COMPONENTS OF GROWTH IN GENETICALLY DIVERSE POPULATIONS OF TRIBOLIUM CASTANEUM

1969 ◽  
Vol 11 (4) ◽  
pp. 896-907 ◽  
Author(s):  
DuWayne C. Englert ◽  
A. E. Bell
Keyword(s):  
Tribolium Castaneum ◽  
Adult Emergence ◽  
Pupal Weight ◽  
Diverse Populations ◽  
Correlated Responses ◽  
Larval Weight ◽  
Developmental Patterns ◽  
Adult Weight ◽  
Total Growth ◽  
Selection For

The growth and developmental patterns of 19 genetically diverse populations of Tribolium castaneum were examined. Measurements were obtained on three primary traits (13-day larval weight, pupation time and pupal weight) and three secondary traits (number of larval molts, adult emergence time and adult weight). The populations were chosen on the basis of their previous selection histories. Selection for different primary traits produced profound effects upon the total growth and development complex.Genetic and environmental relationships between primary traits were estimated within each population, and a consistent asymmetry of correlated responses was observed to be determined by the direction of selection.Possible effects upon the disruption of an intricate balance of the three metamorphosis hormones (activation, molting and juvenile) through selection were postulated.

scholarly journals Simultaneous selection for two correlated traits in Tribolium

1973 ◽  
Vol 21 (1) ◽  
pp. 29-46 ◽  
Author(s):  
A. E. Bell ◽  
Martin J. Burris
Keyword(s):  
Genetic Correlations ◽  
Adult Emergence ◽  
Pupal Weight ◽  
Correlated Traits ◽  
Developmental Patterns ◽  
Adult Weight ◽  
Population Means ◽  
Simultaneous Selection ◽  
Selected Traits ◽  
Larval Number

SUMMARYSimultaneous selection by independent culling levels of two correlated traits in all four combinations of directions was investigated with Tribolium in a replicated experiment extending over nine generations. In addition to the two primary traits, 13-day larval weight and pupal weight, four secondary traits (pupation time, adult emergence time, adult weight and larval number) were observed.The observed responses for both selected and unselected traits agreed with theoretical expectations after the latter were adjusted for changes which occurred in genetic and phenotypic parameters. Phenotypio variances for the selected traits were correlated positively with population means, yet genetic variances and heritabilities declined in all selected populations. No change was detected in the genetic correlation between selected traits even though the divergent two-trait selection was designed especially to ‘break’ the positive correlation of + 0·55 ± 0·12 present in the base population.Striking changes in growth and developmental patterns resulting from the divergent selection were discussed in terms of metamorphic limits and ‘stabilizing’ genetic correlations.

EXPERIMENTAL INVESTIGATION OF ERRORS OF HERITABILITY ESTIMATES IN INDEX SELECTION

1979 ◽  
Vol 21 (3) ◽  
pp. 303-308 ◽  
Author(s):  
C. Y. Lin ◽  
I. Pevzner ◽  
G. W. Friars
Keyword(s):  
Experimental Investigation ◽  
Parameter Estimation ◽  
Tribolium Castaneum ◽  
Genetic Change ◽  
Pupal Weight ◽  
Index Selection ◽  
Selection Efficiency ◽  
Larval Weight ◽  
Estimation Errors ◽  
Selection For

Three generations of index selection for the combined genetic gain in 13-day larval and 21-day pupal weight were carried out in each of three replicates in Tribolium castaneum. Five indexes were constructed using differing levels of heritability for larval weight (0.9, 0.7, 0.5, 0.3 and 0.1). The effect of parameter estimation errors, involving larval weight, on the efficiency of index selection was thus evaluated experimentally. The results from this experiment confirmed the theoretical expectations that errors of parameter estimation would affect the efficiency of index selection. The present study further showed that the overestimation of the parameters would affect the selection efficiency more than the underestimation. The combined gain was found to be realized mainly through genetic change in pupal weight, a trait with lower heritability.

