Estimation of the Mating System of Eucalyptus obliqua L'hérit. By Using Allozyme Polymorphisms

1975 ◽  
Vol 23 (6) ◽  
pp. 931 ◽  
Author(s):  
AHD Brown ◽  
AC Matheson ◽  
KG Eldridge
Keyword(s):  
Mating System ◽  
Local Variation ◽  
Population Heterogeneity ◽  
Fixation Index ◽  
Viable Seed ◽  
System Parameters ◽  
Quantitative Estimates ◽  
Allozyme Polymorphisms ◽  
Self Fertilization ◽  
Allozyme Genotype

Seeds from four populations of E. obliqua were assayed for their allozyme genotype at three loci (alcohol dehydrogenase, malate dehydrogenase and acid phosphatase) as members of open-pollinated arrays to obtain quantitative estimates of three mating system parameters. These were (i) the pro- portion of seed derived from self-pollination as distinct from the proportion randomly outcrossed, (ii) the allele frequency in the pollen, and (iii) the within-population heterogeneity for the frequency of detectable outcrosses. The rate of selfing varied between loci and populations, but overall suggested that up to 24% of viable seed may derive from self-fertilization. This level of partial self-fertilization, together with local variation in the mating system, yielded an observed average inbreeding coefficient (Wright's fixation index) of 0.123 for these loci. In addition, the populations showed substantial differences in gene frequency at each locus. The statistical techniques appropriate for the analysis of open-pollinated progeny arrays are given in an appendix.

Mating system of Eucalyptuscitriodora in a seed-production area

1983 ◽  
Vol 13 (6) ◽  
pp. 1051-1055 ◽  
Author(s):  
Francis C. Yeh ◽  
Arno Brune ◽  
William M. Cheliak ◽  
Diane C. Chipman
Keyword(s):  
Mating System ◽  
Seed Production ◽  
Local Variation ◽  
Outcrossing Rate ◽  
Mature Trees ◽  
Allozyme Polymorphisms ◽  
Self Fertilization ◽  
Production Area ◽  
Embryo Stage ◽  
Viable Embryo

Arrays of open-pollinated seeds were assayed for allozyme polymorphisms at three loci (Adh, Gdh, and Mdh-2) to obtain a quantitative estimate of outcrossing rate in a seed-production area of Eucalyptuscitriodora (Hook). Rate of outcrossing varied among loci, but suggested overall that up to 14.7% of the seed might be derived from self-fertilization at the viable embryo stage. Such a level of partial self-fertilization, together with local variation in the mating system, yielded an observed average inbreeding coefficient of 0.205 for these loci in the progeny arrays. By contrast, the mature trees exhibited substantial excesses of heterozygotes (F = −0.300), concordant with but not necessarily supportive of earlier hypotheses that selection against homozygotes through the life cycle occurred in eucalypts.

scholarly journals Mating System and Hybridity in Eucalyptus pauciflora

1977 ◽  
Vol 30 (4) ◽  
pp. 337 ◽  
Author(s):  
MA Phillips ◽  
AHD Brown
Keyword(s):  
Mating System ◽  
Outcrossing Rate ◽  
Seedling Stage ◽  
Average Heterozygosity ◽  
Evolutionary Advantage ◽  
Allozyme Polymorphisms ◽  
Self Fertilization

Allozyme polymorphisms at four loci expressed in seeds, and three other loci expressed in seedlings, were used to determine the outcrossing rate in three natural subalpine populations of snow gum (E. paucijlora). Based on the seed loci data, an estimated 37 % of seed was derived from self-fertilization and 63 % from random outcrossing. In the most elevated population the estimate after germination was similar. However, at lower elevations the frequency of effective self-fertilization estimated at the seedling stage was only 16 %. The less elevated populations also showed a greater average heterozygosity and a larger increase in heterozygosity in the adult over the progeny stages. Heterosis apparently operated differentially in these populations-it was more intense at the lower altitudes. Selection in favour of outcrossed individuals may be an important factor in checking the spread through the population of genes which promote self-fertilization, and which would otherwise enjoy an evolutionary advantage.

Allozyme and mating-system variation in balsam fir (Abies balsamea) across a continuous elevational transect

1985 ◽  
Vol 63 (12) ◽  
pp. 2448-2453 ◽  
Author(s):  
D. B. Neale ◽  
W. T. Adams
Keyword(s):  
Mating System ◽  
Abies Balsamea ◽  
Elevational Gradient ◽  
Balsam Fir ◽  
Fixation Index ◽  
Pollen Dispersion ◽  
Adult Trees ◽  
Self Fertilization ◽  
Isozyme Loci ◽  
Elevational Transect

Genetic structure and the mating system of a continuous balsam fir (Abies balsamea (L.) Mill.) population spanning a 610-m elevational gradient on the southeast slope of Mt. Moosilauke, New Hampshire, were investigated by assaying eight polymorphic isozyme loci. In contrast to steep elevational clines for seedling quantitative traits found in an earlier study on the same slope, no significant differences (P > 0.05) in allelic frequencies were found among four subpopulations sampled at 854, 1159, 1312, and 1464 m above sea level. Estimates of the proportion of progeny due to outcrossing [Formula: see text] ranged from 0.78 to 0.99 (mean = 0.89) and were significantly different (P < 0.05) from [Formula: see text] in three of the four subpopulations. At timberline (1464 m), [Formula: see text] was lowest, yet the mean fixation index among adult trees was −0.149, suggesting that selection favors heterozygotes in this marginal environment. Despite the potential for extensive pollen dispersion along the slope, gene flow appears somewhat restricted because of substantial self-fertilization in some subpopulations, localized outcrossing within stands, and asynchrony of flower production among adjacent stands.

