Question

1. which of the following cases best illustrates speciation from a common ancestor? a population of a large turkey - like bird species takes up residence in an isolated mountain meadow with no predators and lush food supply. over many generations the birds lose the ability to fly. a single species of snails colonize a newly formed marshland formed by a retreating glacier. over several thousand years different groups of the snails are separated geographically and are no longer able to breed and produce fertile offspring. rabbits, which did not exist as native australian wildlife, were introduced into the island continent, where they quickly established themselves, and now threaten to displace native marsupial species.

Explanation:

Speciation is the process where a single species splits into two or more distinct, reproductively isolated species from a common ancestor.

• The first case shows adaptation (loss of flight) but no formation of a new, reproductively isolated species.
• The second case describes a single snail species splitting into geographically separated groups that can no longer breed to produce fertile offspring, which matches the definition of speciation.
• The third case is about invasive species outcompeting natives, not speciation from a common ancestor.

Answer:

B. A single species of snails colonize a newly formed marshland formed by a retreating glacier. Over several thousand years different groups of the snails are separated geographically and are no longer able to breed and produce fertile offspring.