The effect of different selection intensities on selection response in egg-laying of<i>Tribolium castaneum</i>

Ruano, R. G.; Orozco, Fernando; López-Fanjul, Carlos

doi:10.1017/s0016672300015391

Cited by 12 publications

(6 citation statements)

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“…S ilvela et al (1989) also indicated that total response to selection increased with larger selection intensities; when the population size was small, total response in lines with 5% selection intensity was almost twice that in lines with 17% selection intensity; the same was true with the high population size. In addition, these results agree with those of R uano et al (1975), showing that the 5% and 10% selection intensities had a larger response in the initial generations than the 20%, 33%, and 50% selection intensities.…”

Section: Discussionsupporting

confidence: 88%

“…C layton et al (1957) and F rankham (1977) considered individual selection for abdominal bristle score in Drosophila the first experiment studied three different intensities (20, 27, 40, or 80%) with the same number of parents (20), whereas the second experiment compared three selection intensities (10, 20, or 40%). R uano et al (1975) analysed the effect of five different intensities (5, 10, 20, 33, or 50%) on selection response in egg laying in Tribolium. In general, the lines selected at the lowest proportions led to the largest initial responses.…”

Section: Introductionmentioning

confidence: 99%

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Population size and selection intensity effects on short‐term response for a selection index in Tribolium

Campo

Turrado

1997

J Animal Breeding Genetics

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The effects of population size and selection intensity on the short-term response to selection were investigated in an experiment with Tribolium, using a two-trait empirical selection index for pupal and adult weights. Twenty lines were selected following a factorial design of five population sizes (1, 2, 4, 8, and 16 pairs of parents) and four selection intensities (20, 25, 33, and 50%), with three replicates. For each replicate, an unselected control with 16 pairs of parents was produced. There were four generations of selection per line. Selection response was significant in all lines with the 20% selection intensity and/or the 16-pair population size. Selection intensity and population size were significant effects and there was significant interaction between them. Higher selection intensities produced more overall significant response to selection (20% > (25% = 33%) > 50%); this significance was also found for the 16-pair population size. There was an overall significant difference among population sizes, with the larger population sizes giving more response than the smaller sizes (16-pair = 8-pair = 4-pair) > (2-pair = 1-pair); this significance was also found for the 20% selection intensity. There was a good agreement between observed and expected responses, except for the 50% selection intensity and/or 1-pair population size; expected values in generation 1 overestimated observed values. The realized heritability was similar in all lines. With equal and high numbers of individuals scored, it was better to choose a high selection intensity than a large population size. The results show that the effect of population size cannot be ignored, even in short-term selection response; the main influence of population size is through selection differential. RESUMEN: Los efectos del tamaño de población y la intensidad de selección sobre la respuesta a corto plazo para un índice de selección en Tribolium Los efectos del tamaño de población y la intensidad de selección sobre la respuesta a la selección a corto plazo fueron estudiados en un experimento con Tribolium usando un índice empírico de selección para dos caracteres (peso de pupa y peso adulto). Se seleccionaron 20 líneas siguiendo un modelo factorial de cinco tamaños de población (1, 2, 4, 8 y 16 pares de padres) y cuatro intensidades de selección (20, 25, 33 y 50%), con tres repeticiones. En cada repetición, había una línea control sin seleccionar con 16 pares de padres. Se hicieron cuatro generaciones de selección, por línea. La respuesta a la selección fue significativa en todas las líneas con el 20% de intensidad de selección y/o 16 pares de padres. Tanto la intensidad de selección como el tamaño de población fueron efectos significativos y hubo interacción significativa entre ellos. Las intensidades de selección más altas produjeron significativamente más respuesta en general (20% > (25% = 33%) > 50%), y esta significación se mantenía cuando el tamaño de población era de 16 pares de padres. Hubo diferencias significativas entre tamaños de población, dand...

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Population size and selection intensity effects on short‐term response for a selection index in Tribolium

Campo

Turrado

1997

J Animal Breeding Genetics

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“…Similar regular patterns were observed in a Tribolium egg production selection experiment (i.e. a character closely related to fitness) initiated from a cage population (Ruano, Orozco & Lopez-Fanjul, 1975) and in a selection experiment of cannon-bone length in Scottish blackface sheep (Atkins & Thompson, 1986). In the latter case, Atkins & Thompson showed that the response closely matched the predicted response of an 'infinitesimal model' which incorporated the effect of disequilibrium on the additive variance (Bulmer, 1980 ch.…”

Section: (I) Mutation-stabilizing Selection Balancementioning

confidence: 55%

Quantitative genetic variability maintained by mutation-stabilizing selection balance: sampling variation and response to subsequent directional selection

Keightley

Hill

1989

Genet. Res.

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A model of genetic variation of a quantitative character subject to the simultaneous effects of mutation, selection and drift is investigated. Predictions are obtained for the variance of the genetic variance among independent lines at equilibrium with stabilizing selection. These indicate that the coefficient of variation of the genetic variance among lines is relatively insensitive to the strength of stabilizing selection on the character. The effects on the genetic variance of a change of mode of selection from stabilizing to directional selection are investigated. This is intended to model directional selection of a character in a sample of individuals from a natural or longestablished cage population. The pattern of change of variance from directional selection is strongly influenced by the strengths of selection at individual loci in relation to effective population size before and after the change of regime. Patterns of change of variance and selection responses from Monte Carlo simulation are compared to selection responses observed in experiments. These indicate that changes in variance with directional selection are not very different from those due to drift alone in the experiments, and do not necessarily give information on the presence of stabilizing selection or its strength.

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“…Both mean and variances of virgin female egg laying were higher at 33°C. Orozco and Bell (l974a); (c) Ruano, Orozco and López-Fanjul (1975); (d) Orozco (1976b).…”

Section: Results (I) the Base Populationmentioning

confidence: 99%

The genetic properties of egg laying of virgin females of Tribolium castaneum

López-Fanjul

Jódar

1977

Heredity

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SUMMARYInbreeding was established by brother-sister matings and it was carried out for seven generations in the Consejo population of Tribolium casianeum. From 105 inbred lines at the start, 53 lines reached the end of the experiment. Losses of lines were independent of the level of inbreeding.The trait studied was 4-day egg laying of virgin females. It has been shown that this trait did not present either inbreeding depression or hybrid vigour. The phenotypic variance and its between-and within-line components also behaved as expected under the additive model as inbreeding progressed. Estimation of genetic parameters in the base population confirmed that egg laying of virgin females is an essentially additive trait.Other traits-2-day egg laying of fecundated females, precocity and percentage viability-showed a smaller heritability than egg laying of virgin females and considerable inbreeding depression. No connection was found between virgin female egg laying and percentage viability.The suggestion is made that egg laying of virgin females in the Consejo population can be considered a peripheral trait with respect to fitness.,

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The effect of different selection intensities on selection response in egg-laying ofTribolium castaneum

Cited by 12 publications

References 10 publications

Population size and selection intensity effects on short‐term response for a selection index in Tribolium

Population size and selection intensity effects on short‐term response for a selection index in Tribolium

Quantitative genetic variability maintained by mutation-stabilizing selection balance: sampling variation and response to subsequent directional selection

The genetic properties of egg laying of virgin females of Tribolium castaneum

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