scholarly journals Sex without sex chromosomes: genetic architecture of multiple loci independently segregating to determine sex ratios in the copepod Tigriopus californicus

2015 ◽  
Vol 28 (12) ◽  
pp. 2196-2207 ◽  
Author(s):  
H. J. Alexander ◽  
J. M. L. Richardson ◽  
S. Edmands ◽  
B. R. Anholt
Keyword(s):  
Sex Chromosomes ◽  
Genetic Architecture ◽  
Sex Ratios ◽  
Tigriopus Californicus ◽  
Multiple Loci

scholarly journals Fisher vs. The Worms: Extraordinary Sex Ratios in Nematodes and the Mechanisms That Produce Them

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1793
Author(s):  
Justin Van Goor ◽  
Diane C. Shakes ◽  
Eric S. Haag
Keyword(s):  
Sex Ratio ◽  
Sperm Competition ◽  
Sex Chromosomes ◽  
Sex Ratios ◽  
Environmental Sex Determination ◽  
Fitness Advantage ◽  
Selection For ◽  
Facultative Parthenogenesis ◽  
Multicellular Organisms ◽  
Inbred Populations

Parker, Baker, and Smith provided the first robust theory explaining why anisogamy evolves in parallel in multicellular organisms. Anisogamy sets the stage for the emergence of separate sexes, and for another phenomenon with which Parker is associated: sperm competition. In outcrossing taxa with separate sexes, Fisher proposed that the sex ratio will tend towards unity in large, randomly mating populations due to a fitness advantage that accrues in individuals of the rarer sex. This creates a vast excess of sperm over that required to fertilize all available eggs, and intense competition as a result. However, small, inbred populations can experience selection for skewed sex ratios. This is widely appreciated in haplodiploid organisms, in which females can control the sex ratio behaviorally. In this review, we discuss recent research in nematodes that has characterized the mechanisms underlying highly skewed sex ratios in fully diploid systems. These include self-fertile hermaphroditism and the adaptive elimination of sperm competition factors, facultative parthenogenesis, non-Mendelian meiotic oddities involving the sex chromosomes, and environmental sex determination. By connecting sex ratio evolution and sperm biology in surprising ways, these phenomena link two “seminal” contributions of G. A. Parker. 

Genetic architecture of traits associated with reproductive barriers in Silene: Coupling, sex chromosomes and variation

2018 ◽  
Vol 27 (19) ◽  
pp. 3889-3904 ◽  
Author(s):  
Xiaodong Liu ◽  
Sophie Karrenberg
Keyword(s):  
Sex Chromosomes ◽  
Genetic Architecture ◽  
Reproductive Barriers

scholarly journals Multigenerational response to artificial selection for biased clutch sex ratios in Tigriopus californicus populations

2014 ◽  
Vol 27 (9) ◽  
pp. 1921-1929 ◽  
Author(s):  
H. J. Alexander ◽  
J. M. L. Richardson ◽  
B. R. Anholt
Keyword(s):  
Artificial Selection ◽  
Sex Ratios ◽  
Tigriopus Californicus ◽  
Selection For

scholarly journals Seed sexing revealed female bias in two Rumex species

2011 ◽  
Vol 80 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Dagmara Kwolek ◽  
Andrzej J. Joachimiak
Keyword(s):  
Sex Ratio ◽  
Sex Chromosomes ◽  
Dna Markers ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Ratio Bias ◽  
Sex Ratio Bias ◽  
Y Chromosomes ◽  
Sex Chromosome System ◽  
Female Bias

Sex-ratio bias in seeds of dioecious <em>Rumex</em> species with sex chromosomes is an interesting and still unsettled issue. To resolve gender among seeds of <em>R. acetosa</em> and <em>R. thyrsiflorus</em> (two species with an XX/XY1Y2 sex chromosome system), this work applied a PCR-based method involving DNA markers located on Y chromosomes. Both species showed female-biased primary sex ratios, with female bias greater in <em>R. acetosa</em> than in <em>R. thyrsiflorus</em>. The observed predominance of female seeds is consistent with the view that the female biased sex ratios in <em>Rumex </em>are conditioned not only postzygotically but also prezygotically.

GENETIC ARCHITECTURE OF ISOLATION BETWEEN TWO SPECIES OFSILENEWITH SEX CHROMOSOMES AND HALDANE'S RULE

Evolution ◽  
2013 ◽  
Vol 68 (2) ◽  
pp. 332-342 ◽  
Author(s):  
Jeffery P. Demuth ◽  
Rebecca J. Flanagan ◽  
Lynda F. Delph
Keyword(s):  
Sex Chromosomes ◽  
Genetic Architecture ◽  
Haldane’S Rule ◽  
Haldane's Rule

Temperature and sex chromosomes govern sex ratios of the mouthbrooding Cichlid fishOreochromis niloticus

1995 ◽  
Vol 273 (3) ◽  
pp. 216-223 ◽  
Author(s):  
Jean François Baroiller ◽  
Daniel Chourrout ◽  
Alexis Fostier ◽  
Bernard Jalabert
Keyword(s):  
Sex Chromosomes ◽  
Sex Ratios

