Genetic Variation, Breeding Systems, and Patterns of Diversification in Hawaiian Polypodium (Polypodiaceae)

1999 ◽  
Vol 24 (3) ◽  
pp. 339 ◽  
Author(s):  
Jianwei Li ◽  
Christopher H. Haufler
Keyword(s):  
Genetic Variation ◽  
Breeding Systems

Breeding systems and genetic variation in Amsinckia spectabilis (Boraginaceae)

1985 ◽  
Vol 63 (3) ◽  
pp. 533-538 ◽  
Author(s):  
Fred R. Ganders ◽  
Susan K. Denny ◽  
David Tsai
Keyword(s):  
Genetic Variation ◽  
Gel Electrophoresis ◽  
Allelic Variation ◽  
Outcrossing Rate ◽  
Breeding Systems ◽  
Rare Alleles ◽  
Mixed Populations ◽  
Highly Correlated ◽  
Allozyme Loci ◽  
Very High

Samples from 10 populations of Amsinckia spectabilis var. spectabilis and three populations of A. spectabilis var. microcarpa were analyzed for allelic variation at 17 allozyme loci using stareh gel electrophoresis. This species is a self-compatible annual which has heterostylous populations, homostylous populations, and mixed populations containing heterostylous and homostylous plants. Heterostylous populations had the highest outcrossing rates, homostylous populations the lowest, and mixed populations were intermediate in outcrossing rate. Outcrossing rate is highly correlated with the average stigma–anther separation in flowers in the populations. Genetic variability was highest in heterostylous populations, lowest in homostylous populations, and was intermediate in mixed populations, although one large homostylous population was as variable as were mixed populations. Genetic identities among populations were very high with the exception of the two northernmost, isolated homostylous populations which were fixed for rare alleles at some loci. In the rest of the populations, genetic identities were higher between populations of the same taxonomic variety than they were in intervarietal comparisons.

scholarly journals Genetic variation and genetic structure within metapopulations of two closely related selfing and outcrossing Zingiber species (Zingiberaceae)

AoB Plants ◽  
2020 ◽  
Author(s):  
Rong Huang ◽  
Zong-Dian Zhang ◽  
Yu Wang ◽  
Ying-Qiang Wang
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Habitat Fragmentation ◽  
Spatial Genetic Structure ◽  
Full Range ◽  
Breeding Systems ◽  
Dispersal Ability ◽  
Phylogenetic Distance ◽  
Plant Populations

Abstract Habitat fragmentation strongly affects the genetic diversity of plant populations, and this has always attracted much research interest. Although numerous studies have investigated the effects of habitat fragmentation on the genetic diversity of plant populations, fewer studies have compared species with contrasting breeding systems while accounting for phylogenetic distance. Here, we compare the levels of genetic diversity and differentiation within and among subpopulations in metapopulations (at fine-scale level) of two closely related Zingiber species, selfing Zingiber corallinum and outcrossing Zingiber nudicarpum. Comparisons of the genetic structure of species from unrelated taxa may be confounded by the effects of correlated ecological traits or/and phylogeny. Thus, we possibly reveal the differences in genetic diversity and spatial distribution of genetic variation within metapopulations that relate to mating systems. Compared to outcrossing Z. nudicarpum, the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity was not different. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum, depending on whether the degree of subpopulation isolation surpass the dispersal ability of pollen and seed. A stronger spatial genetic structure appeared within subpopulations of selfing Z. corallinum potentially due to restricted pollen flow and seed dispersal. In contrast, a weaker genetic structure was apparent in subpopulations of outcrossing Z. nudicarpum most likely caused by extensive pollen movement. Our study shows that high genetic variation can be maintained within metapopulations of selfing Zingiber species, due to increased genetic differentiation intensified primarily by the stochastic force of genetic drift among subpopulations. Therefore, maintenance of natural variability among subpopulations in fragmented areas is key to conserve the full range of genetic diversity of selfing Zingiber species. For outcrossing Zingiber species, maintenance of large populations is an important factor to enhance genetic diversity.

scholarly journals 561 Using AFLPs to Examine Genetic Diversity in Umbrella Fern

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 543A-543
Author(s):  
F.J. Keiper ◽  
R. McConchie
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Molecular Markers ◽  
Dna Markers ◽  
Morphological Traits ◽  
Natural Populations ◽  
Cost Effective ◽  
Molecular Techniques ◽  
Breeding Systems ◽  
Detailed Knowledge

