Midterm - Topic 4 Flashcards
Is behaviour the genotype of phenotype?
Behaviour is the phenotype
The genetic components are the alleles
Reflexes
basic involuntary kind of behaviour that happens in response to a specific kind of stimulus
Eg. blinking is a reflect to air in eye
Fixed action pattern
behaviours in a sequence that occur in a specific order
Once the behaviour is initiated, it will go to the end
A series of reflexes
Eg. goose, once it starts to observe a round shape object, it will almost always go through the same pattern of rolling the round object under her body. Even when the round thing is removed, the goose will continue to move her neck and roll nothing under her neck
Behavioural differences between wildtype and mutanttype fruit flies (D.melanogaster)
Research question:
Why aren’t yellow forms of fruit flies more common in nature? (Bastock 1956)
Wild-type Vs. Mutant-type
Wild-type → typical form of an organism or gene that occurs in nature. Most flies are grey
Mutant type → rare form → in this case is yellow
Does the yellow colouration produce some change in behavior, which perhaps places the mutant form at some sort of a disadvantage. Is the difference related to reproductive success?
Flies will orient, vibrate, release hormones, then sex → ethogram is clear
Methods:Interbred wild-type and mutant “yellow” flies to create inbred flies
Inbreeding made them very genetically similar except for their colouration
Conducted mating trials
Record the behaviours in comparison to the ethogram
Results:
Wild-type males had higher mating success + mated sooner + showed more courtship behaviour than mutant yellow males
Conclusion:
Differences in courtship behaviour result in reduced mating success of yellow individuals
Having a particular genotype influences the reproductive success
Note that an additional experiment was preformed to reject the alternate hypothesis, the females were responding to different colour and pheromone in the yellow male
Video on Peromyscus Mice
Questions asked:
- Are adaptive alleles usually dominant or recessive
- -> Many people argue that yes, these alleles express themselves more and are more likely to spread in the population - How many and what are the effects size of genes that contribute to a phenotype → how many traits are there that contribute to adaptation
- -> just because there is a new trait does not mean it has an adaptive function
3.Do different genotypes work together to produce an adaptation or do they work independently
4.Adaptive mutations → mutation is a change in the DNA
Are these adaptive mutations in the coding occuring in the area that codes for proteins or are they occuring in places in the DNA they we don’t necessarily see the result of
5.What are the sources of the muttation
Do they just occur or are there just modifications to the DNA sequence
6.Are these mutations always beneficial? Is it beneficial in all populations or just some
Why are mice used in the lab
They can survive in a lab
There is diversity
There are a lot
NCBI
National Center for Biotechnology Information
Advanced science and health by publishing the known genome and genetic variation of known species
Quantitative Trait Loci (QTL) analysis
Quantitative: number
Trait: what is on interest to the researcher
Loci: location
This is a statistical technique that allows for us to make an educated guess that the trait we are interested in is linked with a certain amount of probability is linked to a certain area of the genome
Shows you what genes might be linked to the phenotype → suspect genes
Shows which trait is probably associated with a certain part of the genome
After a QTL test what happens
A selection experiment is conducted
Takes around 15 generations to see the divergence.
