Question

Don’s question: Are these two morphs different species?

Hypothesis (you will be testing the following hypothesis):



H

a

: Benthic and Limnetic Sticklebacks are different species.



H

0

: (null) Benthic and Limnetic Sticklebacks are the same species.

1. Methods

a.

What kind of

field data

would you need to collect in order to test your hypothesis? (1.5

points)

b.

What kind of experiment would you design to test your hypothesis in a

laboratory

setting? (1.5 points)

2. Results

Assume that you have gathered the field data and conducted lab experiments as stated in

Question 1. From data sheets 1–11, select those that pertain to the experiments you devised in

Question 1. Consider these as the data from your observations and experiments. Do these

address your hypothesis? What do you conclude? Explain your answer based on the data.

(2 points)

3. Discussion

(For the questions below you must refer to data from the sheets provided in your answers.)

a) What niches do the two morphs occupy and what evidence is there that each morph is better

adapted to its respective niche than either the other morph or hybrids? (1 point)

b) What are some things that prevent the two forms of sticklebacks from breeding with each

other in Paxton Lake? Explain. (1 point)

Answer 1

• benthic and limnetic sticklebacks are sympatric species that is they are two species from same ancestor. And which are different feeding habitat , that is limnetic consume zooplankton whereas benthic feed on benthic invertebrates
• also both require different habitat based on season
• but the both species have almost same appearance
• the hypothesis can check by observing their feeding habitat
• in the experiment a control plate with same amount of benthic invertebrates and zooplankton must be grown
• then two test sample with invertebrates and zooplankton of equal number should be prepared.And in one of the sample add some benthic sticklebacks and in another limnetic sticklebacks at same amount in both samples and at same time
• data should be collected such as the number of invertebrates and zooplankton in each sample at different time
• the result can be obtained by comparing this values with that of control sample.
• in test sample 1 the number of invertebrates will be reduced
• And in the sample 2 the number of zooplanktons will be reduced
• based on this result we can find which organism dwell there type of organism can be found
• benthic are found in the litter zone , there morphological changes are robust body shape with wide gape and are having shorter fewer number of gill rakers. These characters help in the benthic feeding
• limnetics are seen on limnetic zone , that is they are seen in well lit area which remain open
• limnetic shaped fusiform shaped body and gill rakers are denser
• these morphologies help both sticklebacks in survival
• the two species cannot interbreed as they are of different genotype and their habitat are different
• these two species are evolved based on adaptive evolution, which help them to survive in that habitat
• this will be lost if they interbreed , so they will not interbreed