phenomenon · claim-type · cross-domain-transfer · mechanism · claim-relation · replication-status · limitation — grounded in the full text| phenomenon | seasonal cycles in chromosomal inversion frequencies— “These changes are cyclic and connected with the succession of the year's seasons.” | |
| claim-type | mechanism— “Furthermore, the selective values are quite different under different conditions, temperature being at least one of the modifying agents.” | |
| method — evidence | — “In the experiments described in this report a fly population with known frequencies of different types of third chromosomes was introduced into a cage, and the incidence of these chromosome types in the progeny of the initial population was observed from time to time.” | |
| mechanism | Heterozygote superiority: because ST/CH heterozygotes are fitter than either homozygote, selection drives the population towards an intermediate equilibrium of chromosome frequencies rather than fixation.— “It is very probable that neither homozygotes for ST (ST/ST) nor for CH (CH/CH), but the heterozygotes ST/CH are the most favored genetic constitution. If so, the changes in the populations will proceed toward equilibrium values at which the relative proportions of the three genotypes will give the maximal degree of fitness of the… | mechanisms[0] |
| mechanism | The inversions themselves are adaptively neutral, but they lock up different gene complexes that adapt their carriers to different seasonal environments, so seasonal change in the environment shifts their frequencies.— “The gene arrangements may be in themselves adaptively neutral (that is, free from position effects), but they contain different gene complexes which make their carriers adapted to different seasonal environments {DoBZHANSKY 1943).” | mechanisms[1] |
| mechanism | Frequency-dependent selection through niche filling: a rare genotype occupies only the niches it is best adapted to and is favoured, but when abundant it must spill into niches it fits poorly and is selected against.— “Each genotype may be favored by selection when rare and unable to occupy fully the ecological niches to which it is best adapted, but selected against when so abundant that it must in part occupy ecological niches to which it is less well adapted than other genotypes.” | mechanisms[2] |
| builds-on | L'Heritier and Teissier's population cage— “Population cages used in the present experiments (fig. I) are a modification of the L'HERITIER and TEISSIER model.” | claim_relations[0] |
| contradicts | Hovanitz (1944) migration explanation of the seasonal changes at Pinon Flats and Andreas Canyon— “An alternative explanation has been suggested by HovANITZ (1944) namely, that the populations of Pinon and Andreas are swamped in summer by migration from the flourishing populations higher on the mountain, which resemble Keen in chromosome frequencies.” | claim_relations[1] |
| sense | evidence of selection - a TWO-PART criterion: the average rate of change per generation AND the regression of that rate on chromosome frequency, both of which must be considered— “Both the average rate of change per generation and the regression of rate of change on chromosome frequency must be con sidered.” | senses[0] |
| sense | evidence of selection - AS A REGRESSION OF RATE ON FREQUENCY, which the paper says indicates selection EVEN IF the average does not differ significantly from zero— “but even if the average does not differ significantly from zero, a significant regression indicates a selective process which changes in amount or even in direction” | senses[1] |
| sense | initial population composition - not measured but INFERRED from the composition of the parents, while the control sample describes something else— “On the other hand, it should be kept in mind that the composition of the initial population is inferred from that of its parents, while the Control sample describes the genetic constitution of the eggs being deposited in the cage about a week after the beginning of the experiment.” | senses[2] |
| control | a Control sample whose gene-arrangement frequencies should match the initial population, against which the experimental cages are read — held — rules out drift and sampling as the explanation of a frequency change - the Control sample is the one that should show no change, and it is what makes a change elsewhere readable— “The incidences of the several gene arrangements in the Control sample therefore should be the same as in the initial population.” | controls[0] |
| edge | Standard —is-a→ gene arrangement— “Three gene arrangements are common among the third chromosomes of the San Jacinto populations. One of them, called Standard (abbreviated ST), is most frequent in the populations in winter and in early spring” | concept_edges[0] |
| outcome (stated by the tagger, no quotation) | control — held | controls[0] |
| for which use | limitation — the low-temperature null: THIS DOES NOT IMPLY THAT THERE WERE NO CHANGES BUT MERELY THAT ANY CHANGES WERE TOO SMALL TO BE DETECTED WITH CONFIDENCE IN THE SMALL NUMBER OF INTERVALS— “This does not imply that there were no changes but merely that any changes were too small to be detected with confidence in the small number of intervals in these sets of experiments.” | limitations[0] |
| for which use | limitation — any choice among the selective models: UNFORTUNATELY THE DATA AT HAND DO NOT YIELD A UNIQUE INTERPRETATION— “Unfortunately the data at hand do not yield a unique interpretation.” | limitations[1] |
| for which use | limitation — the correspondence with the wild population: the spring reversal was not reproduced, and THERE ARE IMPORTANT FACTORS YET TO BE DISCOVERED— “It appears that there are important factors yet to be discovered.” | limitations[2] |
