genetics Flashcards
behavior is influenced by what two factors?
- hereditary
- environmental
act in _____ to form behavioral characteristics and patterns
concert
Highly heritable traits are readily altered through ___________
selective breeding
what gives the phenotype?
genes and environment
define heritability
ratio between genotypic and phenotypic variance, genotypic variance/phenotypic variance
which of the following situations is heritable based on genes? number of legs in dogs or length of dog legs
length of dog legs
If a trait is highly heritable then the trait in _______ is largely due to genetics
phenotype
do low heritability have more to do with genes or the environmental influences and why?
environmental influences because progress through selection will be small
define low heritability
planned changes in environmental elements if it is desired to alter them
Hereditary influences are evaluated through _______________________
studies in behavioral genetics
hereditary influences are a major consideration in understanding _________ and ___________
evolution and domestication
how is evolution and genetics important in genetic traits?
so the animal can adapt to the environment we provide
describe the scientific field of behavioral genetics
the component of a given behavior that is controlled by inheritance and approaches to altering behavior through selective breeding
what are the relative influences on the desired or undesired behavior in order to change animal behavior?
environment and genetics
behavior is controlled by which two primary systems?
central nervous system and endocrine
Systems develop and become active under control of?
genes
a given behavioral characteristic represents a ______ array of _____ and _______ control mechanisms
complex
neural
endocrine
a given behavioral characteristic most likely involves what kind of genes?
polygenes
name some behavioral traits that has been observed due to a single gene effect
- nest cleaning in bees
- aggression toward strangers in Shiba inu
aggression toward strangers in Shiba inu is due to what and how does it work?
- polymorphism of neuronal/epithelial high-affinity glutamate transporter
- glutamate hangs around and acts as a neurotoxicity, glutamate builds up in the cell which can lead to aggressive behavior
define scientific term behavior and how it is accomplished
◼ result of transmissions through neural and endocrine mechanisms, and the response functions
◼ accomplished by specific target tissues responsible for the mechanics of executing the action
Craig and Muir studied selection for low levels of feather and cannibalistic pecking, what was their result?
they found to be successful with selective mating
we can reduce low levels of feathers and cannibalistic pecking to eliminate the need for ?
beak trimming
why do we want to eliminate the need for beak trimming?
it is a painful procedure that results in sensitivity of remaining tissue for extended period
Craig and Muir’s study of selective mating selected stock resulted in what three characteristics?
- lower death loss
- higher egg production
- improved feathering
what are some traits that have responded to selection?
◼ Temperament in dairy cattle
◼ Mating and maternal behavior in beef cattle
◼ Temperament and trainability in horses
◼ Trainability, docility, hunting, working characteristics in dogs
◼ Broodiness and cage adaptability in chickens
utility of heritability estimates is in predicting the response to _________ ?
artificial selection
behavioral characteristics are determined by what? and what is the formula?
heredity and environment
P = G + E
what are the three major categories of factors which determine the behavioral phenotype of an individual?
◼ Physiology = Internal environment
◼ External environment
◼ Heredity
define sexual effects
Sexual reproduction occurs in life forms that can adapt to wide variety of environments (that fluctuate)
what is the primary biological function of sex & sexual reproduction?
◼ to allow fresh samples to be drawn from populations gene pool
◼ maintain genetic variability
sex is determined by?
sex chromosomes
what are the chromosome combination for males and females?
females: XX
males: XY
what are the chromosome combinations for bird females and males?
female: ZW
male: ZZ
sex-linked genes can influence what?
behavioral traits
what is an example of a sex linked effect
white leghorns = nonbroody
cornish = broody
what happens when selecting for desirable traits?
you can inadvertently select for undesirable traits that may not show for several generations
according to the breed crossing study, which had the greater effect on incidence on broodiness, sire or dam?
sire
cross of parental stock / phenotype of F1 hens
which breed of sire contributed to broodiness? nonbroody?
cornish
white leghorns
which chromosome has most of the genes influencing broodiness that results can be explained?
Z
what is the nonbroody allele and from what breed?
Z-
white leghorn
what is the broody allele and from what breed?
