flow filtration system was designed to identify and quantify the removal mechanisms of Cyanobacteria (Microcystis aeruginosa) by... 相似文献
89.
90.
We report the use of DNA probes to determine carrier status in three young women from a large kindred with Norrie disease. One of the women requested prenatal diagnosis during pregnancy. In this pedigree, Norrie disease was not characterized by a deletion at DXS7. 相似文献