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DEATH AS ADAPTIVE. "A common theme in all the hypotheses discussed above is that the organism is the primary unit of selection. In contrast, other authors have advanced alternative views for the adaptive value of programmed organismal death in a multilevel selection framework. Among those authors that accept organismal death as programmed, many also support the hypothesis that death is adaptive, generally at a level of function other than the individual organism." https://lnkd.in/ecP3KMX View in LinkedIn

ADAPTIVE DEATH. "How could an inherited trait that promotes death, rather than survival, possibly be adaptive?" https://lnkd.in/ecP3KMX View in LinkedIn

SENESCENCE AS BYPRODUCT. "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." https://lnkd.in/ecP3KMX View in LinkedIn

SO ENDS this first of two weekend Fragments on extinctions versus diversity explosions during the history of life. The staggering facts that 99% of life that ever existed has gone extinct, amounting to an estimated 5 billion species, are a snapshot of both the robustness of life, and that it hangs like a thread in the flow of time. Looking around at the diversity around us, it seems hard to fathom. But each expansive radiation of life post-extinction takes about 5 million years, as we will see next weekend. Breathtaking numbers. View in LinkedIn

INTERNAL TRIGGERS. "These experiments indicate that rapid senescence and death following reproduction in at least some semelparous animals are genetically “programmed” and internally controlled." https://lnkd.in/ecP3KMX View in LinkedIn

DIVERSITY EXPLOSIONS. “The most dramatic and creative evolutionary role of mass extinctions is the promotion of postextinction diversifications, typified most vividly by the exuberant radiation of the mammals after the demise of the dinosaurs and other reptilian clades at or near the end-Cretaceous boundary.” https://lnkd.in/epHhn4i) View in LinkedIn

SURGICAL LIFE EXTENSIONS. "Optic gland removal in O. hummelincki causes cessation of brooding, reinstates normal feeding behavior, and extends life. In fishes, removal of the gonads (Pacific salmon, lampreys) or of the pituitary gland (lampreys) and prevention of mating (eels) can substantially increase life span. Similarly in small marsupials, castration or prevention of mating can increase male life span up to that of females." https://lnkd.in/ecP3KMX View in LinkedIn

FAILURE TO CROSS. “The intervals after mass extinctions tend to be significantly enriched in taxa that failed to cross the next stage boundary, relative to other intervals before the extinction event; in other words more clades that survived a mass extinction tend to dwindle or disappear shortly after the event than would be expected by chance.” https://lnkd.in/epHhn4i) View in LinkedIn

MANIPULATION OF GRIM REAPER. "In both plants and animals, life span can be is extended by experimental manipulations of physiology and/or reproduction, indicating that senescence is not the inevitable outcome of physical constraints. For example, lifespan of semelparous annual plants can often be artificially extended by removing reproductive structures." https://lnkd.in/ecP3KMX View in LinkedIn

ENDOCRINE DEATH TRIGGERS. "In Octopus hummelincki, brooding females alter and reduce feeding behavior and die shortly after their eggs hatch. These traits are influenced by endocrine secretions from the optic gland." https://lnkd.in/ecP3KMX View in LinkedIn