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 Paternal bottlenecks in fragmented populations of the grassland daisy Rutidosis leptorrhynchoides

1999 ◽  
Vol 73 (2) ◽  
pp. 111-117 ◽  
Author(s):  
ANDREW G. YOUNG ◽  
ANTHONY H. D. BROWN
Keyword(s):  
Mating System ◽  
Inbreeding Depression ◽  
Outcrossing Rate ◽  
Small Populations ◽  
Isolated Populations ◽  
Fragmented Populations ◽  
System Parameters ◽  
Large Populations ◽  
Spatial Isolation ◽  
High Level

Allozyme markers were used to estimate mating system parameters in nine fragmented populations of the grassland daisy Rutidosis leptorrhynchoides that differed in size and spatial isolation. Multilocus estimates of outcrossing rate did not differ significantly among populations, all indicating a high level of outcrossing (tm=0·84–1·0). Small populations showed greater divergence than large populations between the allele frequencies in the population and those in the pollen pool, indicating paternal bottlenecks. Isolated populations of fewer than 200 individuals also exhibited higher correlations of outcrossed paternity (rp) than larger populations, indicating the production of more full-sibs within families. The combination of paternal bottlenecks and correlated paternity increases the genetic identity of progeny across families and predisposes populations to biparental inbreeding in subsequent generations. As over half the remaining populations of R. leptorrhynchoides contain fewer than 200 plants, such second-order inbreeding may threaten the viability of the species if it is associated with significant inbreeding depression.

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.

scholarly journals Life history and past demography maintain genetic structure, outcrossing rate, contemporary pollen gene flow of an understory herb in a highly fragmented rainforest

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2764 ◽  
Author(s):  
Pilar Suárez-Montes ◽  
Mariana Chávez-Pesqueira ◽  
Juan Núñez-Farfán
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Habitat Fragmentation ◽  
Mating System ◽  
Population Expansion ◽  
Outcrossing Rate ◽  
Mixed Mating ◽  
Long Distance ◽  
Mixed Mating System ◽  
Genetic Structure Of Populations

IntroductionTheory predicts that habitat fragmentation, by reducing population size and increasing isolation among remnant populations, can alter their genetic diversity and structure. A cascade of effects is expected: genetic drift and inbreeding after a population bottleneck, changes in biotic interactions that may affect, as in the case of plants, pollen dynamics, mating system, reproductive success. The detection of the effects of contemporary habitat fragmentation on the genetic structure of populations are conditioned by the magnitude of change, given the few number of generations since the onset of fragmentation, especially for long-lived organisms. However, the present-day genetic structure of populations may bear the signature of past demography events. Here, we examine the effects of rainforest fragmentation on the genetic diversity, population structure, mating system (outcrossing rate), indirect gene flow and contemporary pollen dynamics in the understory herbAphelandra aurantiaca. Also, we assessed its present-day genetic structure under different past demographic scenarios.MethodsTwelve populations ofA. aurantiacawere sampled in large (4), medium (3), and small (5) forest fragments in the lowland tropical rainforest at Los Tuxtlas region. Variation at 11 microsatellite loci was assessed in 28–30 reproductive plants per population. In two medium- and two large-size fragments we estimated the density of reproductive plants, and the mating system by analyzing the progeny of different mother plants per population.ResultsDespite prevailing habitat fragmentation, populations ofA. aurantiacapossess high genetic variation (He = 0.61), weak genetic structure (Rst = 0.037), and slight inbreeding in small fragments. Effective population sizes (Ne) were large, but slightly lower in small fragments. Migrants derive mostly from large and medium size fragments. Gene dispersal is highly restricted but long distance gene dispersal events were detected.Aphelandra aurantiacashows a mixed mating system (tm = 0.81) and the outcrossing rate have not been affected by habitat fragmentation. A strong pollen pool structure was detected due to few effective pollen donors (Nep) and low distance pollen movement, pointing that most plants received pollen from close neighbors. Past demographic fluctuations may have affected the present population genetic structure as Bayesian coalescent analysis revealed the signature of past population expansion, possibly during warmer conditions after the last glacial maximum.DiscussionHabitat fragmentation has not increased genetic differentiation or reduced genetic diversity ofA. aurantiacadespite dozens of generations since the onset of fragmentation in the region of Los Tuxtlas. Instead, past population expansion is compatible with the lack of observed genetic structure. The predicted negative effects of rainforest fragmentation on genetic diversity and population structure ofA. aurantiacaseem to have been buffered owing to its large effective populations and long-distance dispersal events. In particular, its mixed-mating system, mostly of outcrossing, suggests high efficiency of pollinators promoting connectivity and reducing inbreeding. However, some results point that the effects of fragmentation are underway, as two small fragments showed higher membership probabilities to their population of origin, suggesting genetic isolation. Our findings underscore the importance of fragment size to maintain genetic connectivity across the landscape.

