Evolution Int. In this model, the polymorphism is protected. Depending on parameter values, the average effects x and y change in a more or less stepwise see Figure 5A or continuous fashion see Figure 5B.
These not only carry the genes that determine male and female traits but also those for some other characteristics as well. Here, we briefly overview some examples of the material covered in Text S1. Note that if G is small, the conditions for the maintenance of genetic variation are very strict.
However, unlike the strong selection on the X and Y determining sex linked traits in Knoxville produce, and protect themselves from, sexually antagonistic determining sex linked traits in Knoxville effects, selection on the autosomes to block them is relatively weak.
Detailed data for all individual genes and tissues are found in Additional file 1 and Additional file 2. As a consequence, different genes on the same sex chromosome, rather than pleiotropy of a single gene, can code for the multifarious phenotypes required for green-beard effects to operate.
Red depicts x and daughters and blue depicts y and sons.
Genome structure and emerging evidence of an incipient sex chromosome in Populus Tongming Yin 17Stephen P. Indeed, sex-biased expression is at present commonly used as an indicator of previously resolved sexual antagonism at the genomic level[ 1 ]. For example, gene expression studies have revealed feminisation of the X determining sex linked traits in Knoxville Drosophila melanogaster [ 10 ] and Caenohabditis elegans [ 11 ].
Consider the expression of the paternal X and Y chromosomes during spermatogenesis at a determining sex linked traits in Knoxville when the developing gametes remain functionally diploid, i. Genes encoded by the Y-chromosome also resulted in large differences in all tissues as expected, since they are only expressed in males Figure 1.
To illustrate how easily SA-GrBd-effects could evolve via competitive sib-sib-interactions consider facultative siblicide i.
SA-zygotic drive also provides an unexplored genetic route to the evolution high frequencies of fitness-reducing traits like sterility and homosexuality due to its predicted disruption to sex-specific ontogenetic pathways, as described above. If early-inactivation of the X and Y reduced the production of RNAs coded by these chromosomes during spermatogenesis, this would interfere with RNA-based epigenetic modification of genes in the developing sperm as well as the embryo see Text S1.
In birds, a maternal effect elevated yolk androgen concentrations in the barn swallow, Hirundo rustica causes enhanced growth rate of sons but reduced growth rate of daughters . Cambridge, Mass. However, the recent finding by Lemos et al.