prinCiples of evolution 457- Explain the difference between
a. divergence and gene flow
b. homologous and analogous structures - Explain the difference between a primate and a hominin.
- Describe the chemical and physical environment in which
the first living cells may have evolved.
seLf-Quiz Answers in Appendix VI
- A is a genetic unit consisting of one or more
populations of organisms that usually closely resemble
one another physically and physiologically. - The relative numbers of different genes (alleles) in a gene
pool change as a result of four processes of microevolution:
, , , and. - A difference in survival and reproduction among
members of a population that vary in one or more traits
is called. - The fossil record of evolution correlates with evidence
from.
a. the geologic record
b. radiometric dating
c. comparing development patterns and morphology
d. comparative biochemistry
e. all of the above
Alternatively, analogous structures arise when different line-
ages evolve in the same or similar environments. In comparative
biochemistry, gene mutations that have accumulated in different
species provide evolutionary clues.
section 23.7 In a mass extinction,
major lineages perish abruptly. Adaptive
radiation is a burst of evolutionary activity; a
lineage rapidly produces many new species.
Both kinds of events have changed the course
of biological evolution many times.
section 23.8 We see five major evolu-
tionary trends in the primate lineage leading
to H. sapiens. These are (1) a transition to
bipedalism, with related changes in the
skeleton; (2) increased motor skills related
to structural modification of the hands;
(3) more reliance on daytime vision, including color vision
and depth perception; (4) transition away from specialized
eating habits, with corresponding modification of dentition;
and (5) the enlargement and reorganization of the brain.
section 23.9 Humans (Homo sapiens)
are classified in the hominin family of the
primate order and are members of the only
existing species of the genus Homo. In human
evolution, the development of a larger, more
complex brain correlated with increasingly
sophisticated technology and with the development of
complex behaviors and culture. For about the last 40,000
years, human cultural evolution has outpaced our species’
biological evolution.
section 23.10 Life originated on
Earth about 3.8 billion years ago. Various
experiments provide indirect evidence
that life originated under conditions that
presumably existed on the early Earth.
Comparisons of the composition of
cosmic clouds and of rocks from other
planets and Earth’s moon suggest that precursors of the
complex molecules associated with life were available.
When researchers simulated primordial conditions,
chemical precursors assembled into sugars, amino acids, and
other organic compounds.
Metabolic pathways could have evolved as a result of
chemical competition for the limited supplies of organic
molecules that had accumulated in the seas.
Self-replicating systems of RNA, enzymes, and coenzymes
have been synthesized in the laboratory. How DNA entered
the picture is not yet understood.
revieW Questions
- Distinguish between microevolution and macroevolution.
- As shown in Figure 23.25, there is considerable variation in
the facial features of humans. Explain this fact in terms of
the concept of the gene pool. - Explain how natural selection differs from adaptation.
Figure 23.25 Humans show a great deal of variation
in their outward appearance. (Top: Tomas Rodriguez/Fancy/
Jupiterimages; Bottom left: © Owen Franken/Corbis; Bottom right:
Christopher Briscoe/Photo Researchers, Inc.)Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).