BIOL 2620
Week 13 Homework
Name: James Kurui
Watch the documentary Unnatural Selection
(https://youtu.be/x4ruDIkRets?si=P87Da9ZpcIDSNJJ9) and answer the following
questions. The questions follow along in order of the film so it may be easiest to answer
them while you’re watching.
1. Describe the scientific experiment from the 1950s with foxes. Explain the research
question/hypothesis, brief methods, and brief results.
the research question for the fox experiment was to investigate the domestication process
and weather selective breeding could produce domesticated traits in foxes. These experts
sought to explore methods, such as selection criteria, breeding projects, behavioral
assessment and physical characters observation. The noticeable results from brief
methods were, change in behavior, change in physical appearance.
2. What is artificial selection, and which animal did Charles Darwin take interest in
studying this idea? Charles Darwin concentrated on domesticated animals,
specifically pigeons, to demonstrate the idea of artificial selection. He observed
that breeders could produce a variety of forms and traits through selective breeding
practices
3. Why are deer quickly evolving smaller antlers and smaller bodies?
BIOL 2620
Week 13 Homework
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Smaller body sizes can help deer to preserve and reduce the heat load in hotter
climates
To improve movement and speed to escape from predators
With limited resources, deer evolve smaller bodies so as to survive on less food
4. What is the selection pressure causing this change?
• Limited resource
• Hunting pressure
• Predation
• Climatic conditions
5. Why are diamondback terrapins in Chesapeake Bay evolving to be larger? What is
the selection pressure causing this change?
Th changes in food availability are causing development of huge body sizes diamondback
populations, large body sizes is a advantage in accessing food resources.
6. What type of selection (stabilizing, directional, or disruptive) and what type of
speciation (sympatric or allopatric) is described by the finches on a Galapagos
Island that only have either a small beak or a large beak? What is the selection
pressure influencing beak size changes?
The Galapagos finches show directional selection and allopatric speciation. The main selection
pressure influencing beak changes in Galapagos is food availability.
7. At around 26 minutes into the video, the concept of “reversal of evolution” The
traditional diversification of beak sizes which allowed these birds to adapt to
different food sources is being disrupted. Due to Human activities, the selective
BIOL 2620
Week 13 Homework
pressure that once favored specific beak sizes are diminishing, consequently the
initial divergence into species of distinct forms is diminishing and merging back into
fewer species
8. Do you think it’s possible for evolution to be “reversed”?
Yes, In the Galapagos islands, the introduction of human food sources has caused reversal in the
speciation process of Darwin Finches. Initially these birds showed a split in to two distinct
species, but with availability of new food resource s such as rice and potato chips, they began to
merge back into single forms. That shows a collapse in speciation.
9. Every year over 18 million birds are killed by cars. What adaptation is occurring in
the cliff swallow population of Oklahoma that is studied by the man wearing the
“Half-Human, Half-Cliff Swallow” hat? (what a ridiculous hat!)
The wing length of cliff swallows has decreased by 5-7 mm over 30 yrs,the shorterwings provide
advantage in swift movement to avoid cars
10. Based on what you’ve learned about speciation, what would need to happen for the
urban peregrine falcons to become a new species?
For the falcons to speciate there must be a selection pressure to induce significant environmental
adaptations and behavioral changes which must occur over time.
11. Thinking back to island biogeography, for white-footed mice in New York City, what
is their habitat “island” and the habitat “sea”?
Habitat “sea’ is the urban environment mainly composed of concrete, buildings and roads which
act as barriers to movement and gene flow between mice population in different parks.
Habitat “island ‘These are green patches, such as parks and forest fragments that serve as
isolated habitats for these mice allowing them to thrive despite being surrounded by the “sea”
12. What processes of evolution suddenly allowed PCBs and dioxin to switch from
being fatal to cod in the Hudson River to being 100x less toxic to them?
BIOL 2620
Week 13 Homework
Mutations Through unnatural selection
13. How did cane toads arrive in Australia?
In 1930 100 cane toads were introduced into Australia for The purpose of pest control in sugar
cane plantations
14. Why is the size of the red-bellied black snake decreasing in Australia?
The large snakes consuming cane large cane toads ends up consuming more toxins than the
smaller snakes which eat smaller cane toads with low levels of toxicity. Therefore, the larger
snakes tend to die while the smaller snakes survive.
15. What do you personally think of the term unnatural selection? Do you think this is
the real thing? Why or why not?
Unnatural selection refers to changes in species driven by human influence. Humans have
become predators altering ecosystem and evolutional directions, these human activities can
rapidly change the course of evolution and even reverse processes that have taken million of
years. The evolutionary changes in cliff swallows and snakes in Australia is enough proof that
indeed unnatural selection is real and its happening.