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.

Significant levels of self-fertilization in natural populations of tamarack

1987 ◽  
Vol 65 (6) ◽  
pp. 1087-1091 ◽  
Author(s):  
Peggy Knowles ◽  
Glenn R. Furnier ◽  
Mary A. Aleksiuk ◽  
Daniel J. Perry
Keyword(s):  
Adult Stage ◽  
Natural Populations ◽  
Stand Density ◽  
Outcrossing Rate ◽  
Larix Laricina ◽  
Northern Ontario ◽  
Marker Loci ◽  
Self Fertilization ◽  
The Mean ◽  
The One

The mating system in five northern Ontario populations of tamarack (Larix laricina (Du Roi) K. Koch) was investigated using five allozyme marker loci (Aat3, G6p, Mdh3, Pgi2, and 6pg2). The mean multilocus outcrossing rate was 0.729, lower than estimates reported for most other conifers. The one population with a much higher stand density than the others had the highest outcrossing rate (0.908). Significant heterozygote deficiencies, relative to Hardy – Weinberg expectations, were observed at most loci in all five embryo populations. In contrast, there appeared to be few cases of heterozygote deficiencies in the adult populations, indicating that many inbred seedlings do not survive to the adult stage.

Evidence of high self-fertilization in natural populations of eastern white cedar (Thuja occidentalis)

1990 ◽  
Vol 68 (3) ◽  
pp. 663-668 ◽  
Author(s):  
Daniel J. Perry ◽  
Peggy Knowles
Keyword(s):  
Natural Populations ◽  
Outcrossing Rate ◽  
Significant Heterogeneity ◽  
Embryo Survival ◽  
Thuja Occidentalis ◽  
White Cedar ◽  
Northwestern Ontario ◽  
Outcrossing Rates ◽  
Self Fertilization ◽  
Eastern White Cedar

Arrays of open-pollinated seeds were assayed for allozyme polymorphisms at four loci (Mdh-1, Me, 6Pg-2, and Pgm) to obtain estimates of outcrossing rates for three eastern white cedar populations in northwestern Ontario, Canada. Multilocus population outcrossing rate estimates were low, ranging from 0.507 to 0.745, with significant heterogeneity among populations. Low stand densities and relatively high selfed embryo survival may have contributed to the low effective outcrossing rates observed. Single-tree multilocus outcrossing rate estimates were obtained for nine trees from one population. When estimated jointly with outcross pollen pool allele frequencies, these outcrossing rate estimates ranged from 0.253 to 1.023 with significant heterogeneity among trees. Key words: mating system, outcrossing rate, Thuja occidentalis L.

Mating system in natural populations of eastern white pine in Quebec

1995 ◽  
Vol 25 (10) ◽  
pp. 1697-1703 ◽  
Author(s):  
J. Beaulieu ◽  
J.-P. Simon
Keyword(s):  
Family Structure ◽  
Mating System ◽  
Natural Populations ◽  
Outcrossing Rate ◽  
The Other ◽  
Single Locus ◽  
White Pine ◽  
Eastern White Pine ◽  
Gene Frequencies ◽  
Self Fertilization

The mating system in two natural eastern white pine (Pinusstrobus L.) populations in Quebec was investigated. These populations contrasted in density and age. The single-locus as well as multilocus outcrossing rate estimates were obtained from four polymorphic enzyme loci using open-pollinated progeny data. The single-locus outcrossing rates ranged from 0.934 to 1.110 with a mean of 1.026 in one population and varied from 0.862 to 1.186 with a mean of 1.007 in the other population. Multilocus estimates exceeded 1.0 in both populations, suggesting the possible absence of self-fertilization. Pollen pool gene frequencies were homogeneous in one population and heterogeneous in the other. The positive or less negative F-values found in the filial populations compared with those observed in the parental populations suggest the presence of a family structure favouring consanguineous matings.

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.

Estimation of mating system parameters in two Italian natural populations of Fagussylvatica

1996 ◽  
Vol 26 (7) ◽  
pp. 1187-1192 ◽  
Author(s):  
Patrizia Rossi ◽  
Giovanni Giuseppe Vendramin ◽  
Raffaello Giannini
Keyword(s):  
Mating System ◽  
Natural Populations ◽  
Female Parent ◽  
European Beech ◽  
Allele Frequencies ◽  
Mixed Mating ◽  
System Parameters ◽  
Fixation Indices ◽  
Mixed Mating Model ◽  
Allozyme Loci

Mating system parameters were estimated in two Italian natural populations of European beech (Fagussylvatica L.) using a mixed mating model and considering seven allozyme loci (Idh-A, Lap-A, Mdh-B, Pgd-A, Pgd-B, Pgd-C, Skd-A). High values of multilocus estimates of the outcrossing rate were found in both populations, ranging from 94 to 98%. Comparison of single- and multi-locus estimates of outcrossing rates seems to indicate the presence of consanguineous matings, probably because the populations are substructured. This hypothesis seems to be confirmed by the presence of a heterogeneity of the pollen allele frequencies across female parent trees and by the significant coefficient of the regression of pollen allele frequencies on ovule genotype. Variation in the fixation indices in different life-cycle phases was observed, indicating possible presence of selective processes between seed set and sexual maturity. Possible explanations of these results are presented.

