Quantification of genetic diversity at allozyme loci

1997 ◽  
Vol 27 (3) ◽  
pp. 415-424 ◽  
Author(s):  
E E Berg ◽  
J L Hamrick
Keyword(s):  
Genetic Diversity ◽  
Allozyme Loci

Allozyme Variation and Population Substructuring in the Caucasian Ground Lizards Lacerta derjugini and Lacerta praticola

2011 ◽  
Vol 4 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Ross D. MacCulloch ◽  
Ilya S. Darevsky ◽  
Robert W. Murphy ◽  
Jinzhong Fu
Keyword(s):  
Genetic Diversity ◽  
Allozyme Variation ◽  
Close Proximity ◽  
Geographic Separation ◽  
Population Substructuring ◽  
Allozyme Loci ◽  
Two Populations

Genetic diversity at 35 allozyme loci was surveyed in Lacerta derjugini (3 populations) and L. praticola (2 populations). Indices of variability were consistent with those found in other Caucasian Lacerta. There was little genetic substructuring between two populations of L. praticola despite considerable geographic separation. Conversely, populations of L. derjugini in close proximity to one another exhibited considerable substructuring.

Indicators of population viability in red spruce, Picea rubens. II. Genetic diversity, population structure, and mating behavior

2000 ◽  
Vol 78 (7) ◽  
pp. 941-956 ◽  
Author(s):  
Om P Rajora ◽  
Alex Mosseler ◽  
John E Major
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Picea Rubens ◽  
Red Spruce ◽  
Past Century ◽  
Stage Of Development ◽  
Outcrossing Rates ◽  
Population Sizes ◽  
Allozyme Loci ◽  
Filled Seeds

Red spruce (Picea rubens Sarg.) has become increasingly rare across large portions of its range in eastern North America as a result of a general and widespread decline over the past century. Genetic diversity, population genetic structure, outcrossing rates in the filled seeds, and actual inbreeding levels were characterized in five small, isolated, remnant red spruce populations from the disjunct northwestern limits of its range in Ontario and five populations from the larger, more extensive Maritime populations of Nova Scotia and New Brunswick to determine genetic and reproductive status, to provide some benchmarks for monitoring genetic changes resulting from isolation and restricted population sizes, and to assist the development of restoration and conservation strategies. Thirty-seven allozyme loci coding for 15 enzymes were used for genetic diversity assessments, and six of the most polymorphic loci were used for mating system determination. On average, 29.1% (95% criterion) of the loci were polymorphic, the number of alleles per locus was 1.60, and the observed and expected heterozygosities were 0.097 and 0.100, respectively. The Ontario populations were comparable to or slightly less genetically variable than those from the Maritimes. Only 4.7% of the detected genetic variation was among stands; the remainder was among individuals within stands. The Maritime populations were genetically less differentiated from each other than those in Ontario. With the exception of three Maritime populations clustering tightly in one group, there was no clear separation of Ontario red spruce populations from Maritime red spruce populations based on genetic distance as well as canonical discriminant analyses. The average multilocus (tm) and single-locus (ts) population outcrossing rates were 0.595 and 0.558, respectively, indicating a comparatively high tolerance for inbreeding up to the filled seed stage of development in red spruce. The Ontario populations, on average, showed higher outcrossing rates (tm = 0.654, ts = 0.641) than the Maritime populations (tm = 0.535, ts = 0.475). Individual family outcrossing rates were similar to their respective population outcrossing rates and no significant differences were observed among families within populations for the multilocus estimates. When such high levels of inbreeding in filled seeds were combined with the proportions of empty (post-pollination-aborted) seeds, it appears that actual inbreeding levels may vary from 48 to 86%. The highest inbreeding levels occurred in the smallest, most isolated Ontario populations and in those populations most likely to have been affected by poorer pollination conditions. Allozyme variation indicates that in the short term, extant remnants of Ontario red spruce have maintained their genetic diversity and integrity. For artificial restoration of red spruce in Ontario, local seed sources could be used without undue concern over losses of genetic diversity. However, over the longer term, genetic drift and inbreeding may be expected to result in further losses of genetic diversity and (or) reproductive fitness if population sizes, numbers, and distribution continue to decline.Key words: Picea rubens, allozymes, gene conservation, restoration, genetic diversity, population structure, outcrossing rates, inbreeding.

