Q2 - Only 1,000 to 2,000 species of fruit flies exist

[DanyalLloyd]

Hi,
I am a little slow with LR. Can someone please explain the answer to this question?

[sumukh09]

This is an inference question so we have to find an answer choice that must be true based on the information in the stimulus. Let's break it down sentence by sentence.

1st sentence: 1000 - 2000 fruit flies species exist worldwide

(simple enough, all we know from this is that only a minimum of a 1000 fruit flies species and a maximum of 2000 fruit flies species exist world wide)

2nd sentence: Hawaii is home to the most diverse collection of fruit flies species where some 500 species live

(Hawaii has the most diverse population of fruit flies species than anywhere else in the world; the remaining 1500 are probably scattered throughout the globe)

3rd sentence: a particular specie called the picture winged drosphilids makes 106 out of 500 of the different species in Hawaii

Last sentence: the 500 species in Hawaii are thought to be descendants of the same one or two ancestral females

Answer choices:

A) we can definitely infer this. Why? Because the last sentence says ALL the fruit flies species in Hawaii are descendants of the same one or two ancestral female fruit flies AND we KNOW that part of those species that are categorized under "ALL" is the picture winged drosphilids so we can infer that they were descendants of the same one or two ancestral females

B) Nope can't infer this because they could be found in other areas

C) We only know the ones in Hawaii are descendants of the same one or two ancestral females

D) way off

E) We simply have no proof of this

[tommywallach]

Hey Guys,

Great explanation from Sumukh, but I'd like to go into a little more detail on the wrong answers, just so it's super clear.

Also, if you didn't know, the correct answer to an inference question is something that you absolutely know is true. Sometimes, people who are new to LR find this shocking. In other words:

I have wet hair and it's raining outside. What can you infer?

You could only infer a few things: My hair is not impermeable to moisture. My hair is not dry. Etc.

You could not infer: I was out in the rain. I don't have an umbrella. I took a shower. I'm sweaty.

So the correct answer must be true.

We know three things:

1) There are 106 species of PWD in Hawaii.
2) PWDs are fruit flies.
3) All fruit flies in Hawaii are thought to be descended from the same 1 or 2 females

(A) Yep. PWDs are fruit flies, and all fruit flies in Hawaii are said to come from these ancestors.

(B) Though we know there are 106 species of PWDs in Hawaii, that doesn't mean there aren't 100 more somewhere else.

(C) This extrapolates out too far from the last sentence. We know this is true about all the fruit flies in Hawaii, not all the fruitflies in the world.

(D) This is an interesting one. There are about 500 species in Hawaii, so if, say, 600 species were found in another place, this answer would be true. However, 500 alone wouldn't be enough. ALSO (and more important), those 600 species would have to be found somewhere other than Hawaii.

(E) This goes into way more detail than the passage does. We don't know about the migrations of the fruit flies.

Hope that helps!

-t

[aaronwfrank]

This is an inference question so we have to find an answer choice that must be true based on the information in the stimulus. Let's break it down sentence by sentence.

1st sentence: 1000 - 2000 fruit flies species exist worldwide

(simple enough, all we know from this is that only a minimum of a 1000 fruit flies species and a maximum of 2000 fruit flies species exist world wide)

2nd sentence: Hawaii is home to the most diverse collection of fruit flies species where some 500 species live

(Hawaii has the most diverse population of fruit flies species than anywhere else in the world; the remaining 1500 are probably scattered throughout the globe)

3rd sentence: a particular specie called the picture winged drosphilids makes 106 out of 500 of the different species in Hawaii

Last sentence: the 500 species in Hawaii are thought to be descendants of the same one or two ancestral females

Answer choices:

A) we can definitely infer this. Why? Because the last sentence says ALL the fruit flies species in Hawaii are descendants of the same one or two ancestral female fruit flies AND we KNOW that part of those species that are categorized under "ALL" is the picture winged drosphilids so we can infer that they were descendants of the same one or two ancestral females

B) Nope can't infer this because they could be found in other areas

C) We only know the ones in Hawaii are descendants of the same one or two ancestral females

D) way off

E) We simply have no proof of this

D is also wrong because most diverse is unsupported. Just because there are 600 fruit flies in Borneo doesn't mean they're more diverse than Hawaii's