Archive for the ‘Unit 4-Evolution & Population Dynamics’
Hey guys, so I was reading through the book tonight, and I came across a section talking about Keystone and Foundation species. In one sentence it talked about an elephant being a foundation species. I immediately thought back to the worksheet we did for homework that night and remembered we put an elephant as a definite K species because it had large adults, long maturity rate, etc. The book says the elephant does many things to disturb the environment that in the long run, helps it out. SO, my question is, would we consider all animals that do this to be foundation species, even if they are obviously keystone? If a clear keystone species impacts the environment in some way that turns out to be helpful, like the elephant, is it foundation as well? Just need some clarification on how to classify…thanks:)
So this is pretty random, but I was looking through the study guides and got to the question that asked about the difference between mass and background extinction. In my answer I had that background extinction is basically happening all the time and that there have been five mass extinctions in Earth’s history, but I was wondering, if you’re alive during a mass extinction, would you know it,seeing as they take place over millions of years? I don’t mean to sound morbid or anything, but I remembered that during the mass extinction video, scientist were wondering whether or not we are in a sixth mass extinction phase, and I didn’t know if we would know if we were or not.
The three aspects of sustainability/stability seem kind of sketchy/all the same…the three are inertia/persistence, constancy, and resilience. Resilience and inertia/persistence sound almost exactly alike…it’s number 2 on the study guide of Chapter 6. If anyone could kind of clear these up…it says that inertia/persistence is the “ability of a living system to resist being disturbed or altered” while resilience is “ability of a living system to repair damage after an external disturbance that is not too drastic.” For whatever reason, these are just not making sense to me. If anyone could clear these up that would be great!!
And just a minor question–it says on number 11 of Chapter 4 I wrote down that background extinction is “as local environmental conditions change, species disappear at a low rate.” could anyone provide maybe a time scale for this “low rate”? And maybe give an example? Just sounds a bit vague.
So I have a similar question to Emily’s. I understand the difference between macroevolution and microevolution because macroevolution occurs over a much longer period of time, and it is when new species are formed. But when you say that microevolution occurs over a shorter period of time, what is that estimated time span? Within an individuals life? Years? I know that an individual cannot evolve, and only populations can, but I guess I’m just still a little confused on microevolution and the example that Andy gave in his post… I’m having trouble recalling AP Bio material. If anyone could try to explain microevolution in another way that would be great! Sorry this is repetitive!
I think I missed the day when we covered evolution, and I was looking over microevolution and macroevolution, and I just wanted to make sure that I understand it correctly because I’m a little confused. Is macroevolution only creating a new species from an already existing one? It seems as if there should be more to it then that, so I’m not sure if I’m missing any aspect of it. Also, microevolution only alters gene pools, so is that physical appearances, such as the mice example Andy used? Does microevolution help select for certain species by making them more able for survival? If someone could clarify for me that would be great, thanks!
In class, we classified foundation species as the dominant photo synthesizers in an ecosystem, for example seaweed in the ocean. However, the book explains that animals like elephants and beavers are foundation species because they are “ecological engineers” who create additional habitats in ecosystems. I’m a little confused about this, especially since in class we classified elephants as a keystone species. What’s the definition of foundation species for this exam? Are foundation species plants, or animals whose behaviors induce plant growth? (The text says that the elephant behavior of uprooting trees and such promotes plant growth.)
Looking over the study guide, I’m not sure I really understand the difference between artificial selection and genetic engineering. I know they are both used to create certain traits in organisms, but is one more effective than the other? Which is used more often, and does the type of species depend on which is the more frequently chosen method of controlling characteristics?