Low genetic diversity at allozyme loci in Juglans cinerea

2000 ◽  
Vol 78 (9) ◽  
pp. 1238-1243 ◽  
Author(s):  
Ricardo Morin ◽  
Jean Beaulieu ◽  
Marie Deslauriers ◽  
Gaëtan Daoust ◽  
Jean Bousquet
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Deciduous Forest ◽  
Polymorphic Locus ◽  
Natural Populations ◽  
Minor Component ◽  
Temperate Deciduous Forest ◽  
Juglans Cinerea ◽  
Low Genetic Diversity ◽  
Allozyme Loci

Butternut (Juglans cinerea L.) is a minor component of the temperate deciduous forest region of northeastern North America, but it is severely affected by the butternut canker (Sirococcus clavigignenti-juglandacearum Nair, Kostichka, and Kuntz) in the southern part of its natural range. Genetic diversity and population structure in as-yet unaffected or only slightly affected natural populations were evaluated at 12 isozyme loci. The genetic diversity estimates were low with values much below those estimated in other species of the same genus or in boreal tree species, with 25 and 13.9% polymorphic loci at the species and population levels, respectively; 1.3 and 2.3 alleles per locus and per polymorphic locus, respectively, at the species level; and an average observed heterozygosity of 0.028. Population differentiation was low, with the exception of one unique population. The implications for advanced conservation are discussed.Key words: butternut, isozymes, Sirococcus, canker, population structure.

Genetic Diversity and Population Genetic Structure in the Rare Chittering Grass Wattle, Acacia anomala Court

1988 ◽  
Vol 36 (3) ◽  
pp. 273 ◽  
Author(s):  
DJ Coates
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Genetic System ◽  
Small Population ◽  
Vegetative Multiplication ◽  
The Mean ◽  
Allozyme Loci

There are 10 known populations of Acacia anomala occurring in two small disjunct groups some 30 km apart. The Chittering populations reproduce sexually whereas the Kalamunda populations appear to reproduce almost exclusively by vegetative multiplication. The level and distribution of genetic variation were studied at 15 allozyme loci. Two loci were monomorphic in all populations. In the Chittering populations the mean number of alleles per locus was 2.0 and the expected panmictic heterozygosity (genetic diversity) 0.209. In the Kalamunda populations the mean number of alleles per locus was 1.15 and the expected panmictic heterozygosity 0.079, although the observed heterozygosity of 0.150 was only marginally less than the Chittering populations (0.177). These data support the contention that the Chittering populations are primarily outcrossing whereas the Kalamunda populations are clonal, with each population consisting of individuals with identical and, in three of the four populations, heterozygous, multilocus genotypes. The level of genetic diversity within the Chittering populations is high for plants in general even though most populations are relatively smsll and isolated. It is proposed that either the length of time these populations have been reduced in size and isolated is insufficient for genetic diversity to be reduced or the genetic system of this species is adapted to small population conditions. Strategies for the adequate conservation of the genetic resources of Acacia anomala are discussed.

Genetic diversity and population structure of disjunct Newfoundland and central Ontario populations of eastern white pine (Pinus strobus)

1998 ◽  
Vol 76 (3) ◽  
pp. 500-508 ◽  
Author(s):  
Om P Rajora ◽  
Linda DeVerno ◽  
Alex Mosseler ◽  
David J Innes
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Pinus Strobus ◽  
Population Bottleneck ◽  
Genetic Distances ◽  
Population Variation ◽  
White Pine ◽  
Eastern White Pine ◽  
Genetic Diversity And Structure ◽  
Allozyme Loci

