Genetic Variation and Population Differentiation in Natural Populations of Cryptomeria japonica

1994 ◽  
Vol 9 (3) ◽  
pp. 191-199 ◽  
Author(s):  
NOBUHIRO TOMARU ◽  
YOSHIHIKO TSUMURA ◽  
KIHACHIRO OHBA
Keyword(s):  
Genetic Variation ◽  
Population Differentiation ◽  
Cryptomeria Japonica ◽  
Natural Populations

Genetic architecture and adaptive landscape of interior lodgepole pine (Pinuscontorta ssp. latifolia) in Canada

1995 ◽  
Vol 25 (12) ◽  
pp. 2010-2021 ◽  
Author(s):  
Chang-Yi Xie ◽  
Cheng C. Ying
Keyword(s):  
Genetic Variation ◽  
Central Region ◽  
Population Differentiation ◽  
Genetic Architecture ◽  
Lodgepole Pine ◽  
Natural Populations ◽  
High Elevation ◽  
Population Variation ◽  
Adaptive Landscape ◽  
Growth And Survival

The genetic architecture and adaptive landscape of interior lodgepole pine (Pinuscontorta ssp. latifolia Engelm. ex S. Wats.) in Canada were investigated in a provenance–family plantation located in central British Columbia. Fifty-three natural populations were sampled from three geographic regions covering the entire Canadian range, and their performance in growth and survival was recorded periodically over 20 years. Test results indicate that genetic variation among regions and among populations within regions was highly significant in all the traits investigated and accounted for, respectively, 53% and 41% of the total genetic variation in growth and 41% and 54% in survival. Within-population variation was also significant in growth but not in survival. Interior lodgepole pine in the central region demonstrated less genetic variation than in the northern and southern regions at both the population and family levels. In addition, the proportion of genetic variation associated with population was lower in the central region than in the other regions. Population differentiation in both growth and survival showed discernible elevational and geographic patterns. Regression models describing these adaptive patterns accounted for more than 80% of the among-population variation, and their veracity was verified with independent data. Populations of northern, coastal–interior transition, and high-elevation origin tended to have smaller trees with higher mortality. However, the patterns were not linear but differed in slope and (or) direction among regions. The adaptedness of populations tended to decrease as they were farther away from their origin, with a few exceptions displaying broad adaptation across more than 3° of latitude. As the test proceeded, population differentiation became more evident and adaptive clines became steeper. Some practical implications of these findings have been discussed.

scholarly journals POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 785-805
Author(s):  
P T Spieth
Keyword(s):  
Genetic Variation ◽  
Vegetative Reproduction ◽  
Vascular Plant ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Regular Feature ◽  
Local Populations ◽  
Neurospora Intermedia ◽  
Pattern Of Variation ◽  
High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

scholarly journals Female Genotypes Affect Sperm Displacement in Drosophila

Genetics ◽  
1998 ◽  
Vol 149 (3) ◽  
pp. 1487-1493 ◽  
Author(s):  
Andrew G Clark ◽  
David J Begun
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Populations ◽  
Isogenic Line ◽  
Female Fitness ◽  
Sperm Displacement ◽  
Extensive Variation ◽  
Polymorphic Genes ◽  
Displacement Parameter ◽  
Competitive Success

Abstract Differential success of sperm is likely to be an important component of fitness. Extensive variation among male genotypes in competitive success of sperm in multiply mated females has been documented for Drosophila melanogaster. However, virtually all previous studies considered the female to be a passive vessel. Nevertheless, under certain conditions female fitness could be determined by her role in mediating use of sperm from multiple males. Here we ask whether females differ among genotypes in their tendency to exhibit last-male precedence. Competition of sperm from two tester male genotypes (bwD and B3-09, a third-chromosome isogenic line from Beltsville, MD) was quantified by doubly mating female lines that had been rendered homozygous for X, second, or third chromosomes isolated from natural populations. The composite sperm displacement parameter, P2′, was highly heterogeneous among lines, whether or not viability effects were compensated, implying the presence of polymorphic genes affecting access of sperm to eggs. Genetic variation of this type is completely neutral in the absence of pleiotropy or interaction between variation in the two sexes.

