scholarly journals Adaptation at specific loci. V. Metabolically adjacent enzyme loci may have very distinct experiences of selective pressures.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 913-924
Author(s):  
P A Carter ◽  
W B Watt
Keyword(s):  
Assortative Mating ◽  
Food Resource ◽  
Male Mating ◽  
Multilocus Genotype ◽  
Selective Pressures ◽  
Enzyme Loci ◽  
Genotype Frequencies ◽  
Positive Assortative Mating ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Weinberg Expectation

Abstract The polymorphic phosphoglucomutase (PGM) and glucose-6-phosphate dehydrogenase (G6PD) loci have been studied in parallel to experimental work on the phosphoglucose isomerase (PGI) polymorphism in Colias butterflies. PGI, PGM and G6PD are also autosomal in Colias. PGM and G6PD are loosely linked (and represent the first identified autosomal linkage group in Colias); they assort independently from PGI. Recombination occurs in both sexes. Neither PGM nor G6PD shows large, consistent differences in flight capacity through the day among its genotypes, as PGI does. PGM shows some change of allele frequencies, and match to Hardy-Weinberg expectation, with air temperature in middle and latter parts of the season, but not early in the season. G6PD may show some heterozygote excess over Hardy-Weinberg expectation early in the day, but more testing is needed. No evidence for differential survivorship was seen at PGM or G6PD, in contrast to PGI. At the PGM and G6PD loci, male heterozygotes are advantaged in mating with females, but without the evidence of female choice which occurs for PGI. These effects are not correlated among the three loci. There is no assortative mating at G6PD (nor at PGI). There is minor positive assortative mating of PGM heterozygotes, but it is too weak to account for the PGM-genotype-specific male mating advantage. No trends of multilocus genotype frequencies involving PGI are seen. Certain PGM-G6PD two-locus genotypes are over-represented, and others under-represented, in wild adult samples, particularly among males and uniformly among successfully mating males. Our results emphasize that enzyme loci sharing a substrate need not have common experience of the existence or strength of natural selection, and suggest initial food-resource processing and allocation as a possible context for fitness-related effects of the PGM and G6PD polymorphisms.

Size does not matter for male Marbled Salamanders (Ambystoma opacum)

2015 ◽  
Vol 93 (10) ◽  
pp. 735-740
Author(s):  
D.A. Croshaw ◽  
J.H.K. Pechmann
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Reproductive Success ◽  
Large Male ◽  
Male Mating ◽  
Ambystoma Opacum ◽  
Positive Assortative Mating ◽  
Important Trait ◽  
Breeding Groups ◽  
Gravid Females

Understanding the phenotypic attributes that contribute to variance in mating and reproductive success is crucial in the study of evolution by sexual selection. In many animals, body size is an important trait because larger individuals enjoy greater fitness due to the ability to secure more mates and produce more offspring. Among males, this outcome is largely mediated by greater success in competition with rival males and (or) advantages in attractiveness to females. Here we tested the hypothesis that large male Marbled Salamanders (Ambystoma opacum (Gravenhorst, 1807)) mate with more females and produce more offspring than small males. In experimental breeding groups, we included males chosen specifically to represent a range of sizes. After gravid females mated and nested freely, we collected egg clutches and genotyped all adults and samples of hatchlings with highly variable microsatellite markers to assign paternity. Size had little effect on male mating and reproductive success. Breeding males were not bigger than nonbreeding males, mates of polyandrous females were not smaller than those of monogamous females, and there was no evidence for positive assortative mating by size. Although body size did not matter for male Marbled Salamanders, we documented considerable fitness variation and discuss alternative traits that could be undergoing sexual selection.

scholarly journals Sexual Size Dimorphism and Positive Assortative Mating in Alpine Choughs (Pyrrhocorax graculus)

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 553-556 ◽  
Author(s):  
Anne Delestrade
Keyword(s):  
Sample Size ◽  
Assortative Mating ◽  
Body Condition ◽  
Sexual Size Dimorphism ◽  
Morphological Characters ◽  
Positive Trend ◽  
Tarsus Length ◽  
Size Dimorphism ◽  
Positive Assortative Mating ◽  
Larger Sample

Abstract The degree of sexual size dimorphism in a number of different morphological characters was examined in a social corvid, the Alpine Chough, using measurements taken on 178 males and 144 females. A small amount of size dimorphism appeared in all morphological characters, and weight was the most dimorphic character. To identify if Alpine Choughs mate assortatively, measurements of mates were compared in 76 pairs. A positive assortative mating was found on tarsus length, and a small positive trend is suggested between body condition of partners, but that needs to be confirmed with a larger sample size.

scholarly journals Marry Your Like: Assortative Mating and Income Inequality

2014 ◽  
Vol 104 (5) ◽  
pp. 348-353 ◽  
Author(s):  
Jeremy Greenwood ◽  
Nezih Guner ◽  
Georgi Kocharkov ◽  
Cezar Santos
Keyword(s):  
Income Inequality ◽  
Assortative Mating ◽  
Household Income ◽  
The United States ◽  
Census Bureau ◽  
United States Census ◽  
United States Census Bureau ◽  
Positive Assortative Mating ◽  
High Level ◽  
Married Female

