Question

wenheng zhang and colleagues have explored how convergent evolution--a phenomenon that occurs when the same trait evolves independently in two reproductively separate lineages--can result from a genetic mechanism shared by both lineages. meanwhile, patricia j. wittkopp and colleagues have investigated how convergence occurs through different genetic mechanisms, but the relative prevalence of convergence through shared and different genetic processes is still poorly understood. this motivated biologists delbert a. green ii and cassandra g. extavour to evaluate both types of convergence in a single study for their 2012 paper. which choice best states the function of the underlined portion in the text as a whole? a it clarifies a concept that the author implies was unclear in the studies mentioned in the text. b it provides examples of how a phenomenon was studied by scientists in the field before green and extavours study. c it introduces a method of scientific analysis that is discussed in greater detail later in the text. d it gives a basic description of a phenomenon that is central to the discussion that follows.

Explanation:

The underlined portion defines convergent evolution. This phenomenon is central to the subsequent discussion about different studies (Zhang et al., Wittkopp et al., Green and Extavour) related to it.

• Option A: The text doesn't imply the concept was unclear in previous studies. The issue was the relative prevalence of different genetic processes causing convergence.
• Option B: It's not providing examples of how the phenomenon was studied but rather defining the phenomenon itself.
• Option C: It's not introducing a method of scientific analysis.
• Option D: Correct as it gives a basic description (definition) of a phenomenon (convergent evolution) that is central to the following discussion (different studies on convergent evolution).

Answer:

D. It gives a basic description of a phenomenon that is central to the discussion that follows.