Population Genetics of Ambystoma jeffersonianum and Sympatric Unisexuals Reveal Signatures of Both Gynogenetic and Sexual Reproduction

Copeia ◽  
2008 ◽  
Vol 2008 (3) ◽  
pp. 586-594 ◽  
Author(s):  
Cadhla Ramsden
Keyword(s):  
Population Genetics ◽  
Sexual Reproduction ◽  
Ambystoma Jeffersonianum

scholarly journals Meiosis in the human pathogen Aspergillus fumigatus has the highest known number of crossovers

2022 ◽  
Author(s):  
Ben Auxier ◽  
Frank Becker ◽  
Reindert Nijland ◽  
Alfons J.M. Debets ◽  
Joost van den Heuvel ◽  
...  
Keyword(s):  
Population Genetics ◽  
Aspergillus Fumigatus ◽  
Sexual Reproduction ◽  
Recombination Rate ◽  
Sexual Cycle ◽  
Human Pathogen ◽  
Crossover Rate ◽  
Eukaryotic Species ◽  
Global Spread ◽  
The Impact

Evidence from both population genetics and a laboratory sexual cycle indicate that sex is common in the fungus Aspergillus fumigatus. However, the impact of sexual reproduction has remained unclear. Here, we show that meiosis in A. fumigatus involves the highest known recombination rate, producing ~29 crossovers per chromosome. This represents the highest known crossover rate for any Eukaryotic species. We validate this recombination rate by mapping resistance to acriflavine, a common genetic marker. We further show that this recombination rate can produce the commonly encountered TR34/L98H azole-resistant cyp51A haplotype in each sexual event, facilitating its rapid and global spread. Understanding the consequences of this unparalleled crossover rate will not only enrich our genetic understanding of this emergent human pathogen, but of meiosis in general.

Why have sex? The population genetics of sex and recombination

2006 ◽  
Vol 34 (4) ◽  
pp. 519-522 ◽  
Author(s):  
S.P. Otto ◽  
A.C. Gerstein
Keyword(s):  
Population Genetics ◽  
Finite Number ◽  
Mathematical Models ◽  
Sexual Reproduction ◽  
High Frequency ◽  
Evolutionary Biology ◽  
Reproductive Age ◽  
Complex World ◽  
Theoretical Analyses ◽  
Theoretical Results

One of the greatest puzzles in evolutionary biology is the high frequency of sexual reproduction and recombination. Given that individuals surviving to reproductive age have genomes that function in their current environment, why should they risk shuffling their genes with those of another individual? Mathematical models are especially important in developing predictions about when sex and recombination can evolve, because it is difficult to intuit the outcome of evolution with several interacting genes. Interestingly, theoretical analyses have shown that it is often quite difficult to identify conditions that favour the evolution of high rates of sex and recombination. For example, fitness interactions among genes (epistasis) can favour sex and recombination but only if such interactions are negative, relatively weak and not highly variable. One reason why an answer to the paradox of sex has been so elusive is that our models have focused unduly on populations that are infinite in size, unstructured and isolated from other species. Yet most verbal theories for sex and recombination consider a finite number of genotypes evolving in a biologically and/or physically complex world. Here, we review various hypotheses for why sex and recombination are so prevalent and discuss theoretical results indicating which of these hypotheses is most promising.

Sexual Reproduction of Cryptococcus gattii: a Population Genetics Perspective

Cryptococcus ◽  
2014 ◽  
pp. 299-311 ◽  
Author(s):  
Dee Carter ◽  
Leona Campbell ◽  
Nathan Saul ◽  
Mark Krockenberger
Keyword(s):  
Population Genetics ◽  
Sexual Reproduction ◽  
Cryptococcus Gattii

scholarly journals The Population Genetics of Clonal and Partially Clonal Diploids

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1635-1644 ◽  
Author(s):  
François Balloux ◽  
Laurent Lehmann ◽  
Thierry de Meeûs
Keyword(s):  
Population Genetics ◽  
Sexual Reproduction ◽  
Extreme Values ◽  
Genotypic Diversity ◽  
Clonal Reproduction ◽  
Effective Population ◽  
Multiple Loci ◽  
Subdivided Population ◽  
Asexual Populations ◽  
Neutral Markers

Abstract The consequences of variable rates of clonal reproduction on the population genetics of neutral markers are explored in diploid organisms within a subdivided population (island model). We use both analytical and stochastic simulation approaches. High rates of clonal reproduction will positively affect heterozygosity. As a consequence, nearly twice as many alleles per locus can be maintained and population differentiation estimated as FST value is strongly decreased in purely clonal populations as compared to purely sexual ones. With increasing clonal reproduction, effective population size first slowly increases and then points toward extreme values when the reproductive system tends toward strict clonality. This reflects the fact that polymorphism is protected within individuals due to fixed heterozygosity. Contrarily, genotypic diversity smoothly decreases with increasing rates of clonal reproduction. Asexual populations thus maintain higher genetic diversity at each single locus but a lower number of different genotypes. Mixed clonal/sexual reproduction is nearly indistinguishable from strict sexual reproduction as long as the proportion of clonal reproduction is not strongly predominant for all quantities investigated, except for genotypic diversities (both at individual loci and over multiple loci).

Coevolution of hosts and parasites

Parasitology ◽  
1982 ◽  
Vol 85 (2) ◽  
pp. 411-426 ◽  
Author(s):  
R. M. Anderson ◽  
R. M. May
Keyword(s):  
Genetic Diversity ◽  
Population Genetics ◽  
Sexual Reproduction ◽  
Parasite Species ◽  
Natural Populations ◽  
Selective Force ◽  
Biological Interest ◽  
The Subject ◽  
Host Parasite ◽  
Practical Implications

The coevolution of parasites and their hosts has both general biological interest and practical implications in agricultural, veterinary and medical fields. Surprisingly, most medical, parasitological and ecological texts dismiss the subject with unsupported statements to the effect that ‘successful’ parasite species evolve to be harmless to their hosts. Recently, however, several people have explored theoretical aspects of the population genetics of host-parasite associations; these authors conclude that such associations may be responsible for much of the genetic diversity found within natural populations, from blood group polymorphisms (Haldane, 1949) to protein polymorphisms in general (Clarke, 1975, 1976) and to histocompatibility systems (Duncan, Wakeland & Klein, 1980). It has also been argued that pathogens may constitute the selective force responsible for the evolution and maintenance of sexual reproduction in animal and plant species (Jaenike, 1978; Hamilton, 1980, 1981, 1982; Bremermann, 1980).

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