scholarly journals Multiple factors influence population sex ratios in the Mojave Desert moss Syntrichia caninervis

2016 ◽  
Author(s):  
Jenna T. Baughman ◽  
Adam C. Payton ◽  
Amber E. Paasch ◽  
Kirsten M. Fisher ◽  
Stuart F. McDaniel
Keyword(s):  
Sex Ratio ◽  
Mojave Desert ◽  
Natural Populations ◽  
Sex Expression ◽  
Differential Mortality ◽  
List Type ◽  
Male Mortality ◽  
Syntrichia Caninervis ◽  
Sex Ratio Bias ◽  
Female Bias

ABSTRACTPremise of research: Natural populations of many mosses appear highly female-biased based on the presence of reproductive structures. This bias could be caused by increased male mortality, lower male growth rate, or a higher threshold for achieving sexual maturity in males. Here we test these hypotheses using samples from two populations of the Mojave Desert moss Syntrichia caninervis.Methods: We used double digest restriction-site associated DNA (RAD) sequencing to identify candidate sex-associated loci in a panel of sex-expressing plants. Next, we used putative sex-associated markers to identify the sex of individuals without sex structures.Key results: We found an 18:1 phenotypic female: male sex ratio in the higher elevation site (Wrightwood), and no sex expression at the low elevation site (Phelan). In contrast, based on genetic data we found a 2:1 female bias in the Wrightwood site and only females in the Phelan site. The area occupied by male and female genets was indistinguishable.Conclusions: These data suggest that both differential mortality and sexual dimorphism in thresholds for sex expression likely contribute to population genetic and phenotypic sex ratio biases, and that phenotypic sex expression alone fails to capture the extent of actual sex ratio bias present in natural populations of S. caninervis.

The genetic basis of sex ratio in Silene alba (= S. latifolia).

Genetics ◽  
1994 ◽  
Vol 136 (2) ◽  
pp. 641-651
Author(s):  
D R Taylor
Keyword(s):  
Sex Ratio ◽  
Sex Ratios ◽  
Natural Populations ◽  
Sex Ratio Bias ◽  
Deleterious Alleles ◽  
Silene Alba ◽  
Biased Sex Ratio ◽  
Paternal Parent ◽  
Reciprocal Crossing ◽  
Female Bias

Abstract A survey of maternal families collected from natural populations showed that the sex ratio in Silene alba was slightly female biased. Sex ratio varied among populations and among families within a female biased population. Crosses among plants from the most female biased population and the most male biased population showed that the sex ratio polymorphism was inherited through or expressed in the male parent. Males from one family in particular exhibited a severe female bias, characterized by less than 20% male progeny. The inheritance of sex ratio was investigated using a reciprocal crossing design. Sex ratios from reciprocal crosses were significantly different, indicating either sex-linkage or cytoplasmic inheritance of sex ratio. The sex ratios produced by males generally resembled the sex ratios produced by their male parents, indicating that the sex ratio modifier was Y linked. The maternal parent also significantly influenced sex ratio through an interaction with the genotype of the paternal parent. Sex ratio, therefore, is apparently controlled by several loci. Although sex ratio bias in this species may be due to deleterious alleles on the Y chromosome, it is more likely to involve an interaction between loci that cause the female bias and a Y-linked locus that enhances the proportion of males in the progeny.

scholarly journals Sex expression and genotypic sex ratio vary with region and environment in the wetland moss Drepanocladus lycopodioides

2019 ◽  
Vol 192 (2) ◽  
pp. 421-434
Author(s):  
Irene Bisang ◽  
Johan Ehrlén ◽  
Lars Hedenäs
Keyword(s):  
Sex Ratio ◽  
Life Histories ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Environmental Parameters ◽  
Sex Expression ◽  
Ratio Variation ◽  
Female Flowering ◽  
Female Bias

