Year: 2022

THE ONION QUESTION. "Why does an onion require five times more of it (the genome) than a human? " https://lnkd.in/eT5V5Xc View in LinkedIn

BEYOND THE ONION. "Importantly, the comparison is not restricted to onions versus humans. It could as easily be between pufferfish and lungfish, which differ by ∼350-fold, or members of the genus Allium, which have more than a 4-fold range in genome size that is not the result of polyploidy." http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351 View in LinkedIn

CONFOUNDING PROBLEM. "Comparative genomics reinforced the complex relationships between the different levels of complexity in the most convincing manner by demonstrating the lack of a simple link between genomic and organismal complexities." http://onlinelibrary.wiley.com/doi/10.1002/bies.201300037/full View in LinkedIn

FLY IN THE OINTMENT. "Suffice it to note that the largest bacterial genomes encompass almost as many genes as some “obviously” complex animals, such as for example flies, and more than many fungi." http://onlinelibrary.wiley.com/doi/10.1002/bies.201300037/full View in LinkedIn

SO ENDS this first of two weekends on reductive evolution. This report suggests that reductive evolution is not only far from being rare, rather it is a common form of evolution, characterized by explosive bursts of genomic complexity followed by slow winnowing of the chaff. This it at odds with the popular view of evolution as an inexorable ascent to complex (human) perfection. The Copernican Revolution has been slow to take hold, it seems. View in LinkedIn

THE FORMAL THEORY. "The ‘mutation accumulation’ theory, first proposed by Medawar...refers to the fact that deleterious alleles with effects restricted to late stages of life equilibrate at higher frequencies at mutation–selection balance than alleles that act earlier […].” https://lnkd.in/eDZKgvJ View in LinkedIn

IN PLAIN WORDS. "Mutation accumulation theory: From the evolutionary perspective, aging is an inevitable result of the declining force of natural selection with age." http://longevity-science.org/Evolution.htm View in LinkedIn

NUANCED EXCEPTIONS. "The results here show that there is an unexpected and far-reaching difference between effects restricted to late stages and effects only concentrated at late stages, carrying with them some small crucial share of early-age effects." http://www.pnas.org/content/110/25/10141.full View in LinkedIn

THE THEORY. "Lotka’s intrinsic rate of natural increase, with respect to an increment to age-specific mortality at an age a. Thus, he obtained a linear approximation for loss in fitness due to any deleterious mutations that raised mortality at an age a. The greater the loss in fitness, the faster should mutant alleles be selected out of a population, and the fewer should be found at equilibrium as recurring mutations balance natural selection." https://lnkd.in/eyTNv3H View in LinkedIn

THEORY CONTINUED. "At sufficiently advanced ages, remaining net fertility necessarily drops below any mutation rate that is bounded below. If the force of selection depends only on remaining net fertility, selection cannot balance mutation, and such ages must lie beyond a wall of death." http://www.pnas.org/content/110/25/10141.full View in LinkedIn