Z+
cornish
what was the result of the reciprocal crosses of a WL x bantam?
there was no significant difference for incubation behavior, environment plays a big role and there are at least 2 dominant autosomal genes involved
◼ One causing, one inhibiting the behavior
When the progeny of reciprocal crosses between parental stock differ in a behavioral trait are compared
Possibility that differences between F1 progeny of the crosses may be caused by differences in maternal environment (before or after birth)
why would use a reciprocal cross for a basenji and a cocker spaniel?
Compare F1 progeny for behavioral traits
◼ Cockers are friendly, nonaggressive
◼ Basenjis are aggressive & wary
what was the result of the basenji x cocker spaniel study?
◼ F1’s behaved same as breed of dam
◼ F2 pups showed same behavior
how did most behaviors show of the basenji x cocker spaniel and what were exceptions?
- no difference in most behaviors
◼ Attraction behavior
◼ Scored as number of times 13-15 wk old pups approached/followed experimenter
define attraction behavior
how likely a puppy is to follow experimenter
Approaching & following humans learned from mother
◼ Persisted from weaning (_ wk) to ~__ wk
8-15
Continuation of behavior w/ F2 pups indicates ____ inheritance by way of _____ influence
social
maternal
what were the three main takeaways from the chicken and dog research?
◼ Sex-linked effects
◼ Autosomal gene effects
◼ Environment- (maternal influence) effects
define inbreeding
◼ Mating individuals that are more genetically related than average of population
- Relatives
increased homozygosity =
decreased heterozygosity
inbreeding depression =
loss of hybrid vigor
list two intensive inbreeding pairing
◼ Mating full sibs
◼ Sire/daughter
what happens when there are successive generations of full sib matings ?
◼ Population becomes subdivided into many small sub-populations (lines)
◼ Different lines would drift apart genetically
◼ Individuals within lines would become more alike
list the four things that happen when there is close inbreeding
- Population divided into subpopulations
- Lines become very different from one another
- Uniformity increases within lines
- General loss of vigor
list inbreeding effects
- Loss of heterozygosity
- More detrimental alleles expressed
- Loss of overdominance
out of the 8 original lines of the poland china swine, how many survived?
3 but only 2 with sufficient numbers for comparison
what happened when there was extreme loss of vigor in poland china swine
◼ Delayed maturity
◼ Small litters
◼ ↓ disease resistance
◼ Minimal boar libido
compare the two lines of poland china swine
- M ◼ Friendly ◼ Too mild tempered ◼ Indifferent to squeals of piglets -crushed - N ◼ “Wild” ◼ Savage defense of piglets ◼ Trampled young
what is the purpose of “mild” inbreeding
“fix” desirable gene combinations in a line
what are examples of using mild inbreeding and what effects come from each
- guide dogs but loss of reproductive fitness
- produced lines of german shepherds with greater uniformity in appearance and trainability , improved temperament
define outbreeding
breeding animals that are less genetically related
◼ Heterosis
◼ Crossing breeds w/in species
◼ Crossing lines w/in breed
list what heterosis increases
◼ Repro
◼ Fitness
◼ Survivability
◼ Growth rate
behavior traits = _____ traits
fitness
example breeds of guide dogs and how we use heterosis with them
◼ Crossing Breeds or lines w/in breed
◼ Labs/Golden Retriever
what does “more uniform” mean?
◼ More Aa vs. AA or aa
more heterozygous genotypes, not increasing homozygous- increasing heterozygous
which are better buffered: heterozygotes or inbred? what does buffered mean?
heterozygotes
Not as affected by environmental stressors, better suited to survive in the environment
heritability indicates how effective ________ should be
selection
- if heritability is high, selection will be successful, that trait is influenced by ________
- if heritability is low, expression is more dependent upon _________
- genetics
- environment
what does h2 = .25 in quarter horses indicate?
◼ Indicates that 25% of superiority (or inferiority) is associated w/ genetics
◼ Other 75% is associated with environment
if the horse’s average running speed is 40 mph and heritability=.25 and the parent’s speed is 44, what’s the selection differential? whats the EBV? expected progeny difference?
