Evolution__3rd_Edition

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Study and review questions
1 Why could it not be known until relatively recently
in human history that a species had gone extinct?
2 (a) What is the distinction between a real and a
pseudoextinction? (b) How does the distinction
matter for theories of species selection and mass
extinctions?
3 (a) What is the best evidence that the mass extinction
at the Cretaceous–Tertiary boundary was caused by an
asteroidal impact? (b) What predictions about the
pattern of extinctions in the fossil record can be made
if it was indeed caused by an asteroidal impact? What
difficulties arise in testing them?
4 When in the history of life were the two, three,
and five best documented mass extinctions?
5 How do we expect the observed extinction rate to
change if: (a) a geological time interval with a good
sedimentary record is followed by a geological time
interval with a poor sedimentary record; and (b) the
other way round, where a geological time interval with
a poor sedimentary record is followed by a geological
time interval with a good sedimentary record?
CHAPTER 23 / Extinction and Radiation 681
6 What is the relation between the developmental mode
of snail taxa and the chance of extinction at the time of
mass extinctions and at times of normal (or background)
extinction rates? How do you explain the trends?
7 Why cannot the macroevolutionary pattern of
extinction rates in different taxa be simply predicted
from microevolution in the taxa?
8 In Chapter 11, we saw that natural selection does not
generally favor adaptations at the group level, because
group attributes are not heritable. So how is species
selection possible? Do species, but not groups, show
heritability? Or is heritability irrelevant in species
selection?
9 How can we use the patttern of radiation and
extinction over time in two taxa to test whether one
of the taxa replaced the other by outcompeting it?
10 How it is it possible that much the same basic
observations of the numbers of fossil species through
time have been explained by such different models as
logistic or exponential increase, or even constant
numbers over time?