| for which use | limitation — the counts of kinds of chromosomes in table 2: they rest on an assumption the authors state is violated in some strains, so the numbers are minima rather than estimates— “it was assumed that every strain con tains one and only one kind of third chromosome with each gene arrangement found in that strain. Since more than a single kind were doubtless present in some of the strains” | limitations[3] |
| for which use | limitation — the control samples as showing the initial composition: the authors note the initial population's composition is inferred from its parents, and offer sampling error as the alternative explanation— “It is possible that these differences were due merely to sampling errors. On the other hand, it should be kept in mind that the composition of the initial population is inferred from that of its parents” | limitations[4] |
| evidence status note | sense — THE QUOTE CONTINUES A SENTENCE THAT THIS COPY CUTS IN TWO - a running head and a stray full stop stand between it and the words it follows, which read 'obviously indicates a selective' and, after the head, 'process,'.— “but even if the average does not differ significantly from zero, a significant regression indicates a selective process which changes in amount or even in direction” | senses[1] |
| replication | untested | |
| limitation | Absence of significant change at the low temperature may reflect too few sampling intervals rather than genuinely constant frequencies.— “This does not imply that there were no changes but merely that any changes were too small to be detected with confidence in the small number of intervals in these sets of experiments.” | limitations[0] |
| limitation | The data cannot discriminate among the possible selective models (constant selective values, sex-differential selection, frequency-dependent values).— “Unfortunately the data at hand do not yield a unique interpretation.” | limitations[1] |
| limitation | The spring reversal seen in nature was not reproduced and its causes remain unknown.— “It appears that there are important factors yet to be discovered.” | limitations[2] |
| limitation | A counting assumption is made, stated to be false in some strains, and the direction of the resulting error is given: the tabulated numbers are minima.— “it was assumed that every strain con tains one and only one kind of third chromosome with each gene arrangement found in that strain. Since more than a single kind were doubtless present in some of the strains” | limitations[3] |
| limitation | The baseline the experiment is compared against is inferred rather than observed, and the authors offer that as one of two explanations for the unexpected control differences.— “It is possible that these differences were due merely to sampling errors. On the other hand, it should be kept in mind that the composition of the initial population is inferred from that of its parents” | limitations[4] |
finding · quantity · variable · definition · key-term — grounded in the full text| finding | In population cages held at 25°C the frequency of the Standard gene arrangement rose highly significantly at the expense of the other arrangements, especially Chiricahua, whereas at 16.5°C mean frequencies did not change significantly.— “At 25°, with initial frequencies equal or with Chiricahua more frequent than Standard, there was a highly significant increase in frequency of Standard (where present) at the expense of either of the other types but especially of Chiricahua. On the other hand, there were no significant changes in mean frequency at 16.5°C.” | content_tags.findings[0] |
| finding | The rate of frequency change per generation regressed negatively on frequency, meaning each chromosome type gained when it was rare and lost when it became common.— “The rate of change at 25° showed a strong negative regression on frequency in all cases, and a probably significant regression of this sort was observed in one case (Arrowhead) at 16.5°. The data further indicate that all chromosome types are favored when sufficiently rare and opposed when sufficiently common.” | content_tags.findings[1] |
| finding | For cages containing only Standard and Chiricahua at 25°C, relative selective values of 0.70 for ST/ST, 1.00 for ST/CH and 0.30 for CH/CH reproduce the observed changes and put equilibrium at 70 percent Standard.— “The results in the experiments at 25°)n which only Standard and Chiricahua were present can be adequately explained by postulating the relative selective values .7o: 1.oo: .30 for ST/ST, ST/CH and CH/CH, respectively. Equilibrium is indicated at 70 percent Standard, 30 percent Chiricahua.” | content_tags.findings[2] |
| finding | With all three chromosome types present, least-squares selective values (0.43 ST/ST, 0.05 AR/AR, 0.21 CH/CH, 1.30 ST/AR, 1.00 ST/CH, 0.71 AR/CH) place equilibrium at 53 percent Standard, 34 percent Arrowhead and 13 percent Chiricahua, and the assumption that the three heterozygotes are equally fit yields impossible values.— “The selective. values at 25°, indicated by the method of least squares, are ·43 for ST/ST, .05 for AR/AR, .2r for CH/CH, 1.30 for ST/AR, r.oo for ST/CH, and ·7I for AR/CH. E<I,uilibrium is indicated at 53 percent Standard, 34 percent Arrowhead and 13 percent Chiricahua. The hypothesis that all three heterozygotes are equal in selective… | content_tags.findings[3] |