Then, after the selection experiment, the high trait phenotype is bread with the low trait phenotype to produce a genetically diverse offspring
With you results go into the literature and see if there are suspected genes that we already know about that are associated with a certain behaviour
Use genetic markers to tract the gene of interest
What are genetic markers
- Known sequence of DNA, insert them next to all of the genes that are suspected to be involved in expressing a trait
- Markers are not coding sections. They stay in a particular location without impacting the functioning of the DNA sequence
- Breed the animals with these genetic markers
- -> when you start to see a difference in the phenotype, test the genotype of that animal and get a profile of the alleles next to those markers
- this is all done using a statistical software that gives a likelihood that the gene next to the marker is coding for that behaviour (high or low)
Three kinds of genetic markers
- Restriction fragment length polymorphisms
- Restriction means small size
- Fragment means specific piece
- Polymorphism means many type → more of a complex sequences, you have to know the sequence - Simple sequence repeats
- Sequence that repeats it self - Single nucleotide polymorphisms
- DNA sequence only differs in a single base nucleotide
Fire Ant (S. invicta) Genotype and social organization
Research question:
Do genes affect variation in social behaviour in fire ants? (Ross 1997)
Social organization
Very difficult task to unravel
Monogyne Vs. Polygyne
Monogyne → single reproductive queen, she is the mother of every single individual in the colonies
Polygyne → multiple reproductive queens
How does this happen, where are there monogyne and polygyne colonies
Is there a cluster of genes that are coding for this complex social organization
There are also sterile males in the colonies that acts as soldiers
Methods:
Collected monogyne and polygyne colonies
Conducted gel electrophoresis to compare allele frequencies at several loci
Compare the DNA sequence at species spots along a chromosome thought to be involved in the social organization
These bands are separated based on size and charge
Takes macromolecules (RNA,DNA,protein) fragments are separated them based on size and charge
Results:
Genotype and allelic frequency at one locus, Gp-9, differed between two types of colonies
Monogyne colonies all displayed Gp-9BB
–> everyone in the colony had Gp9BB
Polygyne colonies displayed Gp-9Bb
–> more allelic variation but all the queens were Gp-9Bb
There are pre build instructions on whether the ant will be apart of the monogyne society or a polygyne
Note this gene codes for proteins that play a role in initiating psychological changes
Anxiety-related behaviours and knockout of a hormone receptor in mice
Research question:
What is the function of the AVPR1A receptor in mice? (Bielsky et al. 2004)
- AVPR1A is a receptor that has the ability to bind specifically to the hormone vasopressin. Vasopressin need the receptor in order to do its job
- Vasopressin can be in the blood but will not have an effect until it binds to a receptor
Methods: Methods:
Created a knockout of V1aR gene
Conducted stress tests on wild-type and knockout mice
Targeted the V1aR gene that codes for the receptor and knocked it out and then recorded the stress of the wildtype mouse and knockout mouse
3 different experiments
- Open Arm. There was a maze with a central area connected to tunnel
The mice were put in the centre and it was measured how many tunnels it explored
–> the knockout mice explored immediately, while the wildtype stayed in the centre. - Light Box. the mouse is placed in a box with a dark area and light area
- -> the wildtype stayed in the dark and the knockout went out into the wild - Open Field. The mice were put in an open field
- -> the wildtype went to find shelter, while the knockout stayed in the open
Keep in mind we are measuring the immediate response
- Immediate for knock out is to start exploring
- Immediate for wildtype is to not explore
Conclusion:
V1aR gene plays an important role in affecting behaviour when animals are placed in stressful situations
Dog Behaviour Heritability
Examined behavioural field test results of German shepherds of known pedigree
German shepherds must remain calm in a lot of police situations
Trait studying: reaction of hearing a loud sound (gunshot)
Heritability scores ranged from 0.09 to 0.24 for traits like reaction to gunshots
Think of it as 9% - 24%
If the heritability score of the reaction to the gun shots is between 9-24% that is pretty low
This means the majority of it comes from the environment meaning training is very important for this animal
Environment has an important influence so start training them early
Closed ended learners
Bird of study = zebra finches
Close ended learners need to have a tutor to teach them how to sing the song properly
- -> very close to birth, the tutor (usually and adult bird) start to sing the songs so the babies can begin to learn the song right away
- there is a very short time frame and the bird needs to learn the song int his time frame
- They use these songs for mating, important to learn how to sing correctly in order to get a mate
- There were breaks in the song that the male produces called syllables → signify a start to end of a song
Open ended learners
means that you can learn songs all throughout your life, don’t need this early exposure, can learn throughout life
Brain song circuit of the zebra finches