Experimental comparison of restricted selection index and restricted independent culling levels in Tribolium castaneum

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 91-96 ◽  
Author(s):  
J. L. Campo ◽  
B. Villanueva
Keyword(s):  
Tribolium Castaneum ◽  
Selection Index ◽  
Egg Laying ◽  
Experimental Comparison ◽  
Pupal Weight ◽  
Selection Methods ◽  
Adult Weight ◽  
Antagonistic Selection ◽  
Independent Culling ◽  
Restricted Selection

A selection index (I) method was compared with independent culling levels (N), with a restriction in the selection program, using two replicated single generation experiments in Tribolium castaneum, which are considered forms of antagonistic selection. The first experiment was designed to increase adult weight without changing pupal weight, while the second experiment was intended to improve egg laying without changing adult weight. In both experiments the genetic correlation between the traits involved were positive but were higher in experiment 1 than in experiment 2. The proportion of selection was 10%. In experiment 1, the effect of restriction was as expected in both lines since the changes in pupal weight were not significant. Adult weight change was positive for the I line and negative for the N line, showing that the index was a superior method to improve adult weight. In experiment 2, the effect of restriction was also as expected in both lines and changes in adult weight were not significant. Egg laying changed positively in both lines. Therefore, both selection methods were similar in this experiment, even though egg laying change was higher in the I than the N line. Key words: restricted index, restricted culling levels, antagonistic selection, Tribolium.

Realized genetic parameters from an antagonistic selection index in Tribolium castaneum

1986 ◽  
Vol 28 (3) ◽  
pp. 358-364 ◽  
Author(s):  
J. L. Campo ◽  
L. G. Raya
Keyword(s):  
Genetic Correlation ◽  
Tribolium Castaneum ◽  
Selection Index ◽  
Selection Response ◽  
Pupal Weight ◽  
Base Population ◽  
Adult Weight ◽  
Antagonistic Selection ◽  
Individual Trait ◽  
Highly Correlated

Simultaneous selection of two highly correlated traits was practiced in Tribolium castaneum in a replicated experiment for six generations. Two lines were selected in each of three replicates: P+A− for an antagonistic selection index to increase pupal weight at 21 days and decrease adult weight at 31 days, and P−A+ for an antagonistic selection index to decrease pupal weight and increase adult weight. Genetic correlation between pupal and adult weights estimated in the base population was 0.95. Estimates of realized heritabilities and genetic correlation were obtained and compared with full-sib estimates. For the aggregate genotype, the P+A− line had a significant positive selection response, while the P−A+ line showed a significant negative response as would be expected. The response to divergent selection was asymmetrical, being less for the low pupal weight and high adult weight line than vice versa. Less asymmetry was found for the realized heritability, which agreed very well with the index heritability estimated in the base population. Both individual traits changed in the same direction, increasing for the P+A− line and decreasing for P−A+ line, even though a significant response was found only for pupal weight in the P+A− line. Therefore, the response to antagonistic selection for each individual trait seems to be heavily controlled by the strength of the genetic correlation between them. The realized genetic correlation between pupal weight and adult weight obtained from antagonistic selection index was in excellent agreement with full-sib estimates. Realized heritabilities for each trait were overestimated, especially for adult weight, even though there were essentially no differences between realized and estimated values.Key words: selection (artificial), antagonistic index, parameters (realized), Tribolium.

scholarly journals Correlated responses to selection on body size in Drosophila melanogaster

1999 ◽  
Vol 74 (1) ◽  
pp. 43-54 ◽  
Author(s):  
LINDA PARTRIDGE ◽  
ROSALIE LANGELAN ◽  
KEVIN FOWLER ◽  
BAS ZWAAN ◽  
VERNON FRENCH
Keyword(s):  
Growth Rate ◽  
Drosophila Melanogaster ◽  
Body Size ◽  
Larval Development ◽  
Growth Period ◽  
Cell Number ◽  
Correlated Responses ◽  
Larval Weight ◽  
Thorax Length ◽  
Selection For

Correlated responses to artificial selection on body size in Drosophila melanogaster were investigated, to determine how the changes in size were produced during development. Selection for increased thorax length was associated with an increase in larval development time, an extended growth period, no change in growth rate, and an increased critical larval weight for pupariation. Selection for reduced thorax length was associated with reduced growth rate, no change in duration of larval development and a reduced critical larval weight for pupariation. In both lines selected for thorax length and lines selected for wing area, total body size changed in the same direction as the artificially selected trait. In large selection lines of both types, the increase in size was achieved almost entirely by an increase in cell number, while in the small lines the decrease in size was achieved predominantly by reduced cell size, and also by a reduction in cell number. The implications of the results for evolutionary-genetic change in body size in nature are discussed.

scholarly journals Two-way selection for body weight in Tribolium on two levels of nutrition

1967 ◽  
Vol 9 (3) ◽  
pp. 309-330 ◽  
Author(s):  
R. T. Hardin ◽  
A. E. Bell
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Minimum Size ◽  
Direct Selection ◽  
Correlated Responses ◽  
Larval Weight ◽  
Large Size ◽  
Selection For ◽  
Selection Differentials