| finding | The data cannot discriminate equal selection in the two sexes from very unequal selection: values of 1.00:1.00:0.60 in females with 0.40:1.00:0 in males fit the observations as well as the sex-averaged values.— “Thus the data can be fitted sub stantially as well by assuming selective values I.oo: I.oo: .6o for females, .40: I.oo:o for males (for ST/ST, ST/CH, and CH/CH, respectively) as under the previous hypothesis in which both sexes are selected according to the averages of those figures.” | content_tags.findings[4] |
| finding | Because the cages at 25°C and 16.5°C were stocked with sibs, the presence of change at the high temperature and its absence at the low temperature can be attributed to temperature alone.— “It may be noted that the initial popula tions of cages Nos. 6 to 9 consisted of sibs. The difference in the results can be ascribed only to temperature.” | content_tags.findings[5] |
| finding | Varying the food regime (two jars every three days versus one jar every five days) produced no consistent difference in the direction or size of the frequency changes.— “No consistent differences in the trends which could be ascribed to the different food regimes became apparent in the two experiments.” | content_tags.findings[6] |
| finding | In the 14th experiment Standard rose from 31 to 55 percent while Arrowhead fell from 69 to 45 percent.— “In the 14th experiment (table 7) ST increased in frequency from 31 percent to 55 percent, while AR correspondingly dwindled from 69 percent to 45 percent.” | content_tags.findings[7] |
| finding | The spring reversal seen in nature, in which Standard falls and Chiricahua rises, could not be reproduced in any population cage.— “The changes which occur in nature during spring (the reverse of those in summer) however, have not been reproduced in the popula tion cages.” | content_tags.findings[8] |
| finding | Measured fly dispersal rates are far too slow for migration from Keen Camp to explain the seasonal shift at Andreas Canyon 16 kilometres away.— “Since Andreas is about r6 kilometers from Keen down the mountain, it is obvious that random dispersal from Keen at the observed rate is wholly inadequate to account for the rapid shift at Andreas to a Keen-like composition of the population.” | content_tags.findings[9] |
| quantity | s=.3o, t=.7o, q=.7o — Fitted selective disadvantage of ST/ST (0.30) and of CH/CH (0.70) relative to the heterozygote, and the resulting equilibrium frequency of Standard (0.70)— “The values, s=.3o, t=.7o, q=.7o, are as accurate as the data warrant.” | content_tags.quantities[0] |
| quantity | 53 percent Standard, 34 percent Arrowhead and 13 percent Chiricahua — Equilibrium frequencies computed for the three-chromosome experiments at 25°C— “E<I,uilibrium is indicated at 53 percent Standard, 34 percent Arrowhead and 13 percent Chiricahua.” | content_tags.quantities[1] |
| quantity | 124 ... 157 ... II3 ... average of 131 — Estimates of the effective number of breeding parents in a cage derived from the excess variance of frequency change, from Standard, Arrowhead and Chiricahua data respectively— “The estimate came out 124 from the data on Standard, 157 from that on Arrowhead, and II3 from that on Chiricahua, with an average of 131.” | content_tags.quantities[2] |
| quantity | 300 chromosomes — Number of third chromosomes scored per monthly sample from each cage, split into six subsamples | content_tags.quantities[3] |
| quantity | 3·5 weeks ... 5.2 weeks — Assumed generation interval used to convert observed frequency changes into rates per generation, at 25° and at 16.5° respectively | content_tags.quantities[4] |
| quantity | 3ooo-sooo flies per cage — Steady-state size of the experimental cage population at room temperature with one fresh food jar every other day | content_tags.quantities[5] |
| quantity | 71 percent to 42 percent — Fall in Chiricahua frequency in the 13th experiment, while Standard doubled | content_tags.quantities[6] |
| variable | temperature factor (independent) | content_tags.variables[0] |
| variable | food regime (independent) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[1] |
| variable | gene arrangement (independent) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[2] |
| variable | frequencies of chromosomes (dependent) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[3] |
| variable | gene content (control) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[4] |
| definition | selective disadvantage Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[0] |
| definition | ten-day period Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[1] |
| concept | gene arrangement Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[0] |
| concept | Standard Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[1] |
| concept | population cage Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[2] |
| chi-squared x2 | as written: x2's were computed to measure the homogeneity of the subsamples Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[0] |
| t-test (Student's) t | as written: using Students' probabilities for small numbers Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[1] |
| regression b | as written: the regression of rate of change on chromosome frequency Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[2] |
| F-test F | as written: Fisher's test Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[3] |
| least squares | as written: the method of least squares Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[4] |
| p-value | as written: probability between .01 and .02 Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[5] |
| variance | as written: The estimated variance of .:lq for given q Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[6] |
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