Effects of stand density on outcrossing rate in two Norway spruce (Picea abies) populations

1991 ◽  
Vol 69 (12) ◽  
pp. 2704-2708 ◽  
Author(s):  
M. Morgante ◽  
G. G. Vendramin ◽  
P. Rossi
Keyword(s):  
Picea Abies ◽  
Mating System ◽  
Norway Spruce ◽  
Stand Density ◽  
Major Effect ◽  
Outcrossing Rate ◽  
High Density ◽  
Low Density ◽  
The Mean ◽  
Key Words Mating System

The mating system was investigated in two neighbouring Norway spruce (Picea abies (L.) Karst.) populations with markedly different stand densities. The amount of outcrossing was estimated using open-pollinated array data at four enzyme loci. Multilocus estimates of the proportion of viable progeny owing to outcrossing were 0.956 and 0.955 for the low- and high-density stand, respectively, indicating that the large reduction in stand density had no impact on outcrossing rates. The multilocus estimate was higher than the mean single-locus estimate only for the low-density stand. The lowering of the mean estimate in the low-density stand is probably a consequence of the clustering of related individuals. The regression of pollen allele frequencies on ovule genotype, which is a direct measure of the effective selfing caused by consanguineous matings, had a significant coefficient for the low-density stand and a nonsignificant one for the high-density stand. This obvservation confirms that the major effect of low-stand density in Norway spruce is the occurrence of consanguineous matings. Key words: mating system, outcrossing rate, inbreeding, Norway spruce, stand density.

Estimates of outcrossing rates in Lathyrus latifolius populations

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 988-992 ◽  
Author(s):  
Mary Jo W. Godt ◽  
J. L. Hamrick
Keyword(s):  
Mating System ◽  
Outcrossing Rate ◽  
Single Locus ◽  
Heterozygote Advantage ◽  
Significant Heterogeneity ◽  
Isozyme Markers ◽  
Biparental Inbreeding ◽  
Outcrossing Rates

Isozyme markers were used to estimate parameters of the mating system of Lathyrus latifolius, a bumblebee-pollinated legume. Multilocus outcrossing estimates (mean tm = 0.807; range = 0.702–0.870) differed significantly from random outcrossing. Comparisons of single-locus outcrossing estimates (mean ts = 0.756; range = 0.627–0.852) and multilocus estimates suggested that biparental inbreeding contributed about 21% to the apparent rate of selfing. Significant heterogeneity in outcrossing rates occurred among the seven populations studied. A tendency for selection against inbred individuals, or heterozygote advantage, was apparent in all populations.Key words: mating system, Lathyrus latifolius, outcrossing rate, isozymes, Leguminosae.

Effect of forest fragmentation and altitude on the mating system of Eucalyptus pauciflora (Myrtaceae)

2013 ◽  
Vol 61 (8) ◽  
pp. 622 ◽  
Author(s):  
Archana Gauli ◽  
René E. Vaillancourt ◽  
Dorothy A. Steane ◽  
Tanya G. Bailey ◽  
Brad M. Potts
Keyword(s):  
Habitat Fragmentation ◽  
Population Density ◽  
Mating System ◽  
Forest Restoration ◽  
Outcrossing Rate ◽  
Self Incompatibility ◽  
Fragmented Populations ◽  
System Parameters ◽  
Key Factor ◽  
Seed Yields

Habitat fragmentation is a key factor causing variation in important mating system parameters in plants, but its effect is variable. We studied mating system variation among 276 native trees from 37 populations of Eucalyptus pauciflora from Tasmania. We assayed 10 microsatellite loci from 1359 open-pollinated progeny from these trees. Across Tasmania the species’ mating system was characterised by a high outcrossing rate (tm = 0.90) but moderate bi-parental inbreeding (tm–ts = 0.16) and moderate correlated paternity (rP = 0.20) in comparison to other eucalypt species. Despite significant differences in outcrossing rate and correlated paternity among populations, this variation was not correlated with fragmentation. Nevertheless, fragmentation was inversely correlated with the number of germinants per gram of seed capsule content. Outcrossing rate had been reported previously to decrease with increasing altitude in mainland populations of E. pauciflora, but this was not the case in Tasmania. However, a small but significant decrease in correlated paternity occurred with increasing altitude and a decrease in bi-parental inbreeding with increasing altitude was evident in fragmented populations only. It is argued that strong, but incomplete self-incompatibility mechanisms may buffer the mating system from changes in population density and pollinators. While seed yields from highly fragmented populations were reduced, in most cases the seed obtained is unlikely to be more inbred than that from non-fragmented populations and, thus, is likely to be as suitable for use in local forest restoration.

scholarly journals High Levels of Outcrossing in a Family Trial of Western Australian Sandalwood (Santalum spicatum)

2007 ◽  
Vol 56 (1-6) ◽  
pp. 222-230 ◽  
Author(s):  
K. Muir ◽  
M. Byrne ◽  
E. Barbour ◽  
M. C. Cox ◽  
J. E. D. Fox
Keyword(s):  
Genetic Diversity ◽  
Mating System ◽  
Natural Populations ◽  
Seed Orchard ◽  
Seed Crop ◽  
The Mean ◽  
Santalum Spicatum ◽  
High Level ◽  
Western Australian ◽  
Seed Collections

Abstract The mating system of Western Australian sandalwood (Santalum spicatum) was investigated in seed collections from a family trial. The mean outcrossing rate was high (95.2%) although there was variation among families and one family showed particularly low outcrossing, high bi-parental inbreeding and high correlated paternity. Variation in flowering time between this family and others in the trial was the most likely cause of the high inbreeding and low number of fathers contributing to the seed crop in trees from this family. The high level of outcrossing in the rest of the families indicated that S. spicatum has a preferentially outcrossed mating system, but that it is capable of selfing when conditions are unsuitable for outcrossing. The seedling progeny showed no influence of inbreeding on seedling height at 4 months. Analysis of genetic diversity revealed high levels of genetic diversity have been captured in the seed crop from the trial, and this diversity is comparable to that identified in a previous study of natural populations from throughout the range of the species. These results indicated that production of seed through seed orchards will be a successful means of deployment of breeding gains in the species, however it is essential to ensure overlap in flowering times among different families planted in a seed orchard.

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