Parameters necessary for predicting direct and correlated responses for large and small 13-day larval weight in T. castaneum on two levels of nutrition were estimated in the base population. Larval weight in the GOOD environment was approximately twice that observed in POOR. Heritabilities (estimated from the ratio of sire component to total phenotype variance) of larval weight on the two rations were similar, 0·21 ± 0·06 and 0·19 ± 0·05 for GOOD and POOR, respectively. Heritabilities based on dam-offspring covariances were similar to these, but those obtained from full-sib covariances were much larger (0·97 ± 0·07 for GOOD and 0·69 ± 0·07 for POOR). This suggested that considerable dominance rather than maternal effects were present. The genetic correlation between growth on GOOD and growth on POOR was estimated as + 0·60 ± 0·21.The selection experiment was replicated four times with each replication extending over eight generations. Good agreement between predicted and observed values for direct selection was observed for large selection in both environments and small selection in POOR. However, response to small selection in GOOD was significantly greater than predicted in all four replications and was associated with increased selection differentials. Realized heritabilities were approximately the same for both directions in GOOD yet asymmetrical responses occurred for all replications due to unequal selection differentials. On the other hand, realized heritabilities were asymmetrical in POOR. Those observed for small selection were more than twice the size of those calculated for large lines. However, the responses in POOR were symmetrical since the selection differentials varied inversely with the realized heritabilities.Because of the asymmetry observed for heritabilities and selection differentials, correlated responses were poorly predicted. The average effective genetic correlation between growth in GOOD and growth in the POOR environment agreed remarkably well with the base estimate, yet asymmetry of the genetic correlation was a consistent phenomenon with values for the large lines being less than the base parameter while small lines were uniformly larger.Asymmetries of the various genetic parameters were not anticipated from base estimates. They were not caused by sampling or chance fluctuations since all four replications were remarkably consistent. Asymmetry for any one genetic parameter (e.g. heritability) was associated with a particular environment or direction of selection while other genetic parameters reacted asymmetrically in populations exposed to a different set of environmental treatments.For maximum performance in a single environment, these results show that selection should be practiced in that environment. With regard to mean performance in GOOD and POOR environments, selection for large size in POOR gave some 25% more gain than selection in GOOD. Selection for small size in either environment was equally effective in obtaining minimum size in both environments.

TWO-WAY SELECTION ON PUPAL WEIGHT WITH DIFFERENT DEGREES OF INBREEDING IN TRIBOLIUM CASTANEUM

1974 ◽  
Vol 16 (4) ◽  
pp. 765-775 ◽  
Author(s):  
P. Y. Jui ◽  
G. W. Friars
Keyword(s):  
Tribolium Castaneum ◽  
Linear Response ◽  
Significant Interaction ◽  
Pupal Weight ◽  
Base Population ◽  
Significant Progress ◽  
Selected Lines ◽  
Selection Limit ◽  
Selection For ◽  
Seven Generations

Responses to selection for high and low pupal weight in Tribolium castaneum under four different inbreeding systems and two different relative humidities (40 and 70%) were observed for seven generations. By the seventh generation, the coefficients of inbreeding ranged from 0.79 in the full sib lines to 0.12 in the control lines.Heritability of pupal weight estimated by mid-parent offspring regression from the base population was around 0.30 which is lower than the estimates obtained by Bell (1969). However, realized heritabilities were around 0.50. Significant progress was observed for both upward and downward selection. A linear response in pupal weight was observed for most of the selected lines, suggesting that the selection limit had not been reached.Inbreeding caused a reduction of approximately two offspring per 10% increment in the inbreeding coefficient.Asymmetric responses were noted in conjunction with the significant interaction of the degree of inbreeding and the direction of selection.

The effects of alternated cycles of full-sib and random mating on selection for pupa weight in Tribolium castaneum

1985 ◽  
Vol 27 (2) ◽  
pp. 251-254 ◽  
Author(s):  
Nicole Dion ◽  
Francis Minvielle
Keyword(s):  
Mating System ◽  
Tribolium Castaneum ◽  
Random Mating ◽  
Selection Response ◽  
Inbred Lines ◽  
Pupal Weight ◽  
Realized Heritability ◽  
Differential Selection ◽  
Selection For

Individual responses to selection for high pupal weight in Tribolium castaneum under two types of mating, cyclic full-sib random-mating system and random mating, were observed for 15 generations. No significant differences have been observed between the two types of mating for the selection response, differential selection, realized heritability, and the number of larvae per generation. Realized heritability of the pupal weight was 0.33 ± 0.02 and 0.42 ± 0.02 for the inbred lines and for the random-mated lines, respectively.Key words: inbreeding, pupa weight, Tribolium.

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