The dramatic decline of eastern white pine (Pinus strobus L.) populations in Newfoundland over the past 100 years presents an opportunity to determine and monitor population bottleneck effects on genetic diversity in trees. To provide benchmarks and indicators for monitoring genetic changes due to recent and future bottleneck events and to assist development of conservation strategies, we assessed genetic diversity and structure of six small, isolated white pine populations from two regions at the limits of its geographical range in Newfoundland for comparison with three populations from its central range in Ontario for 20 allozyme loci coding for 12 enzymes. On average, 47.8% of the loci were polymorphic, the number of alleles per locus was 1.75, and the observed and expected heterozygosities were 0.215 and 0.195, respectively. Although most of the alleles were widespread, unique alleles were found in three of the nine populations examined. The Newfoundland populations were as genetically variable as those from Ontario. Generally, all populations exhibited slight excess of heterozygotes at most loci. Only 6.1% of the detected genetic variation was among populations, and the remainder among individuals within populations. The genetic distances among the populations within a province or region were as great as those among populations between the provinces or regions. Canonical discriminant functions and cluster analysis from genetic distances separated nine populations into the same four groups. Neither provincial nor regional or geographic gradient-related patterns of population variation and differentiation were apparent. It appears that 8000 years of postglacial geographic isolation and recent population decline have had little or no detectable effect on genetic diversity or differentiation of disjunct Newfoundland white pine populations from their ancestral mainland populations. Assuming their adaptability, the Ontario seed sources may be acceptable for white pine restoration in Newfoundland.Key words : Pinus strobus, allozymes, gene conservation, genetic diversity and population structure, genetic drift, population bottleneck.

The Breeding System, Genetic Diversity and Pollen Sterility in Eucalyptus pulverulenta, a Rare Species With Small Disjunct Populations

1990 ◽  
Vol 38 (6) ◽  
pp. 559 ◽  
Author(s):  
GB Peters ◽  
JS Lonie ◽  
GF Moran
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Rare Species ◽  
Population Genetic ◽  
Pollen Sterility ◽  
Species Range ◽  
Disjunct Distribution ◽  
Eastern Australia ◽  
The Mean ◽  
Allozyme Loci

There are eight known populations of E. pulverulenta, which has a disjunct distribution in south-eastern Australia. Levels of genetic variation were studied in four populations of about 5000 plants in all. Of a total of 16 allozyme loci examined eight were polymorphic, but the level of polymorphism was generally low. Within populations there was a mean 1.42 alleles per locus. Both the total species and mean population genetic diversities were low for a tree species (0.10 and 0.07 respectively), while the between-population genetic diversity was high at 30%. These data are consistent with the effects expected of genetic drift. Population structure may thus have been critical in determining levels of genetic diversity throughout the species' range. Analysis of half-sib arrays in three populations showed that the mean outcrossing rate (t) was 70%, comparable to values from other Eucalyptus species. The mean level of inbreeding (Wright's F) was 0.19, although both F and t varied considerably between populations. Significant levels of pollen sterility have been reported in this species, and data presented here show that this trait extends through much of the species' range. Overall, these data suggest that neither its disjunct population structure nor its tendency to male sterility caused the species' detectable level of outcrossing to differ markedly from levels reported in other eucalypt species. However, it remains possible that pollen sterility may have had some effect in at least one population. Strategies for conservation of this rare species are also considered.

A Cline in Genetic Diversity in River She-Oak Casuarina cunninghamiana

1989 ◽  
Vol 37 (2) ◽  
pp. 169 ◽  
Author(s):  
GF Moran ◽  
JC Bell ◽  
JW Turnbull
Keyword(s):  
Genetic Diversity ◽  
Significant Positive Correlation ◽  
Population Level ◽  
Geographic Range ◽  
Northern Territory ◽  
Height Growth ◽  
Western Population ◽  
Casuarina Cunninghamiana ◽  
Total Genetic Diversity ◽  
Allozyme Loci

Twenty populations of Casuarina cunninghamiana Miq. covering its large geographic range were used in a study of genetic diversity. Genetic variation was measured by analysing 19 allozyme loci using 50 seedlings from each of the populations. The overall genetic diversity (HT = 0.287) in C. cunninghamiana is high compared to many other plant species. A significant fraction (26.4%) of the total genetic diversity could be apportioned among populations. This genetic differentiation between populations was not random. Populations in the eastern part of the range had high correlation (r = 0.91) of genetic diversity with latitude and this involved changes in allelic frequencies at several loci. At the population level, there was a significant positive correlation between genetic diversity and 1 year height growth. The western population from King River in the Northern Territory was very distinct genetically from all the other populations and this supported previous suggestions that the northwest part of the range is occupied by a different race of the species.

