Dynamics of allozyme heterozygosity in Siberian dwarf pine Pinus pumila (Pall.) Regel populations of the Russian Far East: Comparison of embryos and maternal plants

Политов, Д. В.; Belokon, M. M.; Belokon, Yu. S.

doi:10.1134/s102279540610005x

Cited by 13 publications

(9 citation statements)

References 30 publications

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“…In accordance with the results from other studies on stone pines (Krutovskii et al 1995;Politov and Krutovskii 2004;Politov et al 2006Politov et al , 2008Bower and Aitken 2007), we found significantly positive estimates of selfing rates in part of the progeny arrays, but no signs of inbreeding in adult samples. A decrease in heterozygote deficiency with increasing age is considered as an indicator for selection against inbreds during successive life stages in trees (Morgante et al 1993;Krutovskii et al 1995;Mitton et al 1997).…”

Section: Discussionsupporting

confidence: 82%

Reduced fitness at early life stages in peripheral versus core populations of Swiss stone pine (Pinus cembra) is not reflected by levels of inbreeding in seed families

Salzer

Gugerli

2012

Alp Botany

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Small and fragmented populations are prone to mating among related individuals, increasing homozygosity and likely negatively affecting offspring fitness. Such a trend may be enforced by environmental changes in species with narrow ecological niches because inbred populations are more prone to become maladapted as compared to outcrossed populations. Here, we studied differences in offspring fitness and inbreeding levels between core and peripheral populations of Swiss stone pine (Pinus cembra). We collected open-pollinated progenies of P. cembra in large, contiguous and in small, isolated populations (core vs. periphery). Seeds were germinated and grown in a common garden to test for differences in fitness parameters, whereas subsamples of seed lots were genotyped at seven nuclear microsatellites to calculate selfing rates. We found significantly lower seed production, higher embryo abortion rates and lower germination success in small peripheral compared to large core populations of P. cembra. In contrast, winter survival and first-year growth of seedlings did not significantly differ between the two population types. These results indicate higher inbreeding depression at the earliest life stages in small and fragmented populations compared to populations from the contiguous range of P. cembra. However, we found no correlation between any fitness parameters and progenyderived selfing rates. We explain this discrepancy by the fact that inbreeding depression mostly affects embryo abortion rates in Pinaceae. This cannot be genetically quantified because non-developed embryos cannot be genotyped. We infer that population fragmentation in the long term negatively affects natural regeneration in this long-lived, wind-pollinated conifer species.

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Section: Discussionsupporting

confidence: 82%

Reduced fitness at early life stages in peripheral versus core populations of Swiss stone pine (Pinus cembra) is not reflected by levels of inbreeding in seed families

Salzer

Gugerli

2012

Alp Botany

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“…It is common in conifers for populations of mature trees to show a heterozygote excess while seeds have a heterozygote deficiency (Plessas and Strauss 1986;Muona et al 1987;Starova et al 1990;Morgante et al 1993;Ledig et al 2002). This phenomenon has been reported for a number of other pines, including the four other stone pine species (Politov et al 1992;Krutovskii et al 1995;Politov et al 2006). The heterozygote deficiency in seeds is most likely due to inbreeding, and its disappearance by maturity suggests that there is selection against inbreds during the life cycle of the tree (Krutovskii et al 1995).…”

Section: Outcrossing Rate and Inbreeding Coefficientsmentioning

confidence: 85%

Mating system and inbreeding depression in whitebark pine (Pinus albicaulis Engelm.)

Bower

Aitken

2007

Tree Genetics & Genomes

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Mating system and inbreeding depression in quantitative traits of whitebark pine (Pinus albicaulis Engelm.) was determined using isozymes and a seedling common garden experiment. Simultaneous isozyme analysis of embryo and haploid megagametophyes from progeny arrays of families in three distinct geographic regions (Oregon, Montana, and southern British Columbia) was used to estimate parental and progeny inbreeding coefficients, as well as regional and family mean multilocus outcrossing rates (t m ). Quantitative trait family means of seedlings from the same families growing in two temperature treatments in a common garden experiment were regressed on the estimated inbreeding coefficient to determine the presence and magnitude of inbreeding depression. Regional estimates of t m ranged from 0.73 to 0.93, with a mean over all regions of 0.86. Family mean t m values indicated predominant outcrossing; however, some individuals experienced substantial inbreeding. The Oregon region had a significant excess of heterozygotes in the parental generation relative to Hardy-Weinberg equilibrium, while both the Oregon and southern BC regions had a heterozygote deficiency in progeny, suggesting selection against inbred individuals. Biomass in the ambient temperature treatment for the southern BC region was the only trait significantly related to inbreeding coefficient. The mean inbreeding coefficient for this region was 0.25, and based on this relationship, mean predicted biomass would be reduced by 19.6% in this region if inbred individuals are not removed by selection. The estimated outcrossing rate of whitebark pine is slightly lower than most wind-pollinated conifers, and while most individuals are highly outcrossing, some experience substantial inbreeding.

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“…In conifers, low heterozygosity and a high excess of homozygosity at the early ontogenic stages is a relatively common phenomenon resulting from the mixed mating system. Inbreeding is commonly attributed to self-pollination and, in the case of the family structure of forest stands, to crossing between close relatives (Politov et al 2006). Korshikov et al (2007) reported an excess of homozygous genotypes in the genetic structure of the embryo population of Abies alba Mill., Pinus pallasiana Lamb.…”

Section: Discussionmentioning

confidence: 99%

Genetic aspects of age dynamics of a natural Picea abies (L.) Karst. population in the Białowieża Primeval Forest, Poland

et al. 2013

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We studied temporal changes in the genetic structure and diversity of a naturally regenerated Picea abies (L.) Karst. (Norway spruce) population in the Białowie_ za Primeval Forest, Poland. The analysis included five age classes of trees: newly germinating seedlings (in laboratory conditions), seedlings up to 3 years old, young trees 4-10 years old, middle-aged trees 11-100 years old, and trees older than 100 years. We conducted genetic analyses of 26 allozyme loci using dormant buds from 405 individuals and 100 embryos. The results showed that the naturally regenerating Norway spruce population is genetically heterogeneous across the studied age classes. As determined by Chi squared tests, there were statistically significant differences in frequencies of alleles and genotypes as well as Wright's index values (F) among the five age classes. The level of genetic differentiation (pairwise F ST = 0.5-2.3 %) among the age class groups was equal to levels previously determined for various populations of this species. The Ewens-Watterson test for neutrality showed that one or two loci across different age classes of Norway spruce were affected by the selection process. The distinctiveness of embryo and seedling classes was confirmed by the number of detected alleles, the number of private alleles, the level of observed heterozygosity, and Wright's index value. The results obtained in the present study indicate there are interesting dynamics of adaptation processes occurring in the natural age-diverse population of Norway spruce in the Białowie_ za Primeval Forest.

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Dynamics of allozyme heterozygosity in Siberian dwarf pine Pinus pumila (Pall.) Regel populations of the Russian Far East: Comparison of embryos and maternal plants

Cited by 13 publications

References 30 publications

Reduced fitness at early life stages in peripheral versus core populations of Swiss stone pine (Pinus cembra) is not reflected by levels of inbreeding in seed families

Reduced fitness at early life stages in peripheral versus core populations of Swiss stone pine (Pinus cembra) is not reflected by levels of inbreeding in seed families

Mating system and inbreeding depression in whitebark pine (Pinus albicaulis Engelm.)

Genetic aspects of age dynamics of a natural Picea abies (L.) Karst. population in the Białowieża Primeval Forest, Poland

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