Evolution__3rd_Edition

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Study and review questions
1 What difficulties do theories of Lamarckian inheritance
and directed mutation encounter when they are used as
general theories of evolution, independent of (or in the
absence of) natural selection?
2 Outline the main stages by which the vertebrate
or octopus eye might have evolved, with successive
stages showing improvements in the optical properties
of the eye.
3 Some new adaptations evolve by symbiosis. For
instance, plant cells acquired photosynthesis when
cyanobacteria with photosynthetic abilities were
incorporated into a larger cell. Do events of this kind
falsify Fisher’s model of the genetic evolution of
adaptation, and Darwin’s principle of gradualism?
4 What magnitude of genetic steps is expected in the
adaptive evolution of a species that is: (a) near an
adaptive peak and subject to slow environmental
CHAPTER 10 / Adaptive Explanation 291
change; and (b) distant from an adaptive peak, or subject
to rapid environmental change?
5 Feathers seem to have originally evolved for
some function other than flight a perhaps display or
thermoregulation. Feathers are called a preadaptation
for flight. Does this imply that evolution has some
anticipatory, futuristic ability, in which characters
evolve because they will be useful for some function
in the future?
6 Consider a morphospace, such as the one for shell
morphologies, or a brain–body size allometric graph.
(a) There are regions in the space in which there are
no natural representatives. What are the two main
theories to explain the absence of these forms?
(b) How can we test whether a particular interspecies
pattern in morphospace is caused by one theory or
the other?