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Difficulty: MediumModern Evolutionary Theory and Genetic Basis of Evolution

A sudden environmental change occurs in a habitat, favoring beetles with darker pigmentation. According to modern evolutionary theory (Neo-Darwinism), which of the following best explains the genetic basis for how this beetle population evolves over successive generations?

  1. A
    Individual beetles acquire darker pigmentation during their lifetime due to environmental stress and pass these somatic changes directly to their offspring.
  2. Pre-existing gene mutations in germ cells provide dark allele variations, increasing in frequency over generations as natural selection favors darker individuals.Answer
  3. C
    The environmental stress converts discontinuous phenotypic variations directly into continuous environmental modifications without altering allele frequencies.
  4. D
    Natural selection creates new analogous structural adaptations within the somatic cells of surviving adults to ensure immediate individual survival.

Answer

Pre-existing gene mutations in germ cells provide dark allele variations, increasing in frequency over generations as natural selection favors darker individuals.
Modern evolutionary theory (Neo-Darwinism) explains evolution as a change in allele frequencies within a population over time. Gene mutations in germ cells create heritable variations in the gene pool. When environmental conditions change, individuals carrying advantageous alleles experience greater reproductive success, causing those favorable alleles to become more common in the population over successive generations.

Step-by-Step Solution

1
Identify the core principle of Modern Evolutionary Theory (Neo-Darwinism).
Neo-Darwinism integrates Mendelian genetics with Darwinian natural selection, emphasizing that evolution is driven by changes in gene/allele frequencies within a population's gene pool.
Evolution occurs at the population level through genetic inheritance, not at the individual level through somatic modifications.
2
Evaluate the origin and transmission of evolutionary variation.
Random gene mutations occurring in germline cells generate new alleles, creating heritable genetic variation.
Only mutations in germ cells (gametes) are transmissible to offspring, serving as raw material for selection.
3
Determine the effect of natural selection on allele frequencies.
Individuals possessing favorable alleles (darker pigmentation) have higher differential reproductive success, increasing the dark allele frequency in subsequent generations.
Differential survival and reproduction lead to adaptation over generational time.

Key Concept

Modern Evolutionary Theory (Neo-Darwinism) and Population Genetics
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Topics

Modern Evolutionary Theory and Genetic Basis of Evolution

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