Neanderthals disappeared about 40,000 years ago when the modern h...

Question

Neanderthals disappeared about 40,000 years ago when the modern human population increased. This is an example of what outcome(s) of secondary contact (see Table 24.4)? Predict one way this result might have come about.

Accepted Answer

Hi everyone, here's our next question. The introduced species in a lake out compete the deepwater cisco fish, they primarily chose the same niche and use the same resources over time, commercial fishing of the deepwater cisco fish was combined with competition and predation, which of the following was the most likely result of these interactions with the deepwater cisco fish. So the interaction we're talking about is between our introduced species and the Sisko. And we're told that they introduced species out competes the Cisco and they were told that they chose the same nation, used the same resources. So those old here for the cisco is that the resources it needs are being depleted by this competition. We're told directly the introduced species out competes the Cisco. So we know that the Cisco's resources are being depleted. We're also told that commercial fishing uh is affecting them. So we have its numbers, its population is declining due to fishing. And then it says commercial fishing of the deepwater cisco fish was combined with the competition we mentioned and predation, which of the following was the most likely result of these interactions with deepwater cisco fish. So given that we have this introduced species and the Cisco and when they interact, the introduced species is out competing it for resources. So the resources it needs to survive are being depleted by this competition at the same time as its population is declining, its numbers are going down due to fishing and predation, which are actively killing off its population. Well, let's look at our answer choices and see which one would we say is most likely. Well, choice A says the extinction of deepwater cisco fish. Well, I would say this is pretty darn likely. Um given the threefold pressure that the cisco population is under. So since we're talking about most likely as a result, we're not dealing in absolutes. I'm just kind of noting this, but it's a good idea to look at your other answer choices and make sure nothing else pops up as being a little more nuanced, a little more likely. Um Knowing the choice A if I were in a real hurry, I'd probably just select it and move on. But for thoroughness, we'll look at the other choices. Choice B says the formation of new species. While speciation takes time, you have to have mutations arise that are maybe adaptations maybe if the cisco could adapt to a new food source um or a new region of the lake where it's not competing with the new introduced species. But that would take time you'd have to have these adaptations arise and then be selected for over generations. And given that the population is declining steadily due to fishing information, the Cisco doesn't have that time in general. It's population is being smaller and smaller, which doesn't give a lot of material for these changes to arise and be selected for. So that's a pretty unlikely occurrence. And I would say B is definitely less likely than a choice. C. Says the fusion of the two species. Well, we have no indication in our problem the two species can interbreed. Um So that would mean that they would have to interbreed to the extent that they exchange so much genetic material, they essentially become one species, so no indication that would happen. So Choice C. I think we can eliminate and Choice D. Says the formation of a hybrid zone. Well, hybrid zone would be a location where genetically distinct populations meet mate and produce at least some offspring. Again, we have no indication here that interbreeding between the two species would occur. So I would say Choice D. Is not a likely situation. So I think we're pretty safe to say Choice A. The extinction of the deepwater cisco fish is the most likely result of the interactions of this introduced species with the deepwater cisco fish. See you in the next video.

Neanderthals disappeared about 40,000 years ago when the modern human population increased. This is an example of what outcome(s) of secondary contact (see Table 24.4)? Predict one way this result might have come about.

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