Biology 152 Book Exam 1

What happened to Ice Fish that they could no longer make hemoglobin?

The global genes that code for the global part of hemoglobin have gone extinct. One gene has become a fossil gene with only a non-functional remnant remaining in the DNA of ice fish, the other gene has been completely lost

What changes in the environment provided the selective pressure that led to the lose of hemoglobin genes and the evolution of other mechanism for increasing oxygen absorption from cold water in ice fish?

55 million years ago southern ocean temperatures dropped from 68 degrees F to less than 30 degrees F in some places

What four adaptations did Ice fish evolve to increase the absorption of oxygen from cold water?

Larger gills, larger hearts, scaleless skin and unusually large capillaries

In order to adapt to cold water ice fish lost the ability to make hemoglobin and red blood cells. This made their blood less viscous at colder temperatures. In addition to losing this ability, what ability did they invent (evolve) to deal with the extremely cold water of the Antarctic?

Antifreeze proteins

Look at the timeline of icefish evolution (Figure 1.3) What adaptations evolved prior to the loss of hemoglobin genes?

Antifreeze, cold adapted tubules, and reduction of red-blood cell number

What is the relationship between how quickly a trait will spread through a population over generations and the strength of the selection coefficient on that trait?

The stronger the selection coefficient the faster a trait will spread in a population of the same size. If the population is large the trait will spread more slowly than if the population is small.

In the Pinnate desert of Arizona what maintains the genes for both dark and light colored fur in rock pocket mice?

The presence of habitats with both dark and light background color are more likely to survive predation by visual predators (hawks and falcons) and pass on genes for their habitat matching fur color.

Why are large sample sizes typically needed to detect natural selection?

Because some traits provide only a very small, but effective selective advantage.

What questions were asked in the investigation of pigeons and falcon predation?

Whether white-rump feathers conferred a selective advantage and whether the population was evolving towards one that had a higher frequency of individuals with white rump feathers.

When a mutation creates a new variety of a gene, that new version may either be favored (if it generates a trait that makes its bearer more successful at surviving and reproducing than those in the population that don't have the new trait) or disfavored (if it generates a trait that makes its bearer less successful at surviving and reproducing than those in the population that don't have the new trait) by natural selection. If it is favored its frequency will increase over many generations in the population. If it is disfavored, its frequency will decrease. There is also a third possibility. What is it and why is it important for studying the DNA evidence of evolution?

It may be a neutral change. When rates of change deviate from rate of neutral changes, then it is evidence that selection has occurred.