0 0 adult dating x y
In addition to dosage compensation, natural selection is expected to behave differently on the sex chromosomes vs.
When dividing the X chromosome into regions based on linkage groups, we discovered that genes in the first reported X-linked region, anole linkage group b (LGb), exhibit complete dosage compensation, although the rest of the X-linked genes exhibit incomplete dosage compensation.
Dosage compensation is a process whereby genes on the sex chromosomes achieve equal gene expression.
We compared genome-wide levels of transcription between males and females, and between the X chromosome and the autosomes in the green anole, s.
If most new mutations are recessive, then natural selection will be more efficient on the X chromosome, both removing harmful variants and also increasing the frequency of beneficial X-linked variants.
The latter process is expected to generate a higher ratio of non-synonymous to synonymous substitutions on the X chromosome than the autosomes—a phenomenon called the fast-X effect (Vicoso and Charlesworth 2006; Meisel and Connallon 2013).
Fast-X (which is equivalently called fast-Z in species with ZZ/ZW sex determination) has been reported across species with male- and female-heterogametic chromosomal sex determination, including fruit flies (Thornton and Long 2002), birds (Mank et al. Other factors may result in a similar signature: genetic drift on the Z chromosome relative to the autosomes has also been shown to result in a "fast-X" effect (Mank et al. Genomic analyses are crucial for a comprehensive picture of anole sex chromosome differentiation, dosage compensation, and signatures of natural selection. The identification of many genomic regions that are haploid in males but diploid in females suggest that the Y chromosome may be highly degenerated and, if it exists at all, has lost much of the ancestral sex chromosome content during the course of evolution (Rovatsos et al. Y-linked degeneration is expected to result in changes in X-linked transcript levels, a form of dosage compensation to achieve similar X-linked expression in males and females (Wilson Sayres and Makova 2013).