Topic 4 : Aging Flashcards
What is Aging?
Aging (senescence) is a biological process characterized by a decline in physiological function over time.
Aging is a phenotype that can evolve and be subject to natural selection.
What is extrinsic mortality?
Death caused by external factors (e.g., predation, accidents, environmental conditions).
What is intrinsic mortality?
Death caused by internal factors (e.g., tissue deterioration, immune decline, genetic mutations).
What does the Selection Shadow Hypothesis propose?
Aging occurs because natural selection weakens its influence on traits expressed later in life.
What is the concept of deleterious mutations in aging?
Deleterious mutations affecting late-life persist because they are weakly selected against.
What is the Mutation Accumulation Theory?
Mutations that negatively impact late-life accumulate due to weak selection, leading to aging.
What does the Antagonistic Pleiotropy Theory suggest?
Some genes have effects at multiple life stages; beneficial mutations in early life may have negative effects later.
What is the Disposable Soma Theory?
There is a trade-off between energy investment in reproduction vs. somatic maintenance, leading to aging.
What is the Developmental Theory of Aging?
Some developmental pathways continue beyond their benefit, while others shut down, contributing to aging.
What evidence supports the Mutation Accumulation Theory?
Studies show that late-life diseases are linked to genetic variants that persist in populations.
How does Antagonistic Pleiotropy manifest in populations?
Evidence from opossum populations shows that lower extrinsic mortality is associated with slower aging.
What do experimental evolution studies in Drosophila reveal about aging?
High adult mortality leads to increased reproductive investment early in life but faster intrinsic aging.
How has declining extrinsic mortality impacted human evolution?
Humans in industrialized societies experience lower extrinsic mortality, leading to the evolution of extended lifespans.
What are Genome-Wide Association Studies (GWAS)?
A method for identifying genetic variations associated with traits or diseases.
What do life history trade-offs reveal about Korean eunuchs?
Reduced reproductive investment is linked to longer lifespans.
Define Aging (Senescence).
Progressive decline in biological function with age.
Define Extrinsic Mortality.
Death caused by external environmental factors.
Define Intrinsic Mortality.
Death caused by internal biological processes.
What is a Selection Shadow?
Weak natural selection on traits that affect late life.
Define Mutation Accumulation Theory.
Aging results from the buildup of late-life mutations due to weak selection.
What is Antagonistic Pleiotropy?
Genes beneficial early in life may have negative effects in later life.
What does the Disposable Soma Theory imply?
Energy trade-off between reproduction and somatic maintenance leads to aging.
What is the Developmental Theory of Aging?
Aging as a byproduct of developmental pathways.
Define Pleiotropy.
A single gene affecting multiple traits.
