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Difficulty: HardApplying Passage Principles

An excerpt from a passage on evolutionary biology delineates four theoretical frameworks that taxonomists use to define a 'species':

1. Biological Species Concept: Classifies populations as distinct species if they are reproductively isolated and cannot produce fertile offspring under natural conditions.
2. Morphological Species Concept: Classifies populations as distinct species based exclusively on significant, consistent differences in measurable anatomical features.
3. Ecological Species Concept: Classifies populations as distinct species if they occupy completely non-overlapping environmental niches and utilize different resources.
4. Phylogenetic Species Concept: Classifies populations as distinct species if they form the smallest independent branches on a genetic evolutionary tree, demonstrating separate ancestral lineages.

Based on the principles established in the passage, match each of the following newly discovered hypothetical populations to the specific species concept that would most directly classify them as distinct species.

  • Two populations of deep-sea worms that look physically identical and share the same hydrothermal vent habitat, but genomic sequencing reveals they form two distinct, independently evolving clades with separate common ancestors.Phylogenetic Species Concept
  • Two populations of moths that are genetically indistinguishable and possess identical wing structures, yet one population exclusively feeds on and pollinates night-blooming jasmine while the other is strictly confined to moonflowers.Ecological Species Concept
  • Two populations of moss growing on the same rock face that readily cross-fertilize, but one population consistently develops serrated leaves and elongated capsules, whereas the other develops smooth leaves and round capsules.Morphological Species Concept
  • Two populations of crickets that are anatomically indistinguishable and occupy the exact same grassland habitat, but one population's mating call is pitched at a frequency completely inaudible to the other, preventing any cross-breeding.Biological Species Concept

Answer

The deep-sea worms match the Phylogenetic Species Concept; the moths match the Ecological Species Concept; the moss populations match the Morphological Species Concept; and the crickets match the Biological Species Concept.
Each hypothetical scenario contains distractors designed to eliminate three of the four concepts. The deep-sea worms must be Phylogenetic because they share anatomy and ecology. The moths must be Ecological because their only diverging trait is resource utilization. The moss must be Morphological because they share a habitat and reproduce together, leaving only anatomical differences. The crickets must be Biological because their only distinction is a behavioral barrier that prevents interbreeding.

Step-by-Step Solution

1
Analyze the deep-sea worms scenario.
The worms share physical traits and habitat, eliminating Morphological and Ecological concepts. The defining feature is distinct clades and separate ancestors.
Identifying the isolating variable points directly to the Phylogenetic Species Concept.
2
Analyze the moths scenario.
The moths are genetically and physically identical, but occupy non-overlapping niches (jasmine vs. moonflowers).
The division based purely on utilizing different environmental resources aligns precisely with the Ecological Species Concept.
3
Analyze the moss scenario.
The moss populations share a habitat and cross-fertilize, eliminating Ecological and Biological concepts. They are distinct strictly due to anatomical differences (serrated vs. smooth).
Relying exclusively on measurable anatomical features dictates the use of the Morphological Species Concept.
4
Analyze the crickets scenario.
The crickets are identical in anatomy and habitat, but an inaudible mating call prevents cross-breeding, ensuring reproductive isolation.
The prevention of cross-breeding under natural conditions is the exact definition of the Biological Species Concept.

Key Concept

Applying strict boundary conditions of theoretical frameworks to novel scenarios.
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Applying Passage Principles

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