Year: 2022

NO RECOMBINATION OF SEX CHROMOSOMES. "Whatever the mechanism, loss of X–Y recombination has occurred in different taxa, including repeated events in different fairly closely related lineages of birds and insects (Drosophila and mosquitoes, which have different sex chromosome gene content." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

RECOMBINATION SUPPRESSION. "The fact that this evolutionary change occurs repeatedly suggests that recombination suppression between the sex chromosomes was actively favoured by selection, rather than being a consequence of rearrangements such as occasionally occur on all chromosomes." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

SELECTION FAVORED. "Sex chromosomes can evolve in several different ways, and that recombination suppression is favoured when genes are involved that interact with sex with respect to their effects on fitness." https://lnkd.in/gCh5RAX View in LinkedIn

SELECTION FAVORED. "Sex chromosomes can evolve in several different ways, and that recombination suppression is favoured when genes are involved that interact with sex with respect to their effects on fitness." https://lnkd.in/gCh5RAX View in LinkedIn

VIROID FRAGMENT ACCUMULATION. "Transposable element accumulation is probably an early effect of restricted recombination, so one of the first changes affecting sex chromosomes may be increased DNA content. Plant Y chromosomes are often larger than the X chromosomes, consistent with recent origins." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

ACCUMULATED VIROIDS. "The large chromosome size does not imply absence of genetic degeneration, nor a high expressed gene content. On the other hand, accumulation of repetitive sequences such as transposable elements on the Y does not necessarily imply degeneration. It may merely be a sign that recombination is rare." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

REASONS FOR VIROID ACCUMULATION. "The reasons for transposable element build-up probably involve several processes. Elements that would normally be eliminated by ectopic exchange may fail to be eliminated from the neo-Y, due to lack of recombination. The efficacy of selective removal will also be reduced because of low recombination rates." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

"GENETIC DEGENERATION may be partly driven by this accumulation, or may occur independently later on. In the D. miranda neo-Y, transposable elements appear to be inserted either into introns or intergenic sequences, and hence do not directly disrupt gene function (although one insertion causes downregulation of a gene." https://lnkd.in/gCh5RAX View in LinkedIn

"GENETIC DEGENERATION may be partly driven by this accumulation, or may occur independently later on. In the D. miranda neo-Y, transposable elements appear to be inserted either into introns or intergenic sequences, and hence do not directly disrupt gene function (although one insertion causes downregulation of a gene." https://lnkd.in/gCh5RAX View in LinkedIn

REDUCED EXPRESSION. "It is possible that a build-up of transposable elements on a proto-Y or neo-Y could reduce gene expression on these chromosomes, through chromatin modification due to dsRNA interference, which is known to be associated with the presence of transposable elements." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn