Population size and selection intensity effects on short-term response for a selection index in Tribolium
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. © 1997 Blackwell Wissenschafts-Verlag, Berlin.
| Main Authors: | , |
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| Format: | journal article biblioteca |
| Language: | English |
| Published: |
Wiley
1997
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| Online Access: | http://hdl.handle.net/20.500.12792/5678 http://hdl.handle.net/10261/295109 |
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