Abstract

The effects of inbreeding on growth, survival and variance in a 12-year-old radiata pine trial were studied in five populations each inbred to one of five different levels: outcross (F = 0), half-sib (F = 0.125), full-sib (F = 0.25), selfing (S-1, F = 0.5), and two-generations of selfing (S-2, F = 0.75). These five populations were derived from a founder population of eight clones. Inbreeding reduced diameter, growth, and survival but increased the variance for diameter. Inbreeding depression at F = 0.125, 0.25, 0.5, and 0.75 was 5%, 6%, 15%, and 19% respectively for DBH; -3%, 1%, 7%, and 11% respectively, for survival. The standard deviation for diameter increased by 10%, 10%, 30%, and 25% respectively for F = 0.125, 0.25, 0.5, and 0.75 and, similarly, the coefficient of variation increased by 17%, 16%, 53%, and 55% respectively. There were significant differences among the eight rounder clones in their response to inbreeding. The best clone in the trial showed no inbreeding depression. Overall, inbreeding depression was found to be linearly related to the inbreeding coefficient F with no significant quadratic effects for ally trait at any population level. However, two individual clones had a quadratic relationship with F for DBH and one clone had a similar relationship for survival. A significant correlation (r = 0.96) between S-2 and the breeding values of founder clones was observed while the correlation (r = 0.58) between S-1 and breeding values was insignificant. The low inbreeding depression in radiata pine relative to other conifers may indicate that historical purging of detrimental alleles through small geographic populations, a higher degree of population subdivision, and the relative high fecundity of inbred progenies has rendered radiata pine an ideal species to use inbreeding as a breeding tool.

Keywords

Pinus radiata; inbreeding depression; growth; variance; survival; purging

Published in

TAG Theoretical and Applied Genetics
1998, Volume: 97, number: 8, pages: 1256-1268
Publisher: SPRINGER

UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1007/s001220051018

Permanent link to this page (URI)

https://res.slu.se/id/publ/118911