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BIOL 2060 Lecture Notes - Dic Entertainment, Semelparity And Iteroparity, Latvian Lats

Course Code
BIOL 2060
Elizabeth Boulding

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Unit 3: Populations
Section 3.1 Testing for Plasticity and Adaptation
Key Terms:
-Population: A group of individuals of a single species inhabiting a specific area.
-Phenotype: Physical expression of a characteristic of an organism determined by both
genetic constitution and the environment.
-Genotype: The genetic constitution of an organism.
-Common garden study: A type of experiment that can be used to test for genetic
differences among populations by growing individuals from different populations in the
same place.
-Ecotypes: A subspecies or race adapted to a particular set of environmental conditions.
-Genetic drift: Change in gene frequencies in a population due to chance or random
-Local adaptation: When a population survives best in its home environment when
compared to others derived from other environments.
-Reciprocal transplant study: A type of study in which clones of several populations
or ecotypes are grown in different sites to test for local adaptation.
-Unintentional experiments: Studying the effects of experimental treatments that were
not deliberate, such as the effects of an unpredictable hurricane, or the effects of
unplanned human-assisted dispersal of organisms.
Activity for Additional Learning:
1. What is the equation that describes the relative contributions of nature and
nurture to the phenotype that is expressed?
Phenotype = Genotype × Environment
2. How did Bonnier (1890) conduct his experiment to test for
acclimation/developmental plasticity in alpine plants? What were his results?
Bonnier conducted a transplant experiment. He produced genetically identical clones of a
single plant, and transplant one into a lowland site and the other into an alpine site. He
then made measurements and drawings comparing each pair of plants. These results show

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ed that the phenotypic differences between these plants were caused by developmental
plasticity; a single genotype was able to produce morphologically different phenotypes in
response to the environment.
3. How did Turreson (1925) conduct his experiment to test for genetic variability
among plant populations? What were his results?
Gote Turesson (1925) used a common garden study in which representatives from different
populations that had distinctive growth forms, which he called ecotypes, were grown under
the same environmental conditions in a common location. When grown in a common
garden they retained variability in stem length; these persistent differences provided
support for his hypothesis of genetic differences among populations.
4. What two things would you need to demonstrate in comparative studies to infer
that adaptation has occurred?
To demonstrate adaptation, you would have to show that (1) phenotypic differences among
populations are based on genetic differences, using a common garden study. You would
also need to demonstrate that (2) each population survives best in its home environment
(local adaptation) when compared to others derived from other environments
5. Draw a diagram of the results of the study by Clausen and colleagues (1940) on
Potentilla glandulosa., and use arrows to indicate which comparisons are being
made when testing for (a) genetic differences between individuals, and (b) local
- The null hypothesis was that if plasticity was the only cause of the variation in
morphology in this species, then you would expect that plants grown in a common
garden would look the same.
- The results indicate that there were differences in phenotypes in the same environment

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The results did not support the null hypothesis. Clausen and his coauthors concluded that
the study populations of P.glandulosa differed genetically, as each population showed
unique growth responses at each of the transplant gardens.
6. Describe the study by Carroll and Boyd (1992) on soapberry bugs. What question
did they address, and what results did they obtain? What did they conclude?
They asked whether the soapberry bugs were able to adapt to new food sources and expand
their range. They first collected eggs from each population of soapberry bug and grew
them in a common garden. Differences in beak length among populations were maintained
in the common garden, suggesting that beak length is genetically determined The
researchers also found a positive correlation between beak length and the radius of fruits
each population used, suggesting that each soapberry bug population had adapted to its
plant host.
7. Carroll and colleagues (1998) continued the study. What methods did they use, and
what results did they obtain? Do these results
They asked whether soapberry bug populations were ecotypes, and answered this question
by doing a reciprocal transplant study and measuring juvenile survivorship of each
population on different plant hosts
Section 3.2 Speciation
Key Terms:
-Biological species concept: A group of actually or potentially interbreeding
populations, which are reproductively isolated from other such groups.
-Isolating mechanism: Some process that prevents the production of a viable offspring
between two individuals.
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