There are 2 circuits in the brain that are responsible for the trait that is song production
There is a posterior circuit → coding for the trait of song production
Anterior circuit → codes fo song learning
FoxP2 gene expressed itself when the close ended learners are beginning to learn to sing and when open ended adults learn new song
The FoxP2 is an important gene for learning songs
Song Circuit experiment
Research questions: What is the role of the FoxP2 gene in song development? (Haesler et al. 2007)
FoxP2: expression increased when young birds learn to sing & open-ended adults change songs
Methods:
Used a knockdown technique on males
–> only used males because males are the ones that produce the songs
–> knockdown technique is different than a knockout technique
–> knockdown reduces the expression of the FoxP2 gene by inserting a section of RNA into the gene sequence (inserted using a virus)
–> They then housed the adult male tutors with the young juveniles and recorded the songs using a spectrogram
–> knockdown reduced of 70%
Control:
short section of RNA in a noncoding region. These birds were able to learn the songs
2 things to keep in mind: did the knockdown work and what were the effects of reducing FoxP2 expression
Results:
They were successful in knocking down the expression of the FoxP2 gene and knockdown birds tended to omit specific syllables in heir songs
The non knockdown birds began to sound like the adults where as knockdown birds did not
Conclusion: FoxP2 is required for normal song development
Reaction norm
The range of behaviours expressed by a single genotype in different environments
Gene environment interactions (GEI)
When an environment has greater effect on one genotype than others
VP = VG + VE + VGEI
Rover and Sitter Example of Gene Environment Interactions
GRAPH
There are 2 kinds of genotypes in fruit flies: the larva can be a sitter meaning it does not move around as much, or it can be a rover, meaning it does move a round a lot
- manipulate the environment to see the gene-environment interactions
Research question: Do different behavioural polymorphisms in fruit flies exhibit gene-environment interactions? (Sokolowski 2001; Kent et al. 2009)
Rovers Vs. Sitters
Rovers have longer foraging trails and are more likely to leave the food patch than the sitters
Found that differences in feeding behavior was due to different alleles at a single gene.–> the for gene.
forR is dominant and is the rover gene
forS is recessive and it is the sitting gene
This is maintained by frequency dependant selection: rover has increased fitness in crowded populations to go further away, sitter has increased fitness in less crowded environments
The rovers however behave like sitters in the absence of food because there is no advantage to moving if there is no food.
This suggests strong environment-gene interactions because rover behaviour changes with the environment where sitter behavior does not.
Experiment: adult rovers and sitters are exposed to different levels of food availability.
Half were placed in holding vials for 16 hr that contained food
Half were placed in holding vials for 16 hrs that did not contain food
All were then placed in the start vial and were allowed to eat there for 15 minutes before the doors opened allowing them to enter the maze.
At the end of the maze were closed collection vials and the researchers recorded the number of flies in these vials at the end of three minutes which they called food leaving scores
The fed vs. deprived rovers experienced a very different outcome. Fed rovers had much higher food leaving scores than the deprived rovers.
There was little difference in the fed sitters and the deprived sitters. → here again we see that the environment has less of a effect on the sitters.
Both the adult and larvae rovers experience different behaviors in different environments while the sitters do not.
Next experiment: remove heads of fruit flies and use mass spectroscopy to determine the compounds there
Found that rovers and sitter store energy differently.
Fed rovers and fed sitter store the same amount of lipids
In the food deprived sitters, there are more lipids than the deprived rovers.
Sitters always store more CHO than rovers in both conditions. → both were lower in the deprived but the rovers were the lowest.
These finding suggest that gene-environment interactions affect behavioral and metabolic traits.
Conclusion: rovers exhibit a greater change in behavior across different environments
Major genes and minor genes
Individual genes responsible for the majority of phenotypic variation are known as major genes
Those that contribute small amounts of variation are known as minor genes (note that the combination of many minor genes can have a big influence on the phenotype)
Explanation for the major gene influence
One explanation for the major genes large influence is epistasis → they can affect the expression of many other genes (remember epistasis means interactions between genes at different loci)
Another explanation is pleiotropy → major genes can affect multiple traits, just as the yellow gene affected both body color and animal behavior
QTL mapping aphid example
Examines the number of genes involved with plant choice in pea aphids
In New York, there are two genetically distinct races of pea aphids that feed on different plant species
→ one specialized on alfalfa
→ other specialized on clover
Question: How do individuals select the correct plant species for feeding?
