NEXT WEEK IN BIO153
Tuesday: Lecture 19: Human evolution
Thursday: Lecture 20: Intro to ecology
Friday: Good Friday - no tutorial
Readings: Chapter 34
No labs
Assignment 3 due Mar. 24
l|c
Session ID:
TUTORIAL 9:
EVOLUTION OF THE DOMESTIC DOG
How did Darwin study artificial selection?
How fast did domestic dogs evolve and how did they change?
Can we experimentally test hypotheses about dog evolution?
http://blog.blantonmuseum.org/files/
2012/01/Cave-painting.jpg
DOGS CLEARLY WERE AND ARE IMPORTANT TO PEOPLE
Cave painting from ??
RANDOM NOTE
Tullimonstrum gregarium was a vertebrate, all vertebrates are chordates
- fossil evidence of its gut, has to do with the structure of how both these
Dogs of King Antef
from Egyptian
organisms fossilize, 3-dimensional
element
to its fossilization,
relief (2323 BC. to 2134 BC).
https://www.theguardian.com/science/2016/mar/18/tully-monster-mystery-of-the300-million-year-old-fossil-finally-solved
Gaston Phebus, illustration from Le Livre
de la chasse (The Book of Hunting), 14th
- 15th centuries, illuminated manuscript
DOGS WERE THE FIRST DOMESTICATED SPECIES
Domesticated from gray wolves over 15,000 years ago, probably
in several locations
Canis lupus
Canis lupus familiaris
WE STILL HAVE QUESTIONS ABOUT DOMESTICATION AND DOGS
1. What changes occur during domestication?
2. How quickly could domestication occur?
2-stage process, where wolves approached the human sediments and became to rely on
them, and human began to give them large chunks, encouraging them
-and then the process of artificial selection began (on the dogs brave enough to
approach humans)
so 1) approach human sediments 2) artificial selection
By fugzu - originally posted to Flickr as Cody alias Fez delle Caserosse, CC
BY 2.0, https://commons.wikimedia.org/w/index.php?curid=32932031
DARWIN USED DIFFERENT SOURCES OF DATA TO SUPPORT HIS THEORY
Examples of adaptation,
Structural homology,
The fossil record, and
Biogeography,
Domesticated species
Why do you think domesticated species
would be an important part of his theory?
Darwin did not know about Medellian genetics
- he can show that species can change
- the fact that the traits were heritable, and artificial selection showed him that the
traits were indeed heritable, so then artificial selection and domestication showed him
that if you select for a trait in a population it will appear in subsequent generations,
allowed him to make his arguments without understanding how it actually works
(Mendellian genetics)
ARTIFICIAL SELECTION IS THE SELECTIVE BREEDING OF DOMESTICATED SPECIES
DARWIN ALSO NOTED OTHER CHANGES IN ARTIFICIALLY SELECTED ANIMALS
Drooping ears
piebald coloration, forehead
star don't see commonly in wild populations
wavy hair
rolled, shorter tails
changes in reproductive cycles
What does this mean?
if we didn't select for these traits why do they appear?
- maybe the gene that we select for lies close to the one we're not
-linked genetically to those traits we are selecting for, that' why they're showing up
WE STILL HAVE QUESTIONS ABOUT DOMESTICATION AND DOGS
1. What changes occur during domestication?
we need variation for a.s. to work, large population with a lot of diversity so we
actually choose, look for those that are least aggressive - selections based on
2.can
How
quickly could domestication occur?
a behavioural trait
- what's ur hypothesis then?
By fugzu - Flickr: raskal, CC BY 2.0, https://
commons.wikimedia.org/w/index.php?curid=31447186
DR. BELYAEV BEGAN A STUDY ON FOX DOMESTICATION IN 1959
expect to see friendlier foxes in 2016
-look slightly different too/ change the morphology
-
http://scienceblogs.com/thoughtfulanimal/2010/06/14/monday-pets-the-russian-fox-st/
WHAT WOULD YOU DO?
Suppose you had a fox farm with a large diverse population of
animals available for you to study.
Design an experiment you would conduct to see if you could
re-create dog domestication and investigate the genetics of
tameness using foxes.
What is your hypothesis and what would you expect to
observe? Explain.
How would your experiment further our under- standing of
dog domestication? Domestication in general?
HERE IS WHAT BELYAEV DID
Fox pups (called kits) from the population were scored for
tameness and assigned to classes:
Class 3: flee or aggressive response to experimenter
Class 2: allow petting but no emotional response to
experimenter
Class 1: friendly to experimenter (wag tail, whine, etc.)
Next, scientists bred the most friendly Class 1 foxes (Elite
Class 1 = E1) over many generations.
What would you expect?
THESE ARE THE FOXES TODAY!
clearly they are domesticated!!this was just about 60yrs
http://ngm.nationalgeographic.com/2011/03/taming-wild-animals/musi-photography
THE RESULTS
Generation
% E1 Kits
10
18
20
35
35
70-80
by 35 generations u almost have a completely domesticated litter
THE RESULTS
Characteristic
Undomesticated
animals with trait
(per 100,000)
Domesticated
animals with trait
(per 100,000)
Frequency increase
(%)
Star on forehead
710
12,400
1646
didn't select for this
Mottled fur
86
450
423
Floppy ears
170
230
35
Shortened tail
140
6900
Curled tail
830
9400
1033
all these genes are linked to the behavioural ones we selected for
WHAT DO YOU EXPECT?
DAYS
7 8 9 10 11 12 13 14 15 16 17 18 19
WEEKS
4 6 8 10 12
DOGS
WILD
FOXES
DOMESTICATED
FOXES
eyes fully open
(Trut, 1999)
response
to sound
window of
socialization
care is provided by humans so mother fox not needed
IN THIS CASE STUDY, WE
described artificial selection and how it relates to
domestication.
showed how genetic variation, inheritance, and selection can
result in phenotypic changes and adaptation in a lineage or
population over time.
demonstrated that selection on one trait can lead to changes in
other traits.
developed hypotheses to investigate an identified question.
predicted outcomes of experiments.
analyzed data and interpret experimental results in light of
research results.
NEXT LECTURE PERIOD
Lecture 19: Human evolution