Umbrella fern [Sticherus flabellatus (R. Br.) St John] is a successful Australian native foliage product. Currently, all umbrella fern sold on the market is bush-harvested. To meet the growing demand for this product on local and international markets, a commercially viable method for its production must be developed, with effective management of the germplasm resource in terms of conservation and exploitation. To manage this resource, breeders require a detailed knowledge of the amount and distribution of genetic variability within the species. Traditionally, plant breeders focus on a combination of agronomic and morphological traits (phenotype) to measure genetic diversity. In umbrella fern there are a limited number of morphological traits, and these are influenced by environmental factors and therefore do not reflect true genetic diversity. To overcome these problems, molecular techniques such as PCR-based DNA markers are used to complement traditional strategies for genotype assessment. DNA markers have the advantages of being independent of environmental effects, as well as being fast, cost-effective, reproducible, and largely accessible to the nonmolecular geneticist. Amplified fragment length polymorphisms (AFLPs) fulfil many of the desirable features of molecular markers, as well as requiring little knowledge of the genome to be investigated. AFLPs have been used widely in the analysis of breeding systems, ecogeographical variation, and genetic variation within and between natural populations. To date there are no published accounts of DNA molecular marker research on umbrella fern. A DNA extraction protocol has been developed for this species, and AFLP markers have been used to analyse genetic diversity within and between natural populations sampled in the Sydney Basin. A large number of polymorphic loci were revealed using 11 primer combinations. The genetic variation detected was partitioned between rather than within populations, suggesting that the mating system in Sticherus is primarily inbreeding. Data will be presented illustrating AFLPs as useful molecular markers for assessing genetic diversity within and between populations of umbrella fern and providing insight on the breeding system used by the species.

scholarly journals Breeding systems, gene flow and level of genetic differentiation in plant populations

Lankesteriana ◽  
2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Oscar Rocha
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Mating Systems ◽  
Title Page ◽  
Breeding Systems ◽  
Plant Populations

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>Genetic variation and its distribution among plant populations are primarily determined by their breed- ing system and the level of gene flow among them (Bawa </span><span>et al. </span><span>1985, Bawa </span><span>et al. </span><span>1990, Rocha &amp; Aguilar 2001b). It is well known that mating systems influence the amount, as well as the distribution of the genetic variation within and among populations (Wright 1921, Stebbins 1950, 1957, Hamrick </span><span>et al. </span><span>1991). </span></p></div></div></div>

Intra- and interspecific allozyme variation in eucalypts from the spotted gum group, Corymbia, section 'Politaria' (Myrtaceae)

2000 ◽  
Vol 13 (4) ◽  
pp. 491 ◽  
Author(s):  
M. W. McDonald ◽  
P. A. Butcher ◽  
J. C. Bell ◽  
J. S. Larmour
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Differentiation ◽  
Related Species ◽  
Allozyme Variation ◽  
Geographic Range ◽  
Breeding Systems ◽  
Closely Related Species ◽  
Tropical Regions ◽  
Corymbia Citriodora

The distribution of genetic variation within and among species inCorymbia section‘Politaria’ was examined using allozymes.This section consists of four species,Corymbia citriodora (Hook.) K.D.Hill & L.A.S.Johnson, C. maculata (Hook.) K.D.Hill & L.A.S.Johnson, C. henryi (Blake) K.D.Hill & L.A.S.Johnson and C. variegata (F.Muell.) K.D.Hill & L.A.S.Johnson, which are of commercial interest for plantation and farmforestry. Thirty populations representing the species’ range-widedistributions were studied, extending from upland tropical regions of northQueensland, south to eastern Victoria. Despite relatively low allozymedivergence between species, there was a relationship between geographicdistribution patterns of populations and allozyme variation. The section wasshown to comprise very closely related species with only 15% of thetotal genetic diversity attributed to differences between species. Twodistinct genetic alliances were evident:C. maculata–C. henryi andC. citriodora–C. variegata.Corymbia citriodora andC. variegata, however, could not be distinguished bytheir allozyme profiles. The lack of genetic differentiation between thesetaxa suggests that they represent one species composed of two chemical races.Corymbia maculata and C. henryiwere shown to be closely allied but genetically distinct.Corymbia henryi had the highest genetic diversity in thegroup and lowest differentiation among populations, whileC. maculata had the lowest diversity but the highestgenetic differentiation among populations. There was evidence ofisolation-by-distance among populations ofC. citriodora, C. maculata andC. variegata but not in C. henryi,which has a smaller geographic range. The inclusion in the study ofC. torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson asan outgroup accentuated the small genetic differences between species in thegroup. The patterns of genetic diversity are discussed in relation to thespecies’ taxonomic relationships, breeding systems and utilisation.

