What is a Darwinian demon and what characteristics would one have?

An organism perfected for reproduction that would outcompete all other organisms. It would mature at birth, continuously produce high-quality offspring in large numbers, and live forever. There is no Darwinian demon because the environment is always changing and there are fitness tradeoffs.

    How do sand crickets solve the “trade-off” of the allocation of energy for reproduction?  

Long-winged females can disperse via wing useage, but their ovaries grow much more slowly than flightless short-winged females.  Short winged-females use extra energy to make phospholipids which they put into eggs.

 Explain two theories about the evolution of aging.

Rate of living theory – populations lack the genetic variation to respond any further to selection against aging.

Evolutionary theory – there is a trade-off between the allocation of energy to reproduction vs. repair

   Is the aging rate correlated with the rate of metabolism in mammals?

No, energy expenditure varies greatly even within orders.

 Can you force a fruit fly population to evolve greater life-spans through artificial selection, and if you can what would you say about the characteristics of these longer lived flies?

Yes, average life-span increases in Drosophila populations in response to selection for late-life reproduction.

 How and why is the cell cycle related to life-span?

? Cells die, but they divide first and thus life continues.

    Under the evolutionary theory of aging, why can’t organisms fully repair themselves?

Deleterious mutations or trade-offs between repair and reproduction.

    Is inbreeding depression related to age?  If so, how was this discovered?

Yes, inbreeding depression increases with age. Experiments on Drosophila were performed. 10 inbred crosses progeny and 90 outbred crosses progeny were compared for reproductive success at various ages. Calculated inbreeding depression as the difference in fitness between outbred vs inbred lines, divided by the fitness of outbred lines.

   Explain the antagonistic pleitropy hypothesis of aging.  Explain this using the age-1 gene and the hx546 allele of that gene.  

Mutations involve a trade-off between reproduction early in life and survival late in life. The hx546 allele of the age-1 gene increased life span in C. elegans by as much as 80%. The normal allele, however, increases reproductive success of its carriers in young adulthood.

    How do data from island opossums support the evolutionary theory of senescence?  What is ecological mortality?

Ecological mortality is mortality caused by predation, disease, and accidents. 2 pops of opossums under similar environmental conditions but different predation pressures expect that the pop with less predators will show delayed senescence. Island females did show delayed senescence. Evolutionary theory of aging states that there is a cost to repairing oneself. 

  When is natural selection stronger – early or late in life?

Early

 What is Lack’s hypothesis about the evolution of clutch size, and overall do data support it?

Selection will favor the clutch size that produces the most surviving offspring. Sometimes, if assumptions are held true: that there is no trade off between a parent’s reproductive effort in one year and its survival or reproductive performance in other years; the only effect on clutch size on offspring is determining whether the offspring survive; the discrepancy between Lack’s hypothesis and the behavior of individual birds may sometimes be more apparent than rea.

Usually, clutch size is a little bit smaller than the optimal clutch size.

    Why do hatchery salmon evolve smaller and smaller egg sizes and what are the implications of this for Salmon conservation?  How could you avoid this effect?

The hatchery provides a safe environment for young fry. Small fry are more likely to survive in the hatchery. Smaller fry have higher reproductive success. Introduced salmon cause an overall reduction in egg size due to gene flow in the wild. You might avoid this by making the hatchery seem more threatening/ more wild or by catching big males that did not swim back and used them to fertilize eggs.                       

    What is genomic imprinting?  Give an example from nature. 

*there is differential expression of the maternal and paternal genomes. One gene is silenced, the other is not. Often correlated with methylation

The marking of alleles during production of gametes that affects the transcription of the marked genes within cells of the embryo after fertilization. In mice, only the paternal allele of IGF-II is expressed in an embryo. The mother imprints (suppresses) to reduce transcription of the gene. This is due to conflicting interests in alleles from different parents.

    Critique the “optimality” arguments presented in this chapter.  Why should we consider, “suboptimal” life histories?

There has not been enough time nor is there enough genetic variation to reach an optimum. There might be fundamental limits on the ability of populations to evolve an optimum life history. Suboptimal life histories are the reality.