Evolution of Rock Pocket Mice in New Mexico's Valley of Fire

Introduction

• Location: Valley of Fire, New Mexico
• Landscape: Transition from golden desert to patches of black volcanic rock
• Event: Volcanic eruption ~1,000 years ago creating a river of lava
• Concept: Evolutionary adaptation in response to environmental changes

Ecology of the Rock Pocket Mouse

• Habitat: Desert sands and dark lava flows
• Camouflage: Light-colored fur blends with sand, stands out on lava
• Predators: Visual predators including foxes, coyotes, rattlesnakes, owls, and hawks
• Challenge: Need for camouflage on dark lava flows to avoid predation

Adaptation and Evolution

• Fieldwork Observation: Biologist Michael Nachman finds dark-colored mice on lava
  • Dark fur camouflages mice on black rock
  • Dark mice have a white underbelly—no selection pressure for dark underside
• Evolutionary Driver: Predators weed out non-camouflaged mice

Genetic Mutation and Natural Selection

• Mutation Origin: Random mutations lead to dark coloration
• Lab Research: DNA extraction from light and dark mice
  • Gene of Interest: MC1R gene differs by four chemical letters in dark mice
  • Mutation Effect: Controls dark pigment in mouse's hair follicles

Population Dynamics

• Spread of Mutation: Rapid population change possible
  • 5% advantage can lead to widespread adoption of beneficial trait
  • Simulation: 1% advantage can change 95% of population in 1,000 years
  • 10% advantage results in change within 100 years

Natural Selection vs. Random Mutation

• Natural Selection: Non-random process drives evolution
  • Mutations are random
  • Natural selection sorts advantageous traits
  • Evolution repeats under similar conditions

Case Studies and Findings

• Multiple Lava Flows: Different genetic adaptations in black mice
  • Same visual outcome, different genetic paths
  • Proves evolution can repeat with similar results under like conditions
  • Evolution is ongoing, adapting to environmental changes

Conclusion

• Illustration of Natural Selection: Simple ecological model
• Non-random Evolutionary Process: Natural selection's role in shaping species
• Recurrent Evolutionary Outcomes: Similar adaptations across different scenarios
• Continuous Evolutionary Change: Driven by changing environments