Question

Difficulty: MediumAdaptive Radiation and Mechanisms of Speciation

In Lake Malawi, hundreds of distinct cichlid fish species have evolved from a single ancestral lineage within a relatively short geological period, each occupying specialized feeding roles such as algae-scraping, scale-eating, and mollusk-crushing. Which evolutionary process best accounts for this rapid diversification into diverse ecological niches?

  1. A
    Convergent evolution leading to analogous feeding structures among genetically unrelated species
  2. Adaptive radiation resulting in divergent evolution to occupy available ecological nichesAnswer
  3. C
    Inheritance of acquired traits where physical jaw changes developed during an individual's lifetime are passed to offspring
  4. D
    Cryptic mimicry where fish alter their morphology to blend into non-living aquatic surroundings

Answer

Adaptive radiation resulting in divergent evolution to occupy available ecological niches
Adaptive radiation occurs when a single ancestral species rapidly diversifies into a wide array of specialized forms to exploit different ecological niches. In Lake Malawi, the abundant unexploited habitats allowed cichlids to diverge morphologically and behaviorally from a shared common ancestor.

Step-by-Step Solution

1
Analyze the ecological scenario described in the stem
Identified that a single common ancestor colonized an environment with multiple unoccupied ecological niches, giving rise to numerous specialized descendant species.
Tracking evolutionary lineage and niche utilization establishes whether diversification is divergent or convergent.
2
Differentiate between evolutionary mechanisms
Divergent speciation into distinct specialized roles from one ancestral species fits the classic definition of adaptive radiation.
Adaptive radiation typically occurs when organisms colonize new aquatic or terrestrial habitats with abundant ecological opportunities.

Key Concept

Adaptive Radiation and Speciation
Estimated Time:1m 0s
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