scholarly journals Digest: Survey of field-based studies identifies trends in maintenance of sex*

Evolution ◽  
2018 ◽  
Vol 72 (6) ◽  
pp. 1328-1329
Author(s):  
Nicholas Werry
Keyword(s):  
Maintenance Of Sex

On the Maintenance of Sex Chromosome Polymorphism by Sex-Antagonistic Selection

2011 ◽  
Vol 178 (4) ◽  
pp. 515-524 ◽  
Author(s):  
Olivier Blaser ◽  
Samuel Neuenschwander ◽  
Nicolas Perrin
Keyword(s):  
Sex Chromosome ◽  
Chromosome Polymorphism ◽  
Antagonistic Selection ◽  
Maintenance Of Sex

scholarly journals When does parasitism maintain sex in the absence of Red Queen Dynamics?

2020 ◽  
Author(s):  
Ben Ashby
Keyword(s):  
Population Density ◽  
Sexual Reproduction ◽  
Evolutionary Model ◽  
Niche Overlap ◽  
Disease Prevalence ◽  
Heterozygote Advantage ◽  
Red Queen ◽  
Fluctuating Selection ◽  
Antagonistic Coevolution ◽  
Maintenance Of Sex

AbstractParasites can select for sexual reproduction in host populations, preventing replacement by faster growing asexual lineages. This is usually attributed to so-called “Red Queen Dynamics” (RQD), where antagonistic coevolution causes fluctuating selection in allele frequencies, which provides sex with an advantage over asex. However, parasitism may also maintain sex in the absence of RQD when sexual populations are more genetically diverse – and hence more resistant, on average – than clonal populations, allowing sex and asex to stably coexist. While the maintenance of sex due to RQD has been studied extensively, the conditions that allow sex and asex to stably coexist have yet to be explored in detail. In particular, we lack an understanding of how host demography and parasite epidemiology affect the maintenance of sex in the absence of RQD. Here, I use an eco-evolutionary model to show that both population density and the type and strength of virulence are important for maintaining sex, which can be understood in terms of their effects on disease prevalence and severity. In addition, I show that even in the absence of heterozygote advantage, asexual heterozygosity affects coexistence with sex due to variation in niche overlap. These results reveal which host and parasite characteristics are most important for the maintenance of sex in the absence of RQD, and provide empirically testable predictions for how demography and epidemiology mediate competition between sex and asex.

scholarly journals Quantifying the prevalence of assortative mating in a human population

2019 ◽  
Author(s):  
Klaus Jaffe
Keyword(s):  
Assortative Mating ◽  
Genetic Relatedness ◽  
Random Mating ◽  
Human Populations ◽  
Genetic Composition ◽  
Genetic Studies ◽  
Maintenance Of Sex ◽  
Animal Populations ◽  
The Uk ◽  
First Time

AbstractFor the first time, empirical evidence allowed to construct the frequency distribution of a genetic relatedness index between the parents of about half a million individuals living in the UK. The results suggest that over 30% of the population is the product of parents mating assortatively. The rest is probably the offspring of parents matching the genetic composition of their partners randomly. High degrees of genetic relatedness between parents, i.e. extreme inbreeding, was rare. This result shows that assortative mating is likely to be highly prevalent in human populations. Thus, assuming only random mating among humans, as widely done in ecology and population genetic studies, is not an appropriate approximation to reality. The existence of assortative mating has to be accounted for. The results suggest the conclusion that both, assortative and random mating, are evolutionary stable strategies. This improved insight allows to better understand complex evolutionary phenomena, such as the emergence and maintenance of sex, the speed of adaptation, runaway adaptation, maintenance of cooperation, and many others in human and animal populations.

scholarly journals The Maintenance of Sex in Bacteria Is Ensured by Its Potential to Reload Genes

Genetics ◽  
2006 ◽  
Vol 174 (4) ◽  
pp. 2173-2180 ◽  
Author(s):  
Gergely J. Szöllősi ◽  
Imre Derényi ◽  
Tibor Vellai
Keyword(s):  
Maintenance Of Sex

