Systematics of North American Petasites (Asteraceae: Senecioneae). II. Isozyme analysis and population genetic structure

1998 ◽  
Vol 76 (8) ◽  
pp. 1476-1487 ◽  
Author(s):  
Donna M Cherniawsky ◽  
Randall J Bayer
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
North America ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Clonal Plants ◽  
Enzyme Electrophoresis ◽  
Isozyme Loci ◽  
Recent Origin ◽  
Morphological Differences

Petasites Mill. (Asteraceae: Senecioneae) is a genus of diploid, perennial, clonal herbs with a widespread distribution across North America. Because of the low variability in floral morphology and high diversity in leaf morphology, considerable taxonomic confusion surrounds the genus. Petasites is generally recognized in North America by five ill-defined native taxa and two introduced species. Enzyme electrophoresis was conducted to assess the genetic variation in Petasites and obtain an understanding of the evolutionary relationships within the genus. Results show divergence at isozyme loci is not associated with morphological divergence. The mean number of alleles per locus and proportion of polymorphic loci are comparable with plants with similar life-history traits; however, levels of heterozygosity ranged substantially. Although there is a weak, negative association between geographical distance and genetic identity, this is not concordant with morphological differences. Typical of clonal species, genetic identities of Petasites are more comparable with selfing plants than with other diploid, outcrossing perennials. Petasites also maintains a level of genetic diversity that is similar to other clonal plants and exhibits high levels of differentiation among its populations. This study provides the first contribution to the population genetic structure of Petasites. The relatively high values of genetic identities between the different taxa of Petasites and the similarity in isozymes and chromosome number indicates a rapid and recent origin in North America. These data, in accordance with the close morphological associations of the four taxa in Petasites, suggest the recognition of one species only, Petasites frigidus.Key words: Petasites, Asteraceae, North America, clonal, systematics, genetic variation.

Genetic variation in Trillium erectum (Melanthiaceae), a widespread forest herb in eastern North America

2004 ◽  
Vol 82 (3) ◽  
pp. 316-321 ◽  
Author(s):  
Steven R Griffin ◽  
Spencer CH Barrett
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Structure ◽  
North America ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Eastern North America ◽  
Mixed Mating ◽  
Allozyme Loci

Trillium erectum L. is an insect-pollinated understory herb widespread in forests of eastern North America. Marker gene studies indicate that the species has a mixed mating system, but aspects of population genetic structure have not been investigated. Using 10 allozyme loci, we measured genetic variation within and among 23 populations sampled from throughout the species' range. Overall, T. erectum displayed moderate levels of genetic diversity in comparison with other herbaceous plants. The percentage of loci that were polymorphic was 52%, with average values (±SE) of 1.20 ± 0.02, 0.08 ± 0.01, and 0.13 ± 0.01 for the number of alleles per locus (A), observed heterozygosity (Ho), and expected heterozygosity (He), respectively. There was evidence of inbreeding within populations (Fis = 0.39, 95% CI 0.26–0.55) and significant population differentiation (Fst = 0.16, 0.05–0.24). Analysis of genetic data provided no evidence of isolation by distance, and together with the occurrence of population subdivision, this suggests that there is relatively limited contemporary gene flow among populations. Northern populations of T. erectum tended to have less genetic variability than southern populations, probably as a result of historical factors associated with post glacial migration. Limited opportunities for gene dispersal as a result of low plant densities, the capacity for self-fertilization, and local seed dispersal by ants are likely to be the main factors maintaining contemporary patterns of genetic variation in T. erectum. Key words: allozymes, genetic diversity, gene flow, population genetic structure, Trillium.

Significant genetic differences among Heterodera schachtii populations within and among sugar beet production areas

Nematology ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 165-177 ◽  
Author(s):  
Rasha Haj Nuaima ◽  
Johannes Roeb ◽  
Johannes Hallmann ◽  
Matthias Daub ◽  
Holger Heuer
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Spatial Scales ◽  
Geographic Distance ◽  
Heterodera Schachtii ◽  
Parasitic Nematodes ◽  
Neutral Genetic Variation ◽  
Production Areas

Summary Characterising the non-neutral genetic variation within and among populations of plant-parasitic nematodes is essential to determine factors shaping the population genetic structure. This study describes the genetic variation of the parasitism gene vap1 within and among geographic populations of the beet cyst nematode Heterodera schachtii. Forty populations of H. schachtii were sampled at four spatial scales: 695 km, 49 km, 3.1 km and 0.24 km. DGGE fingerprinting showed significant differences in vap1 patterns among populations. High similarity of vap1 patterns appeared between geographically close populations, and occasionally among distant populations. Analysis of spatially sampled populations within fields revealed an effect of tillage direction on the vap1 similarity for two of four studied fields. Overall, geographic distance and similarity of vap1 patterns of H. schachtii populations were negatively correlated. In conclusion, the population genetic structure was shaped by the interplay between the genetic adaptation and the passive transport of this nematode.

scholarly journals Absence of Population Genetic Structure Among Breeding Colonies of the Waved Albatross

The Condor ◽  
2006 ◽  
Vol 108 (2) ◽  
pp. 440-445 ◽  
Author(s):  
Kathryn P. Huyvaert ◽  
Patricia G. Parker
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Breeding Population ◽  
Genetic Structuring ◽  
Galapagos Archipelago ◽  
Phoebastria Irrorata ◽  
Waved Albatrosses

Abstract We used four variable microsatellite loci to examine the distribution of genetic variation and degree of genetic structuring among three subcolonies of Waved Albatrosses (Phoebastria irrorata). The breeding population of this species is almost entirely limited to the island of Española in the Galápagos Archipelago. Such strong philopatry could lead to population genetic structure among subcolonies on the island. Pairwise values of the FST analog, θ, calculated from microsatellite genotypes, were all less than 0.012, indicating little genetic differentiation and the presence of gene flow throughout the population.

Effects of habitat fragmentation on population genetic structure in the white-footed mouse (Peromyscus leucopus)

2001 ◽  
Vol 79 (2) ◽  
pp. 285-295 ◽  
Author(s):  
Catherine A Mossman ◽  
Peter M Waser
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Habitat Fragmentation ◽  
Genetic Differentiation ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Peromyscus Leucopus ◽  
Marginal Effect ◽  
Geographic Scale ◽  
White Footed Mouse

Habitat fragmentation may have significant consequences for population genetic structure because geographic distance and physical barriers may impede gene flow. In this study, we investigated whether habitat fragmentation affects fine-scale genetic structure of populations of the white-footed mouse (Peromyscus leucopus). We studied 27 populations of P. leucopus, 17 in continuous forest and 10 in isolated woodlots. Populations were trapped in pairs that were either 500 or 2000 m apart. We estimated genetic variation at eight P. leucopus specific microsatellite DNA loci. We discovered significant genetic variation within all populations, but no significant differences in numbers of alleles or heterozygosity between populations. For given population pairs, we found significant genetic differentiation even at very short distances, based on multilocus FST estimates. The amount of genetic differentiation between population pairs was similar in the two habitats. Distance had a marginal effect on genetic differentiation when comparing paired populations separated by 2000 m with those separated by 500 m. However, at a larger geographic scale, there was no evidence of isolation by distance. This study confirms that microsatellite-based studies have the potential to detect interpopulation differentiation at an extremely local scale, and suggests that habitat fragmentation has surprisingly few effects on P. leucopus genetic structure.

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