Download DO NOT USE MY WORDING in your answers!!!

General Biology Ch 13 questions – put answers into your own words and explain
DO NOT USE MY WORDING in your answers!!!
1. What was Darwin’s phrase for evolution, and what does this phrase mean?
"Decent with modification" (in your answer, compare this to the steps of natural
selection)
2. Explain the difference between natural selection and artificial selection.
Natural selections requires individuals to have the traits needed to compete to survive
while encountering the stressors and challenges established in nature. Artificial selection
occurs when people decide who gets to breed, and is largely based upon competition for
whatever it is people desire, such as service or financial gain rather than environmental
stress.
3. Explain each step of natural selection and describe how the process of evolution is more
of an “editing” process than a “creating” process?
Figure this out for yourself...by reviewing and understanding the steps
4. Name and describe the different types of fossils. Which type of organism is most likely to
be preserved or recorded in the fossil record and why is that so?
Use your notes and the internet to get this answer.
5. Biogeography is the geographical distribution of a species. Over time, populations can
move or separate. Some have suggested this can cause the development of
homologous structures and vestigial structures. Why is this so? How can molecular
biology be used to confirm such ancestry?
Hint: look into divergent evolution
6. Explain the development of analogous structures. Can molecular biology be used to
confirm the development of analogous structures? Why/why not? How are analogous
structures considered to be evidence for evolution?
look at your notes from class. Elaborate on how a niche can mold phenotypes to similar
types via convergent evolution
7. “Evolutionary trees” are often used to display patterns of descent.
a. Are these “trees” factual or hypothetical? Explain.
b. How are these trees useful when discussing evolution?
You should be able to figure out "A" and be able to Google "B" pretty easily
8. If evolution is described as a change within the genetic make-up, justify why it is said
that populations can evolve and yet individuals cannot.
Hint: compare mutations within mitosis vs. meiosis
9. How do both mutation and sexual reproduction both create genetic variation?
Google this if you don't already know from class...easy to find.
10. Hardy-Weinberg equation says p2 + 2(pq) + q2 = 1, but it should also be noted that
p+q=1 as well. How can these equations be used to determine if a population is in a
state of equilibrium or measure if evolution/adaptation (changes within) the population
are occurring from generation to generation?
Hint: The frequency of the alleles will change when a population is evolving. Explain why
11. Five criteria are listed as essential before a population is able to maintain a state of
Hardy-Weinberg equilibrium over time. These 5 criteria include…
A. A very large population - small populations are sensitive to changes, such as genetic
drift
B. No gene flow between populations - explain how gene flow would alter a population
C. No mutations - explain how mutations can alter a population
D. Random mating - If mates are chosen, then certain traits may be favored preventing
even distribution
E. No natural selection - If mating only occurs due to a certain trait, that type will be
favored
Explain why violating EACH of the above could cause a population to be out of
equilibrium.
12. Why is mutation the least likely to cause a state of non-equilibrium (Hardy-Weinberg)
within a large, sexually reproducing population?
Most mutations are not beneficial, and even when they are beneficial changes from such
would be slow, while gene flow, selective breeding, and natural selection can result in
rapid change.
13. Which of the five criteria required for Hardy-Weinberg equilibrium (genetic stability within
a population…aka, non-evolution) is least likely? How does this relate to the work done
by evolutionary scientists Darwin and Wallace?
Having an environment where there is no natural selection is very unlikely; therefore,
natural selection is the most likely cause of evolution. Darwin and Wallace listed four
steps that could drive natural selection by studying and combining the findings of
Malthus, Lylles, and LaMark.
14. Genetic drift occurs when chance events cause allele frequencies to fluctuate
unpredictably from one generation to the next. Two causes for such include the A)
“Bottleneck effect,” and B) the “founder effect.” Explain each effect and justify why each
can increase “genetic drift.”
The frequency of alleles within a large population is not easily altered; however, if few
individuals are selected from a large population the allele frequency within these few
individuals may not represent the allele frequency in the large population. If for some
reason a small few samples that don't represent the large population somehow create
the next generation (as in the bottleneck effect) or a new isolated population (as in the
founder effect), it is possible that a new generation or new population can be created
with an altered allele frequency.
15. While “gene-flow” (the process of gaining or losing alleles within a population due to
fertile individuals moving into or out of a population) can be used to counter-act the
potentially negative effects of reduced genetic variation within a population (caused by
bottlenecking or founder effects), what is one concern that comes with gene-flow
solutions?
Gene-flow brings in new genes into a population which increases genetic diversity and
often increases fertility; however, this added genetic diversity may also reduce the
specialized selection seen within a population...and can result in lower performance to a
given niche. Meaning, the population may be healthier in some ways, but may also have
a harder time performing specialized tasks that require certain traits.
16. Why is the phase “Survival of the fittest” not completely synonymous with Darwin’s
measure of fitness (look up the biological definition of relative fitness)?
Fit individuals may survive, but that doesn't mean they actually reproduce. Darwin was
more interested in relative fitness, and measured an individual's fitness not by health or
performance, but instead simply by measuring its contribution to future generations.
(Note: please include more information about the term "relative fitness").
17. Why is natural selection described as being a means for adaptive evolution yet genetic
drift, gene flow, and mutation are not described as being able to do so? (Note: Explain
and use the term “relative fitness” in your answer).
Natural selection is a multi-step process where things can occur in succession to one
another...within the time-line of an organism's life...where selection and reproduction
cycle and drive change. The others are more chance oriented and are not a constantly
driven process.
18. Natural selection can alter variation within a population by causing stabilizing selection,
directional selection, and/or disruptive selection. Using BOTH a graph and a written
response to explain a possible cause for each.
Explain how the favoring of one type and the selection against another type can cause
change. Google the graphs for each type of selection.
19. Males and females often appear different (sexually dimorphic). Justify an evolutionary
explanation for such.
Males and females often have a different role to their offspring. Since females typically
invest more to the offspring by carrying them, they often express more interest in raising
them. As a result, blending into the environment is important since females are less
competitive for territories and are also often with young that can't flee rapidly. Males
however are often do not stay with females or young, and instead fight for territory and
breeding rights. By standing out, they are often at greater risk, so if they are able to
survive in spite of being brightly colored, very vocal (mating calls), carrying antlers, or
displaying other male traits...then they must also have traits that are also very good for
survival.
20. Diploid individuals and sexually reproducing populations are less likely to suffer from
genetic loss in a population than are haploid organisms or asexual organisms. How do
each of the following influence this genetic preservation?
A. Balancing selection occurs when there are multiple selective processes that select
for multiple variations of alleles. Each variant is actively maintained (genetically
preserved) in the gene pool of a population since each type has a factor that favors
each type.
B. Heterozygote advantage occurs when the heterozygous genotype has an advantage
over either of the homozygous genotypes in a given environment. As a result, both
alleles are more likely to be maintained (genetically preserved) within the population.
An example is sickle cell anemia, where heterozygous individuals are 1. less likely to
get malaria than is the homozygous dominant genotype and 2. yet don't have the
problems associated with the homozygous recessive genotype.
C. Negative frequency-dependent selection - Negative frequency-dependent selection
helps preserve alleles in a population because as an allele becomes less popular in
a population, it becomes more advantageous...so it is genetically preserved. Positive
frequency-dependent selection does not preserve alleles since rare alleles are at a
disadvantage and are more likely to become extinct.