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Synopsis Young-of-the-year largemouth bass,Micropterus salmoides, were exposed to four concentrations of sulphuric acid (pH levels 7.2, 6.1, 4.8, and 3.7) for 30 days, and the frequencies of feeding acts and activity bouts, and time budgets were recorded. Juveniles at pH 6.1 and at pH 4.8 performed the two feeding acts, bites and orientations, more often, and spent more time feeding than bass at pH 7.2. Bass at pH 3.7, however, reduced feeding, and spent a significantly larger portion of their time hovering in the water column. Frequencies of comfort and agonistic acts increased with a decline in pH. Alterations of behavioural repertoires of young-of-the-year largemouth bass were useful indicators of sulphuric acid exposure. 相似文献
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Synopsis We investigated the ability of two congeneric species of sunfish to learn to forage on a novel prey item in feeding arenas
containing structured habitats. Eight bluegill sunfish and eight pumpkinseed sunfish were given the opportunity to forage
on whiteworms daily for 10 days. Each day, several behavioural measures were recorded for each fish. Both species of sunfish
learned to feed over the 10-day period but the bluegill sunfish learned to feed more quickly than the pumpkinseed sunfish.
Pumpkinseeds, however, attained a higher level of foraging efficiency. The differences in learning and foraging efficiency
were related to body morphology. 相似文献
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Synopsis Laboratory studies were conducted on 15 schools of blackchin shiners, Notropis heterodon, to determine if they altered their structure in response to changing environmental demands. The hypothesis tested was that fish schools should sacrifice a flat, hydrodynamically efficient structure in favour of an unobstructed visual field in the presence of a predator by staggering in the vertical plane. Ten schools were exposed for two weeks to a simple environment with only a current. For the next two-week period a predator was added. Five control schools were exposed to the simple environment for both two-week periods. Six of the ten treated schools increased their staggering in the vertical dimension as predicted while none of the control schools changed. This result was suggestive that hydrodynamic advantages were sacrificed. Respirometer experiments indicated these fish were capable of achieving some hydrodynamic benefits from schooling but these benefits may be a function of fish size. 相似文献
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Alexander Cooke John L. Tolmie James M. Colgan Caroline M. Greig J. Michael Connor 《Human genetics》1989,83(1):83-87
Summary A child with impaired intelligence, minor dysmorphisms, obesity and genital hypoplasia was found to have an apparently balanced translocation, 46,XY,t(4;14)(q12;q13), following cytogenetic analysis. The same rearrangement was also detected in the child's father, who had similar phenotypic abnormalities to his son. Detailed study of flow karyotypes produced from lymphoblastoid cell lines established that in both patients the translocation was in fact unbalanced with approximately 11 million base pairs of DNA (corresponding to about 6.0% of chromosome 4 or 11.0% of chromosome 14) being lost. 相似文献
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Sampling properties of DNA sequence data in phylogenetic analysis 总被引:26,自引:6,他引:20
We inferred phylogenetic trees from individual genes and random samples of
nucleotides from the mitochondrial genomes of 10 vertebrates and compared
the results to those obtained by analyzing the whole genomes. Individual
genes are poor samples in that they infrequently lead to the whole-genome
tree. A large number of nucleotide sites is needed to exactly determine the
whole-genome tree. A relatively small number of sites, however, often
results in a tree close to the whole-genome tree. We found that blocks of
contiguous sites were less likely to lead to the whole-genome tree than
samples composed of sites drawn individually from throughout the genome.
Samples of contiguous sites are not representative of the entire genome, a
condition that violates a basic assumption of the bootstrap method as it is
applied in phylogenetic studies.
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