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|Title:||Response to Selection for Pupal Weight With and Without Assortative Mating in Tribolium Castaneum|
|Author(s):||Mwenya, Wilson Nelson Mulenga|
|Department / Program:||Animal Science|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Joint effects of pre-selection mating system (random: R; assortative: A), selection mating system (R;A) and percent truncation selected (20%; 50%; 0% (control)) were studied in a 2 x 2 x 3 factorial experiment with 5 replicates to examine direct response to selection for pupal weight (PW), and correlated responses for larval weight (LW) and pupation time (PT) in Tribolium castaneum. Prior to selection two groups, each with 50 males mated to 100 females were either R-mated or A-mated for 3 generations. At generation 3, 6 lines were formed in each group, one for each selection mating system-selection intensity combination, and selection began. Each line was maintained during 2 generations of selection by 10 pair-matings.
Half-sib (R-mated group) and minimum chi-square estimates of heritability (A-mated group) were, respectively, for PW: .26 (+OR-) .12 and .39 (+OR-) .02; LW: .36 (+OR-) .13 and .49 (+OR-) .04; and PT: .29 (+OR-) .08 and .25 (+OR-) .03.
Estimates of realized heritability of PW, calculated as the ratio of total response (deviated from the control lines) to cumulative selection differential, were: (UNFORMATTED TABLE FOLLOWS)
Pre-selection x selection mating system
Selected RR RA AR AA
20% .30 (+OR-) .04 .31 (+OR-) .11 .29 (+OR-) .07 .39 (+OR-) .04
50% .12 (+OR-) .04 .19 (+OR-) .16 .23 (+OR-) .08 .30 (+OR-) .05(TABLE ENDS)
Realized heritability of PW was increased by pre-selection assortative mating (P < 0.10), and by more intense selection (P < 0.05); the mating system during selection did not affect realized heritability. There were no clear correlated responses to selection for PW.
The experiment indicated the following: (1) assortative mating of parents for a few generations prior to selection enhanced direct short-term response to selection compared to random mating of parents; (2) assortative mating during selection did not significantly increase realized heritability, irrespective of selection intensity; (3) pre-selection assortative mating would not enhance short-term response per unit time (generation) of preselection and selection compared to selection from the onset; and (4) applying low selection intensity for the purpose of not constraining the effectiveness of assortative mating was not useful. The effects of assortative mating on long-term direct and correlated responses to selection need to be investigated.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
|Date Available in IDEALS:||2014-12-15|