→ the probe the plant, the time spend doing this depends if they are on the right plant or not
QTL analysis → the researchers crossed the 2 species to create an F1 and F2 generation. They used a AFLP marker to mark the gene. They then examined the feeding behavior of the F generations as well as the parents and said a strong preference for a plant was indicated by a quick feeding time (not as much time spent deciding)
Results: There was a small number of QTL and a large proportion of variance so the researchers proposed perhaps that only a few genes are involved in plant selection behavior.
Male fruit flies examined for male female interactions
Male fruit flies were raised and exposed to one of 2 treatments:
Allowed to court a single female
Interacted with rival males
Control group did not interact with any other flies
Microarray of the DNA from the heads was examined. Found hundreds of genes that were socially responsive → 505 responded to male-male interactions, 281 responded to male-female interactions
→ many were expressed in both groups meaning that they are socially responsive genes in conspecific interactions
240 just to male to male
16 just to male to female
Therefore 16 genes are associated with courtship but 200+ are associated with male to male interactions
Environmental Effects on Zebrafish aggression
Question: how do water conditions during development affect the aggression levels
Raised closely related fish in either high O2 water or low O2 water (common stressor).
After the fish had matured they were tested for aggressive behaviors by putting a mirror in the tank.
Interesting results: both fish displayed high levels of aggression in their respective raised environments compared to when they were placed in the environments where they were not raised. Aggression is energetically costly and may become a particularly high expense when the fish is placed in a novel environment
→ makes sense for the fish raised in a normoxic environment as if they were put in a hypoxic environment, they would feel O2 deprive. Not so clear for the reverse situation
Conclusion: Zebrafish display more aggression in the environment they were raised in, indicating an interaction between genes and environment
Bold and shy personalities of streamside salamanders
Live primarily in deep pools of shallow streams in eastern north america
Pools are separated by shallow areas of fast moving water (riffles) in which the eggs are deposited
The larvae must maximize feeding time to metamorphosize before the pools dry up and avoid predation by green sunfish
When there are predators, they seek shelter under rocks but this reduces their feeding time.
Question: are some individuals always more active when predators are nearby?
Larvae were put in an aquarium with water from a sunfish tank (chemicals can be sensed by the larvae) and then in a tank with tap water.
Sunfish tank = 40% time spent feeding, rest spent hiding
Tap water = 75% time feeding, rest spent hiding
There is a response to increased predation
Upon examination of there individual behaviors, a new story appeared
The individuals that spent the most time feeding in the no fish cue also spent the most time feeding in the fish cue tank = bold personality.
Few salamanders exhibited an optimal behavior of spending more time feeding when there is no cue and less time when there is a cue
Question: Is there a genetic component to the personalities?
Found that there is consistency but very large differences in/between sibling group behaviors indicating that genetic differences underlie the observed behavioral differences and we see how genotype can limit behavioral plasticity
Aggressive spiders
Many spiders will attack and eat a courting male before copulation → precopulatory sexual cannibalism
Hypothesis: females in low condition can gain energy from eating the male that outweighs the cost of them not mating
Aggressive spillover hypothesis: highly aggressive feeders will have higher feeding rates as juveniles and will attain larger body size as an adult while less aggressive young will have smaller adult body size
Found that young and adult aggressive spiders had higher prey capture success and young feeding rate was positively correlated with adult size.
Young aggression was positively correlated with adult aggression
Where then exposed to males and examined
Conclusion: those that most rapidly attacked prey had highest feeding rate and body size and were more likely to attack and kill courting mate which suggests spiders experience different personalities
There was no support for the first hypothesis
