SI Worksheet 4.1: Intro to Evolution PDF

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BioPsych
Dr. D'Anna-Hernandez...

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Biopsychology Worksheet 4.1 – Introduction to Evolution 1. Define each of the following terms. a. Evolution: a change in gene frequency over a very long period of time to a particular environment. b. Natural Selection: process by which species who compete well (fit for the environment) survive and reproduce Adaptive traits: traits that are naturally selected that helps you survive and reproduce in your environment. This causes gene frequency for that trait to increase. (gene frequency for nonadaptive traits will decrease because whoever has that trait will not survive and reproduce as well as those with the adaptive trait). c. Selection Pressure: environmental factors/constraints that push species to change adapt (climate, food, predators) 2. Explain the relationship between evolution and natural selection. Natural selection: traits selecte4d for that change species gradually over time that help them survive and reproduce. This drives evolution because those adaptive, naturally selected genes for traits will be spread and cause a change in gene frequency over a long period of time (evolution). So now that traits are being naturally selected, we see a change in gene frequency in a population. 3. What are some of the threats that evolution poses toward commonly held beliefs (religion)? Timeline: of what bible or other religion says is incongruent. Humans and animals are completely different: but evolution suggests that we are very similar (this is because we are still bound to the same rules of natural selection). –“moral animal” Intelligent design: we are too complex for random mutation (evolution). Evolution threat: we have a design flaw, we are not perfectly designed: blindspot -- is a product of evolution. Because we have photoreceptors in the back, which have to communicate with other layers of cells, we get a blind spot. However, if we had photoreceptors toward the front, they would communicate with other cell layers and eventually reach the ganglion cells which would form the optic nerve in the very back and not obstruct where photoreceptors would be and create a blindspot. 4. Explain the evidence for evolution. a. From labs: Drosophilia (fruit flies): in a cold room, the fruit flies that survived bred and spread their “cold survivor” genes. Their offspring then had the adaptive, naturally selected for trait, and we saw a change in the population gene frequency. The ones who didn’t have a random mutation gene to help them survive, died off. They were unable to survive and reproduce. Bacteria: it eveolves when introducing it to acidic solution. Within an hour you have a whole difference lineage and new “survivor” bacteria genes (the bacteria that had these genes, by random chance, were able to survive and reproduce). This change in gene

frequency caused by environmental constraints drove natural selected trait (ability to survive in acid). b. In the wild: White moths: they were able to blend into the white trees before the industrial revolution when the trees were white. The darker moths were scarce because they stood out and predators ate them. However, during the industrial revolution, the trees turned black (with all the pollution), nad the white moths stood out like a sore thumb and got eaten. The darker moths were able to blend into dark polluted trees and survive and reproduce. So we saw a change in gene frequency (high frequency of dark moth genes, and less white moth genes) c. Fossils: Carbon dating/bone traits to date and see changes over long period of time. So we can see phenotypic changes such as the progression of webbed feet to non-webbed feet. So when we see phenotypic changes, we know that genome (or changes in gene frequency) underlie these changes. 5. Why would a lack of individual differences within a species be bad? No variation = we all have the same weaknesses. So if a bacteria or virus comes that we are susceptible to, we all die (no variation in immunity to protect us from a single threat). Genetic diversity (mating with someone genetically different) is important for creating healther offspring, which increase chances of survival and reproduction.

6. At the exact same time as Darwin, ____Alfred Wallace___ also theorized that all living organisms are related. 7. What are adaptive traits? What do they have to do with evolution? Naturally selected for traits (driven by environmental constraits-selection pressures) that help you survive and reproduce in your environment (these are traits adaptive to your specific environment). So these adaptive trait frequencies increase over time gradually. These cause changes in gene frequency -- which is evolution.

8. True/False a. _T___ Superfecundity (more gametes/gamete efficiency) refers to the ability to reproduce. b. _F___ Some animals will sacrifice themselves for the good of a species. This may look like altruistic behavior but anything “good” or “altruistic” they do is to help either their survival, their genes (reproduction), or both. c. ___T_ A population is a geographically defined subgroup of a species. d. __F__ Since evolution is just a theory, scientists aren’t really sure if it’s true. e. __F__ Evolution explains where life came from. f. __F__ When a species evolves, the members of the species are better than their ancestors. Not better, but more fit/adaptive to their particular environment. 9. Explain what Darwin saw on the Gallapagos Islands that led him to his theory of evolution?

Finches on different parts of island had different beak structures. On different islands, there were differnet environmental contraints (food). Their beak structure was well-adapted to their environmental food demands (i.e., long and pointy for digging into holes and getting worms; short and stubby for breaking nuts, etc). Birds that didn’t have the beak structure to fit their particular environment died off. The ones that had adaptive beaks were able to survive better and reproduce, and now we a higher gene frequency of only “adaptive beak” genes Apply the material! 10. Suppose that a certain species of insect has, over several generations, changed from green to brown. Describe how natural selection may have played a part in this change. That is, invent a scenario in which this sort of thing might happen. If there is a drought, the brown bugs will survive. This is because they will blend into (predators cannot see them but see the green and eat them up) the dried up landscape, survive, and spread their genes through reproduction. Now we will see a change in gene frequency such that the “brown trait” genes are higher and the “green trait” genes are lower. The environment changed and selection pressures made it harder for green bugs to survive and pass on their “green trait” genes.

11. Compare the selection pressures acting on two different populations of rabbits – one that lives in a cold, snowy environment and one that lives on an open plain.

12. What is the EEA? When we try to figure out why humans are the way they are, why do we have to think of them in the EEA? Environment of Evolutionary Adaptation: these were evolutionary environmental constraits/pressures that we faced way way back which contributed to eveolution in the past. The environment from the past explains our behavior today. This is because the environment changed too quickly (too fast for us to evolve). We are not caught up to today’s modern environment. So our behaviors and adaptations now reflect and stem from our ancient ancestors. Now we use our old traits for things like: sports (have fast running and tackling traits because it was useful for our survival way back in the day). Hand eye coordination: originally useful for hunting, escaping from predators, etc (now we use it for driving, sports)

Opposable thumbs and flexible fingers: helped you survive, now you use it for texting/typing Our past’s enviroinmental constraints made us what we are today

13. Give examples of human traits that may be beneficial to survival in one environment (in EEA) but detrimental in another (today) Ex: metabolism: back in the day, you might not see food for a few days, which having a slow metabolism benefited you (more fat to store/energy as well). Now we have food readily available and we eat as we please while still having that slow metabolism Eating: we get chemically rewarded for eating, and now we hijack that system and eat more than we need to. So a slow metabolism was good in EEA, but now it could hazardous to our health. Drugs/Aclohol: way bnack when in EEA we did something good like get food/sex, nad we’d get chemically rewarded (DA and SE). But now we have drugs that give the same effect which are often abused. Anxiety: helped us survive in crazy predator environment, today it is somewhat crippling (people dependent on antianxiety medication). 14. Are we simply a product of our selection pressures, destined to do anything we can to survive and reproduce? Why or why not? No because we are the “moral animal,” and we have a higher cognitive capacity to think, plan, and make more sophisticated decisions. We’ve already mastered survival, so behavior due to “selection pressures” are thing of the past. We’re more flexible now don’t just give into primitive urges. We have a higher awareness, underswtand our desires and thoughts, and have metacognitive abilities. So, although we are shaped by our selection pressures, we are not limited to them (if we were limited to them, we’d just be sleeping, eating, doing drugs, and having sex all day)....