Allozyme variation and population structure of Carex humilis var. nana (Cyperaceae) in Korea

2001 ◽  
Vol 79 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Man Kyu Huh
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
North American ◽  
Population Level ◽  
Allozyme Variation ◽  
Population Divergence ◽  
Geographic Ranges ◽  
The Mean ◽  
Allozyme Loci

Genetic diversity and population structure of 22 Carex humilis var. nana Ohwi (Cyperaceae) populations in Korea were determined using genetic variation at 23 allozyme loci. This is a long-lived herbaceous species with a widespread distribution in eastern Asia. The 12 enzymes revealed 23 putative loci, of which 11 were polymorphic (47.8%). Genetic diversity at the varietal level and at the population level was 0.131 and 0.118, respectively. Total genetic diversity (HT = 0.274) and within population genetic diversity (HS = 0.256) were high, whereas the extent of the population divergence was relatively low (GST = 0.068). An indirect estimate of the number of migrants per generation (Nm = 3.42) indicated that gene flow was high among Korean populations. Wide geographic ranges, perennial herbaceous nature, and the persistence of multiple generations are associated with the high level of genetic variation. A distinct difference between Asian and North American Carex is shown in the proportion of genetic variation (GST) (p < 0.001). The mean GST of Asian Carex was estimated as 0.056; thus, only 5.6% of genetic variability was distributed among populations, whereas the mean GST of North American Carex was estimated as 19.5% (3.5 times higher). It is probable that the geographical distance between population pairs and presence or absence of glacial history may play roles in the substantial difference between both groups.Key words: Carex humilis var. nana, genetic diversity, population structure.

Evolutionary Processes and Theory: The Ecological-Genetics Interface

1993 ◽  
Vol 27 (7-8) ◽  
pp. 489-496 ◽  
Author(s):  
Eviatar Nevo
Keyword(s):  
Genetic Diversity ◽  
Life Histories ◽  
Natural Populations ◽  
Evolutionary Process ◽  
Ecological Factors ◽  
Ecological Genetics ◽  
Dna Polymorphisms ◽  
Starch Gel Electrophoresis ◽  
Biological Variables ◽  
Allozyme Loci

The evolutionary process is reviewed in terms of the ecological-genetics interface based on genetic diversity in natural populations of plants and animals, using the environmental-genetic correlation methodology at three geographic levels: (1) Local, several species in Israeli microsites; (2) Regional, 21 species across Israel and 2 species in the Near East; and (3) Global, 1111; 184 and 189 species in three studies across the planet. The species analyzed are taxonomically unrelated, and vary in their ecologies, demographies, life histories, and other biological variables. They were mostly tested by horizontal starch gel electrophoresis for allozymic diversity, averaging 25 gene loci, and other genetic polymorphisms. In addition, ten studies involved DNA polymorphisms. The following results were found at all three geographic levels: (1) The levels of genetic diversity vary nonrandomly and are structured within and among populations, species, and higher taxa; and (2) Genetic diversity is correlated with niche width, and partly predictable, primarily by ecological factors. These results corroborate the adaptive, environmental theory of genetic diversity. They were also verified for several allozyme loci in controlled laboratory experiments in pollution biology. Natural selection in its various forms appears to be a major force maintaining, differentiating and orienting evolutionary change in protein and DNA polymorphisms.

Low genetic diversity at allozyme loci in Juglans cinerea

2000 ◽  
Vol 78 (9) ◽  
pp. 1238-1243 ◽  
Author(s):  
Ricardo Morin ◽  
Jean Beaulieu ◽  
Marie Deslauriers ◽  
Gaëtan Daoust ◽  
Jean Bousquet
Keyword(s):  
Genetic Diversity ◽  
Juglans Cinerea ◽  
Low Genetic Diversity ◽  
Allozyme Loci
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