Hatchling Sex Ratios are Independent of Temperature in Field Nests of the Long-necked Turtle, Chelodina longicollis (Testudinata : Chelidae)

1991 ◽  
Vol 18 (2) ◽  
pp. 225 ◽  
Author(s):  
M Palmer-Allen ◽  
F Beynon ◽  
a Georges
Keyword(s):  
Sex Determination ◽  
Constant Temperature ◽  
Sex Chromosomes ◽  
Sex Ratios ◽  
Seasonal Trend ◽  
Temperature Dependent ◽  
Sharp Drop ◽  
Heteromorphic Sex Chromosomes ◽  
Chelodina Longicollis ◽  
Incubation Temperatures

Eastern long-necked turtles, Chelodina longicollis, are known to lack heteromorphic sex chromosomes and to lack temperature-dependent sex determination when incubated under constant conditions. This study determined whether sex ratios of hatchlings emerging from natural nests of C. longicollis were different from that expected from constant temperature experiments. Temperatures in the eight nests monitored varied considerably each day (by 1.7-12.6�C), with eggs at the top of the nest experiencing the greatest variation (mean range 9.0�C) and eggs at the bottom experiencing least variation (mean range 5.3�C). Temperatures experienced by the top and bottom eggs differed by as much as 5.7�C at any one time. No monotonic seasonal trend was evident, but rainfall caused a sharp drop in nest temperatures. Sex ratios in hatchlings from 14 field nests of C. longicollis did not differ significantly from 1:1, a result in agreement with previous studies conducted at constant incubation temperatures in the laboratory.

scholarly journals Sex chromosome evolution, heterochiasmy and physiological QTL in the salmonid Brook Charr Salvelinus fontinalis

2017 ◽  
Author(s):  
Ben J. G. Sutherland ◽  
Ciro Rico ◽  
Céline Audet ◽  
Louis Bernatchez
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Genetic Architecture ◽  
Salvelinus Fontinalis ◽  
Sex Chromosome ◽  
Brook Charr ◽  
Determination System ◽  
Males And Females ◽  
Sex Determination System ◽  
Sex Determination Mechanisms

ABSTRACTWhole genome duplication can have large impacts on genome evolution, and much remains unknown about these impacts. This includes the mechanisms of coping with a duplicated sex determination system and whether this has an impact on increasing the diversity of sex determination mechanisms. Other impacts include sexual conflict, where alleles having different optimums in each sex can result in sequestration of genes into non-recombining sex chromosomes. Sex chromosome development itself may involve sex-specific recombination rate (i.e. heterochiasmy), which is also poorly understood. Family Salmonidae is a model system for these phenomena, having undergone autotetraploidization and subsequent rediploidization in most of the genome at the base of the lineage. The salmonid master sex determining gene is known, and many species have non-homologous sex chromosomes, putatively due to transposition of this gene. In this study, we identify the sex chromosome of Brook Charr Salvelinus fontinalis and compare sex chromosome identities across the lineage (eight species, four genera). Although non-homology is frequent, homologous sex chromosomes and other consistencies are present in distantly related species, indicating probable convergence on specific sex and neo-sex chromosomes. We also characterize strong heterochiasmy with 2.7-fold more crossovers in maternal than paternal haplotypes with paternal crossovers biased to chromosome ends. When considering only rediploidized chromosomes, the overall heterochiasmy trend remains, although with only 1.9-fold more recombination in the female than the male. Y chromosome crossovers are restricted to a single end of the chromosome, and this chromosome contains a large interspecific inversion, although its status between males and females remains unknown. Finally, we identify QTL for 21 unique growth, reproductive and stress-related phenotypes to improve knowledge of the genetic architecture of these traits important to aquaculture and evolution.

scholarly journals Sex chromosomes, sex ratios and sex gaps in longevity in plants

2021 ◽  
Author(s):  
Gabriel AB Marais ◽  
Jean-Francois Lemaitre
Keyword(s):  
Sex Chromosomes ◽  
Statistical Power ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Y Chromosomes ◽  
Adult Sex Ratio ◽  
Female Longevity ◽  
Males And Females ◽  
The Relationship

In animals, males and females can display markedly different longevity (also called sex gap in longevity, SGLs). Recent work has revealed that sex chromosomes contribute to establishing these SGLs. X-hemizygosity and toxicity of the Y chromosomes are two mechanisms that have been suggested to reduce male longevity (Z-hemizygosity and W toxicity in females in ZW systems). In plants, SGLs are known to exist but the role of sex chromosomes remains to be established. Here, by using adult sex ratio as a proxy for measuring SGLs, we explored the relationship between sex chromosome and SGLs across 43 plant species. Based on the knowledge recently accumulated in animals, we specifically asked whether: (i) species with XY systems tend to have female-biased sex ratios (reduced male longevity) and species with ZW ones tend to have male-biased sex ratios (reduced female longevity), and (ii) this patterns was stronger in heteromorphic systems compared to homomorphic ones. Our results tend to support these predictions although we lack statistical power because of a small number of ZW systems and the absence of any heteromorphic ZW system in the dataset. We discuss the implications of these findings, which we hope will stimulate further research on sex-differences in lifespan and ageing across plants.

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