Positive assortative mating (PAM) may substantially enhance genetic variance in a breeding population (BP). This creates potential for additional genetic gains available through production populations (PP) to forest plantations. Open-nucleus strategies (NB) have been incorporated in forest tree breeding programs. In NB, the BP is subdivided into two hierarchical levels, a nucleus and a main population, and can be considered a less rigorous form of PAM. First, PAM was compared to NB by stochastic simulation considering jointly genetic gain and diversity within the framework of a long-term breeding program. Test effort was either assumed constant throughout the entire BP or was redirected according to the rank of each mate. The simulation revealed that PAM results in larger gains in the PP compared to NB under both situations and at any target PP diversity. Second, the test effort during PAM was redirected by varying family sizes as a linear function of mid-parent BLUP values. The actual distribution of mid-parent BLUP values was standardized by a constant value, which was varied in simulation scenarios to cover the entire range of the distribution of family sizes. When equal numbers of progenies were selected per family and the variation in family sizes was maximized, only a minimal reduction in BP diversity was observed, compared to cases with constant family sizes. Under such favorable conditions, the redistribution of resources increased genetic response and variance in the BP, causing substantially greater genetic response in the PP. These conclusions were verified under a mixed-inheritance model with a major-gene locus contributing to variation in a quantitative trait. Finally, the investigation of PAM was extended by considering correlated traits within the framework of a clonal forestry program. The success of somatic embryogenesis in families generated by crossing elite genotypes developed in the breeding program was either considered exponentially distributed or constant. The distribution of success caused non-significant differences in genetic gain of PP. These conclusions were verified over a range of correlation, heritabilities and economic weights of traits.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-03142005-083542 |
| Date | 14 March 2005 |
| Creators | Lstibůrek, Milan |
| Contributors | Dr. Timothy J. Mullin, Dr. Dag Lindgren, Dr. Trudy F. C. Mackay, Dr. Bailian Li |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-03142005-083542/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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