[Campbell Biology P.561] Which of the following best explains how the Isthmus of Panama cont... | Practice Question

Which of the following best explains how the Isthmus of Panama contributed to allopatric speciation in snapping shrimp Alpheus ?

  • A: It created a new food source, leading to adaptive radiation of shrimp species.
  • B: It acted as a geographical barrier, preventing gene flow between Atlantic and Pacific populations.
  • C: It caused a change in water salinity, leading to different selective pressures.
  • D: It provided new habitats that allowed existing shrimp species to expand their ranges.

Explanation

The text states that 'Before the isthmus formed, gene flow could occur between the Atlantic and Pacific populations of snapping shrimp.' and then 'Did the species on different sides of the isthmus originate by allopatric speciation?'. This clearly indicates that the Isthmus of Panama acted as a geographical barrier, leading to the reproductive isolation and subsequent speciation of shrimp populations on opposite sides.