Evolution in Action: The Rock Pocket Mouse

Introduction

• Location: New Mexico's Valley of Fire
• Landscape: Golden deserts, volcanic rock remnants
• Focus: Evolutionary adaptations of the rock pocket mouse

The Rock Pocket Mouse

• Camouflage:

  • Light-colored fur blends with sandy desert.
  • Dark-colored fur blends with volcanic rock.

• Predators:

  • Visual predators include foxes, coyotes, rattlesnakes, owls, and hawks.
  • Predators drive the selection of fur color.

The Study of Fur Color

• Researcher: Michael Nachman.

• Field Study:

  • Collection of mice from different terrains.
  • Dark mice dominate in volcanic areas.

• Findings:

  • All dark mice have a white underbelly to avoid detection from above.
  • Mice do not prefer light or dark rocks; selection is based on predator visibility.

Genetic Basis of Color Change

• Mutation:

  • Dark coloration due to a random mutation in the gene Mc1r.
  • Four chemical letter differences found between dark and light mice.

• Implications of Mutation:

  • Mutations can be neutral, beneficial, or detrimental depending on the environment.

Spread of Dark Mutation

• Timeframe:

  • Lava flow is about 1,000 years old, enough time for mutation to spread.

• Population Dynamics:

  • Black mice have a competitive advantage, increasing reproductive success.
  • A 5% advantage can lead to rapid population changes—95% dark mice in about 1,000 years if starting with 1%.

Natural Selection vs. Random Mutation

• Natural Selection:

  • Sorting mechanism for advantageous traits.
  • Non-random process that drives evolutionary change.

• Recurrence of Evolution:

  • Similar environmental conditions lead to similar adaptations.
  • Different genetic pathways can yield the same beneficial traits (e.g., black coloration).

Conclusion

• Key Takeaway:
  • Evolution is an ongoing process driven by natural selection.
  • Rock pocket mice are a clear example of how species adapt to their environments, illustrating Darwin's theory of evolution.