Abstract Sex ratio variation is common among organisms with separate sexes. In bryophytes, sex chromosome segregation at meiosis suggests a balanced progeny sex ratio. However, most bryophyte populations exhibit female-biased phenotypic sex ratios based on the presence of reproductive structures on gametophytes. Many bryophyte populations do not form sexual organs, and genotypic sex ratio variation in such populations is mostly unknown. We tested sex expression, and phenotypic and genotypic sex ratios against environmental parameters in natural populations of the unisexual wetland moss Drepanocladus lycopodiodes at 11 sites in each of three regions in southern Sweden. We identified sex in 660 individual ramets, based on sexual structures, when present, or with a specifically designed molecular marker, when absent. All regions exhibited a female bias in phenotypic and genotypic sex ratios. Sex ratio biases and sex expression differed between regions. Sex ratios were less female-biased in larger patches. Wetter patches exhibited a stronger female bias in genotypic sex ratio and lower sex expression. This is the first evidence of environmental effects on genotypic sex ratio in mosses. A higher frequency of females in wet patches could be due to higher female resource demands for sporophyte production or higher male sensitivity to wetness. A higher incidence of females than males in moister sites aligns with female flowering plants, but differs from reproductive bryophytes in drier environments. Taken together with previous results, our data indicate that sex ratio variation and its drivers differ among species, their life histories and environments.

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.

scholarly journals Does polyandry control population sex ratio via regulation of a selfish gene?

2014 ◽  
Vol 281 (1783) ◽  
pp. 20133259 ◽  
Author(s):  
Tom A. R. Price ◽  
Amanda Bretman ◽  
Ana C. Gradilla ◽  
Julia Reger ◽  
Michelle L. Taylor ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Natural Populations ◽  
Low Frequency ◽  
Evolution Of Cooperation ◽  
Northern Population ◽  
Selfish Gene ◽  
Selfish Genetic Elements ◽  
Sex Ratio Bias ◽  
Intragenomic Conflict ◽  
The Usa

The extent of female multiple mating (polyandry) can strongly impact on the intensity of sexual selection, sexual conflict, and the evolution of cooperation and sociality. More subtly, polyandry may protect populations against intragenomic conflicts that result from the invasion of deleterious selfish genetic elements (SGEs). SGEs commonly impair sperm production, and so are likely to be unsuccessful in sperm competition, potentially reducing their transmission in polyandrous populations. Here, we test this prediction in nature. We demonstrate a heritable latitudinal cline in the degree of polyandry in the fruitfly Drosophila pseudoobscura across the USA, with northern population females remating more frequently in both the field and the laboratory. High remating was associated with low frequency of a sex-ratio-distorting meiotic driver in natural populations. In the laboratory, polyandry directly controls the frequency of the driver by undermining its transmission. Hence we suggest that the cline in polyandry represents an important contributor to the cline in sex ratio in nature. Furthermore, as the meiotic driver causes sex ratio bias, variation in polyandry may ultimately determine population sex ratio across the USA, a dramatic impact of female mating decisions. As SGEs are ubiquitous it is likely that the reduction of intragenomic conflict by polyandry is widespread.

Male-biased adult sex ratios in a red squirrel population

1987 ◽  
Vol 65 (5) ◽  
pp. 1284-1286 ◽  
Author(s):  
T. Andrew Hurly
Keyword(s):  
Sex Ratio ◽  
Habitat Use ◽  
Sex Ratios ◽  
Sexual Differences ◽  
Differential Mortality ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Male Mortality ◽  
Adult Sex Ratio ◽  
Sampling Biases

A 3-year study of a red squirrel population revealed that the adult sex ratio was biased towards males. There is no evidence that the skewed sex ratio was prejudiced by sampling biases due to sexual differences in mobility, observability, trappability, or habitat use. The tertiary juvenile sex ratio was even and therefore not the cause of the biased adult sex ratio. The data suggest that the skewed sex ratio may be the result of differential mortality. This is consistent with other reports of higher female than male mortality in red squirrels.

scholarly journals "Sex ratio" meiotic drive in Drosophila testacea.

Genetics ◽  
1990 ◽  
Vol 126 (3) ◽  
pp. 651-656 ◽  
Author(s):  
A C James ◽  
J Jaenike
Keyword(s):  
Sex Ratio ◽  
Genetic Factor ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Female Offspring ◽  
Species Group ◽  
Gene Arrangement ◽  
Ecological Consequence ◽  
Ratio Condition ◽  
Female Bias

Abstract We document the occurrence of "sex ratio" meiotic drive in natural populations of Drosophila testacea. "Sex ratio" males sire greater than 95% female offspring. Genetic analysis reveals that this effect is due to a meiotically driven X chromosome, as in other species of Drosophila in which "sex ratio" has been found. In contrast to other drosophilids, the "sex ratio" and standard chromosomes of D. testacea do not differ in gene arrangement, implying that the effect may be due to a single genetic factor in this species. In all likelihood, the "sex ratio" condition has evolved independently in D. testacea and in the Drosophila obscura species group, as the loci responsible for the effect occur on different chromosomal elements. An important ecological consequence of "sex ratio" is that natural populations of D. testacea exhibit a strong female bias. Because D. testacea mates, oviposits, and feeds as adults and larvae on mushrooms, this species provides an excellent opportunity to study the selective factors in nature that prevent "sex ratio" chromosomes from increasing to fixation and causing the extinction of the species.