- selection differential: 44-40=4mph
- EBV: .25(4)=1mph
- expected progeny difference: 40+1=41 mph
define selection differential and how to calculate it
tells what parents are relative to population
average of parents - average of population = selection differential
how to calculate EBV
selection differential x h2
what is expected progeny difference and how to calculate it
- predictions of the genetic transmitting ability of a parent to its offspring
- take EBV and add to average of population
list heritable behavior traits
◼ Feed consumption in broilers ◼ Temperament in dairy cattle ◼ Running speed in horses ◼ Avoidance learning in swine ◼ Social dominance in chickens
what happens with many generations of selection
◼ Produce large phenotypic differences
◼ Faster with high h2 estimates
why would you need a large animal data pool
◼ Controlled environment
◼ Estimates can change over time
describe the selection study learning ability in rats
- what was the goal
- what strains of rats were used
- how many studies were conducted
- what kind of selection
- what was used to test the performance of the rats
- outcome and results
- Can we select and make progress between two different rats
- Dull rat vs. bright rat strains
- 5
- bidirectional
- mazes
- bright rats were selected for were good at a specific type of mazes,
◼ Clear differences ◼ 4-7 generations of selection ◼ 2 distinct populations
what was selected for in the rat study
- Not selecting for overall intelligence or ability, selected for a certain environment, certain task
◼ Selection was effective in changing ability to solve particular type of problem
◼ Changes in learning ability
◼ Specific for type of mazes used
◼ No carry over to learn how to negotiate different types of mazes
describe dogs and learning ability, what have we selected them for?
We haven’t selected dogs for overall intelligence but for specific traits and behaviors
what do we select for in mating frequency of males?
High libido & related behaviors desirable
Long term selection study in cockerels
- why cockerels?
- how many generations of selection?
- why high line males?
- what was the control
- takeaway?
- use chickens so easier to manage and can use a lot more
- 8
- High line males= line of birds that had high mating ability (4x as many matings). Low lines= cockerels weren’t efficient at mating ability.
- Unselected randomly bred population = controls
- we can select males for mating ability
explain how genetic variation is not exhausted by natural selection
didn’t have those mating cockerels in nature, because they’d be so focused on mating then they’re more subjected to predation instead of looking for food, etc., just bc a male wants to mate a lot doesn’t mean his production is efficient, his fertility could be detrimental if mating too much, concentration of sperm reduced.
define correlated response and provide an example
Strong selection pressure applied to trait
◼ Change other traits as well
◼ Long term selection for speed in TB’s
◼ Lean body, long legs, flighty behavior
Form & ______ go together
function
why would there be extreme selection pressure for turkey breeder?
Width of breast & rapid growth
true/false: turkeys are good breeder
false
what must take place in order for turkeys to be able to reproduce?
AI
Why do we get correlated responses?
- Gene linkage- two genes, two alleles are coupled. Sit next to each other on chromosome, mixing of alleles, neighbors go together through meiosis and end up together in gametes
- Pleiotropy- have an allele that affects expression of more than one trait. Selecting for allele could be good but cold also not be good. A desirable trait could be also detrimental
how does Genotype-Environment Interactions occur?
Occurs when strains or breeds perform differently (relative to each other) in different environments
- Particular strain, animals react differently depending on genetic makeup in environment
what are the 3 distinct situations involving pairs of genetic stock as compared in pairs of environments
Example 1
◼ No interaction
◼ Both stocks do better in environment A vs. B
Example 2
◼ Genotype-environment interaction
◼ Stock W is very superior to Z in environment C
◼ Stock W is slightly better than Z in environment D
Example 3
◼ Extreme case of interaction
◼ Strain U is superior in environment E
◼ Strain V is superior in environment F
Cook & Siegal
◼ Compared 3 genetic stocks for mating ability of
cockerels
◼ Sample halves of each stock reared in all male or bisexual flocks
3 lines had same ranks when tested, regardless of method of rearing
- what was the results?
Line selected for high mating frequency had highest % of males mating once or more (eight 10 minute trials)
Low mating frequency line had lowest %, regardless of how they were reared
Genotype-environment interaction present
◼ Greater difference present between high & low lines when cockerels of those 2 stocks had been reared in all-male flocks vs. when samples of both lines were reared with females
- [ ] Reared in all male vs bisexual: high mating line high mating in al male flock, unselected controls and low mating frequency flocks increased when reared bisexually
- [ ] High frequency may have dropped off in bisexual rearing could just be anomaly
- [ ] Increase in low frequency line: had more environmental influence where they can have more interest in mating when reared bisexually