Analyzing radiation in hawaiian drosophila




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ANALYZING RADIATION IN HAWAIIAN DROSOPHILA
Name: _________________________

Background

The Hawaiian islands are located far away, near the middle of the Pacific Ocean, 4,000 km (2,500 miles) from the nearest continent. The Hawaiin islands are rather young, with islands ranging from 0.5 to 10 million years of age.


As you have learned, the Hawaiin islands are volcanic in origin. J. Tuzo Wilson’s “Hotspot Theory”, that as the pacific plate is moving in a northwesterly direction, at a rate of 10 cm/year, an underlying hotspot regularly erupts forming new islands, is well supported by the fact that the islands increase in age and are lower in elevation as one moves through the island chain to the northwest.
In the following activity, you will come to a deeper understanding of the speciation and adaptive radiation events that have occurred on these islands, and the diversity that resulted from these processes. More specifically, you will learn a little bit about the evolution of over 100 distinct species of Drosophila fruit fly species inhabiting the Hawaiian islands.
The following activity was developed from the information and activity presented in the National Academy of Sciences. (2004). Evolution in Hawaii: A Supplement to Teaching About Evolution and the Nature of Science, Steve Olson. Washington, D.C. The National Academies Press – www.nap.edu/catalog/10865.html

Procedure & Questions




Pre-Lab Questions

Read the Student Background Reading for help in answering the following questions.


1. What characteristics of the Hawaiian islands have been important to the adaptive radiation of the Drosophila fruit flies? Explain how each characteristic you identify is specifically important in the radiation.

2. Sketch two representative polytene chromosomes demonstrating in inversion in the second relative to the first.


3. Contrast ‘homologous’ and ‘analogous’ structures as discussed in your textbook beginning on page 493.

4. Based on your knowledge of homology, can the inversion patterns in the polytene chromosomes of drosophila be used to determine possible evolutionary relationships between currently living species? Explain.

Activity Questions

1. Given the following table of 11 possible inversions in 13 species of Drosophila fruit flies, construct a cladogram or phyogenetic tree suggesting the evolutionary relationship between the four species identified with an astrix. In your cladogram, identify the shared primitive character as well as the location of each of the derived inversions along the appropriate lineage (see page 498-9 for help).



Species

Ch X

Ch #3

Ch #4

Island

D. heteroneura*


i j k o p q r s t

d

b

Hawaii

D silvestris

i j k o p q r s t

d

b

Hawaii

D. planitibia

i j k o p q r s t

d

b

Maui

D. differens

i j k o p q r s t

d

b

Molokai

D. hanaulae*

i j k o p q - s t

d

b

Maui

D. obscuripes

i j k o p q - s -

d

b

Maui

D. hemipeza

i j k o p q - s t

d

b

Oahu

D. oahuensis

i j k o p q - s t

d

b

Oahu

D. substenoptera*

i j k o p q - s -

d

b

Oahu

D. primaeva*

i - k o - - - - -

-

b

Kauai

D. ornata

i - k o - - - - -

-

b

Kauai

D. setosifrons

i j k o - - - - -

d

b

Hawaii

D. setosimenturn

i - k o - - - - -

-

b

Hawaii

Cladogram

2. Based on your knowledge of the ages of the different Hawaiian islands, where do younger species tend to evolve, older or younger islands? Explain.

3. Next, complete the narrative or story detailing the timing, movement, inversion history, and evolution of the four Drosophila in your cladogram.


About four million years ago on the island of ____________ there lived an interbreeding population of picture-winged drosophila fruit flies. Every member of this population had the four chromosomal inversions __, __, __, and __. Then, …

Extention Questions

1. Based on the information in the table, where could the species D. setosimenturn be added to your evolutionary tree? Explain.


2. How would your narrative change to incorporate D. setosimenturn?


3. Based on the information in the table, where could the species D. silvestris be added to your evolutionary tree? Explain.


Using information on more than 200 inversions from over 100 drosophila species in the Hawaiian islands, Hampton Carson suggested the following radiation of the picture-winged Drosophila. Using his image fill out the following table and then answer the remaining questions (The numbers in bold in the table are the number of species currently occupying each island. The example shows Oahu was the probable recipient of 5 species from Kauai, while Kauai received 0 species from Hawaii.)







Recipient Island




Donor Island




Kauai

Oahu

Maui Complex

Hawaii

Kauai

12


5







Oahu



29







Maui Complex







40




Hawaii

0








26

5. Is there a correlation between the age of the island and the number of species? Explain.

6. Are younger islands more likely recipients or donors? Give a few examples to support your answer. Why does this make sense?

7. Finally, read the article on incipient speciation in Drosophila silvestris by Carson and Bryant, and explain how data other than chromosomal inversions have been important in this study.




Species

Ch X

Ch #2

Ch #3

Ch #4

Ch #5

Island

D. setosimenturn

ikouvwxym2

cd

fjkl

bopqb2

f

Hawaii

D. ochrobasis

ikouvwxym2

cd

fjkl

bopqb2

f

Hawaii

D. adiastola

ikouvwxy -

cd

fjk -

bopq -

f

Maui

D. hamifera

ikouvwxy -

cd

f-k -

bopq -

f

Maui

D. toxochaeta

ikouvwxy -

cd

fjk -

bopq -

f

Molokai

D. touchardia

ikouvwxy -

cd

fjk -

bopq -

f

Oahu

D. ornate

ikou- -xy -

c-

- - - -

bo- - -

-

Kauai

D. primaeva

iko - - - - - - -

- -

- - - -

b - - - -

-

Kauai

D. setosifrons

iko - - - - - - -

- -

- - - -

b - - - -

-

Hawaii

D. heteroneura

iko - - - - - - -

- -

- - - -

b - - - -

-

Hawaii


Student Background Reading









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