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Course: Middle school biology - NGSS > Unit 9
Lesson 2: Adaptation and environmental changeEnvironmental change and adaptation in Galápagos finches
Adaptation by natural selection is one important process by which species change over time. After an environmental change, traits that support successful survival and reproduction in the new environment become more common; those that do not become less common. Thus, the distribution of traits in a population changes. Created by Sal Khan.
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- in the 1978 graph why were there so little of the 11.3 beak finches(7 votes)
- There was only one finch born in 1976 (recorded) that had an 11.3 beak depth. The graph exhibits a standard "bell curve", which is used in statistics to display the average of a set of data. Having a beak that large is well outside the average, similar to the way a human 7 feet tall is well above average height for humans(20 votes)
- i want to be bird(10 votes)
- If a species has a shorter lifespan ( and therefore faster results ) will natural selection happen faster?(4 votes)
- Basically. But it's a little tricky depending on the definition of the evolution.
And if they live shorter than another species, it's proven natural selection will occur faster.(4 votes)
- There was only one finch born in 1976 recorded that had an 11.3 beak depth.(4 votes)
- Good notation(3 votes)
- There was only one finch born in 1976 (recorded) that had an 11.3 beak depth. The graph exhibits a standard "bell curve", which is used in statistics to display the average of a set of data. Having a beak that large is well outside the average, similar to the way a human 7 feet tall is well above average height for humans(2 votes)
- a good question indeed(6 votes)
- wait. why did Darwin even have to go?(4 votes)
- Are adaptation and artificial selection the same thing?(3 votes)
- yes they are the same thing(1 vote)
- Thanks teacher(3 votes)
- Can someone explain to me the differences between Macroevolution, Microevolution, and Adaptation please?(2 votes)
- I will simplify.
Macroevolution deals with large-scale evolutionary changes, such as the formation of new species.
Microevolution focuses on small-scale changes within populations, such as allele frequency shifts.
Adaptation refers to the process by which organisms acquire traits that increase their fitness and survival in specific environments.(3 votes)
- why did it become more common(2 votes)
- Evolution as time passes, in order to adapt to the food that are available to them.(2 votes)
Video transcript
- This here is a picture
of the ground finch of the Galapagos Islands. And one of its primary sources of food is seeds that it finds on the ground. And if we go back to 1976, we can look at the
distribution of beak depths. And these beak depths, I would assume these are
given in millimeters. Finches are quite small birds. And you can see in 1976, you have a large number of finches that had a beak depth of 8.8 millimeters, but it was a distribution around that. Now, after this data was collected, it turns out there was a drought
and there were fewer seeds. So the smaller seeds, which were easy to eat
for all of these finches, would have been consumed quickly. And all that would have been
left were the larger seeds, the ones that you need a larger beak in order to crack and
get at the good stuff. So what do you think would have happened to the distribution of beak depths over the course of the next two years? Well, you might guess that the birds, the finches that have larger beak depths, are more likely to survive
because they're more likely to be able to crack the larger seeds. And the finches that are
more likely to survive are also more likely to reproduce, and pass their large beak
trait to their offspring. And that is indeed what
scientists observed. As we go from 1976 to 1978, the distribution has shifted a
pretty good bit to the right. Now the most common beak depth is 9.8. So this is an example of an
environmental change, a drought, changing the food supply, because now there's fewer
small seeds available, that changed a distribution in beak depths over just two years. Now, environmental changes
don't always cause adaptation. If it's too severe, if the drought was so strong
that there were no seeds, you could have extinction. So the species disappears altogether. But here we have an example
that in just two years, a species was actually able
to adapt a pretty good bit. Now, no individual member of the species knew to somehow grew their beak. But as we saw, you always have
a variation of beak depths. And year after year, the birds with the bigger beak depth, were more likely to survive and reproduce. So the species as a whole adapted to the new
environmental conditions.