scholarly journals Mating system parameters in a high density population of andirobas in the Amazon forest

2013 ◽  
Vol 48 (5) ◽  
pp. 504-509 ◽  
Author(s):  
Tatiana de Campos ◽  
Marcia Oliveira da Cunha ◽  
Adna Cristina Barbosa de Sousa ◽  
Renata Beltrão Teixeira ◽  
Andrea Raposo ◽  
...  
Keyword(s):  
Microsatellite Markers ◽  
Mating System ◽  
Reproductive System ◽  
Outcrossing Rate ◽  
Effective Size ◽  
Amazon Forest ◽  
System Parameters ◽  
Carapa Guianensis ◽  
The Individual ◽  
Density Population

The objective of this work was to estimate the mating system parameters of a andiroba (Carapa guianensis) population using microsatellite markers and the mixed and correlated mating models. Twelve open‑pollinated progeny arrays of 15 individuals were sampled in an area with C. guianensis estimated density of 25.7 trees per hectare. Overall, the species has a mixed reproductive system, with a predominance of outcrossing. The multilocus outcrossing rate (t m = 0.862) was significantly lower than the unity, indicating that self‑pollination occurred. The rate of biparental inbreeding was substantial (t m ‑ t s = 0.134) and significantly different from zero. The correlation of selfing within progenies was high (r s = 0.635), indicating variation in the individual outcrossing rate. Consistent with this result, the estimate of the individual outcrossing rate ranged from 0.598 to 0.978. The multilocus correlation of paternity was low (r p(m) = 0.081), but significantly different from zero, suggesting that the progenies contain full‑sibs. The coancestry within progenies (Θ = 0.185) was higher and the variance effective size (Ne(v) = 2.7) was lower than expected for true half‑sib progenies (Θ = 0.125; Ne(v) = 4). These results suggest that, in order to maintain a minimum effective size of 150 individuals for breeding, genetic conservation, and environmental reforestation programs, seeds from at least 56 trees must be collected.

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.

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

scholarly journals Breeding synthetic varieties in annual caraway: observations on the outcrossing rate in a polycross using a high-throughput genotyping system

Euphytica ◽  
2020 ◽  
Vol 217 (1) ◽  
Author(s):  
Daniel von Maydell ◽  
Julia Brandes ◽  
Heike Lehnert ◽  
Wolfram Junghanns ◽  
Frank Marthe
Keyword(s):  
Medicinal Plant ◽  
Dna Extraction ◽  
High Throughput ◽  
Inbred Lines ◽  
High Variability ◽  
Outcrossing Rate ◽  
Breeding Method ◽  
High Throughput Method ◽  
Synthetic Varieties ◽  
Seed Yields

AbstractCaraway (Carum carvi) is an economically important spice and medicinal plant of the Apiaceae family (syn. Umbelliferrae). Farmers often favor annual cultivation of caraway. However, the annual varieties, which are currently available, do not provide satisfying seed yields. Employing heterosis can be a promising approach to increase yield. Breeding of synthetic varieties utilizes heterosis and may be the method of choice for future caraway breeding. Knowledge of the outcrossing rate is important to evaluate the effectiveness of this breeding method. However, the outcrossing rate of caraway is unknown so far. We estimated the outcrossing rate of seven inbred lines under field conditions in a neighbor-balanced polycross design. For this purpose, we implemented a high-throughput genotyping system (PACE), accompanied by a high-throughput method for DNA extraction adapted to caraway. In total, more than 1300 individual plants were genotyped. We found a high variability of lines regarding outcrossing rate and other traits associated with flowering. The outcrossing rate was on average 66.5% and ranged from 51.6 to 82%. We discussed implications of our findings on the targeted breeding method.

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