Month: September 2022

GENETIC DEATH. "In several model organisms, the specific genes influencing life span have been identified and there are now numerous examples where a molecular network promotes fitness early in life only to result in senescence and decreased fitness later. These are the genetic mechanisms for the Anatagonistic Pleiotropy (AP) hypothesis." View in LinkedIn

LEAN TIME EXTENSION. "The IGF-1 signaling pathway is involved in regulating life span in several model organisms, including...nematodes, and rodents. Several loci interact in what the authors term a “survival pathway”. The authors suggest that this pathway is activated to “survive unfavorable conditions in an effort to reproduce at a later time” View in LinkedIn

BYPRODUCT OF ADAPTION? "Most evolutionary explanations of organismal senescence are based on individual selection or selective neutrality, and interpret senescence as a byproduct rather than an adaptation selected for its own sake." View in LinkedIn

FITNESS EFFECTS. "Anatagonistic Pleiotropy (AP) hypothesis and the mutation accumulation hypotheses. These hypotheses are distinguished by the early effects of genes and mutations. AP refers to traits with early positive effects that trade for or against later negative effects while mutation accumulation refers specifically to costly mutations with no fitness effect early in life." View in LinkedIn

REFERENCE FOR TODAY: Are Internal, Death-Promoting Mechanisms Ever Adaptive?" "John W Pepper, Deborah E Shelton, Armin Rashidi, and Pierre M Duran. (This reference refuses to post normally on LI). View in LinkedIn

SELECTION DECLINES WITH AGE. "Both of these hypotheses are based on the proposition that the force of natural selection declines with age, as the potential for further reproduction declines either abruptly or gradually." View in LinkedIn

"THE FAILURE OF SELECTION to maximize life span raises the question of why evolution would favor organisms that forego the potential advantage of longer reproductive lives." View in LinkedIn

ADAPTIVE OR INCIDENTAL? "In many semelparous organisms, the adaptive function of the nominal ‘death program’ is apparently to increase reproduction, with organismal death resulting as an incidental side-effect (making organismal senescence an example of “by-product death." View in LinkedIn

GOING FOR BUST. "In vertebrates, for example, the high levels of free corticosteroids that trigger rapid senescence and death also allow tissue protein to be consumed as an energy source during a brief and intensely competitive breeding season." View in LinkedIn

THE TRADE-OFF GAME. "In Pacific salmon and the marsupial Antechinus stuartii, the ability to exploit tissue protein as an energy reserve may increase reproductive success. In Octopus, the behavioral effects of optic gland secretion are likely to have an impact on hatching success, as time spent feeding is time not spent on brood care. In semelparous plants, a trade-off between survival and reproduction is supported by both experimental and comparative evidence." View in LinkedIn