The mating system in natural populations of Thujaorientalis

1991 ◽  
Vol 21 (3) ◽  
pp. 333-339 ◽  
Author(s):  
Chang Yi Xie ◽  
Bruce P. Dancik ◽  
Francis C. Yeh
Keyword(s):  
Mating System ◽  
Expectation Maximization ◽  
Natural Populations ◽  
Expectation Maximization Algorithm ◽  
Outcrossing Rate ◽  
Significant Heterogeneity ◽  
System Parameters ◽  
Marker Loci ◽  
Self Fertilization ◽  
The Mean

EM (expectation–maximization) algorithm procedures were used to estimate mating-system parameters in four natural populations of Thujaorientalis L. from China using seven allozyme marker loci (Fest1, Idh1, Idh2, Mr, Pgi2, Skdh1, and 6Pg2). The mean single-locus outcrossing rate was 0.70 for the species, but estimates showed that there was significant heterogeneity among loci within populations. Multilocus estimates of the outcrossing rate showed that there was significant heterogeneity among populations and among trees within populations. The mean multilocus outcrossing rate (0.75) was higher than the outcrossing rate (0.63) observed in a closely related conifer, Thujaoccidentalis L., but lower than estimates that have been reported for most other conifers. Significant heterozygote deficiencies, relative to Hardy–Weinberg and mating-system equilibria, were observed in all filial populations. In contrast, the maternal populations conformed to Hardy–Weinberg and mating-system equilibria at most loci. Self-fertilization and other forms of inbreeding (e.g., sibling mating) within the sampled populations are important contributors to the low outcrossing estimates in this conifer.

Joint estimation of immigration and mating system parameters in gymnosperms using the EM algorithm

1991 ◽  
Vol 83 (2) ◽  
pp. 137-140 ◽  
Author(s):  
C. Y. Xie ◽  
F. C. Yeh ◽  
B. P. Dancik ◽  
C. Strobeck
Keyword(s):  
Em Algorithm ◽  
Mating System ◽  
Joint Estimation ◽  
System Parameters ◽  
The Em Algorithm

Floral trait variation and links to climate in the mixed-mating annual Clarkia pulchella

Botany ◽  
2018 ◽  
Vol 96 (7) ◽  
pp. 425-435 ◽  
Author(s):  
Devin E. Gamble ◽  
Megan Bontrager ◽  
Amy L. Angert
Keyword(s):  
Mating System ◽  
Common Garden ◽  
Moisture Stress ◽  
Floral Traits ◽  
Mixed Mating ◽  
Floral Trait ◽  
Local Climate ◽  
Self Fertilization ◽  
Clarkia Pulchella ◽  
Watering Treatment

The benefits of self-fertilization can vary across environments, leading to selection for different reproductive strategies and influencing the evolution of floral traits. Although stressful conditions have been suggested to favour self-pollination, the role of climate as a driver of mating-system variation is generally not well understood. Here, we investigate the contributions of local climate to intraspecific differences in mating-system traits in Clarkia pulchella Pursh in a common-garden growth chamber experiment. We also tested for plastic responses to soil moisture with watering treatments. Herkogamy (anther–stigma spacing) correlated positively with dichogamy (timing of anther–stigma receptivity) and date of first flower, and northern populations had smaller petals and flowered earlier in response to experimental drought. Watering treatment alone had little effect on traits, and dichogamy unexpectedly decreased with annual precipitation. Populations also differed in phenological response to watering treatment, based on precipitation and winter temperature of their origin, indicating that populations from cool and dry sites have greater plasticity under different levels of moisture stress. While some variation in floral traits is attributable to climate, further investigation into variation in pollinator communities and the indirect effects of climate on mating system can improve our understanding of the evolution of plant mating.

scholarly journals The demography and population genomics of evolutionary transitions to self-fertilization in plants

2014 ◽  
Vol 369 (1648) ◽  
pp. 20130344 ◽  
Author(s):  
Spencer C. H. Barrett ◽  
Ramesh Arunkumar ◽  
Stephen I. Wright
Keyword(s):  
Mating System ◽  
Population Genomics ◽  
Molecular Data ◽  
Reproductive Assurance ◽  
Evolutionary Transitions ◽  
Cast Doubt ◽  
Self Fertilization ◽  
Loss Of Diversity ◽  
Linked Selection

The evolution of self-fertilization from outcrossing has occurred on numerous occasions in flowering plants. This shift in mating system profoundly influences the morphology, ecology, genetics and evolution of selfing lineages. As a result, there has been sustained interest in understanding the mechanisms driving the evolution of selfing and its environmental context. Recently, patterns of molecular variation have been used to make inferences about the selective mechanisms associated with mating system transitions. However, these inferences can be complicated by the action of linked selection following the transition. Here, using multilocus simulations and comparative molecular data from related selfers and outcrossers, we demonstrate that there is little evidence for strong bottlenecks associated with initial transitions to selfing, and our simulation results cast doubt on whether it is possible to infer the role of bottlenecks associated with reproductive assurance in the evolution of selfing. They indicate that the effects of background selection on the loss of diversity and efficacy of selection occur rapidly following the shift to high selfing. Future comparative studies that integrate explicit ecological and genomic details are necessary for quantifying the independent and joint effects of selection and demography on transitions to selfing and the loss of genetic diversity.

scholarly journals A multilocus estimator of mating system parameters in plant populations

1981 ◽  
Vol 78 (2) ◽  
pp. 1298-1302 ◽  
Author(s):  
D. V. Shaw ◽  
A. L. Kahler ◽  
R. W. Allard
Keyword(s):  
Mating System ◽  
Plant Populations ◽  
System Parameters
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