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The Isthmus of Panama is a narrow strip of land that joins North and South America - VCE - SSCE Biology - Question 8 - 2006 - Paper 1
Question 8
The Isthmus of Panama is a narrow strip of land that joins North and South America. The land bridge formed approximately 3 million years ago. Snapping shrimps, genu... show full transcript
Worked Solution & Example Answer:The Isthmus of Panama is a narrow strip of land that joins North and South America - VCE - SSCE Biology - Question 8 - 2006 - Paper 1
Step 1
a. Why is the inability to mate sufficient evidence to call the two groups different species?
Answer
The inability to mate is crucial evidence in defining species because it indicates that the groups cannot produce viable offspring together. In the case of the snapping shrimps, the aggressive snapping behavior exhibited between males and females from different sides of the land bridge suggests reproductive isolation. This reproductive barrier signifies that the two groups have diverged sufficiently to be considered separate species, as they are unable to interbreed and produce fertile offspring.
Step 2
b. What type of speciation has occurred in the snapping shrimp?
Answer
The type of speciation that has occurred in the snapping shrimp is known as allopatric speciation. This occurs when populations are geographically separated, leading to the accumulation of genetic differences over time, which ultimately results in the emergence of distinct species.
Step 3
c. Explain how the differences between the shrimp on either side of the land bridge could have arisen.
Answer
The differences between the shrimp on either side of the land bridge could have arisen due to divergent evolution, which was influenced by the different environmental conditions and selective pressures on each side of the land bridge. Over time, as the shrimps adapted to their respective habitats, genetic variations occurred, leading to distinct traits. Additionally, the founder effect might have played a role; if a small group of shrimps colonized one side of the bridge, the limited genetic diversity could have further accelerated divergence from the original population, contributing to the differences observed today.