TJT2
2024-08-29 01:37:48 UTC
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PermalinkIn all the studies, the mean fitness or mean of fitness related traits
declined over time, suggesting that the net effect of spontaneous mutation
is indeed deleterious. Mean decline of the fitness components of MA lines
ranged from 0.1% to 1-2% per generation. Although the reliability of control
populations used to assess erosion of components of fitness has been
questioned (especially for Mukai's experiments: Keightley, 1996); fitness
erosion seems to be the rule over a broad range of organisms.
Estimation of spontaneous genome-wide mutation rate parameters: whither
beneficial mutations?
Thomas Bataillon
Heredity volume 84, pages 497-501 (2000)
Ja Y-kromosomisikin on evotiedemiesten mukaan ihan rappiolla, kaikenlaisia
höpönlöpöjä nuo evotiedemiehet ja evotiedenainen kehtaavatkin väittää,
onneksi sinä, Turo Juurakko, olet täällä kertomassa miten sekin vain
kehittyy, vai mites tää nyt menee??
...extensive genetic decay has resulted in the human Y chromosome losing 97%
of its ancestral gene
Extinction of chromosomes due to specialization is a universal occurrence
Jason Wilson, Joshua M. Staley & Gerald J. Wyckoff
Scientific Reports volume 10, Article number: 2170 (2020)
Y chromosomes are genetically degenerate, having lost most of the active
genes that were present in their ancestors. The causes of this degeneration
have attracted much attention from evolutionary theorists. Four major
theories are reviewed here: Muller's ratchet, background selection, the Hill
Robertson effect with weak selection, and the 'hitchhiking' of deleterious
alleles by favourable mutations
Philos Trans R Soc Lond B Biol Sci. 2000 Nov 29; 355(1403): 1563-1572.
doi: 10.1098/rstb.2000.0717
PMCID: PMC1692900
PMID: 11127901
The degeneration of Y chromosomes.
B Charlesworth and D Charlesworth
Y and W chromosomes start degenerating after they evolve a non-recombining
region that is always heterozygous in males (Y) or females (W), sometimes
losing almost all genes that were originally present on their X or Z
counterparts. A new model for such degeneration
The degeneration of Y chromosomes has been studied by evolutionary
geneticists for over 100 years
However, this simple explanation for the degeneration of Y chromosomes (and
W chromosomes of ZW systems) encounters problems, and another model has been
proposed by Lenormand et al. [6] in this issue of Current Biology.
Evolutionary biologists therefore suspect that something must accelerate the
accumulation of deleterious mutations on Y chromosomes. One possibility is
degeneration by selective interference (called DSI by Lenormand et al. [6]).
When two or more loci are closely linked, chance associations in their
allelic states cause selection at one locus to reduce the efficiency of
selection at the others [7]. On a non-recombining Y chromosome, this impedes
fixations of beneficial mutations and allows fixations of deleterious ones
Evolution: A New Idea about the Degeneration of Y and W Chromosomes
Brian Charlesworth, Deborah Charlesworth
https://doi.org/10.1016/j.cub.2020.06.008
Eikö sinua, Juurakko, yhtään häiritse että peruskoulussa, lukiossa,
telkkarissa, maallikoille tarkoitetuissa sanoma- ja tiedelehdissä, jne, ei
puhuta näistä asioista mitään, vaan höpönlöpötetään kuinka ollaan kehitytty
jostain maalle pompanneesta kalasta joka kehittyi jostain limaisesta
merimadosta, joka kehittyi alkeellisesta alkukopioitujasta?? Siis väitetään,
että trendi on alkeellisesta monimutkaiseen, vaikka evotiedemiestenkin
mukaan mennään monimutkaisesta alkeelliseeen, kunnes kuollaan sukupuuttoon.
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