The Effects of Multilocus Heterozygosity on the Longevity of Seedlings Established on Fallen Logs in <i>Picea jezoensis</i> and <i>Abies sachalinensis</i>

Abstract

Seedling establishment on fallen logs is a major regeneration system for tree species in boreal forests. Seedling survival on fallen logs is affected not only by the microsite environment but also by the genetic factors of individuals. To quantify the genetic effects on seedling longevity, we identified seedlings using a number tag system and collected needles of Picea jezoensis and Abies sachalinensis established on fallen logs in spring 2006. Survival or death of each seedling was investigated during 2006-2012. We genotyped seedlings with microsatellite markers and calculated individual-based multilocus heterozygosity (MLH) for each seedling. A Cox proportional hazards model was applied to evaluate the effects of MLH on seedling longevity of the two species considering the fallen log conditions. The model indicated that MLH positively affected seedling longevity in P. jezoensis, whereas the effects of MLH were not significant in A. sachalinensis. Here, we discuss differences in the effects of MLH on seedling longevity between the two species, considering species characteristics and MLH frequency distribution. Keywords

Distinctions in Fine-Scale Spatial Genetic Structure Between Growth Stages of Picea jezoensis Carr.

“…The decrease in average F is value with life history process might be influenced by inbreeding depression at the growing stages after seedling establishment. Our previous study, based on the same population examined in the present study, indicated that multilocus heterozygosity had an effect on seedling longevity ( Okada et al, 2015 ). Some cross-experiment studies of Picea species have shown that growth in height decreased as the kinship coefficient increased ( Doerksen et al, 2014 ).…”

“…DNA was extracted from dried needle leaf samples from 531 individuals using a DNeasy Plant Mini kit (Qiagen). The following 11 microsatellite loci, GC1, GD1, GG3 ( Pfeiffer et al, 1997 ), PaGB3, PgGB5 ( Besnard et al, 2003 ), EATC1E03, EATC2G05 ( Scotti et al, 2002 ), Pj4, Pj8, Pj22 , and Pj24 ( Okada et al, 2015 ) were analyzed using a Multiplex PCR Kit (Qiagen) together with a 3130xl Genetic Analyzer and GeneMapper ver. 4.0 (Thermo Fisher Scientific Inc.).…”

“…As a matter of course, the survival or death of genetically related individuals may affect the spatial genetic structure of the later life-stages ( Kitamura et al, 2008 ). However, the previous study by Okada et al (2015) did not investigate P. jezoensis FSGS or seed dispersal patterns, which may be expected to strongly reflect a lack of consistent opportunities for regeneration on CWD. Limited seed dispersal and restriction of establishment sites may reduce the effective number of seed parents, which may induce a strong FSGS; however, the genetic or stochastic death of individuals may weaken the FSGS.…”

“…Consequently, a limited number of establishment sites results in the spatially uneven distribution of individuals ( Nakagawa et al, 2003 ). Okada et al (2015) identified P. jezoensis seedlings and saplings established on fallen logs at the same study site as that used by Lian et al (2008) , and they genotyped them using microsatellite markers and monitored survival and death over a 7-year period. They found that individual heterozygosity positively affected seedling longevity in P. jezoensis .…”

Geographical Gradients of Genetic Diversity and Differentiation among the Southernmost Marginal Populations of Abies sachalinensis Revealed by EST-SSR Polymorphism

“…Not only allele frequencies but also the heterozygosity of an individual is often associated with fitness among a changing environment (e.g., [40]). Correlations have been reported between growth rate and heterozygosity in Populus tremuloides [41] and survivorship and heterozygosity in Picea jezoensis [42]. It has been observed that the heterozygosity of a population influences its productivity, fitness, and stability [40,43,44].…”