Only $35.99/year

Terms in this set (10)

1. Observation that leads to an experiment:
- While looking at the larvae of the Drosophila melanogaster (also known as fruit flies) , a researcher noticed fruit fly larvae of the "sitter" strain move
very little on a petri dish with food in it, whereas fruit fly larvae of the "rovers" strain move a lot.
- Note: different behaviours were observed under same condition (food was the same)

2. Researcher did crossing ...
- She took a rover parent mate with a sitter parent and produce the F1 generation (1st generation), and F1 generation was 100% rovers.
- She started to do crosses again, meaning that now 2 members of the F1 generation are mating to produce F2 generation ( F1 X F1 = F2) => the F2 generation three out of four was rover (75% rovers and 25% of sitters), and it's basically as if it was governed by a single trait.

3. What GENE is involved?
- It is the for gene (or the foraging gene) that was involved in the observed behavioral difference.

4. Where was this gene transcribed or expressed?
- The for gene is transcribe/expressed in the olfactory system of these larvae.

5. The follow up experiment to test whether differences in behavior (moving) are due to differences in smelling:
Two types of food were presented to the sitters and rovers larvae which are: 1. Yeast ~ good food; and 2. Agar ~ bad food while observing their movements.

- Under the good food condition => Rovers move around a lot. But sitters did not move around a lot.
- Under bad food condition => Both rovers and sitters moved around similarly.

6. Interpretation/Conclusion:
- Sitters can actually move, but they don't, if the food is good because they are sensing the world differently.
- Rovers have a version of that enzyme the protein kinase g with high activity. And that leads them to smell the world differently and thus move around more
- So this is just one out of 13,000 genes in the Drosophila genome. And yet this slight difference in this one gene leads to a really big difference in the phenotype
- Social

- The male wild type mice (also known as the non transgenic mice) investigate the female less and less each time because they are familiar with her odour, but when presented with a novel female, they investigate more just shows you that their sense of smell is still intact.

- The male knockout mice (those without Oxt) spends the same amount of time investigating the same female in different trials similar to how they would investigate a novel female that they have no prior interactions with.

- Knockout mice don't remember that the female over the trials 1 to 4, and so they keep investigating/smelling which is known as Social Amnesia.

Limitation of the current study:
- People have different types of Oxt receptors. This means person A's Oxt receptors might not work the same as person B's Oxt receptors (e.g., Oxt may binds better to person A's receptor compare to the person B). That means there are a lot of variations here.
Approach 1:
- Presenting the male knockout mice (those without Oxt) with different odour to make sure that lack of Oxt leads to social amnesia (deficits in memory/recognition) and not leads to the deficit in olfaction.

Approach 2:
- To present The male knockout mice (those without Oxt) with different object. For example, we can present the mice with a blue object while investigating how much time they spend investigating this blue object over repeated trials. If the amount of time in each trial does not change, then we can conclude that non-functional Oxt receptors leads to the social amnesia.
1. Natural selection ......(can/cannot)...... operate differently in separate populations of the same species, producing genotypic and phenotypic variation.

2. An example:
- Thamnophis elegans (Garter Snakes) is found in both wet coastal areas and dry inland areas of California. Coastal snakes eat banana slugs; inland snakes eat fish and frogs but avoid banana slugs.

3. Question:
- Why do the diets/food preferences of these two populations of the same species differ?

4. Hypothesis:
- The differences in diet/food preference are due, at least in part, to hereditary food preferences (due to genetic differences between the two populations).

5. Prediction:
- The slug preference of coastal snakes and the slug aversion of inland snakes should still be present if the snakes are separated from their mothers/siblings after birth and raised in the same environment.

6. How to test this?
- researchers did a Uniform environment
experiments, which means animals from both populations were raised in the same environment. (also sometimes called Garden Experiment).

- The uniform environment experiment is build of the idea of keeping the environment similar while allowing the genetic differences to demonstrate themselves.

- Researchers brought the pregnant snakes (from both wet coastal and inland population) into the lab and then they gave live birth in the lab, and then those young were raised in the lab.

- Researchers offered the newborn isolated snakes from both group both banana slugs and fish/frog to test their diet preference

7. Findings:
1. The newborn inland snakes didn't eat banana slugs.
2. The newborn coastal snakes did eat the banana slugs.
3. Young snakes from both populations were interested in frog smells on cotton swabs, but only coastal snakes were interested in slug smells on cotton swabs.

8. Interpretation:
- There is a genetic difference between these two populations of the same species; or differences in food preferences are caused by genetic differences.

9. Limitation:
- The snake mother were already pregnant when they were brought into the lab & the mothers had already been eating slugs or not eating slugs. As we know, the prenatal environment is important, so maybe mothers different diets affected the newborn snakes food preferences.

10. How to address the limitation & results & interpretation?
- Allow the two population to mate in the lab and investigate whether the new generation also show the same food preferences while keeping the prenatal environment the same.
- Result & interpretation: food preferences stills exist which show it is governed by genetic differences.