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BIO115 Evolution: Artificial Selection and Domestication-OPEN University
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Open University
S366_1 5 Hours
Intermediate
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Course Description
Most contemporary evolutionary biologists study
evolution experimentally using laboratory organisms such as Drosophila
or natural systems in the wild. However, 18th and 19th century
evolutionary biologists, including Darwin, emphasised the similarities
between natural evolution and artificial ‘ improvement’ of livestock
under domestication. They believed that studying domesticated animals
and plants could illuminate the mechanisms of natural evolution. Indeed,
Chapter 1 of On the Origin of Species… is entitled ‘Variation
under domestication’. Recent discoveries reveal the relationship between
natural evolutionary mechanisms and the practical technologies used to
breed plants, animals, yeasts and, these days, microbes, to produce
food, clothing, transport, companionship, decoration, entertainment and
most recently medicines. This unit is mostly about mammals, particularly
dogs and other domesticated livestock, but the basic principles are
probably universal. Dogs and other livestock are so familiar that we
hope that you will take the opportunity to observe the characters,
habits and processes described in this unit in animals that you see
around you.
When you have completed this
unit you should be able to:
- define the terms
‘artificial selection’ and ‘domestication’ and explain the relationship
between artificial and natural selection;
- describe some forms of dwarfism in modern breeds of
dogs and explain their relationship to dwarfism in humans and in modern
and extinct wild mammals;
- describe
some features of the skin, fur, feathers and the shape of the head
frequently observed in domesticated livestock;
- outline some major conclusions emerging from the
sequencing of the dog genome and outline some current theories about
when and where dogs were domesticated;
- explain
the functional basis of some of the anatomical changes induced by
selective breeding of some modern dog breeds;
- describe experimental domestication in foxes and
explain its relevance to the origin of anatomical and behavioural
characteristics in modern breeds of dogs and other livestock;
- measure some anatomical changes induced by selective
breeding of bulldogs during the last hundred years and use the data to
assess functionality and rates of evolutionary change.
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Introduction
 Introduction
Resource- Most contemporary evolutionary
biologists study evolution experimentally using laboratory organisms
such as Drosophila or natural systems in the wild. However, 18th and
19th century evolutionary biologists,...
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1 Phenotypes and genotypes
- 1.1 Introduction Resource
- Since the invention of DNA
sequencers in the late 20th century, measuring very small differences
between the genes of different organisms has become much easier and more
precise than quantifying phenotypic...
- 1.2 Artificial selection Resource
- Selection acts on phenotypic
characters whatever their origin, and can retain or eliminate the
characters' genetic basis. Artificial selection is any selective
breeding intentionally practiced by humans...
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2 Phenotypic change under domestication
- 2.1 Introduction Resource
- For centuries, livestock breeders
have nurtured strains of animals that thrive on various diets or in
particular climates, or that excel in certain roles or simply please
their fancy. The variety of such...
- 2.2 Size and shape Resource
- The shape of the head is
determined mainly by the relative sizes of the jaws and the nose and the
back of the skull containing the brain, eyes, ears and, in
artiodactyls, the horns or antlers. All these...
- 2.3 Skin pigmentation and pattern Resource
- Most domesticated livestock differ
from their wild ancestors in the colour and pattern of the skin, hair
or feathers.
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3 Domesticated dogs
- 3.1 The origins of domesticated dogs Resource
- Archaeologists and biologists
agree that dogs (Canis familiaris) were the first species to become
domesticated. Francis Galton, Darwin's younger cousin, suggested at the
end of the 19th century that domestication...
- 3.2 Structure and behaviour in
modern dog breeds Resource
- Dogs are one of the most diverse
of all living species, differing in size and shape of the skull and the
proportions of the body, especially the head and legs, and in the colour
and texture of the coat...
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4 Experimental study of evolution and
domestication
- 4.1 Introduction Resource
- Domestication of dogs and of most
other livestock took place so long ago that reconstructing the course of
events is extremely difficult. Written records and illustrations
describing the origins of many...
- 4.2 Experimental domestication of
foxes Resource
- In 1959, the Russian geneticist
Dmitri K. Belyaev (1917–1985) launched a long-term experiment to tame
captive-bred red foxes by selecting for a single behavioural trait: lack
of fear and aggression towards...
- 4.3 Phenotypic changes that appeared
without being selected Resource
- As well as these behavioural
changes, many of the selected foxes had unusual white markings (Figures
13c and d). The first colour change that the Russian investigators noted
in their foxes was a white...
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5 Summary
- 5 Summary
Resource
- Domesticated organisms evolve in
artificial environments under artificial selection, and opportunistic or
enforced hybridisation often occurs between species that would not
normally interbreed. Natural...
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References and Acknowledgements
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Copyright 2007,
by the Contributing Authors.
Cite/attribute Resource.
administrator. (2010, January 28). BIO115 Evolution: Artificial Selection and Domestication-OPEN University. Retrieved March 11, 2010, from Free University Courses OCW Courses OpenCourseWare Freeversity Foundation Web site: http://freeversity.org/science-and-mathematics/biology/bio115-evolution-artificial-selection-and-domestication-open-university.
This work is licensed under a
Creative Commons License
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