scholarly journals Using Isozyme Polymorphisms for Identifying and Assessing Genetic Variation in Cultivated Pawpaw [Asimina triloba (L.) Dunal]

1997 ◽  
Vol 122 (4) ◽  
pp. 504-511 ◽  
Author(s):  
Hongwen Huang ◽  
Desmond R. Layne ◽  
R. Neal Peterson
Keyword(s):  
Genetic Variation ◽  
Cultivar Identification ◽  
Allozyme Variation ◽  
Breeding Systems ◽  
Pairwise Comparisons ◽  
Shikimate Dehydrogenase ◽  
Woody Perennials ◽  
Asimina Triloba ◽  
Nei's Distance ◽  
Polymorphic Enzymes

The utility of isozyme phenotypes for identifying and determining genetic variation in pawpaw cultivars was studied using isoelectric focusing in thin-layer polyacrylamide gels. Based on a sample of 32 clones (cultivars and advanced selections) and 23 enzyme systems, 7 enzymes were found to be polymorphic, involving 9 polymorphic loci [acid phosphatase (ACP), dihydrolipoamide dehydrogenase (DDH), malic enzyme (ME), phosphoglucoisomerase (PGI), phosphoglucomutase (PGM), peroxidase (PRX), and shikimate dehydrogenase (SKD)]. Altogether these 9 loci and 32 clones yielded 28 multi-locus isozymic phenotypes useful for cultivar identification; 24 of the 32 clones were uniquely identified. The allozyme variation in these clones has the average of other long-lived woody perennials of widespread geographic range in temperate regions with insect-pollinated outcrossing breeding systems, secondary asexual reproduction, and animal-dispersed seed. Genetic differentiation among these pawpaw clones, measured by Nei's distance, D, was substantial: 496 pairwise comparisons of genetic distance among the 32 clones indicated that they differed on average of D = 0.068 ± 0.04 and ranged from 0 to 0.188. Cluster analysis (UPGMA) produced a most likely division of the 32 clones into 7 groups; however, these groups did not conform to known pedigree relations. Additional polymorphic enzymes are needed for accurate allozyme-based genetic discrimination.

scholarly journals Ployandry versus polygyny versus parasites

1999 ◽  
Vol 354 (1382) ◽  
pp. 507-515 ◽  
Author(s):  
Paul Schmid-Hempel ◽  
Ross H. Crozier
Keyword(s):  
Experimental Investigation ◽  
Genetic Variation ◽  
Social Insect ◽  
Variance Reduction ◽  
Breeding Systems ◽  
Mating Frequency ◽  
Reduction Principle ◽  
Queen Number ◽  
Phylogenetic Information ◽  
The Relationship

Although social insect colonies are most easily conceptualized as consisting of a single, once–mated queen and her worker progeny, the number of queens per colony and the number of times queens mate varies broadly in ants and other social insects. Various hypotheses have been suggested for the resulting range of breeding systems and social organizations, respectively; one set of hypotheses relating to both queen number and mate number at the same time is a need for genetic variation, especially in relation to disease resistance. We here carry out a comparative analysis using phylogenetic information and, contrary to one non–phylogenetic previous study, we find that polyandry and polygyny are not significantly associated. However, the level of relatedness within colonies, a quantity affected by both polyandry and polygyny, is significantly associated with parasite loads: species with colonies with low relatedness levels have lower parasite loads. Given that, under the variance–reduction principle, selection on queens for mating frequency ought to continue even in polygynous colonies, we suggest that while parasite loads indeed seem to correlate with intra–colony genetic variability, the relationship to polyandry and polygyny may be complex and requires considerably more experimental investigation.

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