Sex Ratio Variation in the Intertidal Isopod, Jaera Albifrons

1996 ◽  
Vol 76 (3) ◽  
pp. 825-828 ◽  
Author(s):  
Stuart B. Piertney ◽  
Gary R. Carvalho
Keyword(s):  
Environmental Factors ◽  
Sex Ratio ◽  
Natural Populations ◽  
Light Regimes ◽  
Ratio Bias ◽  
Sex Ratio Bias ◽  
Ratio Variation ◽  
South Wales

Thirty ‘rock-populations’ of the intertidal isopod, Jaera albifrons (Isopoda: Asellota), from South Wales area were found to display a significant and persistent sex ratio bias, with females outnumbering males by up to 12 to 1. This thelygeny was not mirrored in broods that were isolated in aquaria after insemination, nor in broods that developed under various temperature and light regimes. Such a discrepancy suggests that the mechanism generating sex ratio biases in natural populations is not innate, nor is influenced by cytoplasmic or environmental factors. The possible causes of thelygeny in natural populations are discussed.

scholarly journals Female bias in an immigratory population of Cnaphalocrocis medinalis moths based on field surveys and laboratory tests

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jia-Wen Guo ◽  
Fan Yang ◽  
Ping Li ◽  
Xiang-Dong Liu ◽  
Qiu-Lin Wu ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Laboratory Population ◽  
Cnaphalocrocis Medinalis ◽  
Energy Reserves ◽  
Field Surveys ◽  
Ratio Bias ◽  
Sex Ratio Bias ◽  
Insect Populations ◽  
Female Bias ◽  
Underlying Mechanisms

AbstractSex ratio bias is common in migratory animals and can affect population structure and reproductive strategies, thereby altering population development. However, little is known about the underlying mechanisms that lead to sex ratio bias in migratory insect populations. In this study, we used Cnaphalocrocis medinalis, a typical migratory pest of rice, to explore this phenomenon. A total of 1,170 moths were collected from searchlight traps during immigration periods in 2015–2018. Females were much more abundant than males each year (total females: total males = 722:448). Sex-based differences in emergence time, take-off behaviour, flight capability and energy reserves were evaluated in a laboratory population. Females emerged 0.78 days earlier than males. In addition, the emigratory propensity and flight capability of female moths were greater than those of male moths, and female moths had more energy reserves than did male moths. These results indicate that female moths migrate earlier and can fly farther than male moths, resulting more female moths in the studied immigratory population.

scholarly journals A Quantitative Genetic Analysis of Nuclear-Cytoplasmic Male Sterility in Structured Populations of Silene vulgaris

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 833-841 ◽  
Author(s):  
Douglas R Taylor ◽  
Matthew S Olson ◽  
David E McCauley
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Genetic Analysis ◽  
Cytoplasmic Male Sterility ◽  
Male Sterility ◽  
Sex Expression ◽  
Silene Vulgaris ◽  
Population Variance ◽  
Quantitative Genetic ◽  
Quantitative Genetic Analysis

Abstract Gynodioecy, the coexistence of functionally female and hermaphroditic morphs within plant populations, often has a complicated genetic basis involving several cytoplasmic male-sterility factors and nuclear restorers. This complexity has made it difficult to study the genetics and evolution of gynodioecy in natural populations. We use a quantitative genetic analysis of crosses within and among populations of Silene vulgaris to partition genetic variance for sex expression into nuclear and cytoplasmic components. We also use mitochondrial markers to determine whether cytoplasmic effects on sex expression can be traced to mitochondrial variance. Cytoplasmic variation and epistatic interactions between nuclear and cytoplasmic loci accounted for a significant portion of the variation in sex expression among the crosses. Source population also accounted for a significant portion of the sex ratio variation. Crosses among populations greatly enhanced the dam (cytoplasmic) effect, indicating that most among-population variance was at cytoplasmic loci. This is supported by the large among-population variance in the frequency of mitochondrial haplotypes, which also accounted for a significant portion of the sex ratio variance in our data. We discuss the similarities between the population structure we observed at loci that influence sex expression and previous work on putatively neutral loci, as well as the implications this has for what mechanisms may create and maintain population structure at loci that are influenced by natural selection.

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