Question

After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island? A) evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks B) evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks C) increased variation in beak size and shape over time D) no change in beak size and shape over time

          After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?
A) evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks
B) evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks
C) increased variation in beak size and shape over time
D) no change in beak size and shape over time

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Added by Tanya W.

Biology for AP Courses

Julianne Zedalis, John Eggebrecht

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Solved by Expert Rachel Griffin

08/09/2022

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This would lead to natural selection favoring these traits, and over time, the population would likely evolve to have larger, deeper beaks. However, with the introduction of the feeding stations, the food is now easily accessible to all finches, regardless of Show more…

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After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island? A) evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks B) evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks C) increased variation in beak size and shape over time D) no change in beak size and shape over time

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00:01 The experiment on the galapagos island concerning our ground finches has been a major example of an experiment conferring natural selection.

00:20 Charles darwin himself did a lot of research with finches and how they do relate to beak size, and the galapagos island experiment is just one major example of this.

00:34 So obviously it was found that over time and with environmental conditions, that finches with larger deeper beaks were selected for due to the fact that they could most easily crack the shells of certain seeds and they could get their nutrition that way.

00:55 So those individuals were naturally selected for as they could confer not only their ability to survive and with eating these seeds but also then their ability to reproduce.

01:07 And we know that now that natural selection overall favors individuals with traits that confer advantage.

01:30 And these traits and this advantages that i'm talking about is oftentimes reproductive advantage and overall survivability.

01:45 So with their team of researchers that hide up to the island, and they want to know what effect this is going to have on the population of finches if they were to offer different types and sizes of seeds, so not just very large, tough seeds, and how this is going to change the beaks of the finches over time.

02:05 And very important to note that natural selection works on populations.

02:12 Not individuals, not on a time frame of a few days or a few weeks, natural selection works on populations over a time of year spans to decades, that sort of.

02:22 Of thing...

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