Class # _____ : Artificial Selection – Dogs!
Name: __________________________________ Core 1 2 3
Activity 1: Read, highlight, and answer questions from the website, Wolf to Woof –
The Story of Dogs. http://www.wolf2woof.com/EVOLUTIO/SELECTIO/INDEX.HTM
Natural and Artificial Selection - Traits can be selected artificially or naturally
Dogs -- wild and domestic -- come in many different shapes and sizes. Where did all this diversity come
from? In the wild, natural selection has led to the many different species of wild canines that inhabit our world.
Here at home, human breeding or artificial selection has created the many different dog breeds we are familiar
with. With both of these processes, some dogs survive to breed and reproduce and others don't. The ones that do
survive and are able to breed pass certain traits down to their offspring: such as a curly tail or a spotted coat.
With artificial selection, humans decide which dogs survive and breed. With natural selection, only those that
can meet nature's challenges are the ones that survive and breed.
Natural Selection
In the wild, animal traits are shaped not by human choices, but by natural forces. Charles Darwin called the
process of change over time due to environmental factors natural selection. Millions of years of natural
selection have led to a range of canines adapted for survival in many diverse habitats.
1. What drives natural selection? n_______________ f_______________ in the environment
Well suited for survival
Today 35 species of wild canines can be found from the tropics to the tundra. Wild canines make their homes in
a wide variety of habitats. From the hottest deserts to the icy arctic, the structure and behavior of each wild
canine has been modified by natural selection so that it is well suited for survival.
Life in the grasslands
The maned wolf is well adapted for life in the tall grass plains or pampas of South
America. Their stilt-like legs aren't for running -- this canine is no speedster. Instead, long
legs help maned wolves peer over tall grasses to spot each other and their prey.
Life in the desert
The fennec fox makes its home in the desert. Pale fur reflects the
sun's rays, and extends over the soles of its paws to protect against
burning desert sands. When fennec foxes overheat, they shunt or send blood to their large
ears to rapidly dump the excess body heat into the environment.
Life in the arctic
Not many wild canines can survive the frigid temperatures of
the arctic. The arctic fox is the only year-round small canine resident of this harsh
environment. Its fur goes from white in winter to brown-gray in summer, keeping
in line with the seasonal change from white snow cover to brown tundra. To keep
warm, it has thick fur that even covers the soles of its feet and tiny ears to reduce
heat loss when the temperature dips far below zero.
Life in the forest
The gray fox has a unique adaptation for life in the forest. In addition to small body
size and short legs that make it easy to move through the underbrush, the gray fox
is the only climbing canine. Using its somewhat curved claws, it scampers up trees
to avoid predators as well as to forage for food such birds or their eggs.
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Jack of all trades
You could find the coyote in any of the above habitats, except the arctic.
The coyote is a generalist. When a species enjoys a wide distribution (when
it doesn't depend on one small, specific habitat for its home) it has better
odds of avoiding extinction. So, for the most part, species that are
generalists have a better chance of long-term survival.
2. Describe 2 example of how environmental factors have shaped the phenotypes of wild canines:
Wild Canine
Phenotype
(Remember? Phenotype is the
physical expression of a genetic
trait.)
How does this trait help the wild
canine survive in their
environment?
Artificial Selection
The domestic dog comes in a mind-boggling array of shapes and sizes.
Whether you prefer a Chihuahua you can tuck in your pocket or a 200-lb Saint
Bernard that can carry you, there's a dog for every human fancy. Over the
years, humans have bred dogs for work and whimsy, creating the hundreds of
domestic breeds we know today. This human-controlled breeding is called
artificial selection.
From one ancestor, many breeds
Starting thousands of years ago, dogs of many sizes and shapes appear in the archaeological and artistic
records of almost all human cultures. Selected for hunting, herding, protection, companionship, and looks, dogs
were welcomed into households of all kinds. Most of today's almost 400 recognizable dog breeds were
established after 1850. This is a sign of those times, reflecting the rising popularity of purebred pets as status
symbols, specialized breeding, and dog shows.
3. How is artificial selection different from natural selection? ___________________________________________________
Activity 2: Watch the Nature Video – Dogs that Changed the World
https://www.youtube.com/watch?v=9axwvymzOrs
4. How long ago did dogs become our best friend? About _________________ years ago They
became our h_________________ partners and protectors.
5. Dogs are an e_________________________________ “miracle.” In the space of about _______ years, they
have become the most v_________________ species on the planet.
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6. With over ___________ recognized breeds, dogs have the greatest range of physical
characteristics of any mammal on the planet.
7. For 6000 years the Bedouin have bred the Saluki for s_____________, l____________ legs and
stamina. They have f_______________________ spines like cheetahs.
8. The Pekingese were bred as “L____________” dogs by the C__________________________.
9. The industrial Revolution created an increase in the Middle Class who had the money to buy
m____________________________ dogs as lap dogs. They also began b___________________ dogs as a hobby.
10. As humans, we are genetically programmed to respond to small creatures with big
e___________ and a small n________________ like human babies.
11. In the late 19th century, the K_______________________ Club was established to keep track of breed
standards and to run dog shows.
12. All dogs, no matter what their current shape or size, are directly descended from a w________.
13. One theory for how a dog grows involves the growth h_____________________ , thyroxin.
According to this theory, each b_______________________ of dog has a different thyroxin rhythm.
14. Older versions of bulldogs were a h___________________________ breed of dog. They were more
a__________________________ and didn’t have squashed in faces.
15. How does the loose skin on Shar-Pei cause health problems? ____________________________________
16. How could problems for breeds be “fixed?” _________________________________________________________
_______________________________________________________________________________________________________________
17. While humans are able to change physical characteristics rather easily, it is not so easy to
change instinctual b________________________. In the United States, 4.7 million people are bitten by
dogs, every year. As many as 1 in 5 will be put to sleep, because owners can not control their
dog’s “h__________-wired” b______________________________________.
@ 37:00 STOP VIDEO! -- WARNING: The video show a rat terrior killing a
rat. So, for all you rat lovers out there, SKIP to 38:00.
18. Terriors were bred to kill other animals. For example, Rat Terriors were bred to kill r________
to protect farmers’ grain stores from being eaten.
19. Why is a dog’s sense of smell so good? ______________________________________________________________
How could this super-sense save human lives? _________________________________________________________
_______________________________________________________________________________________________________________
20. What is your favorite breed of dog? ____________________________________ Why do you like this
breed? __________________________________________________________________________________________________
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