Behavior of Domestic Animals Lecture 3 and 4

While Darwin knew nothing about genes,

he suggested that ‘instinctive’ behavior was somehow transferred from parents to offspring without learning

Dilger’s Lovebird Study, 1962

Crossbred the Fischer’s Lovebird and Preach-faced Lovebird

Created a hybrid Lovebird that had a poor mixture of nest building skills

This showed incomplete dominance and suggests alleles

Manning’s Dropsophila (Fruit Fly) Study, 1961

•100 fruit flies in a chamber

•10 fastest to mate determined (selected)

•10 slowest to mate determined (selected)

•25 generations later

•30 minute difference in time to mating

Lynch’s Laboratory Mice, 1980

•Selected based on amount of cotton used for nesting

•15 generations later

•One line collected 50 grams of cotton

•One line collected 5-10 grams of cotton

Kiaer and Sorensen’s Laying Hens, 1997

•Selected based on decreased tendency to feather-peck

According to Jensen, genetic selection of desired behavior, or against undesired behavior, is therefore also an important means for?

improving animal welfare

Genetic vs. Environmental Effects

Consider indirect effects of environment

ex. Klein’s Study on Feather-pecking and Foraging activity, 2000

Genetics may ________ an animal toward certain behaviors

predispose

_______ can have a profound effect on the expression of those behaviors

environment

More examples of genetic vs. environmental effects

Tryon’s Bright Rats and Dull Rats, 1940 and Cooper and Zubek’s Bright Rats and Dull rats in varying Environments, 1958

Are there single gene influences in animals?

Yes

examples:

Lack of barking in Basenji dogs (only 2 genes, both dominant alleles

Struggle during restraint (only 1 allele)

Genes code for

proteins

Proteins regulate/control

a variety of body systems

ex. hormones/neurotransmitter receptors

enzymes

antibodies

molecular transport

tissues structure

Further genome studies like ____ and ____ will be important moving forward

gene-linkage and non-coding markers

Methods for studying causation

“Knock-out" mice

• certain genes are silenced using embryonic stem cell

CRIPSR-Cas9 technology

• bacterial virus molecules engineered to silence DNA

• Cheap!

Epigenetics

refers to any chemical modification of DNA that affects gene expression without affecting the DNA sequence

For epigenetic

•The genome in not insensitive to environment impacts.

•Regulation of gene activity is dynamic!

•Changes are heritable

2 types of Epigenetic Change

DNA Methylation: addition of a -CH3 group to the Cytosine base

Histone Protein Modification

Changes affect regional gene expression

Documented epigenetic changes/affects in animals:

Kappeler & Meaney’s Study of Maternal Behavior in Rats, 2010

•Intense mothering à increased resilience to stress in pups

•Glucocorticoid receptor gene affected à altered/decreased response to stress hormones

Jensen’s Study of Stress in Chicks, 2015

•Exposure to stress early in life affected learning ability and caused a modified stress response, that was then transferred to offspring

•Modified gene expression found in the brain of hens à chicks

Darwin’s 3 Principles for Evolution

The Principle of Variation

The Principle of Genetic Inheritance

The Principle of Natural Selection

In order for evolution to modify any trait,

all of the principles must be fulfilled simultaneously

Consider how the presence of absence of certain behaviors might affect an animal’s likely-hood

to survive and reproduce

Evolution may cause an ______ variety in behavioral traits, or it may cause ___ of certain behavioral traits

increased, loss

Phylogenic Tree

may help trace evolutional changes

is a hypothesis

based on similar/shared physical or behavioral characteristics

All behaviors we see today are _____ versions of behavior patterns that may have served very different purposes in ancestral forms

modified

Ritualization

the process by which a certain behavior evolves into a signal, by becoming exaggerated and losing its original function

Behavioral modification may progress to

ritualization

Start on slide 8 on lecture 4