Has there been an increase in positive assortative mating? Does assortative mating contribute to household income inequality? Data from the United States Census Bureau suggests there has been a rise in assortative mating. Additionally, assortative mating affects household income inequality. In particular, if matching in 2005 between husbands and wives had been random, instead of the pattern observed in the data, then the Gini coefficient would have fallen from the observed 0.43 to 0.34, so that income inequality would be smaller. Thus, assortative mating is important for income inequality. The high level of married female labor-force participation in 2005 is important for this result.

scholarly journals A test of sexual isolation in Drosophila

1966 ◽  
Vol 8 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Forbes W. Robertson
Keyword(s):  
Assortative Mating ◽  
Sexual Isolation ◽  
Genetic Differences ◽  
Genetic Changes ◽  
Positive Assortative Mating ◽  
Selection For

1. A test is described for the development of sexual isolation between a wild and a derived population of D. melanogaster adapted to a new diet, containing EDTA. Other experiments had shown that adaptation to the new diet involved genetic changes in all chromosomes. Also fitness was reversed on the alternative diets under crowded competitive conditions.2. In three replicated trials flies from each population were used to establish paired cage populations, supplied with the medium to which each was adapted, and the pairs of cages were joined to allow restricted immigration between them. The experiment was run for about twenty-five generations.3. After fifteen and twenty-five generations, flies were collected from each cage to provide eggs which were cultured on the alternative diets to determine how far the members of pairs of populations differed from each other and from the foundation population. There were striking differences between the sub-populations and the parent populations, attributable to immigration between the former. Judged by the differences in performance between the sub-populations, genetic differences persisted but these were minor compared with the differences between the parent populations.4. Tests of preferential mating on the part of flies from paired sub-populations were entirely negative.5. Fourteen generations of selection for positive assortative mating failed to provide evidence of sexual isolation between the two basic populations, adapted to different diets.6. From these and other experiments it is inferred that sympatric divergence is improbable in a species like D. melanogaster.

Differences in male courtship in freshwater and marine sticklebacks (Gasterosteus aculeatus)

1983 ◽  
Vol 61 (2) ◽  
pp. 292-297 ◽  
Author(s):  
J. D. McPhail ◽  
D. E. Hay
Keyword(s):  
British Columbia ◽  
Assortative Mating ◽  
Gasterosteus Aculeatus ◽  
Threespine Stickleback ◽  
Male Courtship ◽  
First Response ◽  
Positive Assortative Mating ◽  
First Contact

Earlier studies indicated that the freshwater and marine forms of threespine stickleback (Gasterosteus aculeatus) in the Little Campbell River are genetically differentiated and that they do not mate randomly. In this study, we examine the possible contribution of male courtship to this positive assortative mating. Marine and freshwater sticklebacks were obtained from the Little Campbell River, southwestern British Columbia. Males were allowed to build nests in large aquaria and court females. The following courtship behaviours were recorded: zigzag bouts per minute, bites per minute, fanning bouts per minute, glueing, creeping through, and the male's first response. Freshwater males zigzag more, bite less, and glue more than marine males. The intensity of courtship in freshwater males depends on the form of female courted, whereas marine males do not alter their courtship with different forms of females. Freshwater males typically zigzag on first contact with a female, and marine males usually bite. This difference in male first response is independent of the type of female courted. Differences in male courtship provide a basis for positive assortative mating between the two forms of sticklebacks. We argue that selection should favour a male first response that signals genotype.

Allozyme Genotype and Differential Resistance to Mercury Pollution in the Caddisfly, Nectopsyche albida. II. Multilocus Genotypes

1992 ◽  
Vol 49 (1) ◽  
pp. 147-149 ◽  
Author(s):  
Michael J. Benton ◽  
Sheldon I. Guttman
Keyword(s):  
Survival Time ◽  
Inorganic Mercury ◽  
Differential Resistance ◽  
Single Locus ◽  
Multilocus Genotype ◽  
Starch Gel Electrophoresis ◽  
Time To Death ◽  
Multilocus Genotypes ◽  
Genotype Frequencies ◽  
Starch Gel

While a number of papers document that sensitivity to pollution is correlated with single-locus genotype, only one has addressed associations with multilocus complexes. We exposed larval caddisflies, Nectopsyche albida, to inorganic mercury and recorded individual times to death, genetically characterized each individual at six polymorphic loci by starch gel electrophoresis, and tested the effects of multilocus genotype on time to death. Two two-locus complexes and two three-locus complexes were significantly correlated with survival time. This supports earlier studies that monitoring multilocus and single-locus genotype frequencies may be useful in detecting and measuring environmental impacts; however, we disagree that variation in survival time among genotypes per se supports selectionist theory, because no heritability of resistance has been demonstrated. We also disagree that enzyme systems not exhibiting such variation are nonadaptive and discuss how the elimination of sensitive multilocus genotypes may hinder population persistence.

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