scholarly journals Genetic variation in the dietary sucrose modulation of enzyme activities in Drosophila melanogaster

1984 ◽  
Vol 43 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Billy W. Geer ◽  
Cathy C. Laurie-Ahlberg
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Enzyme Activities ◽  
Glycogen Synthesis ◽  
Krebs Cycle ◽  
Natural Populations ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
High Sucrose Diet ◽  
Selection Of

SUMMARYGenetic variation in the modulating effect of dietary sucrose was assessed in Drosophila melanogaster by examining 27 chromosome substitution lines coisogenic for the X and second chromosomes and possessing different third isogenic chromosomes derived from natural populations. An increase in the concentration of sucrose from 0·1% to 5% in modified Sang's medium C significantly altered the activities of 11 of 15 enzyme activities in third instar larvae, indicating that dietary sucrose modulates many, but not all, of the enzymes of D. melanogaster. A high sucrose diet promoted high activities of enzymes associated with lipid and glycogen synthesis and low activities of enzymes of the glycolytic and Krebs cycle pathways, reflecting the physiological requirements of the animal. Analyses of variance revealed significant genetic variation in the degrees to which sucrose modulated several enzyme activities. Analysis of correlations revealed some relationships between enzymes in the genetic effects on the modulation process. These observations suggest that adaptive evolutionary change may depend in part on the selection of enzyme activity modifiers that are distributed throughout the genome.

scholarly journals GENETIC VARIATION FOR CLUTCH SIZE IN NATURAL POPULATIONS OF BIRDS FROM A REACTION NORM PERSPECTIVE

Ecology ◽  
2005 ◽  
Vol 86 (9) ◽  
pp. 2344-2357 ◽  
Author(s):  
Erik Postma ◽  
Arie J. van Noordwijk
Keyword(s):  
Genetic Variation ◽  
Clutch Size ◽  
Natural Populations ◽  
Reaction Norm

scholarly journals Behavior and Genetic Variation in Natural Populations

1970 ◽  
Vol 10 (1) ◽  
pp. 53-66 ◽  
Author(s):  
ROBERT K. SELANDER
Keyword(s):  
Genetic Variation ◽  
Natural Populations

scholarly journals Parasite variation and the evolution of virulence in a Daphnia-microparasite system

Parasitology ◽  
2007 ◽  
Vol 135 (3) ◽  
pp. 303-308 ◽  
Author(s):  
T. J. LITTLE ◽  
W. CHADWICK ◽  
K. WATT
Keyword(s):  
Genetic Variation ◽  
Rank Order ◽  
Genetic Relationships ◽  
Natural Populations ◽  
Host Genotype ◽  
Relative Growth ◽  
Trade Off ◽  
Relative Growth Rates ◽  
Pasteuria Ramosa ◽  
Evolution Of Virulence

SUMMARYUnderstanding genetic relationships amongst the life-history traits of parasites is crucial for testing hypotheses on the evolution of virulence. This study therefore examined variation between parasite isolates (the bacterium Pasteuria ramosa) from the crustacean Daphnia magna. From a single wild-caught infected host we obtained 2 P. ramosa isolates that differed substantially in the mortality they caused. Surprisingly, the isolate causing higher early mortality was, on average, less successful at establishing infections and had a slower growth rate within hosts. The observation that within-host replication rate was negatively correlated with mortality could violate a central assumption of the trade-off hypothesis for the evolution of virulence, but we discuss a number of caveats which caution against premature rejection of the trade-off hypothesis. We sought to test if the characteristics of these parasite isolates were constant across host genotypes in a second experiment that included 2 Daphnia host clones. The relative growth rates of the two parasite isolates did indeed depend on the host genotype (although the rank order did not change). We suggest that testing evolutionary hypotheses for virulence may require substantial sampling of both host and parasite genetic variation, and discuss how selection for virulence may change with the epidemiological state of natural populations and how this can promote genetic variation for virulence.

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