Artificial Life as a Tool for Biological Inquiry

1993 ◽  
Vol 1 (1_2) ◽  
pp. 1-13 ◽  
Author(s):  
Charles Taylor ◽  
David Jefferson
Keyword(s):  
Cultural Evolution ◽  
Artificial Life ◽  
Living Systems ◽  
Grand Challenge ◽  
Open Problems ◽  
Maintenance Of Sex ◽  
Open Questions ◽  
Shifting Balance ◽  
The Origin Of Life ◽  
Natural Life

Artificial life embraces those human-made systems that possess some of the key properties of natural life. We are specifically interested in artificial systems that serve as models of living systems for the investigation of open questions in biology. First we review some of the artificial life models that have been constructed with biological problems in mind, and classify them by medium (hardware, software, or “wetware”) and by level of organization (molecular, cellular, organismal, or population). We then describe several “grand challenge” open problems in biology that seem especially good candidates to benefit from artificial life studies, including the origin of life and self-organi- zation, cultural evolution, origin and maintenance of sex, shifting balance in evolution, the relation between fitness and adaptedness, the structure of ecosystems, and the nature of mind.

scholarly journals A theoretical test of the DNA repair hypothesis for the maintenance of sex in eukaryotes

1991 ◽  
Vol 58 (2) ◽  
pp. 157-165 ◽  
Author(s):  
Eörs Szathmáry ◽  
Szilvia Kövér
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Essential Feature ◽  
Genetic System ◽  
Sexual Population ◽  
Maintenance Of Sex ◽  
Successful Establishment ◽  
Heterozygous Form ◽  
Theoretical Test ◽  
Double Strand Dna

SummaryThe DNA repair hypothesis for the maintenance of sex states that recombination is necessary for the repair of double-strand DNA damage. In a closed (mitotic) genetic system crossing-over generates homozygosity. This reduces fitness if deleterious recessive alleles become expressed. Thus, outcrossing is required to restore heterozygosity destroyed by recombination. The repair hypothesis is tested by comparing outcrossing sexuality with a hypothetical parthenogenic strategy (the Prudent Reparator) which destroys as little heterozygosity during repair as possible. In the Prudent Reparator, repair of double-strand DNA damage results in a small amount of homozygosity due to gene conversion only, since this process does not render outside markers homozygous. Diploidy, deleterious recessives, multiplicative fitness and linkage equilibrium in mutation-selection balance are assumed. The average fitness of this population increases, and complementation (i.e. masking of recessives in heterozygous form) decreases with the rate of damage per locus. The equilibrium fitness of the Prudent Reparator can be well above that of the sexual population. A lower complementation ability of parthenogens may not be an impenetrable barrier to their successful establishment if the invader's genome is relatively uncontaminated by mutant alleles: there are always such genotypes in the sexual population. Thus, the Prudent Reparator could solve the problem of repairing damage as well as that of invading an existing outcrossing population. As we do not see this strategy widely adopted instead of sexuality, the repair hypothesis is likely to miss some essential feature of the evolution of sex.

Sex-dependent effect of streptozotocin-induced diabetes mellitus on hepatic steroid metabolism in the rat

1986 ◽  
Vol 111 (2) ◽  
pp. 217-221 ◽  
Author(s):  
Paul Skett
Keyword(s):  
Diabetes Mellitus ◽  
Sex Differences ◽  
Drug Metabolism ◽  
Rat Liver ◽  
Steroid Metabolism ◽  
Hydroxylase Activity ◽  
Dependent Effect ◽  
Maintenance Of Sex ◽  
Streptozotocin Induced Diabetes

Abstract. Diabetes mellitus is known to affect drug and steroid metabolism in the rat liver. Recently it has been shown that the effect on drug metabolism is both transient and sex-dependent. This study shows that the effect of diabetes on steroid metabolism is also sex-dependent i.e. only seen in the male and the effect is always to abolish the sex differences in steroid metabolism found in the intact animals. 7α-hydroxylase activity, which is higher in the female, is increased by diabetes in the male whereas 6β-hydroxylase, 16α-hydroxylase and 17-oxosteroid reductase, which are all higher in the male, are decreased by diabetes. This is a very similar result to that found for drug metabolism and indicates that insulin plays a role in the maintenance of sex differences in hepatic steroid metabolism in the rat as it does for drug metabolism.

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