scholarly journals Feminisation of complex traits in Drosophila melanogaster via female-limited X chromosome evolution

2020 ◽  
Author(s):  
Katrine K. Lund-Hansen ◽  
Jessica K. Abbott ◽  
Edward H. Morrow
Keyword(s):  
Genetic Variation ◽  
Body Size ◽  
X Chromosome ◽  
Complex Traits ◽  
Development Time ◽  
Chromosome Evolution ◽  
Reproductive Fitness ◽  
Male Genome ◽  
X Chromosome Evolution ◽  
Locomotion Activity

AbstractA handful of studies have investigated sexually antagonistic constraints on obtaining sex-specific fitness optima, though exclusively through male-genome-limited evolution experiments. In this paper, we established a female-limited X chromosome evolution experiment, where we used an X chromosome balancer to enforce the inheritance of the X chromosome through the matriline, thus removing exposure to male selective constraints. This approach eliminates the effects of sexually antagonistic selection on the X chromosome, permitting evolution towards a single sex-specific optimum. After multiple generations of selection, we found strong evidence that body size and development time had moved towards a female-specific optimum, whereas reproductive fitness and locomotion activity remained unchanged. The changes in body size and development time are consistent with previous results, and suggest that the X chromosome is enriched for sexually antagonistic genetic variation controlling these traits. The lack of change in reproductive fitness and locomotion activity could be due to a number of mutually non-exclusive explanations, including a lack of sexually antagonistic variance on the X chromosome or confounding effects of the use of the balancer chromosome. This study is the first to employ female-genome-limited selection and adds to the understanding of the complexity of sexually antagonistic genetic variation.

scholarly journals Feminization of complex traits in Drosophila melanogaster via female‐limited X chromosome evolution*

Evolution ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 2703-2713 ◽  
Author(s):  
Katrine K. Lund‐Hansen ◽  
Jessica K. Abbott ◽  
Edward H. Morrow
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Complex Traits ◽  
Chromosome Evolution ◽  
X Chromosome Evolution

scholarly journals The microevolutionary response to male-limited X-chromosome evolution in Drosophila melanogaster reflects macroevolutionary patterns

2019 ◽  
Author(s):  
Jessica K. Abbott ◽  
Adam K. Chippindale ◽  
Edward H. Morrow
Keyword(s):  
Genetic Variation ◽  
Sexual Dimorphism ◽  
X Chromosome ◽  
Experimental Evolution ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Direct Effects ◽  
Metabolic Genes ◽  
X Chromosome Evolution ◽  
Trans Regulation

AbstractDue to its hemizygous inheritance and role in sex determination, the X chromosome is expected to play an important role in the evolution of sexual dimorphism, and to be enriched for sexually antagonistic genetic variation. By forcing the X chromosome to only be expressed in males over >40 generations, we changed the selection pressures on the X to become similar to those experienced by the Y. This releases the X from any constraints arising from selection in females, and should lead to specialization for male fitness, which could occur either via direct effects of X-linked loci or trans-regulation of autosomal loci by the X. We found evidence of masculinization via upregulation of male-benefit sexually antagonistic genes, and downregulation of X-linked female benefit genes. Interestingly, we could detect evidence of microevolutionary changes consistent with previously documented macroevolutionary patterns, such as changes in expression consistent with previously established patterns of sexual dimorphism, an increase in the expression of metabolic genes related to mitonuclear conflict, and evidence that dosage compensation effects can be rapidly altered. These results confirm the importance of the X in the evolution of sexual dimorphism and as a source for sexually antagonistic genetic variation, and demonstrate that experimental evolution can be a fruitful method for testing theories of sex chromosome evolution.

scholarly journals Seasonality and genetic architecture of development time and body size of the birch feeding sawfly Priophorus pallipes

2001 ◽  
Vol 78 (1) ◽  
pp. 31-40 ◽  
Author(s):  
ANTTI KAUSE ◽  
JEAN-PHILIPPE MORIN
Keyword(s):  
Genetic Variation ◽  
Body Size ◽  
Diet Quality ◽  
Development Time ◽  
Genetic Correlations ◽  
Reaction Norms ◽  
High Quality ◽  
Genetic Characteristics ◽  
Mature Leaves ◽  
Final Mass

We tested, using the sawfly Priophorus pallipes feeding on leaves of mountain birch, whether the expression of genetic (co)variation of larval development time and body size can be altered by exposing larvae to diets with differential seasonal changes in quality. In nature, larvae feed mainly on mature leaves, but occasionally they are forced to consume senescing leaves. Sixty families were assayed on three experimentally simulated diets: mature leaves of high quality, senescing leaves of rapidly declining quality, and senesced leaves of low quality. The intuitively obvious positive phenotypic and genetic correlations between development time and final mass were observed when the larvae consumed leaves of stable high quality, but low and declining food quality prevented long-growing individuals and families from achieving high final mass, switching the correlations to close to zero or negative in these treatments. The amount of genetic variation for body size showed a non-linear change across the diet quality gradient, whereas genetic variation for development time increased with decreasing diet quality. The among-trait difference in the degree reaction norms crossed along the diet gradient caused the changes in the expression of genetic (co)variation within the environments. Our results show that seasonally varying diet quality induces dramatic changes in the genetic (co)variation of development time and body size, and that simultaneous analysis of reaction norms and environment-specific expression of genetic (co)variation is necessary for the understanding of the genetic characteristics underlying the construction of phenotypes in heterogeneous environments.

scholarly journals Artificial selection on male size depletes genetic variance but not covariance of life history traits in the yellow dung fly

2019 ◽  
Author(s):  
WU Blanckenhorn ◽  
V Llaurens ◽  
C Reim ◽  
Y Teuschl ◽  
E Postma
Keyword(s):  
Genetic Variation ◽  
Life History ◽  
Body Size ◽  
Artificial Selection ◽  
Development Time ◽  
Life History Traits ◽  
Genetic Variance ◽  
Genetic Correlations ◽  
Male Size ◽  
First Clutch

SUMMARYThe evolutionary potential of organisms depends on the presence of sufficient genetic variation for traits subject to selection, as well as on the genetic covariances among them. While genetic variation ultimately derives from mutation, theory predicts the depletion of genetic (co)variation under consistent directional or stabilizing selection in natural populations. We estimated and compared additive genetic (co)variances for several standard life history traits, including some for which this has never been assessed, before and after 24 generations of artificial selection on male size in the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae) using a series of standard half-sib breeding experiments. As predicted, genetic variances (VA), heritabilities (h2) and evolvabilities (IA) of body size, development time, first clutch size, and female age at first clutch were lower after selection. As independent selection lines were crossed prior to testing, we can rule out that this reduction is due to genetic drift. In contrast to the variances, and against expectation, the additive genetic correlations between the sexes for development time and body size remained strong and positive (rA = 0.8–0.9), while the genetic correlation between these traits within the sexes tended to strengthen (but not significantly so). Our study documents that the effect of selection on genetic variance is predictable, whereas that on genetic correlations is not.

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